Shooting 6x17 - using a roll film back vs split/cropped 5x7 sheet film

**djdister** · 10-Dec-2014, 18:59

Seeing a recent 6x17 roll film back for sale got me thinking - would it be better to use the roll film back or just to shoot 5x7 sheet film with a split back, or just cropping the 5x7 image down to size?

On one hand, there are more film options in roll film, certainly more than in 5x7 sheet film. Also, processing roll film is easier and takes less chemistry.

On the other hand, 5x7 sheet film is on a thicker base, lies flatter than 120 roll film, and thus yields a better, sharper negative. Shooting on sheet film would also give me more alternative cropping options other than just 6x17.

This presumes that I will be using my 5x7 camera in either case - so buying a dedicated 6x17 camera is not part of the equation here.

I am leaning towards just shooting them on 5x7 film, rather than acquiring a somewhat pricey film back.

Are there other reasons why using a 6x17 roll film back would be superior to just shooting the panoramas on sheet film and cropping?

**Dan Fromm** · 10-Dec-2014, 20:00

Dan, after I set up for 6x12 (6x12 roll holder on a 4x5 camera) it occurred to me that if I got a 6x9 roll holder to fit the 4x5 camera I could leave my 2x3 gear at home. So I got an AAR 620. Cheap and cheerful but its gate isn't centered in the back's gate. Centering the roll holder's gate in the back takes some shift. A nuisance, but the AAR was inexpensive.

In your case, if you want to center the 6x17 frame on the lens' axis you'll have use a bit of rise or fall. If your lenses have marginal coverage for 5x7 this could be a minor problem. You'd get better image quality in 6x17's corners with a roll holder centered in the back's gate.

If you want to print selectively from 5x7 and can afford the film just do it and don't look back. This will save you the joy of carrying, attaching and detaching a roll holder.

If I were you and didn't have an unrepeatable opportunity to buy a 6x17 roll holder at a wonderfully low price I'd try the split dark slide trick first to see whether ease of use and results were good enough.

**vinny** · 10-Dec-2014, 21:04

"On the other hand, 5x7 sheet film is on a thicker base, lies flatter than 120 roll film, and thus yields a better, sharper negative. Shooting on sheet film would also give me more alternative cropping options other than just 6x17."

I'm pretty sure the canham 6x17 holder would yield results just as sharp or even sharper than standard sheet film holders. Ask brian kosoff about which is sharper.

**Oren Grad** · 10-Dec-2014, 22:49

Originally Posted by vinny

"On the other hand, 5x7 sheet film is on a thicker base, lies flatter than 120 roll film, and thus yields a better, sharper negative. Shooting on sheet film would also give me more alternative cropping options other than just 6x17."

I'm pretty sure the canham 6x17 holder would yield results just as sharp or even sharper than standard sheet film holders. Ask brian kosoff about which is sharper.

Yes. There's a lot of slop in most sheet film holders, and depending on temperature, humidity, and camera orientation, sheet film may not sit very flat at all. Assuming you have proper alignment between your GG and the film surface, a well-designed 6x17 roll holder with a good pressure plate and adequate tension across the spools may well give you more consistent focus.

**Old-N-Feeble** · 11-Dec-2014, 07:18

From all I've read the Canham 617 holder does a fantastic job of keeping film flat across the full length and width. If I was shooting 5x7 and the camera had a Graflok back and I had plenty of funds then I'd buy the Canham back. However, I wouldn't use it very much because I don't like 1:3 ratio as much as 2:5 or 1:2. For 1:3 and 2:5 ratios I'd use the roll film back but for shorter ratios I'd use sheet film.

**djdister** · 11-Dec-2014, 07:31

There seem to be a lot of votes for how well the Canham 6x17 roll film back holds the film flat - good to hear. But given the thinner 120 film base, how does it apply tension across the frame, and has anyone done a direct comparison between the roll film back and 5x7 sheet film? I have downloaded the directions for the roll film back, so I have tried to do some research, however the directions are geared towards usage of the back but not so much on describing how the roll film is held flat across the wide frame.

I do appreciate the feedback - thanks!

**Old-N-Feeble** · 11-Dec-2014, 07:59

Call Keith Canham. He's a great guy and will tell you all you need to know even if he knows you're buying used. Do us a favor and report back what he says.

**Oren Grad** · 11-Dec-2014, 08:04

Originally Posted by djdister

But given the thinner 120 film base, how does it apply tension across the frame, and has anyone done a direct comparison between the roll film back and 5x7 sheet film? I have downloaded the directions for the roll film back, so I have tried to do some research, however the directions are geared towards usage of the back but not so much on describing how the roll film is held flat across the wide frame.

You may have seen Canham's product description, which claims "The film plane, pressure plate, is flat to within 0.0005 inches (0.0127mm)." (http://www.canhamcameras.com/Roll%20film%20back.html) This is far better than you'd get from a standard 5x7 CFH. Why not contact Keith Canham and ask him for any further clarifications about how this is achieved, and his take on the pros and cons compared to sheet film?

**Daniel Stone** · 11-Dec-2014, 08:20

The biggest upside that I can see with using a 617 rollfilm back, such as the Canham, is that you get to shoot emulsions NOT available in sheet film formats. Now that Velvia 50 is "no more"(except for a VERY shiny penny) in sheet film sizes, you can still easily get it in 120. Or Portra 800, or the multitude of other films out there that aren't sold in sheet form.

But the upside to a single sheet of film is this: you have some "slop" in being able to crop. If you prefer a say, (8)x17, vs 7x17 ratio, or correct for something creeping into the frame you didn't see when lining up the shot initially, etc... Also, you only need to click the shutter (once), since you don't have to feel bad about wasting a following 3 shots on the remaining roll.

If you have the pennies, and a camera that can accept the back, give it a try. I don't believe you'll lose much(if any) on the resale value.

-Dan

**djdister** · 11-Dec-2014, 08:29

Originally Posted by Oren Grad

You may have seen Canham's product description, which claims "The film plane, pressure plate, is flat to within 0.0005 inches (0.0127mm)." (http://www.canhamcameras.com/Roll%20film%20back.html) This is far better than you'd get from a standard 5x7 CFH. Why not contact Keith Canham and ask him for any further clarifications about how this is achieved, and his take on the pros and cons compared to sheet film?

Originally Posted by Old-N-Feeble

Call Keith Canham. He's a great guy and will tell you all you need to know even if he knows you're buying used. Do us a favor and report back what he says.

Okay, okay, you're right, I just need to ask Keith about it. I've pestered him with other questions (since I have two of his cameras), so I might as well ask him about this too...