Help with ETTR Please...

Colt4570 wrote in post #16647262
Just for a quick clarification, I'm assuming, ideally you would use shutter speed or aperture to get the desired ettr histogram (stacked to the right without clipping). And only use ISO to accomplish it, if you had to. Or am I totally missing something, and changing the ISO is the "normal" way to get ettr? Thanks.

It will depend! If the increased noise caused by the increase in ISO is LESS than the reduction in noise gained when pulling the image back down in post, then you should up the ISO to maintain shutter speed/aperture where you want them to be.

Specifically for CANON DSLR sensors it has generally been found that this is the situation for the "Hardware" ISO values. So the full stop ISO values outside of those marked H or L (also known as the extended ISO ranges).

When it comes to the third stop intermediate ISO values, the +2/3rd stop ones normally offer the lowest noise. However you do lose 1/3rd of a stop of DR. This is because for the 2/3rd values the image is actually exposed with the next highest full stop ISO and then the image is digitally pulled back by 1/3rd of a stop in the camera.

If you are shooting in camera JPEG this is good as it is effectively giving you 1/3rd of a stop ETTR. If however you are shooting RAW, then you are much better off using the full stop ISO value and managing the ETTR yourself, you will have much more control, and the full DR of which ever ISO setting you are using. The in camera 1/3rd stop "pull" is pretty much applied linearly across all of the tones. When you do it yourself in post with a RAW file you have the possibility of applying the "pull" nonlinearly, generally you are more likely to pull the highlights much more than the shadows, enhancing the shadow detail without having to boost them, which would otherwise add noise to the shadows.

Once you run out of base ISO and shutter speed/aperture then you have no option but to digitally boost the signal. Be that in camera by using the expanded ISO settings, or simply underexposing and boosting the brightness in post. This will of course soon add lots of noise to the image (especially in the shadows) but it is at this point the only option you have, unless you can somehow add more light to the scene. So you either take the noise hit or put the camera away.

Alan

That was a good group of feedback and some good advice, the last paragraph by Alan kind of sums ups what i was getting my head around - eg - Outdoors widest aperature, slowest shutter speed for the subject, +1.5 stops of EC and already at 400Iso where the camera starts to get quite noisy, probably a different scenario if your camera can go upto 1000 Iso without seeing any noise.


P.

Thanks for the explanation BigAl007!

I've also read about base ISO's being different for different brands and models. Does anyone know what the base ISO's are for the 7d and the 5d3, and whether 1/3 or 2/3 stops are best for less introduced noise?

ie... iso 160 being rumored to be better than iso 100.

Colt4570 wrote in post #16647712
Thanks for the explanation BigAl007!

I've also read about base ISO's being different for different brands and models. Does anyone know what the base ISO's are for the 7d and the 5d3, and whether 1/3 or 2/3 stops are best for less introduced noise?

ie... iso 160 being rumored to be better than iso 100.

Me too ^ but for me my nikon d200, i cant find info on native-good Iso's any where on the net.

P.

Colt4570 wrote in post #16647712
Thanks for the explanation BigAl007!

I've also read about base ISO's being different for different brands and models. Does anyone know what the base ISO's are for the 7d and the 5d3, and whether 1/3 or 2/3 stops are best for less introduced noise?

ie... iso 160 being rumored to be better than iso 100.

The base ISO to +2/3rd value ISO question is apparently the same for all the Canon manufactured CMOS sensor chips, including my two cameras (300D & 20D), as well as your two cameras. The specific noise levels will be different between the different sensors, but the relative noise levels are about the same for each step of ISO.

The ISO setting with the LOWEST noise is indeed ISO160, and then the 1 stop multiples of that setting, so 320, 640 etc. However that is achieved by exposing with the sensor electronics set at ISO 200 (or 400, 800 etc) and then a simple 1/3rd stop reduction in brightness is applied digitally in camera. So although this has less noise it has 1/3rd of a stop less DR than the ISO 200 shot.

Now if you are shooting IN CAMERA JPEG IMAGES then this is the closest that you can come to shooting ETTR and will give you the cleanest images.

So SHOOT JPEG go ISO 160, 320, 640 etc.

Now if you are shooting RAW you have a choice. Shoot ISO 160 and allow the camera to apply a 1/3rd stop ETTR for you with no control. OR shot ISO 200 and do your own pull in post processing where you have full control of how you want to apply the changes to the different tones in the image. Now the ISO 200 shot pulled 1/3 will have the same noise as the ISO 160 shot.

So SHOOT RAW go ISO 100, 200, 400 etc

So far we have not really mentioned ISO 100. If we shoot at ISO 100 and apply the same -1/3 rd stop pull in post processing then the image will actually be even cleaner than the ISO 160 shot was. We are starting with a cleaner base ISO after all, ISO 100 is cleaner than ISO 200. Infact some Canon cameras have an L ISO setting to give ISO 50 and effectively a full stop of ETTR for JPEGs.

So always shoot at the lowest ISO you can, but ETTR and NEVER NEVER UNDEREXPOSE. If you need more ISO to keep the histogram over to the right then that's fine add it as long as it is a base ISO value and you are shooting Canon.

If you shoot another make to Canon then you will need to experiment to see if the amount of noise added by upping the ISO is less than the amount of noise removed by pulling the image in post. This may well NOT be the case for older Nikon CCD sensors such as in the D200.

Alan

So you could say if i want to use higher Iso speeds with my ccd sensor d200 - im screwed- sell it and get a cmos camera?


P.

Pagman wrote in post #16648399
So you could say if i want to use higher Iso speeds with my ccd sensor d200 - im screwed- sell it and get a cmos camera?


P.

No just be realistic in your expectations of your cameras performance. You do not have the latest camera nor the the best of lenses. Your circumstances preclude you getting anything better either, just like mine. I'm sorry but you will have to accept that what you want to photograph pushes beyond what your equipment is capable of, so go find something else to photograph that is within it's capablities. Although I love aviation photography I am normally only able to go out and shoot it two or three times a year these days so I put up with that and either photograph other stuff, or not use the camera as much as I would like.

Constantly trying to exceed your and the camera's capablity is like banging your head on a brick wall, eventually you will get tired of the dull squishy thud and try something else. Unfortunatly I think even a 1Dx and 600 L would disapoint you, as much of what you are trying to do is beyond even that combinations capablity. I am not trying to be rude, but sometimes reality is not as pleasant as we would like.

Alan

Thanks again for the detailed info Alan. Much appreciated.