[MF3D.FORUM:431] Re: fl/30

["Bill Glickman" <bglick@xxxxxxxx>]

Greg

        That makes sense, if your right, sure will simplify our lives!!  :-)
thank you

Bill G


----- Original Message -----
From: Greg Erker <erker@xxxxxxxxxxxxxx>
To: Medium Format 3D Photography <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Friday, April 07, 2000 7:54 AM
Subject: [MF3D.FORUM:424] Re: fl/30


>
> >    But the question that arose earlier.....that is still not clear to me
is
> >this.... if your formula is accurate than I guess the answer to the
> >deviation question must be..... the deviation does not change even when
the
> >fl of the camera lens is increased or decreased.  A few posts ago, it was
> >suggested that when you double the camera  fl, you halve the deviation?
But
> >on the other side of the coin, when you go to shorter fl camera lenses
you
> >should never go below 2.7 deviation. When using longer fl lenses this
logic
> >appealed to me, hence why I am pursuing this one till the bitter end :-)
>
>   If you are always viewing with the same lenses
> then you want the on-film deviation to be unchanged
> (2.7mm for MF w/ 80mm viewer lenses) when you change
> taking lenses.
>
>   If you are changing the viewing lenses to match
> the taking lenses then the OFD (in mm) needs to scale so
> that the angular deviation you view remains unchanged.
> So if you take with a 50mm lens and then view your
> MF with a 50mm lens you need to scale the 2.7mm OFD
> to 1.7mm to avoid eyestrain due to excessive angular
> deviation when viewing.
>
> My understanding - Greg E.
>