ISO Invariance

Discussion in 'Casual Photo Conversations' started by Larry_G, Feb 28, 2017.

  1. I just read a couple of Internet blurbs about ISO invariance. What is your experience with this? Would or do you trust that adding exposure in post processing will result in images as good or better than those created using ISO at the appropriate setting for the light conditions for your images? I've included one article on ISO invariance for your perusal. I use a Nikon D7000. I'm more than a little skeptical about this. I appreciate your input. Larry

    http://improvephotography.com/34818/iso-invariance/
     
  2. It's highly praised on dpreview.com and other sites. I don't have a camera to test it so I left my final conclusion for later. When I worked in a laboratory some 30 years ago we used to say "garbage in - garbage out", meaning that the analysis has to be good in the first place despite the possibilities of computers for later recalculations. IMO a similar principle applies to photography. Start with the best possible picture.
     
  3. One of the great things about digital photography is that you can do an experiment and see the outcome straight away, so you don't have to sit by the computer waiting for someone to reply to you. Skepticism is a totally wrong approach.

    Try it out and see for your self. There is more information on https://photographylife.com/iso-invariance-explained/ . FYI the D7000 is ISO invariant and the proof is here - just click on D7000 to see the chart http://www.photonstophotos.net/Charts/PDR.htm
     
  4. Josvan, I agree that it is the quality of the image as captured that matters most. With this invariance ISO, the captured images in the camera are likely to be grossly underexposed. The original capture on the camera's screen, as I understand it. would not be too useful for measuring the image's quality because it will be way too dark. This is why I want to get real experience from others who have used this technique. Thanks for reading my post and for your response. Larry
     
  5. Net R Thanks for your response and for the attached link. It is good to know that the D7000 is ISO invariant. I don't agree that I can get usable results straight away from the camera's display because as I have noted above, the images would likely be too underexposed. I couldn't understand the numbers in the chart you attached. Thanks, again. Larry
     
  6. Your question is about getting the best exposure. You may want to read Lee Varis' Mastering exposure and the zone system for digital photographers. Yes, post can help, but only so much with shadows before they muddy and blown highlights have no information to pull back. And with the still limited dynamic range of our sensors, maximizing the exposure can result in a better starting point in post. Placing the brightest area with desired detail as far to the right as possible will get best results on the other side of the histogram when pulling back shadows in post. I use a meter that is calibrated to my sensor's highlight and shadow clipping points so I can place the highlights right at the limit and at the same time be absolutely sure I am not blowing out any desired highlight detail. Necessary all the time, no, casual photos, dynamic range of scene withing camera's dynamic range, not as critical.
     
  7. My feeling is that the tools available when you shoot RAW can come pretty close to making amends for less-than-perfect original imagery.

    ISO settings were (and are) always arbitrary


    GIGO is still true, but the definition of garbage has shifted.
     
  8. Bob and JDM, Thanks for your input. You confirm my sense. Getting the best exposure in camera using ISO normally seems best and then tweaking it in Camera RAW in post is my procedure. I think I will stick with it. Bob, I will look at Lee Varis' book. We always need to learn more. Thanks to you both. Larry
     
  9. I've been reading up on this, and beginning to understand it at least. My experience is a little limited because until recently I've been using a D3200 which is not usefully invariant below high ISO where it's already too noisy. Basically, on that one, it's always better to use the correct ISO. The D7100 is a bit closer, and it appears to be possible to shoot at a lower ISO and get comparable results from post processing, but it's a little clumsy, and some of the advantage disappears owing to banding which seems a little worse when exposure is raised than when the correct ISO is used. So in this one, unless one needs to get added dynamic range on highlights, there's little benefit, and since it's fairly forgiving of a stop or so of exposure compensation, it's often easier to set the compensation down than it is to switch to manual and set the ISO down, and to settle for the slight extra noise.

    **** ​

    My wife just got a D7200, which is supposed to be quite invariant, and also immune to the banding problem, but I have not had a chance to play with it yet.
     
  10. +1 NetR. Just try it and then you can tell us:) But since I'm basically a know-it-all I'll say, it depends on how much post is needed and if, of course, were talking about raw files. I always thought its best to get it as right as possible in-camera.
     

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