Physical Camera Exposure?

[alexthg]

i'm no real-world camera expert, so i'm gonna ask what's the 'exposure' thing really do in vrayphysicalcamera setup? vrayhelp doesn't explain pretty much, it just says "when this option is on, the f-number, Shutter speed and ISO settings will affect the image brightness."

one thing i know is if it turn it off, my render overbrights

[siliconbauhaus]

Its just like a real camera mate. When you go outside to take a photy in the sun you need to adjust your settings. Start with f8 and shutter of 3 - 400 film speed 100 - 200.....and see what happens

[alexthg]

i've tried with f8, shutter 300, ISO 200, exposure ON, and generally it works really well.
But when i turn OFF exposure.... the image blowns out no matter how i change the f, shutter, or ISO...

so, what's its main purpose? when do we need to turn on or off exposure?

[SteveC]

Hi Alex,

I think you should leave the exposure turned on if your using the vray
camera with the vray sun. Below are some decent fstop with their
associated shutter speeds based on 100 iso film speed for external
views only.

You'll need to tweak these slightly, using the shutter speed, get the effect
your after.

I would only play with the fstop if your after some depth of field, 8 should
be fine for most external scenes, you can get depth of field by using
larger lens sizes and by reducing the fstop down, but you will need to
compensate for extra light entering the camera due to the lower fstop by
increasing the shutter speed.

Settings for external camera use based on iso 100 fim speed.

fstop shutter speed
1.0 1/8000 (enter 8000 in vray camera shutter speed)
1.4 1/4000
2.0 1/2000
2.8 1/1000
4.0 1/500
5.6 1/250
8.0 1/125
11.0 1/60
16.0 1/30
22.0 1/15
32.0 1/8

These should give you a decent starting point, but you will need to adjust
shutter speed to get the look your after.

Not sure if ozone and turbidity has any effect on the light entering the
camera, not tried it yet, but if it does you should probably be able to use
a faster film speed to take in to account this.

hope this helps in some way.

stevec

[TRGraphics]

Is it best not to use exposure control for interior or product shots? This is all new to me as well. Cameras are not my thing.

Can anyone recommend a good site to learn about these things?

[SteveC]

Hi TR,

You could try http://www.123di.com/ for their learing software, I found
this really usefull, It's basically a digital photography learning package
that takes you from the basics to fairly advanced photographic
techniques.

I just applied what i learned from this to using the physical camera in
vray. Now we have a physical camera to work with photographic
knowledge is going to be very usefull.

stevec

[alexthg]

i guess we need a new subforum... "photography"

has anyone made a comparison between vraycamera+vraysun/sky and real camera? I mean as a "proof" that they can be used to simulate realworld photo

[Dman3d]

This one is pretty good, cut and dry and explains alot with a camera
simulator to help understand cameras

http://www.photonhead.com/simcam/

[Da_elf]

basically when the exporure s turned on then F-stop and all those things effect the exposure of your image. when its turned off then f-stop and all those things will effect DOF and other things however NOT the exposure. when its off you would need to manually calibrate your lighting to give a good image like how you would do before you had the camera

[alexthg]

so, when i turn OFF exposure, vrayphysicalcamera exposure = standard max camera exposure? CMIIW pls

[plastic_]

with my nikon i use either Aperture priority or Shutter priority, depending on the DOF i want, or depending on the max. shutter time i need for a sharp picture.
the camera basically does all calulations for me.
now i got a physical vray camera i have to adjust manually. that seems a bit backwards.

[Neilg]

now i got a physical vray camera i have to adjust manually. that seems a bit backwards.

Not really. Its the manual mode, shutter and ap priority are dependant on your cameras built in light meter - For a light meter to work, it needs to judge it from the rest of the scene.
Theres a small chance it could be implemented on a basic level, but it'd need to render it first to figure that out, and I dont know how the dynamics of light changes through the physical camera so it could get thrown off and be useless for anything but fine tuning anyway.

Suck it up and start using your manual mode anyway, you've got a good excuse to now.

[Da_elf]

i hateed that priority crap. my camera has those and doesnt have any manual mode. so its always trying to give me a balanced image which sucks since i cant do HDRI's with it since when i lower f-stop the damn thing will correct on shutter speed

[plastic_]

i hateed that priority crap. my camera has those and doesnt have any manual mode. so its always trying to give me a balanced image which sucks since i cant do HDRI's with it since when i lower f-stop the damn thing will correct on shutter speed

yeah well making hdri's is a very special situation.
for making photos, i never ever had to use manual mode (of course digital SLR's have manual mode). and i can't imagine using manual mode without a light meter, etc.
i don't like trial&error (test-renders) to find the right exposure settings.

[Neilg]

for making photos, i never ever had to use manual mode (of course digital SLR's have manual mode). and i can't imagine using manual mode without a light meter, etc.
i don't like trial&error (test-renders) to find the right exposure settings.

Youve lost me. To be able to set the priority of something the camera needs to know how much light is in the scene, which with the physical camera would basically amount to a test render - it would do exactly the same thing as the manual trial and error method.

Any priority setting is just the cameras interpretation of its own light meter, taking this into 3d all it would do is take away more control from you which I dont understand why you'd want. Isnt the point of the physical camera to have more control?