Re: [photo-3d] Re: viewers

[Linda Nygren <lnygren@xxxxxxx>]

George, do you know what the focal length is of the replacement lenses
you put in my White Button for me a while back? I think they might be
Revere lenses. I hadn't really noticed much difference between it and a
Red Button, but when I compare them directly it looks like maybe the
image is a little larger in the WB? I do not get the impression of much
difference in the amount of "stretch" on the particular slides I
compared, or of how "immersed" I felt in the scene. The main difference
I am aware of is that I am able to focus the modified WB without my
glasses, just barely. This is not true with the RB. (I am nearsighted.)
Viewing without corrective lenses between me and the viewer is more
"immersive", when I remember to use that viewer and take my glasses off.
I wonder if something like "eye relief" of a particular viewer might be
as important as the focal length of the lenses? (BTW, when comparing
viewers I did this with glasses on.) -Linda

"Dr. George A. Themelis" wrote:
> 
> > Dr. T wrote:
> > >What is the focal length of the lenses in your achomatic Franka
> > >viewer???
> >
> >
> > Darn.  I was hoping no one would ask.  Don't know how to measure it
> > accurately.  I think it was 47mm.  What I can say for sure is that that the
> > view through the Red Button is slightly wider than through the Franka.
> 
> Yes, but the difference is very small and this was my point.
> I suspect your Franka has the 47mm Wollensak lenses.
> The FL of these lenses is 47mm, vs. 44mm for the Realist
> red button.  The difference is very small so I doubt that this
> small difference in FL makes such a difference in viewing.
> 
> George Themelis