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Real f-stop measurements in a depth of field


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If I try to use a real life measurement for a camera f-stop lets say of 1.5 with with my camera 6M away from the target focus with a aperture of 24.89, according to the houdini's manual this should be a default of a 35mm film, I get a very deep depth of field comparing to a real life camera it seems that f-stop in houdini is not a physical accurate number is that correct? If so is there a way to match it to the real camera's f-stop values? 

Edited by Mzigaib
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If I try to use a real life measurement for a camera f-stop lets say of 1.5 with with my camera 6M away from the target focus with a aperture of 24.89, according to the houdini's manual this should be a default of a 35mm film, I get a very deep depth of field comparing to a real life camera it seems that f-stop in houdini is not a physical accurate number is that correct? If so is there a way to match it to the real camera's f-stop values? 

 

Would totally depend on the focal length of the lens. A 135mm lens @ f2 focused 6m is going to have a really thin DoF with only around 15cm of depth actually in focus. A 24mm @ f2 focused 6m is going to have ~5.6m of depth in focus.

 

Also just to make sure you've got the names all right here, the 24.89 is the aperture of Super 35. "35mm film" as we think of it in the context of a DSLR has an aperture of 36.

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Thanks for the tips guys I'll try to do some tests with those tips I'll let you know.

 

My only question is, since I don't remember seeing anything like this in the manual how did get the number 36 for the DLSR 35mm sensor?

 

Cheers!

Edited by Mzigaib
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My only question is, since I don't remember seeing anything like this in the manual how did get the number 36 for the DLSR 35mm sensor?

 

The sensor size on full frame DSLR is 36mm x 24mm which is what 35mm film is (or number 135 film). Houdini is looking at the horizontal size for the aperture.

 

https://en.wikipedia.org/wiki/135_film

 

Houdini default is based on this.

 

https://en.wikipedia.org/wiki/Super_35

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