How do you go about Exposing VRayCam?

[Morne]

If you don't have SolidRocks, VRayRT, or Lele's exposimeter, then how do you go about getting the correct exposure for your renders? I mean do you set it more or less like a real world cam, hope for the best, render, then set it again, render, etc?
Is there some kind of formula to follow not to over or under expose? I mean besides judging it by eye?

[Brian Bradley]

If your lighting has followed a 'Physical' base setting then Real World exposure settings
definately make a good starting point.

Regards
Bri

[wxyz]

Big problem with Max2011 even if you try to use SolidRocks or the Matrix Exposimeter

[JeffG2]

What's the problem???

[glorybound]

Tweak it until it looks good. I bought a couple books on cameras and exposure to understand the basics. I start with F-Stop of 8, Shutter Speed of 100, and ISO of 100. If my scene is to dark I can raise the ISO, lower the Shutter Speed, or lower the F-Stop.

I haven't found a way to mimic real world. I think I should be able to look at a photo and see what camera settings they used and recreate the scene, but it doesn't seem to be that way. In Adobe Bride I can see the F-Stop, ISO, and Shutter Speed, but If I punch in those number I don't get favorable results. In MAX I can set the lat/long, day, time of day, and camera settings, which should give me the results of the photo, but it never does. I usually scrap the science of it all and do what looks good.

[JeffG2]

I just did a test with a NikonD60 and a 60w bulb on a table in a dark room.

I bracketed several shots and recreated the scene in Max (LWF) with a photometric light and camera settings I got from the D60.

The match was very, very close.

[Morne]

can you post the comparison?

[samuel_bubat]

When will people realize that if you want really a physically correct rendering, you´ll need Physically correct materials in the first place.
Maybe some will remember reflectance and transmitance values from radiosity rendering, where you would have an index like IOR for
different materials. You would need somethin similar within Vray, too.
I had a discussion about this on the area forums with a guy, who told me that he has to measure each an every material in realworld first.
So unless you do that, physically correct rendering with sun, sky and physically camera is pretty much pointless.

Like glorybound said, tweak until it looks good. But if you go that way, working with non physical cameras/exposure is much easier,
because you can get results a physical camera can´t do. I so often see, read people using physical camera/sun setup but than use
dummy lights to brighten up dark areas of a room for example. Or they use physical exposure and afterwards gamma correct their image
wich is below the line nothing else.. than adjusting exposure. I for my part completely stopped using anything physical, because
it´s much more unflexible than using reinhard color mapping (exposure)/ overbright default lights.. for example.

edit:
http://area.autodesk.com/forum/autod...tions-with-gi/

To get physically correct reflectance values, I have been using measurements from a colour measuring device; and making sure the RGB values are in a linear colour space before inputing them into Max. Of course, without very expensive tools for measuring specularity etc. this can always only be an approximation.

[Sawyer]

The other part of this conversation is that architectural photographers always use fill lights to light a space. It seems to me that most renderings want a photographic style of image not a camera placed in a room. To create attractive imagery a photographer has lots of tricks that are much more limited by real world physics than we as illustrators are bound by.