Dual Focusing Mechanism

[Dan Fromm]

If I'm not mistaken the stereo microscope I use in the lab - Leica SZ 12.5 -- has only coarse focus. The cheap Unitron stereo 'scope I use at home also has only coarse focus. The Leica goes up to 50x (it has an 0.5 supplementary lens), the Unitron to 60x with a 2x supplementary, and neither is hard to focus.

If fine focus were needed, I'm sure the Leica would have it.

[Bernice Loui]

Majority of Stereo microscopes do not have fine focus. Exceptions, few of the Zeiss SV and Stemi series, Wild-Leica M420 series and very few others. Fact is at 50X fine focus is not really needed. On microscopes with MUCH higher magnification, fine focus becomes a must have.

Difficult to see the real world need for "fine focus" on a view camera.

BTW, nothing "cheap" about Unitron microscopes, they are often very good for what they cost.


Bernice

If I'm not mistaken the stereo microscope I use in the lab - Leica SZ 12.5 -- has only coarse focus. The cheap Unitron stereo 'scope I use at home also has only coarse focus. The Leica goes up to 50x (it has an 0.5 supplementary lens), the Unitron to 60x with a 2x supplementary, and neither is hard to focus.

If fine focus were needed, I'm sure the Leica would have it.

[B.S.Kumar]

Thanks to all of you. It does look like a planetary gear is involved. I will read up some more.

Kumar

[Bob Salomon]

Majority of Stereo microscopes do not have fine focus. Exceptions, few of the Zeiss SV and Stemi series, Wild-Leica M420 series and very few others. Fact is at 50X fine focus is not really needed. On microscopes with MUCH higher magnification, fine focus becomes a must have.

Difficult to see the real world need for "fine focus" on a view camera.

BTW, nothing "cheap" about Unitron microscopes, they are often very good for what they cost.


Bernice

I sold Unitron branded products for EPOI after Unitron was bought by Ehrenreich, never the microscopes though.

[Peter De Smidt]

I’d ask here: http://www.photomacrography.net/

[MartinP]

The planetary gear (I assume that's how it works) coarse/fine idea was used by Meopta (who still make microscopes etc.) as a replacement for the standard focussing wheel on their later enlargers. It works well on my Opemus-6, and also enables the fitting of a flexible extension-shaft to avoid the gorilla-arms focussing dilemma. On the other hand, De Vere have a perfectly adequate, single-speed, focussing system with the focus and stage-height controls in a static position at the front of the baseboard. Both systems are functional, with the De Vere one being less fiddly to use.

My current 4x5 is an Intrepid, so no multi-speed focussing there, and in my limited experience of two other cameras I don't recall using a camera with this feature before. Is it common? Maybe on supa-dupa mono-rail Sinars or something like that?