# RAW and AEB



## lifeafter2am (Jul 18, 2007)

As I was going through my large amount of RAW files, creating stacks of three in Lightroom (which is just a cool feature!), I was wondering: Does one really need to use AEB when shooting in RAW?  There seems to be so much room to work with in RAW, do you really need to have a an underexposed and overexposed shot?  What is your experience / opinion?

(This is not a RAW vs. Jpeg debate!)


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## Garbz (Jul 19, 2007)

I posted the same thing in a thread where someone asked should he use RAW and underexpose to compensate for blowing his flash.

RAW is not a magic bullet. It contains extra data in between shades. You are still limited by the 5stops or so of dynamic range a sensor can record whether you are shooting RAW or not. So if you underexpose you sacrifice shadow detail, and when you over expose you sacrifice highlights. These can not be properly brought back.

Even if the said details are not important the extra bit count just prevents posterisation when adjusting in post processing, and the extra information required for accurate white balancing. If you take a photo that is under exposed by 2 stops and push it in Lightroom or any other program, you will not get as good results as you would taking the picture properly to begin with.

To go along with the problems of actually pushing the data is that increasing overall frame brightness also causes noise to be pulled out of the shadows. In my experience it is actually more pleasant to raise the ISO and induce extra noise that way, than under expose and post process.


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## PatriK-b (Jul 19, 2007)

Hum, I didn't notice there was that much room in RAW.

HDR user.


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## lifeafter2am (Jul 19, 2007)

Ah ok, thanks Garbz!  :hail:

I was shooting a sunrise yesterday and used AEB with RAW to make sure that I didn't miss any of the shots.  I have not had an experience yet where I truely needed to push a RAW file to its limits, so I haven't seen any of the problems you are talking about yet (although I am sure I will eventually).  It makes sense though.  I hadn't shot AEB in a long time, and never on digital, and wanted to make sure that it was really worth it.  

So I guess I did the right thing yesterday!!


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## PatriK-b (Jul 19, 2007)

I'm not sure AEB makes sense in digital world.
With film, it makes because you can not check the exposure until it's... too late.
But with digital, you check the exposure (with histogram and clipping highlight, not with the picture on the LCD), if it's not ok, correct and shoot again.

I use bracketing only with +/-2 if feel a need for HDR, but others will have other habits.


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## lifeafter2am (Jul 19, 2007)

PatriK-b said:


> I'm not sure AEB makes sense in digital world.
> With film, it makes because you can not check the exposure until it's... too late.
> But with digital, you check the exposure (with histogram and clipping highlight, not with the picture on the LCD), if it's not ok, correct and shoot again.
> 
> I use bracketing only with +/-2 if feel a need for HDR, but others will have other habits.



I can understand what you are saying, but in this case I didn't want to miss any shots by constantly looking at the histogram.  It was surfers on a dawn patrol, sunrise in the back, nice shots.  Especially during a sunrise or sunset time, you would probably have to constantly check the histogram since the lighting conditions are constantly changing.

I was wondering about what I should use for trying some HDR.  Thanks for answering a question without me needing to ask it!


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## Big Mike (Jul 19, 2007)

With digital, you could set AEB and snap the three shots...then just review them and delete the ones  you don't want.  Or, you could save them for HDR.  As long as you have enough memory card space, there is nothing to loose.


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## jon_k (Jul 21, 2007)

Big Mike said:


> With digital, you could set AEB and snap the three shots...then just review them and delete the ones  you don't want.  Or, you could save them for HDR.  As long as you have enough memory card space, there is nothing to loose.



If by AEB you're talking about auto bracketing by shutter speed, I'd much rather just snap a picture I think will turn out good and look at the RGB histogram.


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