Optimum high ISO for D200

[Mike_Guilbault]

That's what I thought. Thanks all for your feedback. I'll be trying these techniques this weekend.

[DouglasUrner]

Let us know what you found out in the real world

Doug

[DouglasUrner]

Originally Posted by diglloyd

Yes, I definitely meant RAW. Underexposing JPEGS with only 8 bits is a real problem.

Indeed

Your observation that a raw image (presumably from a 12 bit camera) could be underexposed by 4 stops and still have a reasonable image got me wondering if there was something "magic" about 8 bits (which is what you've got left when you underexpose by 4 stops). Is 8 bits per color what it takes to create a good file? Kind of like 300 ppi being about the right amount of data to create a good looking print.

That would be an interesting way to think about exposure and it would suggest that there is more latitude to protect highlights than is commonly assumed.

Doug

[DragonflyDM]

And if I remember properly (this has been a LONG time since I used to really know the ins-and-outs of this) 8-bit information is on actually called a byte because each "bit" is a "01" piece of information. When you mix in eight of those bits the possible combinations of 01010101010101 (or some combination of zeros and ones) give you 256 possible combinations.

As we all know that all the proper range for black and white film are 256 shades of grey and happens to be the great mathematical solution, since two to the eigth power (or 8 bits) comes out to 256.

Of course, on a computer we have zerio...so color goes from 0-255.

When we give a tumbler of all three colors we can get that to the third power and have millions of colors for our little computers to work out. Each color is then put into a red.green.blue math number. So 201.125.063 would be something reddish/green.

This means that all 8 bit JPEGS images are really 24 bit-- but we don't reference them by the total bits, but just the singular color field of 0-255.

When you are using 12 bit images, the range of pure black to pure white the range is 0-4095. That is 16 times the amount of information. Now think of formulas that work out in color depths like 1265.0030.0945. That is a LOT of color depth and information to deal with.

That takes us from 16 million colors in 8-bit jpegs to 68 trillion colors in 12-bit RAW images.


Whew...I can't believe I was able to bring all that crap back up in my memory bank. If I am faulty-- it is only because that information is hard to remember with all that dust on it.

[DouglasUrner]

Originally Posted by DragonflyDM

Whew...I can't believe I was able to bring all that crap back up in my memory bank. If I am faulty-- it is only because that information is hard to remember with all that dust on it.

Sounds like you got the dust cleared off very nicely

Doug

[robwouds]

I just shot a bas mitzvah and some raw shots at 400 iso have much more noise than jpegs at 500. It seems to have something to do with underexposed dark areas. Sometimes 1600 looks relatively clean. Why would a consevative iso be noisy? Camera is d200! What is happening?

[robwouds]

I could show you shots that are clean at 1600 and dirty ones at 400. I really don't understand. It seems that if a shot is well exposed it will have less noise. That said 100 iso on my d200 is really clean.