Camera match a 90 deg rotated camera

[tomorrow_ab]

Hi, here's a camera match question:

I have a photo taken with a camera with a 36 mm film gate and a focal length of 24 mm. (Canon 5D Mark II)
The photo however is taken with the camera rotaded 90 degrees.

How do I translate this into a new film gate and focal length in the V-Ray Camera?
I'm guessing 24 mm film gate, but what about the focal length?

[Joelaff]

Rotate the Camera object? Parent it to a dummy and animate the dummy...

(OK,. That doesn't work too well.. Nevermind

[Morne]

I dont see why it should make any difference that the camera was rotated 90 degrees. If you then went and rotated the resulting jpg, then just render portrait instead of landscape with the same film gate and fov you would use when the camera wasnt rotated 90?

[peterguthrie]

I think with a standard max camera you can switch between horizontal fov and vertical fov. According to a table here: http://en.wikipedia.org/wiki/Angle_of_view a 24mm lens has a horizontal fov of 73.7 and a vertical fov of 53.1 so maybe try typing in 53.1 into the vrayphysicalcamera fov? (fov of 53.1 equates to 36mm...)

I just did a camera match like this and it turned out well (with a 24mm lens too)

[Joelaff]

This work fine if you keep the frame aspect landscape (i.e. your render is landscape). However, it looks sideways in the viewport...

If you make the frame aspect portrait then your film gate and focal length (and even FOV) will change because VRay uses the horizontal film gate and horizontal FOV.

Multiply your focal length by the image aspect in the render dialog (after you make it vertical).

So if your film gate was 24mm high x 35mm wide for landscape and you were rendering to 2400px high by 3600px wide...

then duplicate your camera.

Make the new camera have a 24mm film gate

then change the frame size in the render dialog to 2400 wide by 3600 tall

Read the Image Aspect (0.66666 in this case).

Multiply the focal length by this number. Now you should have the same horizontal FOV.

[Joelaff]

Note that for it to be like a real camera, though just setting the frame size portrait and setting the gate size to 24mm (or whatever the vertical gate size WAS) works.

A real camera does not change the magnification/FOV when you rotate it.

[grantwarwick]

Note that for it to be like a real camera, though just setting the frame size portrait and setting the gate size to 24mm (or whatever the vertical gate size WAS) works.

A real camera does not change the magnification/FOV when you rotate it.

This is the best and "only" way I could ever imagine achieving this lol

[tomorrow_ab]

Thanks for the answers, I didn't get to try this since the client changed to another photo which was landscape.
I will try a standard Max camera next time.

[Sketchrender]

May I ask a simple and may be a silly question.
Why isn't a 24mm lens and 24mm lens in max and vray when a full frame camera is used.
?

[Dave_Wortley]

Here's a quick demonstration of the correct way to have a portrait camera and an incorrect, spot the difference, and compare with the landscape camera to see why it's correct. I unfortunately can't share the powerful script we have for doing this properly, but it's pretty simple math.

[peterguthrie]

Dave, for the standard camera, isnt it just a case of noting the horizontal FOV and then putting that value into the vertical FOV or vice versa?

[Dave_Wortley]

Yes that works but there isn't a way to do that for Vray cameras, so we have a solution which works on both Standard Cameras and Vray Cameras.

[Neilg]

Yes that works but there isn't a way to do that for Vray cameras,

You can match vray cameras to standard cameras, so this doesn't matter.

[Dave_Wortley]

You can match vray cameras to standard cameras, so this doesn't matter.

Except there is a difference with how Vray Cameras and Standard cameras operate with FOV, Vray Cameras adjust FOV for focus depth (which annoys me).

[Neilg]

edit: nevermind