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February 20, 2007


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Chris Ratcliff

Good guide Seb! I always think of RAW as nothing more than a saftey net just in case things go awry.

Will have to give Bibble a go...

Phillip Stasiw

Another great burst of info! I too agree on RAW, Curves in CS2 work a treat, but the File sizes are such a pain, your cards fill up so quick!

Seb Rogers

Hi Phillip,

Maybe it's because I've come from a film background (36 shots per 'card'), but I've never had an issue with file sizes. I run 2Gb cards in my cameras, which give 120 shots in the D200 and 100 in the D2X. Given that good quality 2Gb cards can be had for around the £50 mark (and that external drive storage is less than £0.50/Gb), it's not that hard to deal with the extra space that raw demands (I can remember when the first 1Gb CF microdrives were launched... I seem to recall they were well over £500...)

The other thing that I do is edit as I shoot, time permitting. Some photographers think that deleting in-camera is more likely to result in corrupt card directories, but so long as you always re-format in-camera every time you put a new card in, I don't think you'll have any trouble (I haven't had a single card failure yet, at least).


It's a fallacy that the white balance cannot be tweaked in jpeg. You can alter the balance with the mid-tones dropper in levels. You can record and batch process your jpegs the same way as you would when processing Raw files into some form a magazine might want!

Seb Rogers

Up to a point, Geoff, but you're still working with just 8 bits in jpeg, whereas raw is 12 bits. Arguably you'd be hard pushed to see the difference in most circumstances, but the perfectionist in me likes to know that it's there anyway :)


RAW is so much better than jpeg in every way except file size.

Most people would get more benefit simeply shooting RAW ather than JPEG and learning how to process the results than they ever would from, say, a new camera.


"Another is that, armed with a raw file, the photographer can effectively make whatever white balance and exposure changes they like without affecting the quality of the outcome. "

you can with the white balance, as this is purely a post processing option, whether done in camera or subseuently...

Seb Rogers

'you can with the white balance, as this is purely a post processing option, whether done in camera or subseuently...'

In practice this is mostly true. But clipped channels can show up any major white balance changes post-capture. Getting white balance and exposure right, or close to right, in camera can make a difference to the quality of the end result. Shunting pixel values around after the fact only works within the dynamic range limitations of the sensor.

If you don't believe me, go outside and shoot a landscape on a cloudy day so that the ground's correctly exposed and the sky is blown. Shoot every white balance option with the same exposure. Then bring the white balance back to daylight values in raw software. The sky will acquire a colour cast in the most extreme cases.

Like I said, raw is not the lazy option. It's the best option for getting it right, but that involves capturing the best possible data in the first place :)



are you saying the manufacturers are lying when they say the data is the raw capture from the sensor then ? If it were then whatever white balance selection you made would have no effect - unless that is, all RAW postprocessors treat the white balance profile included in the file in some unrecoverable way - I know the EXIF data contains a large block of data describing the white balance...

Seb Rogers

No, I'm saying that there are limitations to shunting pixel values around after the fact. White balance affects the outcome of processing the raw data off the sensor. If the captured data isn't optimised then big shifts in white balance can lead one or more channels to clip earlier than the others, causing colour casts in highlights. It's why some photographers use the uniWB technique (which I've not tried), which takes white balance processing out of the capture equation but gives you a file that looks damn odd until you shunt everything back into place.


Ah, I see, so one of us has the wrong idea of what "RAW" is supposed to mean. I think raw means raw, numbers from the sensor pixels, you think it means those numbers after they've been processed to factor in the white balance ?

Seb Rogers


I think we actually agree. We're just talking about slightly different things :)

Raw is, as you say, numbers from the sensor pixels. Each proprietary raw format also adds some tags relating to white balance etc. that allow raw processing software to spit out something that looks about right.

Clipped channels in particular can impact the results of applying white balance tags to the raw data at the highlight end. Doesn't make any difference if you apply that tag in camera or in software later. What does make a difference is the resulting colour balance in the highlights (and to some extent noise in the shadows) when the white balance has been shifted to resemble a mid-tone point that's close to 128, 128, 128 in terms of colour.

The point I'm trying to make is that there's no such thing as a free lunch when it comes to white balance. You can't necessarily expect to retrieve a raw file shot with the wrong white balance if you didn't make sure to get the exposure right at the time of capture. Since exposure choices are affected by white balance if you use the camera's histogram to tweak exposure, getting the white balance wrong can cause all kinds of problems later.

A bit of fiddling one way or t'other is fine. Shooting everything with (say) tungsten white balance and then correcting later isn't likely to look great unless the raw data you're working with is optimal - which means correct exposure.

Which is where I came in to start with. Yes, raw gives you more flexibility to retrieve bad exposure and white balance choices than jpeg. No, correcting in software later is NOT the same as recording the best possible raw data in the first place.


Oh, I get you, using the wrong white balance might skew your exposure...

Seb Rogers

Yep. And, potentially, leave you with hard to resolve colour casts in highlights if you got the exposure badly enough wrong that you clipped channels....

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