Gaoersi 617 infinity focus probs

Ian, would you do me a favour and measure the depth of your adaptor/cone. Mine is 24mm deep and suspect that a slightly deeper one is required for the SA. It's likely the one I have will work with your Grandagon with its shorter flange to film distance. Thanks.

Cheers, Blair

24mm deep, and the mount flange appears to be 55mm maybe 55.5mm,

I have a feeling there was a good reason why I used my main 5x4 lens WA rather than the Super Angulon I bought second hand at the same time as I was buying the 6x17, there's a bell ringing in my head about the 90mm f5.6.

Ian

Ian, thanks. It looks like there is a Grandagon in my future. I should look at this as a positive experience that fully justifies the purchase of another lens.

On an entriely different front, the Gaoersi finder is approximate at best, especially as I wear glasses. Does anyone have any suggestions on either improving this finder, using another brand, or making one's own, e.g., some sort of wire frame. Thanks.

Blair

After a suggestion from a LFP member and some head scratching on my own, I made a gasket out of an old mouse pad and inserted it between the body and the cone. This gives me a 5mm of extension, which provides both infinity focusing and a sub 2m close focus. The rear element of the SA still bumps into the inside of the helecoid, but helecoid is now securely screwed into the cone. There goes my opportunity to buy a new lens.

I also found that a 21mm finder for a 35mm rangefinder is a very close match for the angle of view for a 90mm @ 6x17. I need to figure out how to mount it to the Gaoersi and my vertical masks need to be reconsidered (post-its at the moment).

Blair

Ian Grant said:

Large format lenses are normally designed and optimised for use at f22, they are not diffraction limited to f16,

Click to expand...

Diffraction is physics. No one can design it to be better or worse.