[tech-3d] Re: Stereo base calcuations

["Michael K. Davis" <zilch0@xxxxxxxxxxxx>]

Don,

I ran your base calculation examples through the General Solution used by
Bercovitz and others, to see what deviations they would produce.  

Here's what I got:

 75mm lens with a 1-ft base,  75-ft Near and 3000-ft Far:  39.1% of MAOFD
100mm lens with a 1-ft base, 100-ft Near and 3000-ft Far:  29.1% of MAOFD
135mm lens with a 1-ft base, 135-ft Near and 3000-ft Far:  21.3% of MAOFD

So, the longer your lens, the less OFD you produce, using this approach,
and you're right - your images would all have less than maximum stereo effect.

Your method is very interesting and I can tell you are able to predict the
results you'll get as long as your subject distances match the
circumstances you describe.  When they don't, I suppose you are able to
interpolate the base, relying on your experience.

Thanks for sharing it!

Mike


>Date: Fri, 1 Dec 2000 22:39:19 -0800
>From: "Don Lopp" <dlopp@xxxxxxxxxxxxxxx>
>Subject: Re: Digest Number 36
>
>To Mike Davis reguarding stereo base- or 20 plus years I have been using a
>simple way of figuring out the stereo base for taking hyper scenics. For a
>135 mm lens I figure that the base of one foot gives me stereo depth of 135
>feet to infinity or five times 135  gives me a stereo depth  of 675 feet to
>infinity. For a 75 mm lens , I figure a one foot base gives me  a stereo
>depth of from  75 feet to infinity. For a 100 mm lens, a one foot base gives
>me a stereo depth of 100 feet to infinity and so on. For a 100 mm lens I
>figure that infinity is any thing past 3,000 feet, or 30 times the near
>point. I dont try to maximize the stereo effect in my pictues as some of  my
>best ones have a deviation of less than one mm. My mental state because of
>my use of methadone and morphine is such that I can not handle any thing
>very complicated and it has been some 6 months since I have been able to
>take any serious scenics-may be next year ? DON
>



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