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Topic : Photographic

Article 16 bullet 13 January 2007

Shooting Birds RAW Mode

by Guy Upfold

Even though RAW Mode is very well known, it seems it is still very misunderstood and underutilized.

What is RAW?

There is no one RAW format: manufacturers use their own proprietary formats, which are generically known as RAW format. This can be seen by the different file extensions used like .CRW and .CR2 for Canon and .NEF for Nikon files etc. A raw file is unaltered data from the camera and camera sensor. It is sometimes compressed but without loss of data.

To get a better understanding of what a raw file is, it is useful to understand how it is recorded.

Setting up Raw mode

This is a Canon EOS 30D showing RAW Mode set up in the menu

A digital camera has a solid state device called an image sensor to capture the image information (two main types of sensors are used in digital cameras, CCD and CMOS sensors). The sensor is divided up into millions of photo sensitive (light sensitive) areas called photosites. These photosites have a coloured filter over them, either red, green or blue which is in a specific pattern. The most common is the Bayer pattern which has twice as many green as red or blue (this is because the eye is more sensitive to green).

bayer pattern

This is a representation of the bayer pattern which is most commonly used in digital cameras

These photosites record the brightness level when they are exposed to light (when the shutter opens) as a charge; the more light the higher the charge. The sensor can provide data at 12 to 14 bits per pixel (4096 to 16,384 levels of intensity). These brightness levels are then recorded and stored as a set of numbers. This mosaic of data made, up of different intensities of 3 different colours, is stored in the RAW file.

So whats in a RAW file

When you take a photo in RAW Mode the camera doesn’t only record this mosaic of data onto the card but also the other settings used in your camera, like the date and time, type and model of camera, lens used, f-stop, shutter speed, white balance and more. This data or Meta-data can either be used for reference later or can help in the processing or Demosaicing of the raw file to produce an RGB file. Demosaicing uses an algorithm where the different intensities of the 3 colours are interpolated and averaged to get the different colour pixels that make up the RGB image. This processing of the RAW file from uncompressed Data to an 8bit or preferably 16bit RGB file is done in a “RAW converter” like Adobe Camera Raw, Capture one, Bibble or one of the many others.

Meta Data

This is a part of a screen grab from Adobe Bridge showing the Exif data from the Camera and lens that was captured and saved in the raw file when the photo was taken

Why use RAW?

In this age of processed, reprocessed and pre-processed products why deal with all this uncompressed unprocessed data?

The only real answer is quality!

Any photographer wants to take the best image he can so why leave the processing decisions up somebody that designed the camera when you can have complete control.  There are also many other reasons:

  1. Possibly the biggest advantage of shooting in RAW is that the image can be processed into a 16bit file. This is important when doing any edits on the file as you now have 65,536 levels of brightness to work with compared to a 8bit jpeg file which will have only 256 levels. So much larger edits will have less of a damaging effect on the file.
  2. You are editing with no loss of data or quality.
  3. Demosaicing is done on a computer with a fast and powerful processor and complex software which allows more sophisticated algorithms to be used than those used in a camera.
  4. You can attach the colour space of your preference to suit your needs.
  5. A  RAW file can be compared to a film negative. It has only what the camera captured, but can be processed in a number of ways to get different effects with no effect on the original file.
  6. RAW files have not had white balance set. They have the cameras settings recorded but the actual data has not been changed. This allows you to make big colour decisions after the photo has been taken, with no degradation to the original file.
  7. Contrast and saturation is stored by the camera but the image data has not been changed so can be set altered during processing without loss.
  8. There has been no sharpening done to the image so you can use advanced software and techniques to get better results.
  9. Because a raw file has not been processed in any way, when new and improved methods of processing files or other image processing advances are made, you can use your archived raw files at a later date and work on them afresh to get better results.  This also applies to your skill levels so as you learn more, you can reprocess your files and get better results.

Shot in JPG+RAWShot in JPG+RAW

These two photos were taken with the RAW+JPG option, the JPG on the left as was out of the camera and the raw file on the right with a minor white balance adjustment and white and black point set

Reasons to shoot in JPEG Mode

I cant think of any, are there any?
Yes! JPEGs most definately do have a place and advantages for example smaller file sizes, less processing to do and so less time spent in front of the PC to mention just a few.

However to really squeeze the most out of your photographs shooting in RAW mode is the way to go.


This article is my interpretation and opinion of RAW. As a conclusion to this short article, I believe that if you take photos of birds and want to get the most out of them, you should always be shooting in RAW Mode if your camera has this facility.



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