[acquiesse]

This is getting confusing I thought 35mm film is called that way since it's 35mm wide. Why would you use a bigger filmback than 36x24mm (the size of the picture on 35mm film), if you're using 35mm film?

Hi,

I had a read of the website referenced above, it seemed to suggest that it isn't a question of having a larger filmback, but rather a smaller one.

Due to the fact that there is image from the lens is circular and that there is distortion at the edges of a lens, the image is cropped...

As I understand it, it maybe that some camera's crop more than others? I might have misunderstood!

[mverta]

Yes, camera crop, and the resultant "35mm-equivalent" stuff is a whole other aspect. But I was referring to the direct relationship between filmback and focal length, whether it's smaller or larger. Either way, it affects the field-of-view for a given focal length.

_Mike

[joshh]

For 35mm film a 50mm lens is considered normal and is also the diagonal measurement of a 35mm frame, so a simple rule of thumb for the film size to focal length ratio is to have the diagonal measurement of the film frame roughly equal to the lens focal length.

[adamwade]

Mihai is correct. Assuming the lenses on the 5cmx5cm and 35mm cameras are the same focal length.

Put a 35mm film back on a 5cmxcm camera with 50mm lens and you will get the same image as a regular 35mm SLR with a 50mm lens.

[mverta]

I don't think that's what he was saying... when you talk about putting a different filmback on a system, the system is making use of the entire filmback, not exposing just a "portion" of it, unless it's a special rig. I was saying that in some theoretical situation where the film is floating in the gate, then whatever the actual gate full size is, is the film back, regardless of what actual strip of emulsion is in there.

People should be well confused by now

_Mike

[Q2]

I am!

Q! Berlin

[mverta]

In terms of working with Maxwell - you simply have to know that how "wide angle" or "telephoto" your camera view is depends not just on what your focal length is set to, but ALSO on what size your filmback is.

If you set your camera to a focal length of 27mm, you will see a very different image with a filmback size of 36mm x 24mm than with a filmback size of 28.7mm x19.1mm, for example, even though in both cases you still are using a 27mm lens (focal length).

In the real world, all this affects the depth-of-field of the image - it does in Maxwell, too - but unlike the real world, with Maxwell you aren't restricted to a certain range of depth of field depending on the camera/lens. You can have as much or as little DOF as you want, no matter what size filmback you use or what focal length you use.

HOWEVER... I can not recommend strongly enough, for photorealistic renders, that you Google your favorite digital camera, find the sensor size, enter this as the filmback, and then use real-world focal length ranges, AND real-world f-stop settings (that's what controls depth-of-field).

The more you replicate real camera settings, and the more photographically you approach the renders, the more photographic they tend to be.

_Mike