Re: [APML] Focusing the Mamiya and getting diff results

[Wei-Hao Wang <wang@IfA.Hawaii.Edu>]

Hi Phillip,

I'm a Mamiya 645 and FM60 user.  My model is Mamiya 645 Super (identical to
the current 645 Pro TL) and might be different from your M645.  My asnwer
below assumes that my 645 is the same as yours.

Your method (2) should be avoid, definitely.  In order for FM60 to work,
FM60 has to be first focused on the fuzzy side of the focusing screen 
(or the ground glass that comes with FM60).  You can adjust the front end 
of FM60 to do this.  However, the focusing screen of Mamiya 645 is so thick 
that FM60 can never be focused on its fuzzy side.  If you use this method to 
focus, the image plane will fall behind film plane and thus will be out of 
focus.

Method (1) and (3) should give you similar results.  The only difference
is that method (3) only has 2x magnification is is not that accurate 
comparing to (1).  Again, make sure that you focus FM60 on the fuzzy side 
of the ground glass first.  

Hope this helps.

Wei-Hao


______________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       Phone: 808-956-9867                  
2680 Woodlawn Drive            Personal Website:
Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
______________________________________________________________________



>From: "Phillip Jones" <starfest@comcast.net>
>To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
>Date: Thu, 13 May 2004 20:53:30 -0500
>Subject: [APML] Focusing the Mamiya and getting diff results
>
>I am achieving three different focusing points with my Mamiya M645 using the
>following three methods:
>
>1) Tak FM60 with included ground glass against the film plane.
>2) Tak FM60 placed on top of the focus screen after removing the prism.
>3) Prism attached and Mamiya 2x magnifier attached to the prism viewfinder.
>
>Each method brings me different results. I focused on an object 6 ft away
>using my Mamiya 150mm lens. Camera was mounted on a sturdy tripod. Last time
>I tried imaging with the Mamiya, I didn't yet own the FM60 and so I relied
>on the prism + 2x magnifier. None of my medium format images came out in
>focus.
>
>For those of you unfamiliar with the FM60 focusing eyepiece, here is a link:
>http://www.buytelescopes.com/container.asp?dest=/manufacturers/takahashi/fm60in
st.htm
>
>Question: should I go with the film plane result?
>
>Thx,
>-Phil
>
>P.S. sorry for the cross post with Tak Yahoo group.

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