Koni-Omega 58mm f/5.6 finder?

DGS · Feb 6, 2023

Hello all -- I just received the 58mm f/5.6 Hexanon lens for my Rapid Omega 100, but without the finder. I can search for a finder on the auction site, but barring that, I wondered if anyone knew whether another accessory viewfinder might work, and if so, what type and angle of view (since this is a medium format lens and most accessory finders I've seen are for 35mm camera lenses). Thanks!

reddesert · Feb 6, 2023

The Koni-Omega uses 6x7, which is about a factor of 2 larger than the 35mm frame, and 0.6x smaller than 4x5. A finder for 28mm lens on 35mm film will get you pretty close, although the 35mm aspect ratio is a little wider so they will be a little different at the edges. You could also get a zoom finder like the Linhof finder for 4x5 and set it to the equivalent focal length, about 90-100mm on 4x5. 4x5 is about the same aspect ratio as 6x7 (because 6x7 is about 56x68mm).

DGS · Feb 6, 2023

reddesert said:
The Koni-Omega uses 6x7, which is about a factor of 2 larger than the 35mm frame, and 0.6x smaller than 4x5. A finder for 28mm lens on 35mm film will get you pretty close, although the 35mm aspect ratio is a little wider so they will be a little different at the edges. You could also get a zoom finder like the Linhof finder for 4x5 and set it to the equivalent focal length, about 90-100mm on 4x5. 4x5 is about the same aspect ratio as 6x7 (because 6x7 is about 56x68mm).

Thanks, that's good information!

MattKing · Feb 6, 2023

In the meantime, the in-camera finder will show you most of the view seen by the lens, if you look right out to the edges past the frame lines. It is worthwhile determining that, because sometimes you just want to grab the camera and take a quick shot without the accessory finder.
You can do that by taking a photo of a brick wall with marks (tape?) added at the corners of the view in the camera finder, and then examining how much more shows on the negative.
That is a sweet lens - have fun with it.

OAPOli · Feb 6, 2023

Equivalent focal length in 135 format is 25mm, cropped to 4:5 aspect ratio.

DGS · Feb 6, 2023

Thanks all for your responses.

Koni-Omega 58mm f/5.6 finder?

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