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-   -   formulae used in stereo calculators (https://www.dvinfo.net/forum/3d-stereoscopic-production-delivery/511466-formulae-used-stereo-calculators.html)

Giles Stokoe October 17th, 2012 02:45 PM

formulae used in stereo calculators
 
I have searched high and low for a formula that will allow me to calculate max stereo base from a bunch of known variables such as nearest object distance, furthest object distance, lens focal length, film size, print/projection size... basically all the things that the Mistika Stereo 3D Calculator uses ( SGO Mistika Stereo 3D Calculator | SGO Mistika ) but I cannot find anything that comes close. Everything refers to focal length of viewers, or depth of field of lenses or other such stuff left over from days of yore.

I am not, however, concerned with roundness in this case.

I have the Mistika calculator, but surely the formulae that this and other modern calculators are based on must be out there somewhere?

Wolfgang Schmid October 21st, 2012 08:31 AM

Re: formulae used in stereo calculators
 
Stereo Maths: Bercovitz formula and spread-sheet

Roundness in a stereo image

Giles Stokoe October 21st, 2012 12:35 PM

Re: formulae used in stereo calculators
 
Thanks for that. Oddly, i had not come across that particular page on the nzphoto.tripod site, though I have been looking at many others.

Slightly don't understand the following quote though:

"The media (CCD Chip etc) is hidden inside your tiny digital marvel and you usually have no idea how big it is. MAOMD becomes a big problem. So forget it: use 35mm equivalent measurements. The images from all cameras are enlarged to a consistent size for viewing and so the actual on media measurements do not matter. only the ratio of media size to lens focal length is important. In other words, we are only interested in the camera field of view"

Surely this is not right... using (for example) a 50mm (equivalent) lens with a less than 36mm width CCD, you would get more deflection on the CCD because it is smaller than the 35mm film (i.e. the lens is operating as if it was longer than 50mm focal length), and then to cap it all you would be multipying this deviation up more than for 35mm to get to the size you are going to print/display at. That is to say, you are (effectively) using a longer lens AND multiplying this error up to reach your enlargement... so you cannot just 'pretend' you are using 35mm and hope that not knowing the effective focal length of your lens and the size of your CCD will just magically disappear?! (The Mistika specifically asks you what format you are shooting on).


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