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Mopman
sage
Reged: 10/14/06
Posts: 283
Loc: Richland, WA, USA
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Anyone know where I can find a T-Ring Adapter (to a 2" draw tube) for a Mamyia 645 camera? Will the 6 x 4.5 cm format buy me much more field of view than 35 mm looking through a 2" focuser in prime focus? Thanks! Mopman
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Suk Lee
Post Laureate
Reged: 10/07/03
Posts: 4315
Loc: Pleasanton, CA
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You can buy the adapter from Hutech:
http://www.sciencecenter.net/hutech/borg/parts/html/8645.htm
you'll have to cobble a couple of different adapters together, but you can get there. Note that it will vignette through a 2" focuser, you need a 4" focuser (High end Taks, Astro-Physics) to get complete field illumination on 120/220 film.
Cheers,
Suk
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http://www.siliconvalleyskies.com
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D_talley
professor emeritus
Reged: 07/07/05
Posts: 702
Loc: Richmond VA
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I made one from an old body cap and a two inch lens tube for my M645
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Dwight
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AstroBobo
sage
Reged: 07/04/07
Posts: 395
Loc: Zagreb, Croatia
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For medium format, you'll need a telescope that can cover such a large film area. Even if it has a lagre enough focuser it does not mean there will be no vignetting or if the stars will be sharp at the edges of the frame.
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Boris Stromar : AD Infinitum member : Zagreb, Croatia, Europe
P75SDHF : P105SDP : MN71 : CGE : STL-11000
http://www.astrobobo.net
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Mopman
sage
Reged: 10/14/06
Posts: 283
Loc: Richland, WA, USA
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Thanks guys!  I have a call into Hutech; sounds like they can fix me up; but not sure on the cost yet. I thought about modifying a Mamiya extension ring to make my own T-ring / 2" nose, but the cost on e-bay has been too high so far.
Astro Bobo, thanks for the info! I've been wondering how much I will gain over 35 mm? The setup will be a 333mm f4.8 Newt w/ 2" focuser and a Lumicon OAG Coma corrector. Just looking at simple geometry and assuming the 2" focuser is fully illuminated, I calculate the 6 by 4.5cm film would have some vignetting and give ~93% of the 2" circle (you waste 30% of the film). I think that is a bout 220% of what a 35mm format yields. Sounds like it might not be that simple though?  Thanks again! Mopman
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