Monday, November 17, 2008

RAW revisited...again.

Hi pentaxian friends,

This article is not intended to be a highly technical dissertation. It is intended to be a real life shooting approach for better pictures.

Early in 2008, I posted several articles (Link) (Link) about shooting RAW. It seems that many photographers had reservations about shooting RAW. The most common reason was that RAW took too much space on the memory cards and that JPG were just fine for what they were shooting. Well, I think it’s time that you shoot RAW if you haven’t already done so. I just purchased an 8GB SDHC card for $49.00. With the K20D @ 14.6MP, that gives me 330 image files and 482 image files with the K200D. Long gone are the 128MB SD cards.

With the Pentax newer generation of DSLRs, you can shoot RAW-PEF (Pentax RAW format) or RAW-DNG (Adobe universal format). Some or most of the photo galleries even upload the DNG files, such as Google’s Picasa.

Therefore, why anyone would keep shooting JPG is beyond me.

RAW files are the “negatives” of the digital world. In the film era, the negatives were vital in making multiple prints or enlargements. With the negatives, through the lens of an enlarger, the development of the images on emulsion paper could be further modified with dodging, burning, as well as color corrections. You would never have thrown away negatives on purpose. The RAW files are the information recorded by the DSLR in it’s purest useable form. The images are recorded at 12-bit per channel color bit-depth. In simple terms, Pentax RAW files contain 4096 levels of information or tones per channel. JPG files are 8-bit and support only 256 levels of information or tones per channel. The more information you have saved, the better the end results will be.

JPG files are in-camera processed and compressed image files. The camera applies pre-determined settings for white balance, contrast, color correction, sharpening and saturation. The files are then compressed to reduce the sizes. The results; completed and processed image files written to the camera’s storage card. You can never go back to the original RAW files taken by the camera.

On the other hand, you can manipulate RAW files on a computer with much more latitude. Desktop computers have much more powerful tools to convert your RAW files to JPG, in a non-destructive way. The RAW files can be saved for future enhancements, if needed. (Actually, highly recommended). Who knows what new software will be coming out in the future?

Here is a neat trick you can use with RAW files. When the lighting is less than perfect, instead of pumping up the ISO, go ahead and under-expose by about 1 to 2 stops. (Instead of say f4 @ 1/60 sec as per the DSLR metering system, use f4 @ 1/250 sec.) Yes, the picture will be a little too dark. Later, using tools like Lightroom or similar software lighten up the image and you will have a tack-sharp image with minimal noise. Try it; you will see that it really works.

Thank you for reading,

Yvon Bourque

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