vray physical camera and 3ds max system units

#1

Hello there,
I need some help with the vray physical camera and how it relates to the system units in 3ds max. I’m working with a scene where both the display and system units are set to centimeters/1 unit =1.0 centimeters. FWIK:

Film gate - specifies the horizontal size of the film gate in milimeters. Note that this setting takes into account the system units configuration to produce the correct result.

Focal length - specifies the equivalen focal length of the camera lens. This setting takes into account the system units configuration to produce the correct result.

So if I drag a camera in one of the views it comes set to the default values of Film gate=36 and Focal length=40

I assume that since I’m working in centimeters /system and display units/ I need to change this values accordingly to Film gate = 3.6 and Focal length=4.0 ? Is that correct?
I also think that working in centimeters affects the f-number values too?

Light units are set to international btw.

#2

It says (mm) in the physical camera film gate and focal length. So it is always in millimeters. “Takes into account” means that you don’t have to change it yourself whenever the system units change.

Maybe you should’ve posted this in the 3ds max forum?

#3

Thanks for your reply. Wasn’t sure where to put it because the vray physical camera and the lighting are related. I had very different answers and opinions about this question.

My understanding is that the focal length and film gate are meant to be in mm, so if your system units are cm you need to change the values:
for example - 35mm focal length should be set to 3.5 cm and if you have for example film gate that is 40 it should be 4.0 cm. The other values – are not directly dependent on system units their are related to the focal length and film gate but not the system units.

Still not sure about it, but that’s what I think it should be.

Btw Can I repost this in the 3ds max section or I should leave here? I don’t want to flood the forum…

#4

This is a quote from Vlado, who works for chaosgroup (vray) from their forums:

What is meant in the V-Ray documentation, is that the focal length is always specified in millimeters, but V-Ray will take care of converting this internally to the current scene units.

If you have access to the chaosgroup forums, the thread can be found here.

#5

Ah… finally, no more doubts about it. I can’t thank you enough for this, ebee, had so many different opinions on that - it got me very confused. Wasn’t able to find it myself… googled it for weeks LOL…
:bowdown:

#6

Here’s a test scene /modeling is done in 3ds max 2012 and rendered in Vray 2.0/
Few IES lights and a Vray sphere for the floor lamp, there’s a bluish vray-dome light coming from the right through a window /the window is not visible here though/
nothing special…

Thanks again!

#7

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