Using 120 Film in 220 back?greenspun.com : LUSENET : Large format photography : One Thread
I went to a favorite sunrise location this morning (thankfully only about 20 minutes from my home) had GREAT light, but then realized I had the wrong back -- I'd brought 120 film but had my 220 back. I ended up shooting with my new toy, a Canon G2 digital (which is really pretty awesome!), so it wasn't a total loss. Then, about 15 minutes later, after the light wasn't as good anymore, I realized I probably could have just shot my 120 film in the 220 back. Has anyone ever tried this? Any problems?
-- Howard Slavitt (email@example.com), January 27, 2002
I have been using 120 in my 220 back for awhile and have had no problems, just have to remember to stop shooting at 15 exposures, I lost a great shot because i forgotten. but no problems with the equipment.
-- Gary (firstname.lastname@example.org), January 27, 2002.
I do it all the time with my A-24 back. I just shot 11 exposures and waste the last as it will be partly off the film. I've also found that leaving the 12th blank allows for handling when loading development reels and getting the crimp marks outside any images.
-- Gene Crumpler (email@example.com), January 28, 2002.
I'm not a medium format user, so you can take this advice with a grain of salt, but the only difference between 120 and 220 is that 220 is twice as long and doesn't have backing paper along the entire strip of film. The difference between a 120 holder and a 220 holder is mainly just a shim to hold the 220 film in the correct focal plane. Otherwise it would be a paper-thickness too far back.
I would assume that you could probably shoot 120 in a 220 holder if you 1. either compensated for the backing when you focus or 2. stopped down and extra stop or two to get some extra depth of focus.
-- Nathaniel Paust (firstname.lastname@example.org), January 28, 2002.
Every camera and back I've seen for 120/220 holds the film flat by applying pressure to the back of the film to to hold the emulsion surface against an aperture gate. Thus, differences in film thickness and paper backing don't change the focus.
Now, that isn't to say some fool engineer (I get to say that 'cause I'm an engineer) didn't figure it would be better to apply pressure from the emulsion side--just that I'haven't seen it. If you have a back that does this, then of course you'd have to compensate.
-- Charlie Strack (email@example.com), January 28, 2002.
Nat. you've got it backwards. The film will always lie at the same plane, the paper is behind the film, up against the pressure plate. Using 120 in a 220 back will increase the drag on the film during winding, adding excessive stress to the components. But the film will be in the same position (unless the excessive pressure deforms the paper).
-- Wayne DeWitt (firstname.lastname@example.org), January 28, 2002.
Charlie beat me to it, but we may have overlooked something. If the back has a cutout to relieve pressure then misalignment is possible. Remember the problems with 35 mm film and the 72 exposure rolls of HP5 and the thinner based Tech Pan - there were alignment problems. But it will only affect 220 in a 120 back, not the other way 'round.
-- Wayne Dewitt (email@example.com), January 28, 2002.