Exposure

V-Ray V-Ray for 3ds Max General
1

I have my trusted FotoSharp Day & Night Exposure Guide, but what should work, doesn’t. For example:

Front lit - Sunny Day should be
ISO 100
f/Stop 8
Shutter Speed 500

But, this produces a dark render when using VrayCamera and VraySun/Sky. I have to drop my Shutter speed down to 250 for it brighten up. Now, this isn’t a big deal, but why doesn’t VRay match real world camera settings?

2

because you’re “photographing” shaders, for which the albedo (total reflectivity, or brightness) doesn’t necessarily match your control conditions (unless you scanned the materials in.).
Further, are you under Linear Workflow?
If not, that will also contribute to it all.
Thirdly, it may also be that the preetham model doesn’t exactly match the real sky conditions at your latitude on the given day (or that of the guide, which seemingly doesn’t mention the HOUR of the day, which does change the sun intensity.)

Trust me, Vray DOES match real life conditions pretty damn accurately, IF you are doing it right (for Oblivion, i managed to get the bubbleship to look indistinguishable from the real model, even feeding in the exact make and model of LEDs used for the lights, and counter checking with normalised HDRI probes of the said ship.)

3

I am working in a linear manner, and I am using MAX’s sky system, so the location is accurate. I get the materials, but the VRay sky is dark, too.[quote=“bigbossfr, post:6, topic:45261, username:bigbossfr”]
because you’re “photographing” shaders, for which the albedo (total reflectivity, or brightness) doesn’t necessarily match your control conditions (unless you scanned the materials in.).
Further, are you under Linear Workflow?
If not, that will also contribute to it all.
Thirdly, it may also be that the preetham model doesn’t exactly match the real sky conditions at your latitude on the given day (or that of the guide, which seemingly doesn’t mention the HOUR of the day, which does change the sun intensity.)

Trust me, Vray DOES match real life conditions pretty damn accurately, IF you are doing it right (for Oblivion, i managed to get the bubbleship to look indistinguishable from the real model, even feeding in the exact make and model of LEDs used for the lights, and counter checking with normalised HDRI probes of the said ship.)
[/quote]

4

Firstly it sounds like the sunny 16 rule should work on this occasion which is:
F16
ISO and Shutter speed the same (it doesnt matter what they are as long as they match).

Secondly using an exposure guide is sort of redundant for ArchViz I feel. If it looks good, who cares what the numbers are? The Physical camera is just a way of matching elements that you’ve photographed (a back plate for instace). So unless you’re doing a photo-montage, there’s really not a whole lot of point…

5

Location, maybe.
But what does “sunny day- front lit” means, HOUR-wise?
Quite nothing, and everything, don’t you think?

6

I like the chart because it gives me a baseline, however, I render 32bit so I can pull the light out in the post production.

7

I wouldn’t trust that guide too much because 1/500 even full frontal bright lit is way too low imo. 1/200-1/250 is more realistic (with F8 ofcourse) .

8

http://www.fotosharp.com/day\_night\_exposure\_calculator.html

Here is what I have :slight_smile:

9

a sunny day in miami could be 1/2000, and one in england might be 1/50.

Stop following a rulebook. do a low res test, if it’s too dark, make it brighter. who cares what the numbers end up at.

10

Exactly. Quick test - job done.