Mamiya 6x4.5 mask help needed

EdColorado · Mar 22, 2009

I have a 6x4.5 back for my RB67 but no finder mask. I've never seen one of these masks but I'm guessing its just a piece of card stock. Is that correct or did Mamiya do something more? Does anyone have the dimensions of the mask so I can make myself one?

I've been thinking of something made from soldered together wire that would mimic the lines engraved on a focusing screen and that would delineate both the horizontal and vertical dimensions of the 6x4.5 area. This would remove the need to move the mask whenever the camera back is rotated. In the end though, a card stock mask might be enough....

I appreciate any help,

Ed

John Koehrer · Mar 22, 2009

Mark your lines on clear acetate either with a scribe or knife & drop it in place. It will be thin enough to close the WL finder on.

EdColorado · Mar 22, 2009

John, so simple but such a great idea. A real "why didn't I think of that" number! Thanks!

Any idea of the dimension of the 6x4.5 frame in the viewfinder?

EdColorado · Mar 22, 2009

Never mind on the mask dimensions. It just hit me that the image on the ground glass is actual frame size.

ic-racer · Mar 23, 2009

You can also use tinted acetate and cut out the 6x4.5 frame from the center.

k_jupiter · Mar 25, 2009

EdColorado said:
Never mind on the mask dimensions. It just hit me that the image on the ground glass is actual frame size.

No... unless I am misunderstanding you. If you are using the 645 backs on your rb, the image size is not the frame size. There is a 'official' 645 mask and it will give you a cross type mask (for vertical and horizontal compositions). You still need the guidelines to accurately compose your image.

tim in san jose

EdColorado · Mar 25, 2009

A misunderstanding I think Tim. What I meant was that the image on the ground glass would be actual size...how do I put this... My 6x4.5 image will be 6x4.5 on the ground glass so I need to make a mask that has a 6x4.5 rectangle drawn or scribed on it and that has it centered on my ground glass. So if I'm shooting in 6x4.5 then my coverage area on the ground glass will measure 6x4.5cm.
What I guess I'll do is get a piece of clear acetate and scribe marks delineating two rectangles, one in portrait orientation and the other landscape. Both rectangles will measure 6x4.5cm .
This would be so much easier to explain in person. Does my plan make sense?

k_jupiter · Mar 25, 2009

EdColorado said:
A misunderstanding I think Tim. What I meant was that the image on the ground glass would be actual size...how do I put this... My 6x4.5 image will be 6x4.5 on the ground glass so I need to make a mask that has a 6x4.5 rectangle drawn or scribed on it and that has it centered on my ground glass. So if I'm shooting in 6x4.5 then my coverage area on the ground glass will measure 6x4.5cm.
What I guess I'll do is get a piece of clear acetate and scribe marks delineating two rectangles, one in portrait orientation and the other landscape. Both rectangles will measure 6x4.5cm .
This would be so much easier to explain in person. Does my plan make sense?

I think.
The image you see on the entire ground glass is approximately 7x7. So if you lay a piece of acetate over it with the correct sized (horizontal and vertical) rectangles on them, centered, then yes you have it. It was just the wording that confused me, like if you put a 645 back on, it would somehow change the image size on the entire back.

tim

xtolsniffer · Mar 26, 2009

If you wanted to be super-accurate, then you could always take one picture on your 6x4.5 back in portrait, one in landscape, and use those as a template for an acetate, or even....take some slide film, expose one frame in portrait, use the mutliple-exposure switch to take another overlapping frame in landscape, then cut out the image, pop it into your viewfinder and voila! A ready-made frame. No idea if that would work, but it sounds like a good idea...

michiel fokkema · Mar 31, 2009

Hi,
I have 2 on sale at Ebay.

Cheers,
Michiel Fokkema

Mamiya 6x4.5 mask help needed

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