Re: [photo-3d] Camera separation in stereo photography

["don lopp" <dlopp@xxxxxxxxxxxxxxx>]

I think Where I get lost is the deviation  of 2.5 mm which is much more than
I can handle . I have never worried about deviatin before and when the Bill
G thing came up I suggested that 18 feet was as close as he could  shoot
with 43mm lenses someone called in and said the correct amswer was 8 feet.
Well I have shot with 45 mm lenses and 18 feet was the closest I could
handle and I have since measured some of my older slides and I was hard
pressd to find any with more than 1.5mm dev. I then made  guage to measure
some more and got the same results--like I said before , mine shood look
awfull flat ,but I have not heard any complaints except for one time when
the closest thing was probably 150 feet. I found plenty , that looked great
with 1mm deviation. Way back when Joel was kind enough  to send guages
around but I didnt take one as I did not see a need for one. Apparently my
mistake. Don. Incidentall my wife says I can go to Messa but I am probably
too late unless Someone is kind enough to share aroom like I have done at4
other conventions where we had 5 to 7 in aroom some sleeping on the floor
which is no problem. This typing sure wears me out as you can see- old age..
Don.
----- Original Message -----
From: "Greg Erker" <erker@xxxxxxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Monday, June 26, 2000 1:03 PM
Subject: Re: [photo-3d] Camera separation in stereo photography


>
> >>Back to basics 101 -- I believe that the 1:30 rule only applies
> >>when using 35 mm lenses Don.
> >
> >  I believe it applies any time the viewing
> >FL matches the taking FL.
> >
> >  I wish John B. were here to make sure
> >I'm not spreading errors, but I'm pretty
> >sure I understand this correctly.  If Tom
> >or George and anyone else wants to correct
> >me feel free.
>
>   I just did some playing with the MAOFD
> spreadsheet that John B. created.  The
> comments say:
>      "Bercovitz & Spicer's formula to limit
>       maximum on-film deviation by limiting
>       stereobase.
>       The on-film deviation should not exceed
>       one thirtieth of the focal length of the
>       stereo system.
>       The effective focal length of the camera
>       lens should match the stereoviewer's focal
>       length."
>
>   So if I use a 35mm lens the desired OFD is 1.17mm
> (35/30). If I use 7' (2.13 metres) as the near distance
> and infinity (999 metres) as the far, the spreadsheet
> says the "maximum allowable stereobase" is 70.4mm.
> Just like a Realist. (Note: this is assuming I am
> viewing with a 35mm viewer lens which most of us
> don't have).
>
>   For a Sputnik the lens is 75mm so the desired OFD
> is 2.5 mm. If I use the same near and far distances
> the spreadsheet gives the max stereobase as 69.9 mm.
> Basically the same as the Realist case. (Note: this
> assumes I am viewing with 75mm lenses).
>
>   Both of these match the 1:30 rule. 30 times 70mm
> = 2.1m which is 7'.
>
>   BUT: if you change my taking FL without changing my
> viewing FL then you get different results.  If I shoot
> with a 135mm lens and still view with the 35mm lens
> my OFD remains at 1.17mm but now the spreadsheet
> gives a max stereobase of 17mm, for the same 7' to
> infinity shot.
>
>   Shooting with a 24mm wide angle lens with the same
> near and far (but still viewing with 35mm) gives
> max stereobase of 177 mm.
>
> My understanding (and I'm willing to be corrected) - Greg E.
>
>
>
>