@mattdm I'm thinking in general. I know there's forums for Pentax and the like, but I'm thinking more of places where there'd be at least a few people with in-depth knowledge of vintage lenses and compatibility. Do you think dpreview is good for this?

I had a thought last night. Would it be possible to have an anamorphic adapter between the lens and camera on full frame if you use it for medium format lenses? A kind of focal reducer / anamorphic adapter for medium format.

Let's just say last night got hot. Hahaha

@Expotr correct me if I'm wrong, but isn't the anamorphic element usually in front of the lens?

scottbb It usually is, but that might be because if you put it on the back with a regular lens, it wouldn't fill the image circle. The anamorphic adapter already expands the field of view

@scottbb

@Expotr horizontally, yes. But not vertically. A "normal" focal reducer would expand the image circle from a lens onto a larger sensor / film format. Also, when you de-anamorph the image when you go to develop / print, an anamorphic element behind the lens wouldn't give you the oval bokeh that is usually so highly prized. If you put the anamorphic in front of the lens, then when you go to stretch it out, the bokeh stays oval.

@Expotr DPreview is mostly populated by people most excited about gear. Makes sense, because it's a gear-review forum. And, it gained prominence as a serious, numerical and objective review site, and while it's actually gotten better on this front in recent years, it tends to therefore have a lot of people obsessed with 90.5 of something vs 89.2 of another.

I would maybe suggest photo.net — there's a bunch of old-timers there :)

and it has more of an actual photography focus

@Expotr I don't see why not. It'd be basically an anamorphic version of the metabones speedbooster.

@scottbb I thought focal reducers, such as the metabones speedbooster, contract the image circle as opposed to expanding it?

@MichaelClark You are right about that.

I have gotten stuck in a pickle today. Got a Vega 12B lens and a cheap Pentacon Six to Canon EOS adapter, and the adapter immediately got stuck (hard) to the lens