Toyo 45CF Fresnel Screen placement...

[joseph_e._forks]

Background: I am new to LFC's, with 30 experience in 35mm & MF, and

several years in Digital. I recently purchased a lightly used Toyo

45CF with GG and Fresnel installed. I have read nearly every post I

can find on this board relating to the subject and have come up with

conflicting info so I'm throwing it out to the experts.

 

Question: The instructions for installing Toyo Fresnel screens say

the screen goes in front of the GG - i.e. closer to the lens board.

I have read several opinions (facts?) that state the fresnel must be

placed behind the GG - i.e. further from the lens board. For

instance this Web site http://www.wisner.com/viewing.htm, see "What

is the Proper Placement of the Fresnel?"

 

There is a spacer which I suppose makes accomodations for this

placement but it doesn't make sense to me, I don't understand how my

focused image can reside at the same registration as my film plane?

Can someone shed some light on this for me?

 

Lastly, Since this fresnel was installed when I purchased the

camera, I'm looking over the diagram and it appears I may be missing

two pieces but will have verify that. The instructions provided by

Toyo failed to identify part #7 (spacer) on the diagram that

accompanies the instructions, so at best I am unclear on this point.

 

Thanks in advance for any help or clarification.

Joe Forks

[jim_rhoades]

Joe, I will answer the conflicting info part. Some camera's were not designed from the start for a fresnel screen. To keep the focus plane (Image on ground glass)and film plane (negative) in the same spot, the fresnel has to be mounted behind the G.G. ie. Wisner

 

Other camera's, say a late Crown Graphic, already have a fresnel built in and it's in front of the G.G.

 

Toyo has a web site with a forum and a factory rep will give you a detailed answer.

[joseph_e._forks]

Thank you Jim,

Your answer, and the fact that I took it apart again makes enough sense now.

 

What I see is that the spacer is built-in to the Toyo 45CF, thus the missing part(s) or so I thought. The GG can only sit on one plane and the Fresnel lays in the groove on the frame under the GG (on the lens side of the GG). Fresnel or not, the GG will always be on that exact same plane.

 

So thanks for that.

 

Forks

[huw_finney]

I installed a fresnel in my CF in front of the GG, to maintain focus a small amount of metal needs to be removed from the GG mounting plane (0.6mm in my case). Chat up a local metal workshop, I had to the works shop is fully booked for ages!