Accuracy of lens length in Rhino for Mac?


#1

Hi,

I’m using Rhino with different lens lengths to try and preview how much of a set I need to build. Right now with a 40mm lens 30" from my subject a backdrop of 8’ wide, 10’ feet from the lens, covers me. At 12’ from the lens, I need a wider backdrop. So my question is, how accurate are these lens simulations? Does it recreate traditional 35mm lenses? Anyone any experience of this?

Thanks


#2

good question, i am also interested in that. logically for an angle to be calculated one would have to consider the size of the “sensor”. in digital space this can be of course any size including the size of the monitor which then would be ridiculous to compare. i had the feeling that using 50mm on a 24" screen is wider then on a 32" screen… setting the 32" to 35mm has about the same feeling.


(David Cockey) #3

A previous thread about lens length: Lens length for rendering

The Rhino “lens length” is based on the focal length a lens used with standard 35mm film/sensor size of 24 mm x 36 mm which provides the same field of view. For view ports with other than a 3:2 aspect ratio I don’t know if the Rhino lens length is based on view port width, height, diagonal, square root of area or something else…

Equivalent full frame 35mm" is currently, the de-facto standard in photography for comparing focal lengths of different cameras with different sensor sizes. Point and shoot cameras are frequently advertised and even marked with the equivalent 35mm format focal length rather than the actual focal length. Technically, field of view angle would be better because it is independent of format/sensor size but it very rarely used.


(David Cockey) #4

[quote=“RichardZ, post:2, topic:45502”]
i had the feeling that using 50mm on a 21" screen is wider then on a 32" screen… setting the 32" to 35mm has about the same feeling.
[/quote]Rhino does not know what size monitor is being used.

Do you move the 32" monitor 50% further away from you when making the comparison so that your view angle of the screens remains the same?


#5

nope this would also not make any difference, whatever comes from a flat screen does not change the focal length it just becomes linear smaller.

as i pointed out it might just be a feeling, but it was quite evident so that i had to reset the focal length why ever.


#6

a possible way to check:

• use the _Camera command while in perspective viewport (with 4-views showing) which will show the camera in the other three viewports.

• use an online camera calculator to find the angle of view for a particular lens / format.

• measure the angle of the rhino camera.

compare.

?


#7

I think my question has been answered. As I hoped Rhino is basing its lenses on the 35mm film standard, which is still standard where I work, so what I see in the model will be close to what happens when we throw a lens up in the studio. Now my only concern is the aspect ratio I’m seeing. In Rhino for Mac, we have those sliders that hide the toolbars and expand the view, making it wider. It brings it closer to 16:9 on my monitor so I’m going to use that for my final frame reference.


#8

Thanks for the link David!