For those of you lucky enough to have a 1D Mark IV, here as a follow-up to my review a few days ago is another tip.
Canon by default has the “Auto Light Optimizer” set to “ON”, and this is a custom function you may well miss.
If you shoot RAW (as you really ought to), go into custom functions II, function 4, and take that off zero (0=”standard” Auto Lighting Optimizer” setting) and turn that to custom setting 3 (“Disable”).
What does ALO do to your RAW image? Nothing. And you shoot RAW. So why does it matter? Here’s why.
If you set ALO to ON, your camera will, where necessary, apply “fill light” to the data that comes from the sensor, and use the result to make its little embedded JPG. That will make dark areas lighter.
And that little embedded JPG is what you see on the back of your camera.
So when you look, you will see a well-exposed picture. Happily, you shoot more. But in fact, unbeknownst to you, the actual data is darker. You may well be underexposing the dark areas of your picture! And like me. you wonder why when you import your image into Lightroom (which does not honour that same “fill light” setting) it looks so much darker than on the camera. Or rather, you wonder why the histograms are so different (you should probably not judge exposure just by the image on the LCD).
So when you turn ALO off, the camera no longer shows you an “enhanced mini JPG”; instead, it shows something closer to the real RAW image. And if that is dark, you can fix it by adding light, not by tweaking bits (which can add noise).
UPDATE: Chuck Westfall agrees. See the comment below.
Canon’s Chuck Westfall (the real one, not fakechuck), agrees. He answered my email just now, as follows:
Your article raises a valid point for RAW shooters.
I am glad my analysis was correct!
A few people here and there are saying “yeah that is obvious”. They are missing the point!
The point is this. Unlike on the Mark 3 etc, Canon by default on the 1D Mark IV turns “ALO” on, and it hides this in an obscure custom function. How many shooters will, like me, do their first shoots missing this, and hence will be getting noisy images?
I also see a discussion about this post here: http://d-spot.co.il/forum/index.php?showtopic=222144&pid=1738302&st=0& – I just wish I could speak and read Hebrew so I could participate in the discussion!
And here: http://www.sportsshooter.com/message_display.html?tid=35570
Again, it is a mystery to me that Canon would turn this on by default, hidden in a custom function. Guarantees badly exposed photos that have to be rescued in post – that is what “ALO” is, an in-camera, JPG only, “shadows” function that misleads the photographer into underexposing shadow areas.
What I really dont understand is why on some can cameras with ALO and PIC turned on it does not pose the same problems. For example my 5d MkII with these features on do not have this issue. For me it seems very specific to the 1d MKIV…
For now I have to shoot using the these features off on the 1d MK IV. If I want the benifit of using them with raw I open them up in DPP and turn the options on there.
This kinda stinks as that is not my normal work flow as I normal post process in ACR 5.6.
I am wondering if this will be fixed down the road some how..
I share your feelings and your hope that ACR will learn these settings.. but it probably still does not solve anything really, since ALO can make you expose badly and then rely on ALO to “fix” it, at the expense of increased noise.