Hey DJ,
Raw is pretty simple to understand. It is simply the unprocessed capture data from your cameras chip.
If you choose the save as a jpeg file then the camera will process the RAW image 'in-camera' based on the settings you specify [and some you don't] and using the preinstalled algorithms. All is fine if the settings, for example colour temp is correct, but if you make a mistake then it is difficult [and limited] as to the range of changes available to you before you start to seriously degrade the image. You also have to contend with the data loss of the jpeg compression and the conversion to an 8 bit file.
With a RAW capture, the file remembers all the camera settings but it doesn’t commit them to the file. When you open a RAW file in either your generic manufacturer supplied software or in Photoshop [or Lightroom] you have access to all the captured information and you are free to change or tweak the image characteristics as you see fit. When you are happy you can then process the image for printing. Additionally the RAW file will remain untouched, so you can go back and have another go if your not happy with the end result.
But probably the biggest advantage of a RAW file is that it is a 16-bit file.
An in-camera processed jpeg image is saved as an 8-bit file, which means there are 256 tonal levels between 100% colour and 0% colour in each of the 3 capture channels [RGB]. A 16-bit image has 65,536 tonal values between 100% and 0% for each channel. This vastly larger colour space allows significant and aggressive [if you choose] manipulation of the image before you start to degrade the resultant file. And if you use Photoshop Smart files or Lightroom then you have even greater control of the image before you reach significant degredation.
[As the next step HDR will then take you way beyond that, with muliple 32-bit images combined to allow an almost limitless contrast range. But you can’t take action photos in HDR].
The ways you can manipulate a RAW file before processing is truly astounding and continues to evolve at a great rate. Compared to in-camera processing it is another world.
DNG is a generic algorithm created by Adobe for the long-term storage and retrieval of bitmap files. Each manufacturer has their own version of a RAW file and you can’t [if you don’t have the software] open another makers RAW file on your computer. If as Graeme says he as the option of a Pentax PEF RAW format, he will have problems sending the file to DJ to process using his Canon RAW converter. Photoshop continually updates its list of RAW converters, but potentially older RAW file formats could be left behind and become unopenable [is that a word] in years to come. Kind of like having all your favourite MX footage on VHS tapes and only being able to access a DVD player.
So DNG has been created as an open platform format to try to ensure that you will be able to open your images in years to come. I don’t use the format so I can’t comment on the workflow, but I can’t imagine it would be a problem.
Like all things, it is good to be aware of the basics and make your own choices about how to incorporate this info into your photography. Don’t let the detail weigh you down and take the enjoyment out of it, but conversely if you know what you are doing: you can survey a scene, understand how the camera will see it, consider the histogram and get a picture in your mind as to how the capture will look before you press the shutter – then you will be able to really move forward with your photography. There is nothing worse than getting one great image and not knowing how to do it again.
But again it is horses for courses, I know many successful professional photographers who couldn’t care less about this stuff. They immerse themselves in the shoot and enjoy the spontaneous results – I am a bit of a control freak and I like to know and anticipate what results I am going to get. I think that explains why I will never be a highly paid fashion photographer.
VMX42
