High ISO noise vrs underexposed noise

Discussion in 'Wedding and Event' started by rocky_g., Dec 13, 2010.

  1. I am amazed at the quality of images my 5D mark 2 produces at higher ISOs, but I am not sure where to draw the line in low light receptions. I usually wont bump it up pass 800 but I wondering if thats a mistake. As I increase the exposer and fill in post I bring out a good amount of noise. Dose anyone think that although shooting at even higher ISOs (1000 or higher) I will be better off since I wont have to make such drastic changes to the raw file?
     
  2. Absolutely raise the ISO so that you can get a proper exposure. The minor increase in noise from the higher ISO is nothing compared to the mess created when you bump up underexposed areas in post production. The higher the ISO, the less wiggle room you have, so it's that much more important to get the exposure right. But if you hit the sweet spot, the results are far, far better than torturing an underexposed, lower-ISO shot into being a decent print.
     
  3. That sounds right. I am not making huge adjustments. I never have to push the exposer past a stop and I never increase fill past 20 points. That being said, what limits do others put on ISO at a reception?
     
  4. Yes, absolutely. I pretty regularly dabble in the 2500 range, 3200 if I reallly need to push it. And as long as it's exposed correctly I don't have distinguishable noise. Obviously it's not completely as vivid as shooting at iso 200, but that's easy to push in PS/LR, and much more worth it to get the shot.
     
  5. If I recall correctly from when I shot Canon (5D, 5DII), the 5D was pretty good to around 1600 and the 5DII to 3200.
     
  6. I am completely comfortable with my 5dII at iso 1600, I don't usually go much past that, but with a fast (faster than f 1.8) lens I rarely need to! I agree that proper exposure is less noisy than doing it in post.
     
  7. At a reception, I'm not using the extremely high ISOs, because more troubling than noise control is lack of dynamic range. I see the advantage of shooting with ambient light because many times, ambient light is just 'nicer' than flash only and you don't have the disadvantage of the flash slowing you down. However, I personally hate the dead shadows and other not-so-nice effects of lack of dynamic range, even with high ISO files exposed correctly. The day I can get a pleasingly full dynamic range using ISO 6400 is a good day.
    As for noise, remember that it doesn't look half as bad printed as when you view it on a monitor. Clients also don't routinely look at images at 100 percent. You also have to take into consideration your particular camera. I have an original 5D, and I don't worry about using ISO 1600, ISO 3200 with some care, but I usually like ISO 1250 as my limit at receptions, using flash. And for ceremonies, I like to stay at ISO 1600 as much as possible. However, sometimes, the ability to use high ISO overrides everything else, even for a person like me, who uses the lowest ISO I can get away with, and who consciously chooses flash rather than shoot an entire dim reception using ISO 3200 and getting flat files and noise all night long. I might shoot some with flash and some without, but not the entire thing.
    Forgot to add--I agree with others above--your goal, when using high ISO, is to not have to increase exposure at all in post. Shoot to the right, and even overexpose a bit. So if you have an ISO 800 limit, make sure you are not underexposing at ISO 800, because that would be worse than shooting at ISO 1600 with good exposures. Try it for yourself and you'll see.
     
  8. Thanks for everyones advice. This community has been invaluable to me
     
  9. Have some test prints made so you can see with your own eyes. That's what got me over high ISO concerns. Up to 8"x12" I'm amazed at how good the old 5D looks at ISO 3200. I'll take it over 35mm Fuji NPH any night.
     
  10. For an example of an image shot at ISO 5000 on my 5D Mkii, take a look at a blog post on my website at this link:
    http://www.bellissimaphoto.co.uk/?p=811
    The shots of the couple walking back up the aisle: F5.6, 1/125, ISO 5000 with a bit of flash bounced forward with a Demb Flipit. Exposed correctly and zero noise reduction applied in post. Why did I ned to go to ISO 5000...? Because I needed that F stop and that shutter speed for DOF and to freeze motion whilst capturing the ambient light as well.
    May other images in my blog, and galleries, were shot at ISO 3200 with the 5D Mkii - especially receptions. Don't be afraid of going this high, it is more than capable!
     
  11. "even for a person like me, who uses the lowest ISO I can get away with, and who consciously chooses flash rather than shoot an entire dim reception using ISO 3200 and getting flat files and noise all night long. I might shoot some with flash and some without, but not the entire thing."
    Nadine, I couldn't agree more!!! In my opinion, anyone who almost "romantically" says they don't use flash or are complete natural light shooters cannot get 100% of the shots nicely lit. There absolutely will be limitations in certain venues and if flash is permitted then it can really help. If the light is flat, it is flat. Yes can can up the ISO but it will still be lifeless. I shot a wedding in a registry office in the UK recently and although I could comfortably get a decent ambient exposure, the lighting was flat with no directionality. So I simply underexposed the ambient a touch and added some on-camera bounced flash (off a wall/ceiling) to give the images some lovely directional lighting. It works.
     
  12. There is something called unity gain and it's the breaking point when one photon equals one electron in the sensor. To many that's techno babble - the take home message is that at this point raising the ISO in the camera will have the exact same effect as raising the exposure in the raw converter.
    According to this author unity gain on the 5D Mk II is ISO 1600 (I don't have a 5D MkII so I can't verify that the breaking point is ISO1600).
    That means on the 5D MkII that an image shot at ISO1600 one stop underexposed and +1EV exposure in raw will look identical to the same image properly exposed at ISO3200. Or even a ISO 1600 shot two stops underexposed will look the same as if shot properly exposed at ISO6400.
    If you shoot raw this could be used to your advantage in some situations.
    For instance let's say you have a scene with high dynamic range and you need ISO6400 to get a properly exposed image. If you shot that at ISO6400 you would get a properly exposed image but you would also clip a lot of highlights in the raw file. If you however shot it at ISO1600 the raw file will have two stops more highlight information. Then when you raise the exposure in raw the raw converter can recover those two stops because that information is not actually clipped in the raw file. You can also raise the exposure with curves or midpoint with the same effect of retaining these highlights.
    Remember though that iso must be set at ISO1600 or higher for this to work - ISO800 one stop underexposed will have more noise after correction than ISO1600 properly exposed.
     
  13. That's really interesting Pete. Now I always thought the way that Michael Church did (he doesn't post here much now) about a +1 overexposure being 'better' re noise than a -1 exposure brought up in post. It is discussed in the following thread, somewhat.
    http://www.photo.net/wedding-photography-forum/00FmAt
    Perhaps you can do a test and share with us? I would do it, but I am not a heavily technical person and wouldn't trust myself to do it right.
     
  14. Pete, raising an exposure by 2 stops in RAW is definitely not a wise idea given the horrendous amplification of shadow noise. I would rather expose properly at ISO 6400 and live with the DR limitations.
     
  15. Wow, thats extremely informative Pete. With that information can I conclude the following? It is not necessary to shoot at a higher speed then 1600 because after that the noise produced by increasing the exposer in APR is equal to the noise produced shooting at the corresponding ISOs. For example you get the same amount of noise at 1600 increased one stop in post as you would shooting at 3200, or you would get the same amount of noise at 6400 as you would shooting at 1600 increased 2 stops in post. Secondly, you would be better off not increasing ISO past 1600 because you would be less likely to clip your highlights. Of course all under the assumption that your shooting RAW. Is that right? This info could make the ISO decision process at receptions much easer.
     
  16. Today I'm gona to test that theory and I will post the images magnified to 100% on this thread.
     
  17. Yes Rocky, you got it.
    To make test shots I would take a tripod, set the camera to ISO6400 and adjust the shutter speed and aperture in manual mode to get a proper exposure. Then shoot a ISO6400 properly exposed, ISO3200 1 stop underexposed and ISO1600 2 stops underexposed by just changing the iso on the camera.
    If you're using ACR you should set black point, recovery and fill light to 0 and use the exposure to raise the exposure (not brightness) for a fair comparison. And disable sharpening and noise reduction.
    I look forward to your test shots!
    Meanwhile have a look at this test:
    http://ishootshows.com/2009/01/28/push-processing-and-unity-gain/
     
  18. Nadine, I read the link you referred to and I think Michael Church is talking about another thing. He is saying that if he dials in +1 exposure compensation he can shoot usable ISO3200 with his cameras.
    Since all camera manufacturers and almost all raw converters don't tell anyone about the inner workings of their product technical discussions are many times fruitless. Sometimes you need both photography skills, post processing skills and certain equipment or software to make something work. So I think it is better to test an idea by doing some test shots and then decide for yourself if it works for you and has any benefits.
     
  19. I shoot Nikon, but in low light vs ISO settings, I feel the best solution is to set ISO higher and get your histogram shifted well to the right (tend to overexpose a bit). The worst solution is to underexpose at lower ISO and then do post process correction. IMHO.
     
  20. There is a very good technical article on the subject here:
    [Link1] and [Link2]
     
  21. Thanks, Pete. I will await Rocky's tests.
     
  22. Rocky--I am curious--why would you need to use higher ISOs at receptions than ISO 1600 anyway, unless you are not using flash?
     
  23. Even with my flash I would still like a little more exposer then I'm getting with ISO 800. I might not need to go as high as 3200 but It would be nice to have a little more faith in those tools if I so need them. I do use a defuser so I lose a little light from my 580. I don't want to shoot too slow because I don't have the worlds steadiest hands. I'm mostly using my 28-105L F4 because it gives me so much perspective freedom. I tried faster primes but I feel it's a real inconvenience for me and my subject to have to walk back and forth in order to get them framed correctly, especially in a crowded reception. I hope I didn't just open a can a worms regarding lens selection.
     
  24. Thanks for explaining, Rocky. The reason I asked is because I actually find that with flash, existing light fixtures blow out really fast if using a really high ISO. I use ISO 800 with flash for receptions unless I'm in a really dark place with low or almost no reflectance, where I'll go up to ISO 1250 or 1600. It helps a great deal to use off camera flash to open up shadows and add reflectance, though.
    You realize that with flash, you freeze subjects with the flash duration so you can use really slow shutter speeds to pick up more ambient, as long as you aren't 'at' the ambient exposure, and about 2 stops under on the ambient.
    See, I don't really see unity gain being that useful for receptions. For no flash ceremonies, certainly. If a correctly exposed frame which was shot above the unity gain threshold looks basically the same as a unity gain threshold shot, re noise, unless the shot had some readily 'blowable' highlights, why would you want to shoot at the unity gain setting and put extra work on yourself for a whole series of shots, in post processing?
     
  25. Ok, this is a series of images that took at different ISOs. 6400 was a normal exposer, 3200 was - 1 stop and brought up one stop in ACR, and 1600 was -2 stops brought up two stops in ACR
     
  26. William Michael

    William Michael Moderator Staff Member

    “Even with my flash I would still like a little more exposer then I'm getting with ISO 800. I might not need to go as high as 3200 but It would be nice to have a little more faith in those tools if I so need them. I do use a defuser so I lose a little light from my 580. I don't want to shoot too slow because I don't have the worlds steadiest hands. I'm mostly using my 28-105L F4 because it gives me so much perspective freedom.”
    I am not sure I am following the problem here.
    Even with a diffuser (like the Fong?), the 580 is a quite powerful tool. If you are inside and provided it is not a coal mine a lined with black velvet curtains and provided you are within shouting distance you will pull ISO800 most of the time and get adequate Flash illumination on the Main Subject.
    The Ambient of a Reception Lounge with Incandescent Lights usually allows a range of Tv, from (approx) 1/8s to 1/60s - using F/4 @ ISO800.
    The lens you have (I assume a typ0) is 24 to 105F/4 L IS USM – it has IS and provided you set the Tv to shoot the ambient about 2 stops under the flash exposure, with the IS engaged on that lens, you should have very few times where the Tv will be so slow, that you will engage noticeable camera shake in the resultant image.
    If you find yourself in a black velvet-lined cave or outside then use a Bounce card and to hell with the little shadows - also do as Nadine suggested and get an off camera cord and use the bounce card that way – that’s what I do.

    ***

    "Have some test prints made so you can see with your own eyes. That's what got me over high ISO concerns. Up to 8"x12" I'm amazed at how good the old 5D looks at ISO 3200."
    Yes, I agree. The proof is in the printing.
    ***
    "Unity Gain"
    "Since all camera manufacturers and almost all raw converters don't tell anyone about the inner worki1ngs of their product technical discussions are many times fruitless. Sometimes you need both photography skills, post processing skills and certain equipment or software to make something work. So I think it is better to test an idea by doing some test shots and then decide for yourself if it works for you and has any benefits."
    I agree.
    And I add that the Proof (result to set your standards by) is still in the Printing even if the final product to the Client is to be viewed on a computer - or even a TV screen - they will not be looking at 100% and even MORE likely is that the TV or Computer has the aspect ratio wrong and colour and contrast will be off, anyway.
    I had already read Clark's essay on unity gain (and also other of his works).
    I have come to believe the "unity gain" is somewhat analogous with the point at which Canon provides “Extension of ISO”.
    I am sure I read a Canon White Paper in which this is alluded to - certainly the photon bucket was discussed, as was Reciprocity at Longer Tv – which I don’t think Clark gets into.
    For those interested, here are the Summary Results for me as a compulsive tester apropos Limit of Maximum ISO to use:
    P5IS (JPEG only) – fine for an 11 x 14 print at ISO 200: http://www.photo.net/photo/11248154&size=lg
    and can squeeze a very good 5x7 print at ISO 800 if necessary: http://www.photo.net/photo/11248155&size=lg
    Underexpose it - and you are history: but still “just OK” for a small print or a small newspaper picture: http://www.photo.net/photo/11248156&size=md

    400D & 450D Play at ISO800 only – ISO 1600 can be OK, but I would rather use ISO800 and squeeze the Tv or Av, if I can. (No samples from these cameras in my portfolio - but there are some in older threads: note to self - put some in a folder for reference).
    20D & 30D: ISO1600 is very good. Can be close to very good at ISO3200 in a 14 inch wide print: http://www.photo.net/photo/10738830&size=lg but the shadows suffer – the black Racing Skins don’t have a lot of detail - I argue that the TYPE of lighting, plays a part in that.
    5D Ditto the 20D and 30D: http://www.photo.net/photo/10442931&size=lg
    And, for fun, shot at ISO3200 then “Exposure +2.7” in RAW: http://www.photo.net/photo/10442964&size=lg is fine at a 7 x 5 print

    5DMkII – only used her for a few hours but what I found was ISO 3200 was as ISO1600 is, on the 5D. I didn’t get a chance to extensively use the extension ISO on the 5DMkII
    ***
    I have found that using ISO 1600 on a 20D, 30D and 5D and pumping the exposure a stop in RAW: - ON THE AVERAGE is not as good as shooting at ISO3200 (“H”).
    Now that might be because of many elements – perhaps the TYPE of lighting I often encounter is one of those factors.
    So after using both methods for many shots for many shots and comparing the outcomes I now set ISO3200 and don’t fiddle as much later in PP or think about “under by one” at the time of shooting.
    There are more samples of "ISO testing" and also testing other stuff "in the field" in my portfolio, here at Photo.net; most of the tests are obvious and self explanatory.
    WW
     
  27. William Michael

    William Michael Moderator Staff Member

    Ok, this is a series of images [using a 5DMkII] I took at different ISOs. 6400 was a normal exposer, 3200 was - 1 stop and brought up one stop in ACR, and 1600 was -2 stops brought up two stops in ACR I just made a flikr slideshow.​
    I was writing as you were posting the results.
    From the images you posted, viewed on my studio monitor: I would have the “ISO6400 N” - it has more punch in the shadows, to my eye.
    I suggest you make test comparisons shot in your “usual” shooting conditions and think about it.
    IMO your one off test, is in line with what I would expect from a 5DMkII and is commensurate with my above summary.
    Maybe I am biased and I was looking for what I found – I am open to that thought also and I am interested in others’ views, in this regard.
    WW
     
  28. I am surprised no one has mentioned that the major reason, in practice, for bumping the ISO is to avoid motion blur.

    It's obvious that flash is an alternative if getting a 'correct' exposure is of primary importance, but there's really not much you can do about motion blur if you prefer natural light and shoot at too slow a shutter speed.

    At the same time, there are all kinds of things you can do about luminance and chrominance noise, as is evidenced and discussed here a lot.

    I used to be hesitant about shooting at very high ISO until I got my 5D Mark II and at about the same time began using PS CS5, which has much improved RAW noise reduction capability.
     
  29. On my D700 at higher isos teh exposure is critical. An iso 800 image can look like an iso 6400 image is underexposed and pushed in post.
     
  30. Rocky,
    from your samples it sure looks like shooting at ISO6400 is the best alternative for you when needed. The only thing that looks strange is that your images have loads of contrast and saturation and the brightness/exposure after correction is not the same. It also looks like you have sharpening and noise reduction active but there is still a lot of noise in these images. All this could screw things up for an apples to apples comparison.
    I'll post some samples from an older Nikon just for reference. They are processed in C1 without noise reduction and sharpening and are highest quality jpeg for best viewing. This camera only goes to iso1600 hence the selection of iso. The iso 1600 shot is exposed to the right and left that way.
    00XrJ5-311531584.jpg
     
  31. And the 100% crops from the black patch in the lower right.
    00XrJ9-311533784.jpg
     
  32. To me, Rocky's test images show exactly what I expected and nothing not already widely known and accepted:
    - way more noise on the ISO1600 image pulled up by 2 stops
    - shadow detail is a lot worse on the same ISO1600 image
    The second point really becomes obvious when considering that any show detail is now being heavily underoxposed which makes it all the more difficult to extract equivalent (to a properly exposed image) detail from it when dragged up in post processing. The opposite of severely clipping highlighst and trying to recover them in post. Think of the dynamic range limitations......
     
  33. Well David, it's not as simple as it may look like at a first glance.
    You see, with the same aperture and shutter speed the sensor receives exactly the same amount of light regardless of the ISO. Then after the exposure the camera reads every pixel and uses the iso to determine how much to amplify the signal in each pixel. The sensor is a linear device so for each ISO increase the amplification is doubled. Then the signal is converted from an analog signal to a digital. That digital information is then written to the raw file.
    At some point of ISO amplification there is simply not more information to gain from each pixel. At that point it wouldn't matter how much you increased the ISO - there is no more information in the shadows to gain. At that point it is the same if you amplify the raw values in the raw converter or if you increase the ISO further. I don't know where that point is on the 5D MkII though.
    It is also a well known fact that camera manufacturers often change the raw values from the sensor before writing them to the raw file. The raw file is already half-cooked so to speak. This is identical to changing the exposure on the raw file. For instance all 1/3rd stop ISO increments on all Canons except 1D series are done this way. The same with some of the higher ISO settings. It used to be that the "extended" iso settings was the fake ones and it would be better to push the raw file but some say that it has changed since the iso race begun.
    But as I said before it is better to try and see what works for you and your workflow than to generalize.
     
  34. Well Pete, it is not as complicated as it may look at first glance....
    Of course at the same shutter speed and aperture the exact same amount of light hits the sensor, but this is clearly NOT the point.The point is that Rocky's image at ISO1600 has 1/4 the amount of light hitting the sensor compared to the shot at ISO6400. Clearly not the same amount of light. The ISO1600 shot is severely underexposed and pushing the limits of the camera's dynamic range. Imagine if it was 3 or 4 stops under and you tried to pull it back in post. The blacks (which when properly exposed are not blacks) would remain blacks as they would be buried below the dynamic range limit and when attempting to pull them up in post you would have massive loss of detail and horrendous noise issues. The exact same applies to the ISO1600 shots at 2 stops under, pulled up in post, just to a lesser extent.
    One just cannot expect to apply the principle of shooting at 2 stops under, for example, thinking you will get the exact same results when pulling it up in post processing compared to exposing the image properly in the first place. The effect of bumping up exposure (in post) on shadow noise is very well documented on this forum and elsewhere, and I am sure the dynamic range issue is clear.
    Just my thoughts...
     
  35. "Rocky's image at ISO1600 has 1/4 the amount of light hitting the sensor compared to the shot at ISO6400." I thought of and typed out my response way too hastily so I need to make a correction my my statement quoted above => The 2 stops underexposed ISO1600 shot has exactly the same amount of light hitting the sensor compared to the nominally exposed ISO6400 shot. Pretty obvious as all you would do after taking the shot at ISO6400 is change the ISO setting to 1600 and leave the aperture and shutter speeds as-is, so apologies for that! All my other comments hold...
     
  36. I appreciate you taking the time to write down your thoughts. You do have to understand though that what I'm sharing in this thread is nothing new. It's in fact well known even I assume you have never heard or read about it. What you are saying is true but only up to a certain ISO. I leave it up to you to decide if you want to further your knowledge or dismiss it as you have been so far. My participation here is for the moment over.
     
  37. Anyway... I thought I would do a quick test myself. The image below shows two crops, both shot at F5.6, 1/100th. The top image is a nominal exposure at ISO6400 and the lower image shot at ISO1600 at 2 tops under and pulled up by 2 stops in RAW. No sharpening, no noise reduction.
    I stand by my earlier comments that the image shot as ISO6400 has better dynamic range and less noise.
    00Xrkl-311881584.jpg
     
  38. That's a good test shot David. You do have a slightly different exposure in your test though. It's because camera manufacturers lie about the true ISO settings and there may be some variation in shutter speed and aperture between shots as well.
    According to dxomark the 5D Mk 2 ISO6400 is really ISO3990 and ISO1600 is 1093. So if I calculated right that means you need pull up the ISO1600 around 2.13 EV or so for the exposures and histograms to match.
     
  39. PS. I can't raise the brightness on the jpeg you posted but if I lower the brightess of the ISO6400 to match the ISO1600 I get this:
    00Xrmv-311933584.jpg
     

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