mf.vf.01 medium format VF camera concept

[ghost1001]

Hi All,

I have been designing a medium format viewfinder camera. The concept will utilize the mamiya 645 leaf shutter lenses and a rb67 120 back.

Total cost (including used lens, used back and body) should be under $200 usd.

The lenses are available in 55mm,70mm,80mm and 150mm.

The back is available in 6x7 and 6x4.5.

Coverage with 70mm or 80mm lens will be an issue on 6x7, but will obviously work on 6x4.5 format. (I have not tested the 150mm yet)

Film plane register is the stock 63.3mm.

I want a lightweight, durable, easy to carry camera that can be used handheld with scale focus; or tripod mount with ground glass focus, that will also support macro work.

The body will be constructed out of plywood, cut on the router table using templates. The viewfinder will consist of 2 panes of glass with a dot in the center for alignment and frame lines etched on the front glass for framing the picture. The lens will mount via and extension tube attached to 1/8" aluminum plate facilitating interchangeability of lenses.

The body will measure 7" wide x 5.5" high x 2" deep.

Shutter release will be accomplished via a standard cable release attached to the lens shutter. It will be fed up through a hole in the body and fixed via a set-screw (large black circle with red dot). It can then be removed for tripod shooting in the field.

The shooting sequence will need to use the dark slide for the back, due to the design of the shutter in the lens. But other than that I do not see any major issues with the function.

The working mane of the concept is "mf.vf.01" (medium format.viewfinder.01)

Comments and questions?

Thanks for looking.

Kevin

 

[Jeff Searust]

I like --- I would make changes such as the handles. I see no reason that the handles need to be integral to the camera, nor for that matter the rangefinder.

While the concept of using the router table to produce identical "camera units" the thickness of the wood must be more uniform than is really practical without using a thickness sander or planer, and then you get into more and more tools.

 

[ntenny]

Are those cold shoes on the top? It seems like it might be useful to have one atop the viewfinder, so that wide accessories (like a rangefinder) can be mounted without risk of collision.

 

[Frank R]

Go for it; have fun.

Looking through the viewfinder may be difficult with a rollfilm back on the camera. You may need to extend it back with a tube.

 

[keithwms]

Looks good Kevin, I wonder about the flange-to-film distance though. 2" deep seems a bit thin to me for infinity focus, I could be wrong. Also, do these lenses have 645 baffles? I don't know. One final thought, I don't think and of the LS lenses are fast... that's a bit of a negative. I mean, I'd really like to be able to shoot the 80/1.9 on 6x6 format... maybe even with a funky big LF press rigged on there.

 

[ghost1001]

Hi Keith,

The lenses are as follows:

55mm ls 2.8
80mm ls 2.8
150mm ls 3.8

I agree...the 80mm 1.9 would be nice.

I think after I do this i will get a rb or ls lens for parts and try to pull the shutter out of it to use with other non ls lenses.

I have seen 63.3mm listed as the register on the net, I will confirm prior to actually building. I rigged up a "test box" this past weekend to check the the circle of illumination on the lens. It did seem to be in focus at infinity wide open at 63.3mm from the ground glass.

Not sure about the baffles on the 55, 80 and 150...I will check.


Kevin

 

[keithwms]

Kevin, just in case you don't know, the rb lenses are all leaf shuttered and it's damn near impossible to get the leaf shutter out. You might well be able to stick a big press shutter on a 645 lens though. I don't think you'd do better than ~1/125 sec though.

 

[ghost1001]

Thanks for the info...once I get this first cam built I will take a look at the RB lenses more closely and come up with a design....BTW do you know what the max. extension on the RB bellows is?

Also, I checked on the 100-200 zoom you were right...it has helical focus, so that may be an option, I am also looking at the press lens/shutters as you suggested.

Thanks

 

[keithwms]

I don't have my rb here with me but offhand I'd say the max extension is ~8cm. I sometimes carry an extension tube with me for ultramacro but seldom need it.

The rb 100-200 is nice but just too slow for its intended purpose, in my opinion.

 

[ghost1001]

Thanks.

kevin

 

[larsco2002]

Consider using the K type Mamiya Press film backs

You'll accomplish a few advantages.

1) Notorious for flatter film plane because of the S curve
2) Won't stick out the back nearly as much as a Graflex type roll film back
3) Will automatically provide the handles on each side

All you need is a rear adaptor from an old Mamiya Press (Not the Super 23 or Universal - earlier types). You can get old Press parts bodies for paltry sums on eBay. You can also get a Press type roll film back that has inserts for 6X4.5, 6X7 and 6X9 in one back. I paid $60 for the last one I bought on eBay.

 

[ghost1001]

Thanks for the idea....I already have a rb back so for this one I will use it.

But....I have a plan in the works for a 6x9 it sounds like the mamiya press back would be ideal.

Kevin