CV 90mm viewfinder - inside frames?

[suselko]

Hi all,
Recently I bought a CV 90mm viewfinder for my Jupiter-9 (I know J-9 is 85mm, but life's not perfect). I'm a bit confused as to the small inside frames in the corners - what's that? The finder is parallax corrected anyway...
Cheers,
Filip

 

[Fred]

Hi, have a look at the following web page for som interesting external CV vF information, The 90 VF has a dial in parallax correction. I'm not sure why there is an extra inside frame unless the VF is used at infinity.

http://cameraquest.com/voigtacc.htm

Thoughts anyone?

 

[Roman]

Maybe those extra lines are there for the change in field coverage (don't know whether this is the exact term - what I mean: if you focus a lens near, it will cover a lower portion of a given scene than if you focus it at infinity); very few RFs accoutn for that change of field coverage at different distances - the only one I know of is the Konica Auto S2, wher the framelines not only change (vertical & horizontal) position - parralax correction - but also cahnge their size (field coverage correction).

Roman

 

[Doug]

Roman has the answer... As the lens moves away from the film for closer focusing, it covers a gradually narrowing field of view. At its nearest position, the field should be approximated by the inner frames of the accessory viewfinder. The outer frame represents the coverage at infinity focus.

I didn't know about the Konica Auto S2, but the viewfinder framelines of the Fuji GS645S not only move down and right for parallax compensation as one focuses to closer distances, they also shrink slightly to more nearly represent the smaller near-focus field of view.

 

[suselko]

Thanks guys!
Filip