formulae used in stereo calculators at DVinfo.net

Giles Stokoe · October 17th, 2012, 02:45 PM

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

Stereo Maths: Bercovitz formula and spread-sheet

Roundness in a stereo image

Giles Stokoe · October 21st, 2012, 12:35 PM

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).

October 17th, 2012, 02:45 PM	#1
Giles Stokoe Tourist Join Date: Oct 2012 Location: Chillac, France Posts: 2	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?

October 21st, 2012, 08:31 AM	#2
Wolfgang Schmid Regular Crew Join Date: Apr 2005 Location: Vienna/Austria Posts: 152	Re: formulae used in stereo calculators Stereo Maths: Bercovitz formula and spread-sheet Roundness in a stereo image __________________ Kind regards, Wolfgang http://videotreffpunkt.com http://www.vegasvideo.de/forum

October 21st, 2012, 12:35 PM	#3
Giles Stokoe Tourist Join Date: Oct 2012 Location: Chillac, France Posts: 2	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).