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04-21-2013, 03:25 PM   #1
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Catodioptric lenses for the P645N?

It has always been my assumption that the so-called Cat lenses were made specifically for 35mm cameras but is this in fact the case or can a Cat mirror lens be used with a P645N and a suitable adaptor and if so what are the difficulties associated with this apart from one aperture setting of f8 and manual focusing?

Thanks

asahijock

04-21-2013, 04:12 PM   #2
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The existing CATs won't cover the full sensor/film gate of the 645s. I'm not sure that you can get infinity focus out of one either, because of the registration distance. It would be a fun try, though.
04-21-2013, 04:49 PM   #3
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Here you go: SMC Reflex-Takumar 6x7 1000mm F8 Reviews - 67 Telephoto Primes - Pentax Lens Reviews & Lens Database

Usable with an adapter, the problem would be finding one.

I believe that there are also mirror based telescopes that can be used for medium format photography with the right stack of adapters. In addition to the restrictions you pointed out mirror lenses generally have fairly low contrast compared to a regular telephoto lens with the same focal length.
04-21-2013, 08:50 PM   #4
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Some of them are quite good. There is the 500mm/5.6 Rubinar which is designed for medium format. There were some other Russian catadiopric lenses as well. There is also the 1000mm Mirotar and its East German Carl Zeiss Jena variant. Both are excellent. Some hate those donut-shaped diffraction rings and others don't seem to care. I find those lenses quite useful.

04-22-2013, 03:20 PM   #5
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Thanks. The reference to one lens was for the 67 but I have a 645. It seemed to be an incredible weight at 6.6kg for a mirror lens. So can anyone point me in the direction of a usable mirror lens for the P645 in terms of name etc and what adaptor I'd need? The 500mm /5.6 Rubinar sounds great and unusual in that most 500mm are f8 but where might it be available and at what price and what adaptor is needed?

Thanks

ashijock
04-24-2013, 06:11 AM   #6
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The Rubinar 500/5.6 is M42 mount not MF !
04-25-2013, 01:00 PM   #7
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QuoteOriginally posted by fs999 Quote
The Rubinar 500/5.6 is M42 mount not MF !
Thanks. A pity that the poster didn't mention this but to be fair he seemed convinced that it was for MF.

Somebody is wrong clearly

asahijock
04-25-2013, 03:23 PM   #8
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M42 flange distance : 45.46 mm
Pentax 645 flange distance : 70.87 mm

Edit: There was a Rubinar 500mm F5.6 and 600mm F8 for Pentacon Six. There was also an Arsat 600mm F8.
A comparision is here. But that's past now...


Last edited by fs999; 04-25-2013 at 03:40 PM.
04-25-2013, 08:12 PM   #9
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I had the Rubinar 500mm f5.6 but I don't think I had a good copy. It was very soft. I eventually got a Pentax 400/5.6 adn this was much sharper.
04-26-2013, 03:25 PM   #10
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QuoteOriginally posted by wkkato Quote
I had the Rubinar 500mm f5.6 but I don't think I had a good copy. It was very soft. I eventually got a Pentax 400/5.6 adn this was much sharper.
So to be clear, you are saying that you used the Rubinar 500mm f5.6 mirror lens on a P645. Sorry if this appears to be provoking you into saying" Of course I used the Rubinar on the P645. I have just said so in my post, haven't I?

It is just that another poster seemed to say the same as you appear to be saying and yet another has said that this isn't possible. See the reply that says that the Rubinar uses the M42 fitting which is different from the flange setting on the 645.

Thanks

asahijock
04-27-2013, 01:13 AM   #11
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If in the former eastern countries (Comecon) a lens constructed for medium format, would be in Kiev 88 or PentaconSix /Kiev 60 mount. There are adaptors from Kiev 88 to Kiev 60 mount, which ist identical to the Pentacon Six mount (P6).

P6 is good for us, because the flange distance (74.1mm) fit to Pentax 645 and there are various adaptors P6-> Ptx645 on market.
I looked in my literature for medium format east mirror lenses (Scheibel, Pincelle, Pietsch). No russian mirror lens is mentioned*, only the east german Practicar 5.6/1000mm. This "Prakticar" wasn´t manufactured at FOG (VEB Feinoptische Werke Görlitz [former Meyer, Görlitz]) as the name "Prakticar" would suggest, but at VEB Carl Zeiss Jena. It seems to be rare. My suggestion is it wasn´t sold often to the public ( orignal price was something over 10 000 M**), more to state organisations (army, secret service, police....) Pentacon Six: 1000mm lenses

* all russian mirror lenses seemed to be M39/M42, but may be there are "after manufacture" adaptions to P6

** something above the price of the east german "Trabant" car.

Last edited by veraikon; 04-27-2013 at 04:03 AM.
04-29-2013, 07:07 PM   #12
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Well, mine is definitely in P6 mount and came with a P645 adapter. I got some astonishingly nice shots with it, and it is portable as well. The 5.6 appears to be the best of the bunch. They do show up on ebay from time to time.

Amazing level of mis-information here...
04-30-2013, 04:56 PM   #13
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P6 reflex lenses? Go here: Pentacon Six: Further 500-600mm lens tests
05-01-2013, 09:04 AM   #14
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QuoteOriginally posted by Lacunapratum Quote
Well, mine is definitely in P6 mount and ... Amazing level of mis-information here...
May be it´s an "after manufacture" adaptation.
After 1990 a lot of east european workshops lived from this business
05-04-2013, 06:01 PM   #15
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No. No aftermarket adaptation. They were quite common about 10 years ago.
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