Question to the V-Ray users - how do you handle the inconstant exposure?


often I render scenes and products from views based on different lens length. But V-Ray 3/4 makes, that the output brightness is dependent from the lens length. This means a tele lens cause a to dark output and a wide angle lens a to bright if the setup was adjusted for a standard lens.

How do you handle this situation? Readjust the exposure for every view? Did I have overseen something?

(At VfR2 I disabled the exposure and the white balance was still usable. At V-Ray Next the white balance is disabled per exposure option. Also at VfR2 I used the color mapping multiplier if I need to adjust the brightness of a complex scene a little bit. This option isn’t available anymore.)


I haven’t tested this before, but what if you use autoexposure?

Last I tested the auto exposure and it didn’t work, since a bright window or a bright wall washer light caused a to dark rendering. I would be strange to use the auto exposure with bad side effects to get right of the bad side effect of the lens length.

Do you use exposure enabled?

I think about to disable the exposure always and spend more time to adjust the light until it’s white adjusted and the brightness correct. Most it’s needed it against unwanted tints of HDRI or to much cold light from the sky. It’s not so comfortable, but what should I do?

But if render an interior some areas get more or less light and adjusting the exposure would help. Now we need the exposure against the lens length side effect too. More work because a to “perfect” real world camera simulation is implemented?

No I don’t to be honest. But once autoexposure is on you can still tweak the lighting. So so thought if autoexposure gives the same visual exposure at different lens lengths, it might work.
For me also this ‘feature’ is useless. Also it isn’t necessarily real world behavior. Some lenses (the better ones) have a constant f-value over the entire zoom range. Do you know the relationship between lens length and f-stop in Vray? How much do you need to correct the lighting? Maybe it’s scriptable to change the exposure slightly according lens length automatically.