Graflok 4x5 to Graflock 5x7 Adapter --- Does Anyone Make One?

[Old-N-Feeble]

Criteria #1: Fairly short to allow use of wider lenses.

Criteria #2: Flared sides to maximize longer focal length lenses without vignetting.

Criteria #3: Easy to use.

Criteria #4: Well built... accurate, sturdy and long-lasting.

I don't want to buy a 5x7 or larger camera just on the fairly rare occasion I want to shoot 6x17cm images. This adapter would stay in my vehicle unless I want it for a particular image. I'm aware of the Da Yi and Shen Hao varieties and although they're very nice they don't meet my second criteria.

 

[frank]

I think only a 5x7 to 4x5 adapter is available, not the other way around because of vignetting/interference.
Medium format backs on 35mm cameras would be interesting.

 

[Old-N-Feeble]

I think it would be very possible to allow use of a 210mm lens at infinity without vignetting at least on some 4x5 cameras because of the back openings being large enough to rotate the back. IMO, 210mm is "normal" for a 56x168mm image. I'm using a 1.25 X (longest side) calculation rather than the typical square root of [(short side squared) + (long side squared)] calculation because I think it's more appropriate for the way human eyes see.

 

[Ian Grant]

What camera is it to fit ?

I'm building a camera to shoot 6x17 and predominantly 5x4, but I need to be able to use a 75mm lens for both formats.

Ian

 

[Old-N-Feeble]

My current camera is a Chamonix 45N-1 with Maxwell screen and I have no plans to change it.

 

[frank]

My current camera is a Chamonix 45N-1 with Maxwell screen and I have no plans to change it.

Just a little dremel work!


Just kidding, nice camera.

 

[Oren Grad]

To my knowledge, the available expansion backs for 4x5 --> 5x7 don't attach to Graflok fittings, they replace the entire back. The film gate proper - what you'd be stuck with for a rear opening if you attached an expander to the Graflok fitting of a 4x5 camera - is so small that it would likely severely limit the range of usable focal lengths, if it was workable at all with a given camera's bellows. When you replace the entire back you still have issues with bellows and camera body vignetting, but there's at least more wiggle room to work with.

 

[Old-N-Feeble]

Oren... That's true but I think many cameras have openings large enough to allow for lenses up to 210mm lenses used straight on. I consider 210mm normal focal length for 6x17cm.

 

[L Gebhardt]

The Da Yi back I had let you use a 180mm, but would vignette with longer. If you design a back that is set back farther from the 4x5 you could get a 210mm lens to work, at the expense of shorter lenses. I find an 80 to 90mm is more "normal" for 6x17.

 

[Ian Grant]

I asked what camera because it's possible to make an expansion back to tale 6x17 if there's sufficient width. This needs to replace the existing back rather than fit like a Graflok. It should compromise the camera which would need no modification.

Suprised that you consider a 210mm lens as standard, but I guess in the big wide open landscapes in the US it's OK, I use a 75mm Super Angulon as my standard for 6x17, after all the standard lenses on my Yashicamat & Rolleiflex cameras are 75mm/80mm but I have to work much closer in more intimate landscapes.

Ian

 

[Old-N-Feeble]

By "standard" lens I mean "normal" focal length for 56x168mm image area.

Common way of calculation "normal" focal length:
56^2 = 3135
168^2 = 28224
3135 + 28224 = 31359
sqrt 31359 = 177mm

My method of calculating "normal" focal length:
(long side) 168mm * 1.2 = 202mm

On the long side this calculates more closely to how wide a lens looks, IMO. I do love wide-angle lenses though.

I don't have the skills to build a complete back and make a bellows to fit. If I want to shoot 6x17 then I guess I'll either buy a dedicated camera or one that I can buy a conversion kit for. I like the Canham 5x7 Traditional and the matching 6x7cm roll film holder plus the 4x5 reducing back but those are above my budget. Also, I find the Canham, albeit beautiful and very well-built, is a bit finicky for me.

I guess I'm thinking out loud here.