High ISO noise vrs underexposed noise

<p>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? </p>

 

<p>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.</p>

<p>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? </p>

 

<p>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.</p>

<p>If I recall correctly from when I shot Canon (5D, 5DII), the 5D was pretty good to around 1600 and the 5DII to 3200.</p>

<p>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.</p>

<p>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.</p>

<p>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 <strong>all night long</strong>. I might shoot some with flash and some without, but not the entire thing.</p>

<p>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.</p>

<p>Thanks for everyones advice. This community has been invaluable to me</p>

<p>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.</p>

<p>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:</p>

<p>http://www.bellissimaphoto.co.uk/?p=811</p>

<p>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.</p>

<p>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!</p>

<p>"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 <strong>all night long</strong>. I might shoot some with flash and some without, but not the entire thing."</p>

<p>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.</p>

<p>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.</p>

<p>According to <a href="http://www.clarkvision.com/articles/does.pixel.size.matter/#Unity_Gain">this author</a> 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).</p>

<p>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.</p>

<p>If you shoot raw this could be used to your advantage in some situations.<br>

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.</p>

<p>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.</p>

<p> </p>

<p>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.</p>

<p><a href="00FmAt">http://www.photo.net/wedding-photography-forum/00FmAt</a></p>

<p>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.</p>

<p>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.</p>

<p>

<p >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. </p>

</p>

<p>Today I'm gona to test that theory and I will post the images magnified to 100% on this thread.</p>

 

<p>Yes Rocky, you got it.</p>

<p>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.</p>

<p>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.</p>

<p>I look forward to your test shots!</p>

<p>Meanwhile have a look at this test:<br>

http://ishootshows.com/2009/01/28/push-processing-and-unity-gain/</p>

 

<p>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.</p>

<p>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.</p>

<p> </p>

<p>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. </p>

<p>There is a very good technical article on the subject here:<br>

[<a href="http://www.clarkvision.com/articles/digital.sensor.performance.summary/index.html">Link1</a>] and [<a href="http://www.clarkvision.com/articles/index.html#part_4">Link</a>2]</p>

<p>Thanks, Pete. I will await Rocky's tests.</p>

<p>Rocky--I am curious--why would you need to use higher ISOs at receptions than ISO 1600 anyway, unless you are not using flash?</p>

 

<p >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. </p>

 

<p>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.</p>

<p>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.</p>

<p>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?</p>

<p>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</p>