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01-25-2007, 06:47 AM   #1
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What is Pushing the ISO?

Okay I have been around here for a while and photography for many years so this may sound like a silly question to some. I understand when someone in film says they pushed the film to a higher ISO. I take that to mean something in the processing of the film. (I think). In digital I see the same thing here and there when someone says they pushed the ISO to XX form XX. Can I get a explanation on what they mean . I mean are they not just turn the ISO up to what they need. Or is this the same as they are increasing something the in PP work? This has just been on my mind as I read it more lately and would really like to understand what they mean. I am hoping I pretty much understand it, or I am reading more into it.


Last edited by vievetrick; 01-25-2007 at 07:13 AM. Reason: Spelling and forgot a word.
01-25-2007, 07:01 AM   #2
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What they might be refering to is pushing the ISO to more than what the sensor is capable of. This is how you would get to ISO6400 (or up to 3200 on the K10D)

Set your ISO to 3200 on the camera. Say this gives you a shutter speed of 1/30 wide open (at f/1.4 because you're using the awesome FA 50mm f/1.4!) You say "That shutter speed is too slow because my subject (little baby or dog or other family member) is moving around quite a bit. Now if I had ISO6400, my meter would give me 1/60! (not perfect, but a bit better for both subject motion and camera shake). So what do you do? Set the exposure compensation to -1 (or just go manual and set to f/1.4 and 1/60). Now this is going to give you an "underexposed" picture, so you open the file in your favorite RAW program (JPG would work somewhat, but pushing a RAW file is MUCH better), and bump the exposure up one stop to properly expose the photo. Voila! ISO6400! Of course, when you bump up an underexposed ISO3200 shot, you're going to get a bit of noise (especially in shadow areas), but it's better than getting a blurry shot of the subject (or worse, not having any shot)
01-25-2007, 07:48 AM   #3
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Pushing in digital is the same as pushing in film: under-exposing and over developing. It works to varying degrees in both mediums because of the built in latitude of the underlying manufacturing processes that make film/chemistry and sensors. It's typical benefit is low--very low light photography at the expense of greater grain or noise which is readily obvious and a host of other problems that most adepts to the process ignore.

Photographic purists shun the process as a 'child of unwed progenitors'. In some situations it does in fact work well--well it's acceptable. In others its a massive waste of time and materials.

There is an analogous situation at the other end of the scale-pull: over-expose and under-develop. Benefits claimed here are primarily in contrast control--a provable effect.

Pushes and pulls would like to trace some of their origins to the Zone System of Adams and White (et al). But those exposure/development variations are of a very small, very controlled nature entirely withing the sweet spot of the film/developer/paper/paper developer parameters as determined by empirical testing and re-testing. Push/Pull modern day is anecdotal based guessing in the dark at best---i.e. pure luck that anything useful erupts.

The pushing that is producing banding as hysterically reported in many photo forums is simply the natural result of using the digital camera far outside it intended operating environment. Try any film at 6 to 8 stops beyond it's suggested speed rating; can you even imagine that the results might be useful???
01-25-2007, 08:48 AM   #4
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Original Poster
Thanks both for the explanation. I figured I did pretty much understand what it is, but for some reason thought there was some other magical answer I was missing. Oh I realized as well that I myself have been pushing some shots. Now I can sound like I know what I am talking about. lolol

01-25-2007, 11:44 AM   #5
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more technical jargon so that experts can communicate with other experts whilst at the same time leaving none experts in ignorance..

the problem i have with jargon is even thow i dislike useing it if i dont both experts and none experts alike assume i dont know what i am talking about.. he he he..

a paradox is created.. attempt to explain in simple (none jargon) terms and your advice often falls on deaf ears cos as an advice giver your expert status is in doubt..

use the jargon and there is no doubt about your expert status but the advice is still wasted cos the recipient dosnt understand a word of it..

ignorance abounds and i think jargon is the main reason for this which is why i despise it to be honest..

the technical side of photography is loaded with it..

trog
01-25-2007, 12:11 PM   #6
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I have done this without even knowing it....(just discovered what I was doing in this post)
I have put the shutter speed at 1/60 of a second indoor with no flash which gave me an underexposed image in raw. then I used CS2 raw editor to bring it back to "normal" exposure. Yes it did have a bit more noise overall, especially in the shadows, but I was able to capture the photo without having any blur due to people moving.
The quality of the light was very good as well.

cheers

randy
01-25-2007, 12:53 PM   #7
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i used to make the mistake of useing the term (in forums) "depth of focus" instead of DOF.. i know what DOF is short for but i also know it makes no sense at all to the none expert..

i had to stop doing it thow cos it was guaranteed to get picked up instantly and my "error" deliberate or not corrected..

i still use it one to one thow.. just like i use under or over expose..

trog
01-25-2007, 04:40 PM   #8
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Did I use too much "technical jargon" ? Did my answer perpetuate ignorance in "none (sic) experts" ?

Not really sure what the point of your post is. Maybe I missed the point, it was a bit difficult to understand with all the mis-spellings, so maybe I'll give it another read later tonight.

QuoteOriginally posted by trog100 Quote
more technical jargon so that experts can communicate with other experts whilst at the same time leaving none experts in ignorance..

the problem i have with jargon is even thow i dislike useing it if i dont both experts and none experts alike assume i dont know what i am talking about.. he he he..

a paradox is created.. attempt to explain in simple (none jargon) terms and your advice often falls on deaf ears cos as an advice giver your expert status is in doubt..

use the jargon and there is no doubt about your expert status but the advice is still wasted cos the recipient dosnt understand a word of it..

ignorance abounds and i think jargon is the main reason for this which is why i despise it to be honest..

the technical side of photography is loaded with it..

trog


01-25-2007, 04:47 PM   #9
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Hey Randy,
If you're at 1/60 f/<whatever you want for your DOF> and you want a quicker shutter speed, if you can still bump the ISO up in-camera, you're probably better off doing it then and there. (ie you're at 800, go up to 1600)
You arguably get better quality raising the sensitivity right at the sensor instead of once you're in the digital domain (ie during post-processing). When you raise the ISO, you're adjusting the gain of the sensor BEFORE the sensor's signal is converted to digital.

This is similar to audio. When you are recording into a digital system (ie a computer-based recording system), you want a good strong analog signal to be fed into the Analog-Digital converters. If you don't record a strong signal and try to raise the volume when you are "mixing" inside the computer, you will also raise the noise floor quite a bit.

QuoteOriginally posted by slipchuck Quote
I have done this without even knowing it....(just discovered what I was doing in this post)
I have put the shutter speed at 1/60 of a second indoor with no flash which gave me an underexposed image in raw. then I used CS2 raw editor to bring it back to "normal" exposure. Yes it did have a bit more noise overall, especially in the shadows, but I was able to capture the photo without having any blur due to people moving.
The quality of the light was very good as well.

cheers

randy
01-25-2007, 04:59 PM   #10
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OK, I think trog100 is trying to say that "Pushing the ISO" is just a bunch of technical jargon that he would rather not know. OK, for his sake, let us no longer utter the following phrases:
"stop down the lens"
"open up the aperture"
"dodge and burn" (an oldie but goodie, anyone else used to develop B&W film here?)
Additonally, the term "f-stop" has now been banished. You will now refer to it as "the size of the hole in the lens"

Technical jargon is part of any domain, if you don't want to learn the jargon, why bother learning the craft? Do you shy away from the term "aperture" or even worse, f-stop?

Sure, photography is an art, but I think it helps to learn the technical aspects of it, jargon and all. That way you don't have to ask "My K10D doesn't have a portrait mode, how do I get a nice portrait to blur the background?" And if you do ask, I'll be glad to answer "get a really fast lens, go into Av mode, and open up the aperture. f/1.4 would give a nice and shallow DOF"

Now if you don't know the jargon, someone is going to have to take the time to explain aperture/f-stops/DOF/focal length/blah blah blah.

In my musical life, I like that I know theory and reading music. It helps people communicate different musical ideas.

But seriously, I am saying most of this in jest, but technical "terms" have their place in teaching others about photography. Now if someone asks what the term "f-stop" means, I'm sure someone can explain it to them. But to answer "It's all a bunch of stupid technical jargon, all you need to know is it's the size of the hole in the lens"
01-25-2007, 05:18 PM   #11
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"OK, I think trog100 is trying to say that "Pushing the ISO" is just a bunch of technical jargon that he would rather not know. OK, for his sake, let us no longer utter the following phrases:
"stop down the lens"
"open up the aperture"
"dodge and burn" (an oldie but goodie, anyone else used to develop B&W film here?)
Additonally, the term "f-stop" has now been banished. You will now refer to it as "the size of the hole in the lens"

###

is being obtuse egordon99 natural to u or do have to work at it.. ??

i know and have forgotten more technical jargon than u have ever dreamed off my obtuse friend..

if u cant grasp the point of my post the problem is yours not mine..

trog
01-25-2007, 05:35 PM   #12
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QuoteOriginally posted by egordon99 Quote
What they might be refering to is pushing the ISO to more than what the sensor is capable of. This is how you would get to ISO6400 (or up to 3200 on the K10D)

Set your ISO to 3200 on the camera. Say this gives you a shutter speed of 1/30 wide open (at f/1.4 because you're using the awesome FA 50mm f/1.4!) You say "That shutter speed is too slow because my subject (little baby or dog or other family member) is moving around quite a bit. Now if I had ISO6400, my meter would give me 1/60! (not perfect, but a bit better for both subject motion and camera shake). So what do you do? Set the exposure compensation to -1 (or just go manual and set to f/1.4 and 1/60). Now this is going to give you an "underexposed" picture, so you open the file in your favorite RAW program (JPG would work somewhat, but pushing a RAW file is MUCH better), and bump the exposure up one stop to properly expose the photo. Voila! ISO6400! Of course, when you bump up an underexposed ISO3200 shot, you're going to get a bit of noise (especially in shadow areas), but it's better than getting a blurry shot of the subject (or worse, not having any shot)
Excellent post.

Right on the money.

Let me add that pushing isn't free. It's actually more troublesome with digital then slide film. For instance I can push Provia 100F 1-3 stops (1-2 being ideal) with almost no loss of quality and actually if the situation dictates I get a warming effect (so you wouldn't want to push 3 stops on a portrait, but a sunset or a environment with a lot of blue light it is actually helpful, also helpful when shooting with long teles which tend to be cool). Pushing low ISO slide film is still preferential to using high ISO slide film (in most cases)

Anyway, with digital sometimes shooting at 800 -1 and pushing a stop in RAW is actually noisier then shooting at strait 1600.

With the Ist D I underexpose at 1600 by 1/3-2/3 stop giving me a slightly higher shutter for sports. This can be the difference at a night baseball game between unusable 1/250th and usable 1/400th (shooting with a tripod mounted 320-400mm of lens)

When I'm at 800 I might underexpose by 1/2 stop but if I need to go further I just go to 1600 which is still usable. The caveat is I find 1600 works better in B&W so I usually convert them to B&W.

If you find yourself going over 1 stop then you'll be disappointed with the noise.

Pushing is a tool but still a last resort.
01-25-2007, 06:36 PM   #13
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Trog, hush up. egordon99 posted a very useful post for "none (sic) experts", or rather anyone who wanted clarification. You, however, went off topic, and saw fit to pontificate on how dreadfully exclusive jargon is.

Pull yer' head out.
01-25-2007, 07:35 PM   #14
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QuoteOriginally posted by egordon99 Quote
Hey Randy,
If you're at 1/60 f/<whatever you want for your DOF> and you want a quicker shutter speed, if you can still bump the ISO up in-camera, you're probably better off doing it then and there. (ie you're at 800, go up to 1600)
You arguably get better quality raising the sensitivity right at the sensor instead of once you're in the digital domain (ie during post-processing). When you raise the ISO, you're adjusting the gain of the sensor BEFORE the sensor's signal is converted to digital.

This is similar to audio. When you are recording into a digital system (ie a computer-based recording system), you want a good strong analog signal to be fed into the Analog-Digital converters. If you don't record a strong signal and try to raise the volume when you are "mixing" inside the computer, you will also raise the noise floor quite a bit.
thanks I will try this

I was worried that the ISO 1600 would be way to noisy.

cheers

randy
01-25-2007, 08:13 PM   #15
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QuoteOriginally posted by egordon99 Quote
Hey Randy,
If you're at 1/60 f/<whatever you want for your DOF> and you want a quicker shutter speed, if you can still bump the ISO up in-camera, you're probably better off doing it then and there. (ie you're at 800, go up to 1600)
You arguably get better quality raising the sensitivity right at the sensor instead of once you're in the digital domain (ie during post-processing). When you raise the ISO, you're adjusting the gain of the sensor BEFORE the sensor's signal is converted to digital.

This is similar to audio. When you are recording into a digital system (ie a computer-based recording system), you want a good strong analog signal to be fed into the Analog-Digital converters. If you don't record a strong signal and try to raise the volume when you are "mixing" inside the computer, you will also raise the noise floor quite a bit.
here is an example of a photo I "pushed" as the term says

what the origanal looks like.... I set the shutter to 1/60, should have been 1/30
ISO 200. both are no flash.





here is one stop up from the origanal..... according to what I read, this would make it ISO 400 instead



so do you think there would have been less noise if I would have used 400 instead of 200?

any opinion welcome.... trying to learn new technics

thanks

BTW the nearest one is my daughter and the other one is my step daughter... very proud father of both

randy
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