Collapsible Industar question

[Koolzakukumba]

Does anyone know if a collapsible Industar can be fitted to a Pentax K SLR? I'd imagine it would be possible to fit an E39 to M42 adapter then an M42 to K mount adapter. The question is whether or not the collapsed lens would foul the SLR mirror. The camera I have in mind is an MX.

[kevin_v]

Not looking at any numbers or technical specifications, I'm not going to say definitively "no." That being said, I'm strongly inclined to doubt it. SLRs generally require special retro-focus lens designs that allow short-ish focal lengths to be far enough from the sensor plane at infinity focus so not to get in the way of the mirror. I'm pretty sure a traditional 50mm rangefinder lens like the Industrar would get in the way. That is not to say one couldn't physically mount the lens; however if you did, extended, you wouldn't be able to focus at infinity, and collapsed, you'd need mirror lock-up.

[wolves3012]

With a suitable adapter, yes but you had better not collapse it. Plus it'll only work as a close-up lens anyway. A bit of a pointless exercise, in honesty. If you want the Industar's look, buy the SLR version in 42mm and get a screw-to-K adapter. Or buy the 39mm SLR version and then use 39-42mm and 42mm-to-K but that's a bit more complex! I've used the 42mm version with a Minolta-mount adapter.

[Coldkennels]

Wolves is right. You could make it fit, but you couldn't make it focus properly. I've tried most of the Soviet LTM lenses on an SLR (an M39 mount Zenit, with similar flange-to-film distance to the K-mount Pentaxes), and the only one that even approached actual usability was the Jupiter 11 135/4. But even then, it's closeup/macro only.

[David Hughes]

Hi,

Roughly speaking the RF lenses' mounts need to be about 29mm from the film. SLR's have a mirror that swings up and so a lot of space is needed for them. Meaning, far more than about 29mm.

So the RF lens is then in a position where you'll have problems focusing at 2 or 3 ft even when the lens mount says it's at infinity.

Getting the RF lens in the right position to work would mean cutting a lot off of the SLR's body and not having a mirror.

Even when the figures suggest it can be done there are still problems, at times; sometimes because of the path the front of the mirror takes as it swings up and still hits the lens mount.

Regards, David

[Koolzakukumba]

Thanks guys for the replies. Looks like it will just have to be the rigid bodied Industar then!

[Coldkennels]

To be honest, the M42 Industar 50 is so small it basically only juts out as much as the collapsibles do from a Fed or Zorki anyway. The only issue is no automatic aperture linkage, otherwise I would have got one for my Pentax kit a long time ago. It'd be a beautiful thing on the front of an MX.

[Veloman]

Hi Koolzakukumba,

Originally Posted by Koolzakukumba

rigid bodied Industar

AND made for SLR camera! Be aware, both M39 threaded Industar-22 and Industar-50 exist in rigid version for RF and SLR-cameras too!

Cheers!