7D - Grain and Noise - What are the primary factors?

Started Apr 3, 2013 | Discussions thread
Jerry-astro
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Still a bit confused...
In reply to tonyjr, Apr 6, 2013

tonyjr wrote:

under exposing - I can get more out of shadow detail . I threw that out there for others that don't know about it . Anyone looking at shots close enough to pick up grain /noise would / or at least should be looking at shadow detail . Going from a -1 to a +1 - try both overexposed and then check your shadow detail . Granted in studio - may not be needed , both go outside that world and things change . Take a shot of a kid on a swing , now swing camera to his brother under tree .

if you go into an older building , get in an elevator with the old light bulbs , you will see bulbs flicker . Depending on where you are , speeds out 1/60, 1/120 , 1/180 - it can show up [ US , Mexico ] Other countries 1/50 , 1/100 , 1/150 .

Any ideas other wise might help others understand .

I'm still sort of mystified by what you're suggesting here.  Underexposing forces all your tonal distribution into a smaller space on the histogram, effectively collapsing it to the left.  That means that fine detail buried in the midtones somewhere that may only be barely visible in a proper exposure may be lost in an underexposed one.  The reasoning behind ETTR is to use every possible bit of the entire tonal range from black to white, ensuring the preservation of both highlights and detail.  What's worse with underexposure is that you will introduce additional noise into the darker areas of the exposure.  That will also kill fine detail.  So, yeah, I'm still really confused and don't understand how underexposure could improve shadow detail in any way.  If I'm missing something here, please let me know.

I do understand the flicker you're describing.  As I'm sure you know, best way to deal with that is to use a longer exposure... same process to minimize the odd color balance issues you can get with fluorescent lighting.

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