understanding zones and exposure

[akuwen]

I have powershot a630
and I have made 3 photos  of  my chair in .JPG

iso800  f/4.1 and speeds of  2 4 8
+0 stop +1 stop and +2 stop
[attachment=2140:attachment][attachment=2141:attachment][attachment=2142:attachm
ent]
on my lcd screen i saw these histograms
[attachment=2143:attachment][attachment=2144:attachment][attachment=2145:attachm
ent]

when i moved them to photoshop nothing has changed in histograms

but i don't understand  why tones on +1 and +2 in photoshop did not stretched or smth.?

I knew about "Remember — each F stop is a doubling or halving of the amount of light "
I have read http://luminous-landscape.com...understanding-histograms
so I expected more tones in the 5 zone. Were are they?
here are histograms in photoshop
[attachment=2146:attachment][attachment=2147:attachment][attachment=2148:attachm
ent]

[mikeseb]

Do I understand your question?

If you are asking why the tone curve is not broader, but remains narrow and tall despite the exposure: because by altering exposure you've moved the midpoint of the curve left or right, but not changed the relative differences in brightness between the darkest and lightest tones in the image.

You'd need to alter the contrast curve to "spread" the curve out, by "redistributing" the existing tones--some of the lighter ones become even lighter--all the way to burned-out white-- and some of the darker ones become even darker, all the way to solid black.

[djgarcia]

From a Zone System perspective, you have applied exposure compensation but no expansion (N+1, N+2 ...) or compaction (N-1, N-2, ...) of the curve. You can do various versions of that using the Levels, Contrast, Curves, Highlight/Shadow etc. tools in the raw developer (some), PS or what have you.

[akuwen]

thanks for your answers!
I have no raw support in my camera (
maybe I try to speak about things that have no sense for .jpg
I tried to understand the "expose to the right" and made the example that started the topic

I saw things from "simple mathematical point of view" and

here is diagrams that I saw on camera and  red color are my thoughts
[attachment=2154:attachment]
after +1 compensation
[attachment=2155:attachment]
after  converting to 8bit .jpg(I won't be surprised if in my camera no 12bit at all)
[attachment=2156:attachment]
before - 16 levels and  after +1 compensation - 32 levels
(this is the result of 32 levels which I have expected to see in photoshop)

but in real I have nothing like this (

At what point I mistaken?

[MikeMike]

You'd need to alter the contrast curve to "spread" the curve out, by "redistributing" the existing tones--some of the lighter ones become even lighter--all the way to burned-out white-- and some of the darker ones become even darker, all the way to solid black.
[a href=\"index.php?act=findpost&pid=108119\"][{POST_SNAPBACK}][/a]

Hows that done?

Thanks,
Mike

[djgarcia]

See my post above - I mention several raw developer and PS tools you can use.