Pointing Device

Mouse computer
Touchpad dan pointing stick pada Laptop IBM
Sebuah perangkat penunjuk adalah antarmuka input (khusus perangkat antarmuka manusia) yang memungkinkan user untuk ruang masukan (misalnya, terus menerus dan multi-dimensi) data ke komputer. sistem CAD dan antarmuka pengguna grafis (GUI) memungkinkan user untuk mengontrol dan memberikan data ke komputer dengan menggunakan gerakan fisik – titik, klik, dan tarik – misalnya, dengan menggerakkan mouse genggam di seluruh permukaan dari desktop fisik dan mengaktifkan switch pada mouse. Mutasi perangkat penunjuk yang bergema di layar dengan gerakan penunjuk (atau kursor) dan perubahan visual lainnya.
Sementara perangkat penunjuk yang paling umum sejauh ini adalah mouse, lebih banyak lagi perangkat telah dikembangkan. Sebuah “tikus” adalah istilah teknis yang merujuk ke perangkat yang menghasilkan input mouse seperti. Namun, “mouse” istilah yang biasa digunakan sebagai metafora untuk perangkat yang memindahkan kursor.

Untuk perangkat menunjuk kebanyakan, hukum Paulus Fitts bisa digunakan untuk memprediksi kecepatan dengan mana pengguna dapat menunjuk pada posisi target.

Mouse
mouse adalah perangkat genggam kecil ditepis permukaan horizontal.

mouse pointer bergerak grafis dengan menjadi meluncur di permukaan halus. Mouse roller-bola konvensional menggunakan bola untuk membuat tindakan ini: bola yang bersentuhan dengan dua poros kecil yang diarahkan dengan sudut yang tepat untuk satu sama lain. Seperti bola bergerak memutar poros ini, dan rotasi diukur oleh sensor di dalam mouse. Informasi jarak dan arah dari sensor kemudian ditransmisikan ke komputer, dan komputer grafis bergerak pointer pada layar dengan mengikuti gerakan mouse. Lain mouse umum adalah mouse optik. Perangkat ini sangat mirip dengan mouse konvensional tetapi menggunakan cahaya tampak atau inframerah bukan bola-rol untuk mendeteksi perubahan posisi.

Mini-mouse

Sebuah Mini-mouse mouse telur berukuran kecil untuk digunakan dengan komputer laptop, biasanya cukup kecil untuk digunakan pada area bebas dari tubuh laptop sendiri, biasanya optik, termasuk kabel ditarik dan menggunakan port USB untuk menghemat baterai .
Trackball

trackball adalah perangkat penunjuk yang terdiri dari sebuah bola ditempatkan dalam soket yang mengandung sensor untuk mendeteksi rotasi bola sekitar dua sumbu, mirip dengan sebuah mouse terbalik: sebagai pengguna gulungan bola dengan ibu jari, jari, atau telapak mouse kursor pada layar juga akan bergerak. berita bola biasanya digunakan pada CAD workstation untuk kemudahan penggunaan, mana mungkin tidak ada ruang meja yang untuk menggunakan mouse. Ada yang mampu klip ke sisi keyboard dan memiliki tombol dengan fungsi yang sama sebagai tombol mouse.  Ada juga trackball wireless yang menawarkan berbagai posisi ergonomis yang lebih luas kepada pengguna.

Joystick

* Isotonik joystick yang menangani tongkat dimana pengguna dapat dengan bebas mengubah posisi tongkat itu, dengan kekuatan kurang lebih konstan.
o Joystick

o Analog stick

* Isometric joystick – dimana pengguna kontrol tongkat dengan memvariasikan jumlah angkatan mereka mendorong dengan, dan posisi tongkat tetap kurang lebih konstan.
Sebuah tongkat penunjuk (joystick) adalah inti tekanan kecil sensitif digunakan seperti joystick. Ini biasanya ditemukan pada laptop tertanam antara ‘B’ yang ‘G’, ‘H’ dan kunci. Beroperasi dengan merasakan gaya yang diterapkan oleh pengguna. Yang sesuai “mouse” tombol biasanya ditempatkan tepat di bawah spacebar. Hal ini juga ditemukan pada tikus dan beberapa keyboard desktop.
Touchpad

Sebuah touchpad atau trackpad adalah permukaan datar yang dapat mendeteksi menghubungi jari. Ini adalah perangkat penunjuk stasioner, umumnya digunakan pada komputer laptop. Setidaknya satu tombol fisik biasanya dilengkapi dengan touchpad, namun pengguna juga dapat menghasilkan klik mouse dengan menekan di kertas. Fitur lanjutan mencakup sensitivitas tekanan dan gerakan khusus seperti bergulir dengan menggerakkan jari seseorang sepanjang tepi.
Ini menggunakan grid dua lapisan elektroda untuk mengukur gerakan jari:. Satu lapisan memiliki strip elektroda vertikal yang menangani pergerakan vertikal, dan lapisan lain memiliki strip elektroda horisontal untuk menangani gerakan horisontal
Tablet Graphics
Sebuah tablet grafis dengan pena
Sebuah tablet grafis atau tablet digitalisasi adalah tablet khusus mirip touchpad, tetapi dikontrol dengan pena atau stylus yang dimiliki dan digunakan seperti biasa pena atau pensil. thumb biasanya mengontrol mengklik melalui tombol dua arah di bagian atas pena, atau dengan menekan di permukaan tablet itu.

 
Sebuah kursor (juga disebut keping) yang mirip dengan mouse, kecuali bahwa ia memiliki jendela dengan rambut salib untuk menentukan penempatan, dan dapat memiliki sebanyak 16 tombol. Sebuah pena (juga disebut stylus) terlihat seperti bolpoin sederhana namun menggunakan kepala elektronik, bukan tinta. Tablet ini mengandung elektronik yang memungkinkan untuk mendeteksi gerakan kursor atau pena dan menerjemahkan gerakan menjadi sinyal digital yang mengirimkan ke komputer “. [4] Hal ini berbeda dari mouse karena setiap titik pada tablet merupakan titik pada layar.
Touchscreen

touchscreen adalah perangkat embedded ke dalam layar monitor TV, atau sistem monitor LCD layar komputer laptop. Pengguna berinteraksi dengan perangkat dengan menekan fisik item yang ditampilkan pada layar, baik dengan jari-jari mereka atau beberapa alat bantu.

Beberapa teknologi bisa digunakan untuk mendeteksi sentuhan. touchscreens resistif dan kapasitif memiliki bahan konduktif tertanam dalam gelas dan mendeteksi posisi menyentuh dengan mengukur perubahan arus listrik. Inframerah pengendali proyek grid sinar inframerah disisipkan ke bingkai yang mengelilingi layar monitor itu sendiri, dan mendeteksi di mana objek penyadapan balok.
touchscreens modern dapat digunakan bersama dengan stylus menunjuk perangkat, sementara mereka yang didukung oleh infra merah tidak memerlukan sentuhan fisik, tapi hanya mengenali gerakan tangan dan jari dalam beberapa rentang jarak minimal dari layar nyata.
Touchscreens menjadi populer dengan pengenalan komputer palmtop seperti yang dijual oleh produsen perangkat keras Palm, Inc, beberapa kelas range tinggi komputer laptop, smartphone mobile seperti HTC atau iPhone Apple Inc, dan ketersediaan standar driver perangkat touchscreen ke Symbian, Palm OS, Mac OS X, Windows XP dan Windows Vista sistem operasi.

 

Perangkat lain

* Lightpen

adalah perangkat yang mirip dengan layar sentuh, tetapi menggunakan pena khusus yang sensitif cahaya, bukan jari, yang memungkinkan untuk input layar lebih akurat. Sebagai ujung pena cahaya membuat kontak dengan layar, ia mengirim sinyal kembali ke komputer yang berisi koordinat dari pixel pada titik tersebut. Hal ini dapat digunakan untuk menggambar pada layar komputer atau membuat pilihan menu, dan tidak membutuhkan layar sentuh khusus karena dapat bekerja dengan monitor CRT berbasis.

* Lampu pistol

* Palm mouse

diadakan di telapak tangan dan dioperasikan dengan hanya dua kancing; gerakan di layar sesuai dengan sentuhan bulu, dan meningkatkan tekanan kecepatan gerakan.

* Footmouse

kadang-kadang disebut mol – varian tikus bagi mereka yang tidak ingin atau tidak dapat menggunakan tangan atau kepala, melainkan menyediakan footclicks.

* Mirip dengan tikus adalah puck

yang, daripada melacak kecepatan perangkat, melacak posisi absolut titik pada perangkat (biasanya satu set bidik dicat pada tab plastik transparan mencuat keluar dari atas keping ). Pucks biasanya digunakan untuk pelacakan dalam CAD / pekerjaan / CAM CAE, dan sering aksesoris untuk tablet grafis yang lebih besar.

* Perangkat pelacakan mata

Sebuah mouse dikendalikan oleh bola mata pengguna / gerakan retina, memungkinkan kursor-manipulasi tanpa sentuh.

* Jari-mouse

Sebuah mouse sangat kecil dikendalikan oleh dua jari saja; pengguna bisa menahannya dalam posisi apapun

* Gyroscopic mouse

Sebuah indera giroskop gerakan mouse ketika bergerak melalui udara. Pengguna dapat mengoperasikan mouse gyroscopic ketika mereka tidak memiliki ruang untuk mouse biasa atau harus memberikan perintah sambil berdiri. Ini perangkat input tidak memerlukan pembersihan dan dapat memiliki banyak tombol tambahan, pada kenyataannya, beberapa laptop merangkap sebagai TV datang dengan tikus gyroscopic yang mirip, dan ganda sebagai, remote dengan layar LCD built in

* Steering wheel

dapat dianggap sebagai perangkat penunjuk 1D – lihat juga bagian roda kemudi artikel game controller

* Wii Remote (/ Wiimote) – fungsi pointer dengan kontrol motion sensing di Wii

* Laser pena – dapat digunakan dalam presentasi sebagai perangkat penunjuk

Tools ‹ Javadejavu’s Blog — WordPress

Tools ‹ Javadejavu’s Blog — WordPress.

Cyberlaw

Apa itu Cyberlaw?

Cyberlaw adalah hukum yang digunakan di dunia cyber (dunia maya), yang umumnya diasosiasikan dengan Internet. Cyberlaw dibutuhkan karena dasar atau fondasi dari hukum di banyak negara adalah “ruang dan waktu”. Sementara itu, Internet dan jaringan komputer mendobrak batas ruang dan waktu ini.

Contoh permasalahan yang berhubungan dengan hilangnya ruang dan waktu antara lain:

* Seorang penjahat komputer (cracker) yang berkebangsaan Indonesia, berada di Australia, mengobrak-abrik server di Amerika, yang ditempati (hosting) sebuah perusahaan Inggris. Hukum mana yang akan dipakai untuk mengadili kejahatan cracker tersebut? Contoh kasus yang mungkin berhubungan adalah adanya hacker Indonesia yang tertangkap di Singapura karena melakukan cracking terhadap sebuah server perusahaan di Singapura. Dia diadili dengan hukum Singapura karena kebetulan semuanya berada di Singapura.
* Nama domain (.com, .net, .org, .id, .sg, dan seterusnya) pada mulanya tidak memiliki nilai apa-apa. Akan tetapi pada perkembangan Internet, nama domain adalah identitas dari perusahaan. Bahkan karena dominannya perusahaan Internet yang menggunakan domain “.com” sehingga perusahaan-perusahaan tersebut sering disebut perusahaan “dotcom”. Pemilihan nama domain sering berbernturan dengan trademark, nama orang terkenal, dan seterusnya. Contoh kasus adalah pendaftaran domain JuliaRoberts.com oleh orang yagn bukan Julia Roberts. (Akhirnya pengadilan memutuskan Julia Roberts yang betulan yang menang.) Adanya perdagangan global, WTO, WIPO, dan lain lain membuat permasalahan menjadi semakin keruh. Trademark menjadi global.
* Pajak (tax) juga merupakan salah satu masalah yang cukup pelik. Dalam transaksi yang dilakukan oleh multi nasional, pajak mana yang akan digunakan? Seperti contoh di atas, server berada di Amerika, dimiliki oleh orang Belanda, dan pembeli dari Rusia. Bagaimana dengan pajaknya? Apakah perlu dipajak? Ada usulan dari pemerintah Amerika Serikat dimana pajak untuk produk yang dikirimkan (delivery) melalui saluran Internet tidak perlu dikenakan pajak. Produk-produk ini biasanya dikenal dengan istilah “digitalized products”, yaitu produk yang dapat di-digital-kan, seperti musik, film, software, dan buku. Barang yang secara fisik dikirimkan secara konvensional dan melalui pabean, diusulkan tetap dikenakan pajak.
* Bagaimana status hukum dari uang digital seperti cybercash? Siapa yang boleh menerbitkan uang digital ini?

Perkembangan teknologi komunikasi dan komputer sudah demikian pesatnya sehingga mengubah pola dan dasar bisnis. Untuk itu cyberlaw ini sebaiknya dibahas oleh orang-orang dari berbagai latar belakang (akademisi, pakar TekInfo, teknis, hukum, bisinis, dan pemerintah).

Perlukah Cyberlaw

Hukum konvensional digunakan untuk mengatur citizen. Semenatra itu cyberlaw digunakan untuk mengatur netizen. Perbedaan antara citizen dan netizen ini menyebabkan cyberlaw harus ditinjau dari sudut pandang yang berbeda.

Mengingat jumlah pengguna Internet di Indonesia yang masih kecil, apakah memang cyberlaw sudah dibutuhkan di Indonesia?
Digital Signature

Dalam perniagaan, tanda tangan digunakan untuk menyatakan sebuah transaksi. Kalau di Indonesia, tanda tangan ini biasanya disertai dengan meterai. Nah, bagaimana dengan transaksi yang dilakukan secara elektronik? Digital signature merupakan pengganti dari tanda tangan yang biasa.

Perlu dicatatat bahwa digital signature tidak sama dengan mengambil image dari tanda tangan kita yang biasa kemudian mengkonversikannya menjadi “scanned image”. Kalau yang ini namanya “digitalized signature”.

Digital signature berbasis kepada teknology kriptografi (cryptography). Keamanan dari digital signature sudah dapat dijamin. Bahkan keamanannya lebih tinggi dari tanda tangan biasa. Justru disini banyak orang yang tidak mau terima mekanisme elektronik karena menghilangkan peluang untuk kongkalikong.

http://www.cert.or.id/~budi/articles/cyberlaw.html

Apakah UU Cyberlaw memang di perlukan?

Salah satu pertanyaan yang sering muncul adalah apakah dunia cyber ini bisa diatur? Banyak orang yang berpendapat bahwa dunia cyber tidak bisa diatur. Di sana tidak ada aturan.
Pendapat ini tidak benar! Kalau kita perhatikan asal kata “cyber” bermula dari kata “cybernetics”. Norbert Wiener di tahun 1947 menggunakan istilah
ini untuk mendefinisikan sebuah bidang ilmu yang terkait dengan elektro, matematik, biologi, neurofisioligi, antropologi, dan psikologi. Wiener dan kawan-kawan kemudian mengadaptasi
kata dari bahasa Yunani (steersman) yang bermakna atau terkait dengan prediksi, aksi, kendali, umpan balik, dan respon.
Yang menarik juga, kata “governor” juga berasal dari kata Yunani yang sama. Aplikasi dari bidang cybernetics ini sering terkait dengan pengendalian robot (dari jarak jauh). Kalau kita perhatikan, pengendalian secara total merupakan salah satu aspek dari cybernetics. Jadi agak mengherankan kalau “cyberspace” justru tidak dapat dikendalikan, bertolak belakang dengan makna awalnya. Jika dunia cyber dapat diatur, bagaimana cara mengaturnya?
Pakar ilmu hukum Lawrence Lessig dalam bukunya, Code and Other Laws of Cyberspace, menunjukkan berbagai cara untuk mengatur dunia cyber. Salah satu pokok yang dia utarakan adalah pengaturan melalui arsitektur dan code
(program) dari sistem yang digunakan. Saya ambil sebuah contoh, yaitu masalah anonimity. Di Internet, katanya, orang dapat menyaru menjadi siapa saja. Karena itulah, ada penyataan yang mengatakan bahwa “on the internet nobody knows you’re a dog.” Masalah anonimity ini kemudian
menjadi masalah karena orang menjadi lepas tanggung jawab.
Namun, apakah memang di Internet semua harus menjadi anonimous? Tidak juga. Kita dapat menggunakan arsitektur
sistem yang mengharuskan seseorang untuk mengidentifikasikan dirinya sebelum memperoleh layanan.
Sebagai contoh, untuk mengakses web dari kampus ITB, kami menggunakan proxy yang ber-password. Hanya orang yang memiliki user id dan password yang terdaftar yang dapat mengakses web. Dalam arsitektur ini, maka identitas seorang pengguna harus jelas baru dia dapat memperoleh layanan.
Adanya identitas yang jelas ini lebih mudah dalam pengaturan sebab seorang pengguna akan dapat dikaitkan dengan
aktivitas yang dilakukannya (misalnya mengakses web pornografi). Di kampus lain mungkin akses ke web tidak dibatasi dan tidak membutuhkan mekanisme
otentikasi, sehingga orang dapat menjadi anonimous. Jadi, pemilihan arsitektur sistem menentukan mudah atau tidaknya dunia cyber diatur.
Banyak orang yang beranggapan bahwa lebih baik pemerintah tidak ikut campur dalam urusan aturan, dan biarkan
mekanisme pasar (baca: bisnis atau e-commerce) yang menentukan. Kalau kita perhatikan lebih teliti, bisnis lebih
menyukai adanya identitas yang jelas, bukan anonimity. Jadi, sebetulnya mekanisme pasar akan membuat dunia cyber lebih mudah diatur. Mungkin hal ini tidak terlalu intuitif.
Saat tulisan ini dimuat, kedua RUU tersebut sudah siap dan
hanya membutuhkan pembahasan di DPR. Selama belum ada UU cyberlaw tersebut, apakah orang dapat berbuat semenamena di dunia cyber? Tentu saja tidak. Ada sebuah pendapat bahwa tidak ada negara yang vakum hukum. Kita dapat menggunakan undang-undang lain untuk menangani kasus- kasus yang terjadi. Masalahnya UU yang ada saat ini tidak efektif dan efisien untuk menangani kasus yang terjadi.
Permasalahan yang terjadi di dunia cyber, misalnya yang berurusan dengan nama domain atau penipuan-penipuan,
membutuhkan penyelesaian yang cepat. Jadi, UU cyberlaw tersebut masih tetap dibutuhkan dan dibutuhkan sesegera
mungkin.
http://ilmukomputer.org/2007/02/26/hukum-dan-dunia-cyber/

Photography 101.5 – Aperture by Neil Creek

Photo: Rainer Ebert used under CC license

The following post is from Australian photographer Neil Creek who is part of the Fine Art Photoblog, and is developing his blog as a resource for the passionate photographer.

Welcome to the fifth lesson in Photography 101 – A Basic Course on the Camera. In this series, we cover all the basics of camera design and use. We talk about the ‘exposure triangle’: shutter speed, aperture and ISO. We talk about focus, depth of field and sharpness, as well as how lenses work, what focal lengths mean and how they put light on the sensor. We also look at the camera itself, how it works, what all the options mean and how they affect your photos.

This week’s lesson is Aperture.

Here’s What We’ve Covered Previously in this series:

Lesson 1: Light and the Pinhole Camera
Lesson 2: Lenses and Focus
Lesson 3: Lenses, Light and Magnification
Lesson 4: Exposure and Stops

In previous lessons we have talked about the basic theory of how a camera works, including some basic optics, and introduced the idea of exposure and how we control it with the exposure triangle. In this lesson we will be drawing upon what we have learned to understand the first point on the exposure triangle – aperture – and how it works to create your photo.

Aperture

Fig 1.5.1 The iris opens and closes to change the aperture.
Based on (source-http://www.camerarepairer.co.uk/Glossary.htm)

The word aperture simply means “an opening” (reference.com). In the case of photography, the aperture is created by an adjustable iris that can be opened or closed to control how much light enters the camera. This iris is made of a series of thin metal blades that move together to create a roughly circular opening of variable size. In most DSLR cameras, the iris is built into the lens itself. It is the opening in this iris that is actually the aperture.

When adjusting the size of the aperture, we describe “opening” the aperture up and “stopping” it down. That simply refers to making the hole wider or narrower. A photographer may say they are “shooting wide”, meaning they have opened the aperture a lot, or they may say they are “stopped way down”, meaning the aperture has been closed a lot.

f ratio revisited

In Lesson 3, we discussed the f ratio, and described that as the focal length of the lens divided by its diameter. This is the focal ratio. For a single lens, the f ratio is always the same. However, with our adjustable aperture, we can do a very neat trick. The aperture acts on the lens as if it is cutting away the part of the lens which is covered. So as we stop down the aperture, we effectively make the lens smaller, and thus change the f ratio of the lens. As such, the size of the aperture is described by the f ratio that it creates. A wide aperture may be f2.8, a narrow aperture may be f22.

As we discussed in lesson four, we measure the change in exposure with stops – a doubling or halving of the light, and fractions of stops. As such, the same measure applies to aperture. To double the light getting through a lens, we need to double the area of that lens which is uncovered. The area of a circle is determined by the formula πr2, so a doubling of the area increases the diameter by approximately 1.41. From this figure we get the sequence of f ratios:

The f ratio sequence in stops.
1 – 1.4 – 2 – 2.8 – 4 – 5.6 – 8 – 11 – 16 – 22 – 32

Depth of Field

Fig 1.5.2 A narrower aperture has a much greater depth of field.

If we look again at the exposure triangle diagram in lesson 4, you’ll see that the aperture influences the depth of field. The depth of field is the region of the photo which is in focus when the image is captured. It is a range of distance from the camera where objects look to be in focus. Aperture influences the depth of field by widening or narrowing this range, thus bringing more or less of the photo into focus, based on its distance from the camera.

Recalling what we learned back in lesson 1, the larger the hole that the light passes through a pinhole camera, the blurrier the image will be. When a lens is added to the camera, the image can be brought into focus, no matter the size of the hole, however, objects just either side of the focus point will be affected. If the hole, or aperture, is large, only objects very close to the focus point will be in focus. If the aperture is small, then the depth of the focus field is much wider, and more remote objects will be in focus.

Depth of Field can be pretty complex when you look deeply into it (such as: hyperfocal distance, airy discs and diffraction), but for an introductory course, the most important thing to remember is that a wide aperture (low value) means a shallow depth of field with less in focus and a narrow aperture (large value) means a broad depth of field with more in focus. We may return to discuss the more complicated issues in a future course.

Examples

Creative use of DOF isolates subject from background. Photo: annia316 used under CC license

The highlights on the strings clearly shows the changing DOF. Photo: Paul J. S. used under CC license

A narrow aperture gives a very wide depth of field. Photo: wili_hybrid used under CC license

These images show focus from the closest objects to the horizon. Photo: Neil creek all rights reserved.

Read more: http://www.digital-photography-school.com/aperture-101#ixzz11T9qvvdc

Photography 101 – Light and the Pinhole Camera by Neil Creek

Photo: Rainer Ebert used under CC license

The following post is from Australian photographer Neil Creek who is part of the recently launched Fine Art Photoblog, and is participating in Project 365 – a photo a day for a year – on his blog.

Welcome to the first lesson in Photography 101 – A Basic Course on the Camera. In this series, we cover all the basics of camera design and use. We talk about the ‘exposure triangle’: shutter speed, aperture and ISO. We talk about focus, depth of field and sharpness, as well as how lenses work, what focal lengths mean and how they put light on the sensor. We also look at the camera itself, how it works, what all the options mean and how they affect your photos.

This week’s lesson is Light and the Pinhole Camera

About Light

Light is everywhere, even where you can’t see it. Without delving too deeply into the mysterious physics of light, there are some basics that are helpful to know as a photographer:

• We only see light when it reflects from something, or we look directly at the source
• Light can be bounced (reflected) or bent (refracted) and always does so in predictable ways
• Reflected light scatters depending on the “smoothness” of the surface
• White light is made up of all of the visible colours
• Different coloured light has different energy levels or “wavelengths”
• Shadows occur when something comes between a light source and another surface
• Light varies hugely in brightness, and our eyes very cleverly adapt to see clearly in a wide variety of brightnesses
• Cameras are far less capable of “seeing” clearly in as wide a variety of lighting conditions

Fig 1.1.1 Light hitting a textured surface scatters in all directions, like water splashing from a thrown water balloon. Click for clearer version.

These observations are pretty basic, and most of them are either obvious or should have been taught in the science classroom. As straightforward as they are, these basic points are at the heart of photography, and understanding them is very important. Throughout this course, and through your adventures with the camera, you will be working with some or all of these essential principles of light. If you are unclear about any of the above points, it would be helpful to do a little bit of independent research. You’ll find some good links for further reading at the end of today’s lesson, and I encourage you to explore further by searching the ‘net.

The central point of photography is turning light into an image. An image is actually just an illusion. Anything that is a representation in light of a real thing is an image. So how do we turn light, which scatters randomly around the universe into an image that we can recognise?

The Camera Obscura

Fig 1.1.2 – Imagine a typical outdoor scene with the sun shining brightly on a tree. The light from the sun travels in parallel rays, shown here in black. When they hit the tree, the light is scattered in all directions, shown in grey. This is known as “diffuse” light. Because of diffuse light you can see the pretty tree, as some of this scattered light hits your eyes.

Fig 1.1.3 – Now lets imagine we pitch a tent with perfect light blocking material and a tiny hole in one wall. To keep it simple, a single ray hitting the tree will diffuse in all directions, but only a very tiny sliver of that light will go through the small hole. If you were sitting in this tent in the middle of the floor and you closed one eye and looked through the hole from there, you would only see a very tiny part of the tree at once. If you move to the right a bit, you will see the left of the tree. If you move up, you will see further down the tree. Your view of the tree is opposite to the direction of your movement.

Fig 1.1.4 – Of course there is more than one ray of light hitting the tree. These rays reflect diffusely in all directions. This is why you can see more of the tree by moving around inside the tent. If we were to set up a screen in the tent opposite the hole, which is made of nice bright white material, we would actually be able to see an image of the tree, projected onto it! For the reason that we saw parts of the tree in the opposite direction when we moved, the projected image of the tree appears upside down.

Fig 1.1.5 A camera obscura made by blocking a window. Photo by brighterorange, used under creative commons.

The room we just made in our imagination is called a “camera obscura” and you can make one just as I have described. Instead of a tent, you could find a room in your house with one window, and cover the whole window with thick card or foil. Then make a tiny hole (1-5mm) in the cover and look at the opposite wall. You should see a very dim, upside down image of the world outside.

The image will be dim because only a small amount of light can pass through the hole. If you make the hole bigger, the image will be brighter, but less sharp. Why is this? A small hole is very good at restricting the direction from which rays of light can enter the room. If the hole is bigger, then more light can get in, but that extra light comes from a bigger range of angles, and it overlaps nearby parts of the projected image.

Fig 1.1.6 – A small hole through which the light passes, restricts the possible angles of light reflecting from a certain part of the tree. The overlap of light rays on the projection is very small and the result is a sharp image. The trade-off is that the image is dim.

Fig 1.1.7 – A large hole allows a greater variety of angles of reflected light from a particular part of the tree to pass through onto the projection. This means that much light from neighbouring parts of the tree overlap each other. This results in lower contrast and a blurry image. The benefit however, is that more light can get through and the projected image is brighter.

How is it relevant?
The trade-off between sharpness and brightness should be a familiar one to many photographers. The “hole” of the camera obscura is the aperture of a modern camera. When you open up the aperture you let more light into the camera, but the depth of field narrows, and more of the image drops out of focus. We’ll talk more about this in a future lesson.

The Pinhole Camera

The camera obscura is a very old idea, first built around 1000AD in what is now Iraq. A variation on the concept is the pinhole camera. This shrinks the room of the camera obscura into a handheld box, and is the simplest possible camera. Pinhole cameras can easily be made of almost anything. All it needs is a light-proof box, something to project the image onto, and a tiny hole. There are countless projects online to make your own pinhole camera, or make a pinhole “lens” for your DSLR. Due to the tiny hole used in these cameras, one advantage is that they have is an enormous depth of field.

Read more: http://www.digital-photography-school.com/photography-101-light-and-the-pinhole-camera#ixzz11T7zhqCZ

Photography 101 – Lenses and Focus by Neil Creek

The following post is from Australian photographer Neil Creek who is part of the recently launched Fine Art Photoblog, and is participating in Project 365 – a photo a day for a year – on his blog.

Welcome to the second lesson in Photography 101 – A Basic Course on the Camera. In this series, we cover all the basics of camera design and use. We talk about the ‘exposure triangle’: shutter speed, aperture and ISO. We talk about focus, depth of field and sharpness, as well as how lenses work, what focal lengths mean and how they put light on the sensor. We also look at the camera itself, how it works, what all the options mean and how they affect your photos.

This week’s lesson is Lenses and Focus

Bending Light

Last week we discussed how we can use a tiny hole to direct light so that it forms an image. All that a pinhole camera does is excludes all the light that doesn’t make an image. As we learned, however, the problem with that technique, is that it results in very dim images. As photographers we want bright images, and although that may seem obvious, we’ll discuss why in detail in a later lesson. Fortunately, there is a better way to do it.

Fig 1.2.1 A light shone into a glass
tank of water bends. Source.
Fig 1.2.2 As light passes into a more
refractive material, it slows and bends.

As we touched on briefly in Lesson 1, light is a form of energy that can be bent. Bending light is called refraction. What happens when light is refracted is that it actually slows down. It’s a common misconception that light always travels at the same speed. In fact, the speed of the light depends on the type of material that it is travelling through. The really useful thing about refraction is that it can bend the path of light.

I don’t want to get into the mysterious “dual nature of light”, but remember that light can be seen as a series of waves. Line after line of these waves make up light, similar to waves hitting a beach.

Imagine we have a fishtank of water and a torch. For the sake of simplicity lets also imagine that we can see the beam clearly in the air and water. When you shine the torch at the surface of the water at an angle, from the side of the tank, you can see that the beam has been bent, see Fig 1.2.1. The many wavefronts of the light are aligned perpendicular with its direction of travel. When the wavefronts encounter the water, one part of the front hits it before the rest. The part that has entered the water and slows down, while the rest of the wave is still travelling at the same speed. The effect of this is to bend the beam. See Fig 1.2.2.

Okay that’s enough physics for now. Lets talk optics.

Lenses

This bending of light can be very useful! Lets say we wanted to concentrate all the light from a wide beam onto a narrow point. If we can direct each beam of light by bending it slightly – a little right for the light in the left side of the beam, a little left for the light in the right side of the beam – then we should be able to focus the light. This is exactly what a lens does.

There are two main factors that determine how much a lens bends the light. The refractive index of the material, which is how much it slows down the beam, and the angle of incidence. The angle of incidence (or incident angle) is how far from perpendicular the light beam is when it passes through the surface. The greater the angle, the more the bending. This is why wide-angle lenses, that need to bend the light a long way, have such a bulging appearence.

Fig 1.2.3 How much the light beam is bent depends on the angle at which it hits the lens (all other things being equal). Light passing through the very centre of the lens is unaffected, while those at the edge are bent the most. This is why lenses are curved.

Fig 1.2.4 Different shaped lenses focus the light at different distances. This is the focal length of that lens.

A simple experiment

Click for larger version

Fig 1.2.5 An everyday magnifying glass can create an image. In a darkened room, set up a candle, a magnifying glass and a sheet of paper as a screen. With the magnifying glass squared up with the cangle and the screen, slide the glass and screen backwards and forwards until you bring an image of the candle into focus. Just as with the pinhole camera, the image projected by the lens us upside down. Notice that the shadow of the glass is dark except for the candle, even though the magnifying glass is see-through. This is because all of the light that passed through the glass has been focused into the image.

Fig 1.2.6 Click for larger version

Fig 1.2.7 Click for larger version

Not all lenses are equal
It’s not always the case that focal length equals lens length, as the complex optics in modern lenses can give a “virtual” focal length while keeping the actual lens size small. As a rule of thumb, the focal length isusually pretty close to the actual length of the light path through the lens.

Focusing

So far, we’ve been imagining a perfect beam of light hitting a refractive surface. In this beam all the light is parallel. Parallel light passed through a lens will always converge on the same point. The distance from the surface of the lens to the focus point is called the focal length and is measured in milimeters. Most lenses are described by their focal length. Zoom lenses have a range of focal lengths, a feat which is accomplished by using a complex series of lenses which can be moved relative to each other. The mm number translates into a real distance, from the front of your lens to the chip of your camera. In that way you can tell that a 400mm telephoto lens will be much longer than a 24mm wide-angle, without even looking at the lens.

If an object is close to a lens, even several hundred meters away, its reflected light entering the lens isn’t perfectly parallel. The closer the object to the lens, the less parallel, and the more the lens must be moved in order to keep focused. This change is much more noticable when objects are very close to the camera, and is one of the reasons why the depth of field in macro photos is so small – a point we will return to in a future lesson.

Fig 1.2.6 The closer an object is to a lens, the more its focus point moves, and so the more the lens must be moved to compensate.

In order to keep the image of a close object sharp, the lens must be moved relative to the screen (or camera sensor). This process is called focusing. When you are focused on an object at a certain distance, then objects which are closer or more distant than that will not be in focus. The situation can be helped somewhat, by reducing the size of the lens, just like we did with the pinhole camera, to restrict the variety of angles of light entering the lens. But we again are faced with the loss of brightness as a result.

We’ve hinted at the main reasons to use a lens: to make an image brighter and to make it bigger (or smaller!). Next week we’ll take what we have learned about lenses and see how we can use that to understand the concepts of focal length and f-ratios, and how they translate into maginification and image brightness.

Read more: http://www.digital-photography-school.com/photography-101-lenses-and-focus#ixzz11T7HB6aH

Photography 101 – Lenses, Light and Magnification by Neil Creek

Photo: Rainer Ebert used under CC license

The following post is from Australian photographer Neil Creek who is part of the recently launched Fine Art Photoblog, and is participating in Project 365 – a photo a day for a year – on his blog.

Welcome to the third lesson in Photography 101 – A Basic Course on the Camera. In this series, we cover all the basics of camera design and use.

We talk about the ‘exposure triangle’: shutter speed, aperture and ISO. We talk about focus, depth of field and sharpness, as well as how lenses work, what focal lengths mean and how they put light on the sensor.

We also look at the camera itself, how it works, what all the options mean and how they affect your photos.

This week’s lesson is Lenses, Light and Magnification

Last week we looked at the basics of the lens. We saw how lenses bend light by slowing it down, how the angle the light enters the lens affects how much it is bent, and how we can use this property to bring light that enters a lens into focus and create a bright, clear image.

Reading Optics Diagrams
Throughout this series, I will be using optics diagrams to illustrate various concepts. To help you get up to speed, I’ve written a short introduction on how to read these diagrams. I recommend you pausing the lesson for a moment to learn how to read and understand these diagrams.

The power of lenses

The advantage that lenses gives us over pinhole cameras is twofold: brightness and magnification.

Brightness and f-ratios

We saw in lesson two, with our experiment with the candle and the magnifying glass (Fig 1.2.3), that all the light that entered the lens from the candle was focused into the image. If we substituted a larger lens with the same focal length, then more light would be focused, and the resulting image would appear brighter, but no bigger.

It seems logical that if you double the diameter of a lens, you’ll double the size of the image it makes, but as you can see in Fig 1.3.1 below, that’s not true.

Fig 1.3.1 Doubling the diameter of the lens halves the f-ratio (see below) and collects more light but does not change the size of the image, which is a function of focal length (also see below). Doubling the diameter actually more than doubles the brightness of the image, as the light collecting sufrace of the lens increases rapidly as the radius increases (per the formula Πr² – pi times the radius squared).

Fig 1.3.2 The f-ratio indicated on a 50mm f1.8 lens.Fig 1.3.3 The f-ratio indicated on an 80-400mm f4.5-5.6 zoom lens.

F-ratio

In photography there’s a handy number used to describe the relationship between lens diameter and focal length: the “f-ratio”. Simply put the f-ratio is the focal length divided by the diameter. In Fig 1.3.1 above we have a lens with a focal length of 50mm and a diameter of 10mm. 50/10=5 which gives us an f-ratio of 1/5 or f5. If the lens was still 50mm focal length with a 20mm diameter, it would be f2.5.

The f-ratio for an SLR lens should always be written on the lens somwhere. Most compact cameras also describe the f-ratio somewhere on the body. The “shorter” the f-ratio, that is the closer it is to 1, the brighter the image the lens will produce. The term “speed” is also used to describe a lens. The word speed in this case refers to how fast the lens will allow the camera to capture an image, given the amount of light available. If the lens produces a bright image, then the shutter can be open for a shorter time to capture enough light to make an image. Thus a short f-ratio lens like f1.8 is considered a very “fast” lens, while a longer lens such as an f8 or f11 is a “slow” lens.

Recalling lesson 1, we learned that a large hole for the light to pass through makes for a brighter but less sharp image. Now that we know about f-ratios, we can connect these two facts together and understand why faster lenses have a narrower “depth of field” – the area which is in focus. We’ll talk more about this in the next lesson, but it’s helpful to connect the dots and see how all these various principles fit together.

Modern cameras allow a photographer to have some level of control over a lens’ speed by adjusting the aperture, we’ll also cover that in more detail in the next lesson.

Magnification and Field of View

Anyone who has played with a magnifying glass knows that, as the name suggests, lenses magnify. The amount of magnification depends on the focal length. The “longer” the lens, the more it magnifies the image. Short focal lengths have the opposite effect, reducing the size of the image.

Fig 1.3.4 All other things being equal, as the focal length of the lens increases, the relative size of the image also increases.

We saw above that f-ratio affects the image brightness. The two factors in the ratio are lens diameter and focal length. So far we have only talked about changing the lens diameter, but with greater magnification you increase the focal length, so you also increase the f-ratio. This means that the more you magnify the image, the dimmer it becomes. Most telephoto (long focal length) lenses have large f-ratios, and are therefore slow lenses. The exception of course are the hugely expensive and very heavy, giant lenses used by sports photographers. These use long focal lengths, and big diameter lenses. These telephotos are not for the casual photogrpaher!

Fig 1.3.5 A macro zoom lens showing magnification factors on the barrel.
Photo: Martini Captures used under CC license

We’ve talked about how lenses make the image bigger, and that’s certainly how it appears when you look through the viewfinder, or at the print from a telephoto lens. In reality, because most objects are distant, and the sensor is small, the vast majority of lenses produce an image which is smaller than the object itself. There are some specialist lenses, however, which do make an image larger than the subject. For this to be possible, the focal length needs to be long and the subject close. These are, of course, macro lenses.

Macro lenses will often be described by their “magnification factor”. A lens with a 1:1 magnification factor produces a projected image on the sensor which is the same as the subject. So the image of a 20mm diameter coin will span 20mm of the physical sensor, resulting in an image which will nearly fill the entire frame of a typical DSLR. A 1:1 magnification factor is usually considered the minimum for a lens to be described as a “macro” lens. Specialist macro lenses are often 1:3 or even 1:10 magnification factors, meaning that 1mm across the subject becomes 3mm or 10mm when projected onto the sensor, thus 3 or 10 times magnification.

Field of View

The final variable in this initially confusing balancing act of optics is the field of view. This refers to how much of the world the camera can see. A lens’ field of view depends on the focal length of the lens and the size of whatever the image is projected onto. In the case of digital cameras this is the sensor chip.

Fig 1.3.6 As the focal length increases, the field of view narrows and the image enlarges.

Fig 1.3.7 An example photo taken with an 8mm fisheye on a 1.6x cropped sensor.Fig 1.3.8 The comparative differences in frame size from compact camers through film and DSLR to medium format.

Fig 1.3.6 makes it obvious that at the wide-angle end, a slight difference in focal length translates to a large difference in field of view. The difference in field of view between a 10mm and 20mm lens is far greater than the difference between 210mm and 220mm. Some lenses can have exceptionally short focal lengths and wide fields of view, such as 12 or 8mm. These are fisheye lenses, so-called because the front of the lens bulges so much it looks like a fish’s eye. These lenses can have a 180 degree field of view, or even greater.

The size of the sensor also contributes to the field of view of a particular lens. In Fig 1.3.6 a particular sensor is shown at different focal lengths. Obviously if the sensor is smaller, it can see less of the image presented by the lens, thus the field of view is reduced and magnification is increased. This is the case for “cropped sensor” DSLRs, and compact cameras.

The “standard” frame size is 35mm, the size of a single picture on a roll of film. Cameras with this sized sensor are known as a “full frame” cameras. Large format film cameras exist with much larger film sizes, such as 150mm x 100mm. Less expensive, or earlier model DSLRs use sensors smaller than a 35mm film frame, and are referred to as cropped sensors. A typical cropped sensor may be described as a 1.6x, meaning that the apparent focal length of a particular lens is 1.6 times longer. Compact cameras use the smallest frame sizes of all, and as such require very short focal length lenses to get wide angle views.

Read more: http://www.digital-photography-school.com/photography-101-lenses-light-and-magnification#ixzz11T6jSDhX

Photography 101.4 – Exposure and Stops by Neil Creek

Photo: Rainer Ebert used under CC license

The following post is from Australian photographer Neil Creek who is part of the Fine Art Photoblog, and is developing his blog as a resource for the passionate photographer.

Welcome to the fourth lesson in Photography 101 – A Basic Course on the Camera. In this series, we cover all the basics of camera design and use. We talk about the ‘exposure triangle’: shutter speed, aperture and ISO. We talk about focus, depth of field and sharpness, as well as how lenses work, what focal lengths mean and how they put light on the sensor. We also look at the camera itself, how it works, what all the options mean and how they affect your photos.

This week’s lesson is Exposure and Stops

So far we have covered the basics of turning light into an image, starting with the concept of the pinhole camera, then introducing lenses and how they focus light, and last time about how the qualities of the lens affect the size and brightness of the projected image. So far this has all been pretty theoretical, but it’s important groundwork to helping you internalise how the camera works. When you know these basics, you can get to the solutions of photographic problems that much faster.

Some HousekeepingLesson naming
I’ve updated the naming scheme for this series to include the lesson number as a “point” value after 101. This will help you keep track of where you are up to in the series.

What happened to aperture?
Last time I said that this lesson would cover aperture and stops. I think introducing exposure and stops as a concept is important enough to dedicate a whole lesson to. Aperture will be now be discussed in Lesson 5.

This lesson we’re finally going to start getting a bit more practical. You will learn about the brightness of light, and how it is controlled. Of all the fundamentals of photography, this is probably the most important to understand, and can be the most intimidating because of the terminology used. But fear not! The mysteries of exposure and stops are about to be revealed!

What is “exposure”.

In the simplest terms, exposure is: “is the total amount of light allowed to fall on the photographic medium during the process of taking a photograph” (Wikipedia).

Whether it is a digital sensor chip or grains of chemically dosed silver on a film, it is the same thing. The greater the amount of light that falls onto a particular region of the photographic medium, the brighter that part of the recorded image will be when reproduced, whether on screen, print or slide.

The variation of brightness in the real world is absolutely huge, much more than you might think from your subjective experience of it. A subject lit by the midday sun on a beach looks over four thousand times brighter to your camera than the same subject lit by the quarter moon! (fredparker.com)

Brightness is measured in “Exposure Value” or EV.

You might recognize this acronym from your camera’s settings or manual. An EV of 0 is defined an image exposed for 1 second at f1. Steps of one up or down from zero are a change in the light by a factor of two. So an EV of 1 is twice as bright, EV 3 is eight times as bright, and EV -2 is one quarter as bright.

Fig 1.4.1: From a base exposure, the exposure is increased and decreased in one stop steps to +/- 4 stops.

The “Stop”

A step up (doubling) or down (halving) by one EV is called a “stop”.

If you only come away from this lesson having learned one thing, it is this. Photographers talk about light and exposure settings in terms of stops. In photography a stop can refer to different settings in any of the three points of the exposure triangle (more below). One of the most important and useful things you can learn as a photographer is to get an intuitive feel for light levels.

I’m not suggesting that you should be able to walk onto a location and immediately be able to assess the EV of the light and determine the correct exposure settings (although some very experienced photographers can do just that!) – that’s what your exposure meter is for. However, if you can learn to look at a photo you have taken on the back of your camera, and see that the exposure needs to be increased by say 2/3 of a stop, then you will become a much more efficient and successful photographer.

Controlling Exposure

To accommodate the huge variety of brightness levels we see in the real world, we need to be able to control how much light gets to the camera’s sensor. We do this by adjusting one or more of the three points of the “exposure triangle”. These three points are ISO, Shutter and Aperture.

The aperture is an adjustable iris or opening that can be made wider to let in more light, or narrower to let in less. The shutter is the “gate” that allows light onto the sensor, and it can be left open for different lengths of time, to let the sensor collect more or less light. Finally, the ISO once referred to the sensitive to light of the film in the camera. In digital cameras it refers to the “gain”, or amplification of the information collected by the sensor. In film days, changing ISO meant changing films. Today the ISO can be easily adjusted with a dial.

Fig 1.4.2: The exposure triangle.

Each of these points will be the subject of future lessons in Photography 101. For now, you need to know that they are there, and that they all work together to control the exposure. At the centre of the exposure triangle is your camera’s light meter. It is by reading this that you determine how to set each of the three points. We’ll cover that in a future lesson as well, probably in Photography 102 – A Basic Course in Taking Photos.

Read more: http://www.digital-photography-school.com/photography-1014-exposure-and-stops#ixzz11T609dBI

Introduction to Aperture in Digital Photography by Darren Rowse

Over the last couple of weeks I’ve been writing a series of posts on elements that digital photographers need to learn about in order to get out of Auto mode and learn how to manually set the exposure of their shots. I’ve largely focussed upon three elements of the ‘exposure triangle‘ – ISO, Shutter Speed and Aperture. I’ve previously written about the first two and today would like to turn our attention to Aperture.

Before I start with the explanations let me say this. If you can master aperture you put into your grasp real creative control over your camera. In my opinion – aperture is where a lot of the magic happens in photography and as we’ll see below, changes in it can mean the difference between one dimensional and multi dimensional shots.

What is Aperture?

Put most simply – Aperture is ‘the size of the opening in the lens when a picture is taken.’

When you hit the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene you’re wanting to capture. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light.

Aperture is measured in ‘f-stops’. You’ll often see them referred to here at Digital Photography School as f/number – for example f/2.8, f/4, f/5.6,f/8,f/22 etc. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also – this means if you increase one and decrease the other you let the same amount of light in – very handy to keep in mind).

One thing that causes a lot of new photographers confusion is that large apertures (where lots of light gets through) are given f/stop smaller numbers and smaller apertures (where less light gets through) have larger f-stop numbers. So f/2.8 is in fact a much larger aperture than f/22. It seems the wrong way around when you first hear it but you’ll get the hang of it.

Photo by Adam Clutterbuck

Depth of Field and Aperture

There are a number of results of changing the aperture of your shots that you’ll want to keep in mind as you consider your setting but the most noticeable one will be the depth of field that your shot will have.

Depth of Field (DOF) is that amount of your shot that will be in focus. Large depth of field means that most of your image will be in focus whether it’s close to your camera or far away (like the picture to the left where both the foreground and background are largely in focus – taken with an aperture of f/22).

Small (or shallow) depth of field means that only part of the image will be in focus and the rest will be fuzzy (like in the flower at the top of this post (click to enlarge). You’ll see in it that the tip of the yellow stems are in focus but even though they are only 1cm or so behind them that the petals are out of focus. This is a very shallow depth of field and was taken with an aperture of f/4.5).

Aperture has a big impact upon depth of field. Large aperture (remember it’s a smaller number) will decrease depth of field while small aperture (larger numbers) will give you larger depth of field.

It can be a little confusing at first but the way I remember it is that small numbers mean small DOF and large numbers mean large DOF.

Let me illustrate this with two pictures I took earlier this week in my garden of two flowers.

The first picture below (click them to enlarge) on the left was taken with an aperture of f/22 and the second one was taken with an aperture of f/2.8. The difference is quite obvious. The f/22 picture has both the flower and the bud in focus and you’re able to make out the shape of the fence and leaves in the background.

The f/2.8 shot (2nd one) has the left flower in focus (or parts of it) but the depth of field is very shallow and the background is thrown out of focus and the bud to the right of the flower is also less in focus due to it being slightly further away from the camera when the shot was taken.

The best way to get your head around aperture is to get your camera out and do some experimenting. Go outside and find a spot where you’ve got items close to you as well as far away and take a series of shots with different aperture settings from the smallest setting to the largest. You’ll quickly see the impact that it can have and the usefulness of being able to control aperture.

Some styles of photography require large depths of field (and small Apertures)

For example in most landscape photography you’ll see small aperture settings (large numbers) selected by photographers. This ensures that from the foreground to the horizon is relatively in focus.

On the other hand in portrait photography it can be very handy to have your subject perfectly in focus but to have a nice blurry background in order to ensure that your subject is the main focal point and that other elements in the shot are not distracting. In this case you’d choose a large aperture (small number) to ensure a shallow depth of field.

Macro photographers tend to be big users of large apertures to ensure that the element of their subject that they are focusing in on totally captures the attention of the viewer of their images while the rest of the image is completely thrown out of focus.

I hope that you found this introduction to Aperture in Digital Photography helpful.

Read more: http://www.digital-photography-school.com/aperture#ixzz11T29F9Oh

Where to Focus in Landscape Photography by Darren Rowse

Where should I focus when taking a Landscape Shot?

When shooting a normal landscape image it is normal to attempt to keep as much of the image in focus as possible.

This means selecting a small Aperture (remember the larger the number the smaller the actual Aperture) to ensure that you end up with a large depth of field. This will ensure that parts of the image that are both close and far away from you have a good chance of being somewhat in focus.

But at what point in the shot should you actually focus the image?

I suspect that many digital camera owners would set the focal point as the middle of the shot – or even at the horizon – however it might not actually be the ideal place to focus your camera.

I chatted this week with a landscape photographer who shared this tip:

‘Focus in the lower half of the image – at around the ‘thirdway’ point.’

Photo by algo

Ok – I’m not sure if ‘thirdway‘ is an actual word – but what he was suggesting is that the point that will help you get the maximum amount of your shot in focus is at a point around a third of the way up an image (as highlighted above).

This is a fairly general rule and you’d want to ignore if if your landscape shot had a particular point of interest in it that wasn’t on the third line. However if your landscape shot doesn’t have one specific point of interest it is probably a rule worth using.

My photographer friend went on to give a rather complicated reasoning for focusing upon this point a third of the way into an image that I don’t wish to repeat here for fear of losing many – however, in general if you focus too far into your image you’ll end up with objects in the distance nice and sharp but anything close to you noticeably out of focus. If you focus at the lower third you increase the depth of field in the foreground and as depth of field extends further behind a focal point than in front of it the distant objects will be reasonably sharp too.

Disclaimer – I should say that in researching this technique I found a lot of debate on the topic and a lot of technical language – in actual fact this ‘rule’ depends on many factors including the focal length of your lens, the format you’re shooting in (vertical or horizontal), the aperture you’re using and how far the scene extends away from you.

However I’ve found it to be a useful ‘rule’ to know and to start with when shooting landscapes. Whether you focus exactly on the third way point probably doesn’t matter that much – however the key is not to focus on the horizon but closer to you as the photographer.

Perhaps it’s one of those ‘one percent’ rules that won’t make a lot of difference for most of us – but when you’re taking high level landscape shots it’s often the little things that count!

Read more: http://www.digital-photography-school.com/where-to-focus-in-landscape-photography#ixzz11SyR1ufT