Adapting a Long Telephoto for Hasselblad

[Jeff Dyck]

I have an old Pentax 500mm f4.5 manual lens from my very seldom used 35mm system and I was thinking that it would be great if the lens could be adapted to use on my Hasselblad. The only time I seem to use my 35mm anymore is for long telephoto shots. How difficult -if even possible- would it be to adapt this lens for use on a Hasselblad (2000-Series)? The rear part of the lens behind the aperture can be easily detached, so I hoping that this is more of a machining problem. I am assuming that coverage/vignetting won't be an issue(?). Is there anyone out there that has done this?

 

[David A. Goldfarb]

These conversions can be done. Many 35mm tele lenses have enough coverage for MF, and if it's a simple manual lens without any coupling pins, or where you can fix the coupling pins to convert it to a manual lens, and if the focusing helical is in the right place, then it's usually a matter of machining some kind of coupling.

I've converted Schneider Tele-Xenar 500/5.5 for Bronica S2A. S. K. Grimes made the adapter tube to couple the lens to a telephoto focusing helical for Bronica made by Komura.

Aren't some of the Pentax teles designed to be convertible between the 35mm and 6x7 (and perhaps 645) cameras? If they are, then that might mean they are more readily adaptable.

 

[Nick Zentena]

Aren't some of the Pentax teles designed to be convertible between the 35mm and 6x7 (and perhaps 645) cameras? If they are, then that might mean they are more readily adaptable.

Other direction. The 67 lenses can be mounted on the 645 or the the 35mm. The 645 lenses can be mounted on the 35mm. OTOH last time I glanced at the issue you needed an expensive mount adaptor.

 

[gr82bart]

I was thinking the same thing as Nick. I've always seen 6x6 lenses to 35mm, but never the other way around. That is larger frame to smaller frame.

Art.

 

[Dan Fromm]

I was thinking the same thing as Nick. I've always seen 6x6 lenses to 35mm, but never the other way around. That is larger frame to smaller frame.

Art.

Art, I'm sort of with you and Nick in principle, but in practice we're all a little wrong.

On Bob Monaghan's site he gives examples of long lenses made for 35 mm cameras whose rear elements sit deep enough in the barrel -- some are even just simple telescopes, with a two element achromat in front and no rear element -- to allow the rear of the barrel to be chopped. This to get the lenses to focus on a deep MF SLR body. It sounds contrary to nature, but some lenses will accept that kind of abuse.

Cheers,

Dan

 

[gr82bart]

On Bob Monaghan's site he gives examples of long lenses made for 35 mm cameras whose rear elements sit deep enough in the barrel -- some are even just simple telescopes, with a two element achromat in front and no rear element -- to allow the rear of the barrel to be chopped. This to get the lenses to focus on a deep MF SLR body. It sounds contrary to nature, but some lenses will accept that kind of abuse.

Oh God Dan, it pained me to read that! Ouch - you know what I mean? Post a link to the site. I'd like to take a peek at the masochism! LOL

Art.

 

[Nick Zentena]

I meant that Pentax sold adapters to mount the MF lenses on 35mm cameras. Considering the cost of the adapter and the MF lens I'm suprised they sold any.

If my math is right to cover a 6x6 frame with a 500mm lens is only going to take about 7degrees of coverage. But is it possible the lens is some how limited by the manufacturer?

 

[Seele]

Some lenses, abeit not by Pentax, seemed to have been designed for this kind of hacking.

I am more familiar with those by Carl Zeiss (Jena) and Hugo Meyer; many of the long lenses were larger sizes of the standard and telephoto models, remounted for various cameras. For instance, the Telemegor (also spelt as Tele-Megor) covers 30 degrees and made in focal lengths from 5cm to 40cm, the 18cm, 25cm, 30cm and 40cm versions were mounted in helicoid mounts for SLR cameras of various formats. As long as the image circle covers the format, and the "chop" does not interfere with the focussing helicoid then you're good to go.

However, many long Meyers were made with the whole lens barrel unit shorter, to leave the greatest back-focus possible, in the sense that even when used on the intended reflex with the largest format you still need to add an adapter of some length. So, by removing that adapter and replacing it with a custom one for the Hasselblad there would be no chop job required.

If the Pentax lens can indeed cover the larger format, a lot of serious hacking would be required: all the automatic iris function will be lost, and the helicoid might also be shortened; in fact a very serious job which stands a good chance to compromise the lens itself. Personally, I would not recommend that, for my money I would get something like a 40cm Telemegor or something along that line and start from there.

 

[bobfowler]

Some lenses, abeit not by Pentax, seemed to have been designed for this kind of hacking.
<snip>
If the Pentax lens can indeed cover the larger format, a lot of serious hacking would be required: all the automatic iris function will be lost, and the helicoid might also be shortened; in fact a very serious job which stands a good chance to compromise the lens itself. Personally, I would not recommend that, for my money I would get something like a 40cm Telemegor or something along that line and start from there.

This Pentax 500mm has a manual iris...

It would be relatively simple (yes, simple is a relative term) to modify this particular lens for a MF focal plane shutter body.

 

[Dan Fromm]

Oh God Dan, it pained me to read that! Ouch - you know what I mean? Post a link to the site. I'd like to take a peek at the masochism! LOL

Art.

http://medfmt.8k.com/ Explore it, and eventually you'll find his sections on lens hacking.