T3D Re: 1.2mm OFD theory

[John Bercovitz <bercov@xxxxxxxxxxx>]

> Earlier we were presented an example where it required to use a
> 3.6 inch stereo base to get 1.2 mm OFD.  Then we read that you
> might still want to use 2.5 inch base but move the background
> a bit further, so you can still get 1.2 mm OFD.  Seems to me
> that the 1.2 mm target has become an obsession.  So maybe the
> desire for constant "infinity" separation is fueling this.
> But with a close-up and macro, there is no real infinity.
> One could even say that 2.5" separation of the distant points
> on the screen is unatural for a close up.

I don't think anyone is saying that you should attempt to get 
1.2 mm.  Or maybe I misunderstand what folks are saying.  I 
think what's being said is that 1.2 mm is a sort of limit for 
what will be comfortable for almost everyone.  I suggested 
using a 2.5 inch base because that's what I like to do.  I
wouldn't go to a 3.6 base unless it was for effect.  Then I
was trying to say that going to 2.5" base would allow you to extend 
the field out.  I didn't mean to imply that you should extend it,
only that it was there if you wanted to use it.  I do lots of shots
with less than maximum depth.  I think you're supposed to be trying 
to take a good picture, not sit there trying to figure out how to
maximize depth.  I agree that you could say that 2.5" separation
is artificial for macros but I don't think it hurts - vergence
is a weak clue and you are focussing pretty far out when you look
at a screen.

John B


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