Originally Posted by
CatSplat
The rollfilm back is a Shen Hao SH617 6x17/6x12/6x9 back, mounted on my 45N2 in the picture. It comes with the rollfilm back and separate ground glass unit, all mounted via Graflok. It's indeed designed for 4x5 - but since 6x17 is wider than 5", there are some compromises involved to make it work.
The whole back is offset, with the film plane set back ~38mm from the normal 4x5 plane. This is what makes it workable on a 4x5 camera - the additional space allows the image to clear the rear standard and cover 6x17. There are some restrictions, though - for the lens to "see" the corners of the 6x17 past the rear standard, the rear element needs to be fairly close to the film to avoid vignetting. I've read reports that 150mm is the longest focal length you can use without some vignetting, though I did some quick testing with my 180mm Fujinon and didn't spot any problems on the ground glass. The rearward offset also means that a recessed lensboard may be required to properly focus very wide lenses - in the image, the attached 90mm lens is focused to infinity and the Chamonix is almost racked all the way in - wide-open infinity focus with a 75mm or 65mm lens would absolutely require a recessed board. (Some measuring indicated that with the Chamonix a 65mm would need a ~20mm recess and a 75mm would need ~10mm, but I haven't confirmed that yet. I 3D-printed a 24mm recessed board for the 65mm and it was impossible to get my finger in there to operate the shutter.) As well, with the Universal bellows collapsed that tight, there's no movements to be had. Bag bellows would be required for movements at 90mm and wider.
So, you can see that there are definitely some drawbacks to making 6x17 work on a 4x5 camera. However, the good news is that if you're not looking to use long lenses, it's a heck of a lot cheaper than buying a dedicated 6x17 camera! The back itself is well-built (and pretty heavy for its size - there's not much in the way of plastic involved) and operation is pretty straightforward. Exposure spacing is done by a window on the back, and the back has a handy guide that tells you which numbers to use for which formats. It's a fairly recent addition to my fleet, so I've only put a handful of rolls through it, but I have no complaints so far. I just wish it weighed a bit less!
If you find yourself shopping for one of these, there's a few things to watch out for:
- They're sold under 3 or 4 brand names (Shen Hao, DaYi, etc) but all seem to be extremely similar - I assume they all come out of the same factory.
- Some of them have different format options and associated masks. Mine is 6x17/6x12/6x9, but I've also seen 6x17/6x14/6x12.
- DaYi (and Shen Hao presumably) also sell a 6x17 Graflok back that is designed for use on 5x7 or 8x10 cameras and doesn't have the rearward offset. It won't work properly on a 4x5 camera.
Here's a nice video review that does a good job of talking about the back:
Hope that helps!
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