Pentakon 135 Back focus

[Kenza]

Hi! Does anybody know the back focus distance of the Pentakon 135mm f/2.8. It should be longer than Canon's i think.

I want to shoot with my Atik 4000M but all the Canon lenses have a BF distance of 44mm, so I can't use the filter wheel.

[Cornelius Varley]

The flange to film plane distance will depend on the lens mount https://en.wikipedia.org/wiki/Flange_focal_distance

[Kenza]

As I can see the difference between the Canon EF and the Pentakon M42 is only 1.46 mm.

I wonder if that will be enough?

[steppenwolf]

The Pentacon has a 45.46 backfocus and the Atik mounting face to sensor distance is 18.0mm. The Pentacon M42 thread is NOT compatible with the M42 'T' thread standard so you will need to factor in the depth of a Pentacon M42 to 'T' thread adaptor plus the total depth of your filter wheel. The available space is only 27.46mm so your filter wheel and all adaptors will need to be this length or less.

[Kenza]

That's impossible then, because the SX filter wheel is around 25 mm. Tough luck!

[Alien 13]

Old manual Medium format lenses come up from time to time and they have lots of backfocus.

Alan

[Kenza]

Anyway, I can always use this: http://www.teleskop-express.de/shop/product_info.php/info/p2165_TS-Filter-Quick-Changer-for-1-25--filters---T2-mount---length-15-mm.html