GuoHua roll film backs on ebay?

[Craig Wactor]

Anybody used one of these? Looks like they sell cheap. Does it fit in a spring back? Looks too fat.

[Marv Thompson]

I saw these today. They look pretty pedestian although functional. It doesn't appear as they have a stop mechanism, just advance to the mnumber in the red window. They won't fit a spring back as they are designed for a Graflex type back as far as I can tell. My Graflex 23 back looks the same where it attaches to the camera.

I too would be curious if anyone has actual experience with them.

[Richard Littlewood]

I've got one of these backs, and if you are used to high quality gear and you buy one it will seem like you have just bought an expensive kiddies toy. The back is very crude, and gives the impression that it will be crap. However as I forked out way too much for mine I did a bit of tweaking to make it really very good, like making a light tight baffle so the dark slide can be pulled all the way out - this was quite a tricky operation, and I wouldnt like to do it again. I did one or two more things to it and now I'm happy to use it and can't see why it won't do me good for years and years. No it wont fit in a spring back. Given a bit of hindsight I would go for something of a more known quality - there are loads of 6X12 backs, and loads better than this one.

[Stephen Gallivan]

Hi Richard,
I'm new in here. Just bought one of these RFB and i'm curious as to how you made a baffle for it. I'm a pretty handy guy, but you could save me some trial and error if you could give a quick summary. Thanks in advance, Steve

[Richard Littlewood]

Hi Stephen
I'll try my hardest to remember how I did it, I seem to recall the thinking bit was the hardest, then actually finding the tools/parts. I ended up using a very sharp .25 inch wood chissel, and a Stanley knife blade.
First off locate some good baffle bits. I decided (unlike a filmholder) that 1 baffle would be OK and this was some very thin, springy metal out of a wrecked Riteway film holder, about .5 inch wide and at this stage about 3 inches long. I glued on one side some of the black velvet with epoxy then gave it a slight smooth triangular profile - that gives it spring, and acts as a light baffle. Can you visualise this thing!
Take apart the back of the roll film holder - there is some sticky thick glue holding on the metal plate that acts as a spacer. This is tricky to remove but it needs to come off. If you study the parts carefully you will see there is only one place where it is possible to install a slot for the baffle - I'm only saying this as I cant remember! however, what you want is to 'carve' (or machine if you are lucky) a slot in the plastic about a sixteenth of an inch deep, half inch wide, and as long as the width of the dark slide groove. This slot has to accomodate the velvet covered strip. I found it easy to cut, and the strip sits in this slot with the velvet covered raised side facing out, that should be proud of the surface, and be able to flatten into the slot - I'm sure you understand the light baffle stuff!
I have to say even if all this goes wrong nothing is lost as the back can be put back together and nothing is lost. However I found cutting the slot easy. The hardest part was making the velvet covered baffle - it had to have some spring to form a good light seal, but not too much, so it would wear quickly. It had to have accurate, straight, smooth sides for the same reasons and also so it sat properly in the slot and sprung freely. When all this lot is together the idea is that on withdrawing the dark slide the strip will spring up within its slot and the velvet 'top' will make contact with the opposite side of the slide and form a seal - get the finest piece of velvet you can and dont make the profile of the metal spring strip too triangular - more a gentle arc shape, and so it has the spring effect the slot it sits in should allow some movement.
Does all this make sense!
Finally on assembly you will need to replace the gungy glue that came from the metal plate - I used about 3 layers of very sticky double sided carpet tape, because what you will find is you have to create a 'spacer' so the dark slide slides well - too small a gap and it is locked down! too big a gap and it is too slack.
Also at this stage file a 45 degree chamfer(?) on the out side of the film window on that metal plate, then matt black it - no more light reflections there.
I know all this is quite fiddly and those chaps with all those expensive backs will be sniggering! but probably like you I wanted a 6x12 back, saw these things on E-bay, thought yes that will do, only to find that it worked OK apart from the dark slide issue and some annoying light reflecting issues (hence the chamfering). All I can say now is it is good on both those things, in fact I can now draw the dark slide out all the way in full sunlight with confidence, the film passes through it un-fogged and scratch free, and filing angles on flat edges gives no weird build ups on the negs. In short its a bit of a silk purse now where it used to be without doubt a real sows ear!
Good luck and keep me posted.

[Richard Littlewood]

Sorry forgot to mention, the dark slide needs to be really smoothed off along its 'leading' edge so it slides over the velvet without chewing it, and I cant stress enough how accurate a fit the baffle has to be in its slot, especially the springing ability and its overall length within the width of the slot.

[scrichton]

I have one of these backs even after a lot of sanding.. adjusting etc it will rip the emulsion badly. I would say if you are paying peanuts and are good with the healing and clone tools get one otherwise look for a sinar back or a good linhof/horseman. Failing either of those get a graflex 6x9 and just crop down and use slow film.

[Stephen Gallivan]

Thankyou so much for the very detailed help.
You have probably saved me hours of head scratching!
I'll let you know how it turns out.

[Stephen Gallivan]

Hello again Rich,
I recieved my GH6x12 from China today, I was going to throw a fit because it is obviously used instead of new as advertised.
But when I opened it up, I realised the manufacturer must have made an upgrade! it has a rubbery, velvety light trap! Nice surprise. But I do have one more "dumb" question...
What frame numbers do I use with the 120 film? the back arrived in an open box with no instruction sheet.
Thanks again for all your help, Steve

[David A. Goldfarb]

Usually with these multi-format backs each window has a number sequence next to it. The one that gives you six exposures per roll should be for 6x12. If one has 8 exposures per roll, that's for 6x9. 12 exposures per roll would be for 6x6, and 16 exposures per roll would be for 645. Which formats you can use depends on what masks came with the back.