ISO change vs. change during PP

I suppose I could run some tests myself, but in case others have already...

If ISO higher than base ISO is an in-camera amplification of the light received by the sensor, isn't that equivalent to "pushing" the ISO in PP?

The reason why I ask, is that I assume this function maybe hardwire in a cheap inside the camera someplace, while doing it via software, may offer different, perhaps even better options.

Has anyone tried this?

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Lito
D80 + Mac

boosting iso will result in two things -- increase shutter speed to reduce blur and increase brightness (light receptors) in dark situations. either way, these are better achieved before taking the shot. otherwise, how can you eliminate blur in post processing? underexposed images can be improved in the post processing but it is always better achieved before taking the shot. this is why the pros always get it--they nail exposure and focusing before the shot. thanks.

This is smth that can only be done on PCs, not MACs

When you set ISO higher, sensor sensitivity is boosted, so that lowlight areas will have info recorded. If you leave at low ISO and fool the camera by underexposing, it may happen that lowlight details are recorded as complete black in file, so there's no way to recover it in PP.

Same if you overexpose and try to pull ISO down in PP. If highlight is blown, forget it, no detail there, pure white.

They are similar effects of wrong exposure.

LitoD80 said:

I suppose I could run some tests myself, but in case others have
already...

If ISO higher than base ISO is an in-camera amplification of the
light received by the sensor, isn't that equivalent to "pushing" the
ISO in PP?

The reason why I ask, is that I assume this function maybe hardwire
in a cheap inside the camera someplace, while doing it via software,
may offer different, perhaps even better options.

Has anyone tried this?

--
Lito
D80 + Mac

Click to expand...

--
Regards, RHLPedrosa

victor beato said:

boosting iso will result in two things -- increase shutter speed to
reduce blur and increase brightness (light receptors) in dark
situations. either way, these are better achieved before taking the
shot. otherwise, how can you eliminate blur in post processing?
underexposed images can be improved in the post processing but it is
always better achieved before taking the shot. this is why the pros
always get it--they nail exposure and focusing before the shot.
thanks.

Click to expand...

Maybe I did not explain myself properly... On film days, we would "push" film (say use 100 ASA as 400 ASA or 200 as 800, etc.) and "fix" it in the lab, ending up with more grain. The advantage was that you could use the aperture and speed as if you were indeed using faster film. Therefore, no shake. The price to pay was grain and increased contrast... Today's noise I guess you could say.

So, my question is, if you "fake" 400 in camera, or treat 100 as if it was 400 and then correct it on PP, will this be more or less flexible than what the hardware/software in the camera can do?

Or better yet, does the camera achieve this via hardware/software? Or does it use a different mechanism all together?

--
Lito
D80 + Mac

rhlpetrus said:

When you set ISO higher, sensor sensitivity is boosted, so that
lowlight areas will have info recorded. If you leave at low ISO and
fool the camera by underexposing, it may happen that lowlight details
are recorded as complete black in file, so there's no way to recover
it in PP.

Click to expand...

Aha! That is the info I was looking for. Thanks!

rhlpetrus said:

Same if you overexpose and try to pull ISO down in PP. If highlight
is blown, forget it, no detail there, pure white.

Click to expand...

This I was clear about, but never though it in the reverse mode. It makes sense now

--
Lito
D80 + Mac

damiselo said:

This is smth that can only be done on PCs, not MACs

Click to expand...

Maybe now that Mac can also run Windows I'll be OK

--
Lito
D80 + Mac

In that regard digital acts the same way film does. "Pushing" digital will cause more noise than choosing a higher ISO to start with.

This is because there are many less bits describing the shadow areas of the picture.

When choosing a higher ISO value you amplify the analogue signal from the sensor.

Choosing one of the "hi" modes or similar, that some bodies offer, does afaik make the camera do that last amplification outside the "standard" ISO range, in software, though.

Then, of course, if you want to go higher than the camera is specified for you have to "push" the exposure. I've done that with my D70 now and then, to be able to reach ISO3200. It's very important to shoot RAW then, though. JPEG will not give nearly as good results when "pushing".

LitoD80 said:

victor beato said:

boosting iso will result in two things -- increase shutter speed to
reduce blur and increase brightness (light receptors) in dark
situations. either way, these are better achieved before taking the
shot. otherwise, how can you eliminate blur in post processing?
underexposed images can be improved in the post processing but it is
always better achieved before taking the shot. this is why the pros
always get it--they nail exposure and focusing before the shot.
thanks.

Click to expand...

Maybe I did not explain myself properly... On film days, we would
"push" film (say use 100 ASA as 400 ASA or 200 as 800, etc.) and
"fix" it in the lab, ending up with more grain. The advantage was
that you could use the aperture and speed as if you were indeed using
faster film. Therefore, no shake. The price to pay was grain and
increased contrast... Today's noise I guess you could say.

So, my question is, if you "fake" 400 in camera, or treat 100 as if
it was 400 and then correct it on PP, will this be more or less
flexible than what the hardware/software in the camera can do?

Or better yet, does the camera achieve this via hardware/software? Or
does it use a different mechanism all together?

--
Lito
D80 + Mac

Click to expand...

dumbo said:

"Pushing" digital will cause more noise than choosing a higher ISO to start with.

Click to expand...

I've seen people disagreeing with that. I don't know if it was on one of the forums here or at Nikonians but some claim to get equal or better results by underexposing at base iso. I have never tried myself but if you want to know perform a search and you'll probably find something useful.

--
My gallery: http://www.flickr.com/photos/klaastuin/

Thank you all for the participation in this thread.

It seems to me as if some testing might be in order, although I would guess that the replies that explain that "pushing" is not what the camera does (except for the "high" modes) makes sense.

If I find the time and I do indeed do some tests, I will publish the results.

--
Lito
D80 + Mac