CG Exposure or not - what is the difference?!

[olika]

After reading a lot about this and testing a lot for myself i get more and more unsure/confused about the right settings when using a vrayphyscam with exposure.
For example: I have a studio scene with 1-2 lights. So i could use exposure and turning my lights way up to get a *balanced* ( with *balanced* i mean that when u you use override grey material, the result in the render should someway be that same gray value).
With that technique i am always unsure what the right value for the light will be in comparison with the exposure of the cam. I.e. Lights too low, and exposure really long or otherwise. I always have the feeling that in the end i have a scene with every setting out of balance!
Another way is not to use exposure and have the light values between 0,5 - 2 (or use inverse square falloff too but also without exposure) to get a balanced render. So you balance the lighting only with the lightvalues.
So the question is: where is the difference between those two techniques in the visual endresult? And when i use the physcam with exposure what are *normal* lightvalues?
I am a little bit afraid that i miss something and the question is more or less stupid. But hey, there are no stupid questions so i just dare to ask this
Greetings from Germany

[thablanch]

For studio setup, mabee it is not that usefull.. as you said, you have 2 lights to controll with "random" values.. so ain't that much of a deal.. When it gets to interiors, taht is a life saver. When you have a floor with hundreds of ies lights, skylight, fill lights and so on, it is way more efficient to play with the camera exposure. Lets pretend you setup a view, and everything is perfect.. and after that, you want a view from an other angle, but that one is a little off, or lets say darker. You do not want to play with your lights, as your lignting was perfect, and if you have to re-render that first view, you do not want to re do it all over again..

So I guess that is all depending on your workflow. For studios setups, I agree that you can live without it.

Also, if you light with known lumens ( lets say to match a photo studio setup), well exposure is more rational as a work method...

[olika]

Thanks first for your fast feedback!

what you wrote make totally sense to me. I didn`t thought about the worklow problems you get with many lights in the scene at all. And of course you are right, what could be better to change this with just the camera settings .
But how about some technical aspects like the light distribution and so on. Is it just a workflow thing or are there technical differences in a way that you can do something with a exposed camera that you can`t do without it? (except saving time changing hundreds of lights). Because those things like inverse square falloff and such, we all can do that in 3d without exposure, right?!
Maybe the first step for me would be to check the technical things at ERCO Light Distributor or so, what Lumen has a normal downlight etc. ?! Because despite the workflow improvements i am not sure how intense those interior downlights should be... 10-100-1000...?
My sorrows just are, that in the end you have a scene with lights way to bright (or way to dark) and you try to go against it with some "unnatural" camera settings, maybe it will render correct in the end but with way longer rendertimes or more noise?! Is this the case?
Greetings

[Neilg]

There is no difference between powerful lights and a low shutter and dark lights/long shutter. Do whatever you want, so long as it looks good it's right (regardless of what photography convention it may break)