120 film in 220 back

ezwriter · Sep 16, 2012

Havent tried this yet but can u put 120 film in a Mamiya 220 film back?

Ian Grant · Sep 16, 2012

I've used 120 film in a Mamiya 645 220 film insert with no problems, the issue can be that the pressure plate doesn't hold the film flat as there's a difference in the thickness of 220 film compared to 120 film plus its backing paper. Might differ between models/types of back though.

Ian

Vaughn · Sep 16, 2012

One thing to know is that since 220 has no paper backing (except for the start and finish of the roll), the pressure plate of the 220 back will have the 120 film a little forward of the optimal plane due to the 120 paper backing.

Spacing might be a little off since the 120 rolls thicken quicker than 220 film due to the paper backing, also.

MFstooges · Sep 16, 2012

Vaughn said:
One thing to know is that since 220 has no paper backing (except for the start and finish of the roll), the pressure plate of the 220 back will have the 120 film a little forward of the optimal plane due to the 120 paper backing.

Spacing might be a little off since the 120 rolls thicken quicker than 220 film due to the paper backing, also.

No difference in film plane position since it is held against the rail on the body. Using 120 in 220 back will result in uneeded tension on your film and winding mechanism.

markbarendt · Sep 16, 2012

In a practical frugal sense it works fine, at least with RB backs. The 220 backs can be had less expensively than 120 backs.

Watch the counter though. On the RB you get ten 6x7 fames but it will count out a bit further; once you see fame 11 pop up advance through the rest until you are sure the film has wound onto the take up reel.

henk@apug · Sep 16, 2012

http://www.collection-appareils.fr/x/html/appareil-11292-Mamiya.html

It is in french, but there is a note that you can use 120 film in 220 back, by screwing off a little piece on the 220 back
(See 2nd last picture)

ic-racer · Sep 16, 2012

MFstooges said:
No difference in film plane position since it is held against the rail on the body. Using 120 in 220 back will result in uneeded tension on your film and winding mechanism.

True that the inner pair of rails don't change position, but for the film to stay flat during the exposure the film should be lying against the pressure plate, not floating in the channel. The pressure plate is slightly farther forward (toward the lens) in most 220 film backs. A few pieces of tape on the outer rails can re-position the pressure plate farther back in some cases.

markbarendt · Sep 16, 2012

ic-racer said:
True that the inner pair of rails don't change position, but for the film to stay flat during the exposure the film should be lying against the pressure plate, not floating in the channel. The pressure plate is slightly farther forward (toward the lens) in most 220 film backs. A few pieces of tape on the outer rails can re-position the pressure plate farther back in some cases.

I'm not understanding how the tape could help.

An unmodified 220 back will hold 120 film tighter to the rails, there will be less channel float with 120.

MattKing · Sep 16, 2012

Not to long ago, when Mamiya USA maintained an internet archive of information about their "legacy" equipment, they had a "FAQ" section that answered this question about RB backs. In essence they said that it will work, but the extra thickness of the film plus backing may cause premature wear in the 220 insert, due to increased tension. And of course the counter will mislead.

BrianShaw · Sep 16, 2012

MattKing said:
... And of course the counter will mislead.

... especially on that 13th frame!

ezwriter · Sep 16, 2012

I should have said these are Mamiya RZ67 backs, not sure but pix look different than my backs.

ic-racer · Sep 16, 2012

markbarendt said:
I'm not understanding how the tape could help.

An unmodified 220 back will hold 120 film tighter to the rails, there will be less channel float with 120.

The risk is that it will bulge in the middle. The last thing I'd want with 120 is for the film to be closer to the lens. You can get those images where the edges of the frame are in focus but in the middle of the frame the focal point is behind the subject.

Certainly each camera and film back represents its own unique challenges.

MFstooges · Sep 17, 2012

ic-racer said:
True that the inner pair of rails don't change position, but for the film to stay flat during the exposure the film should be lying against the pressure plate, not floating in the channel. The pressure plate is slightly farther forward (toward the lens) in most 220 film backs. A few pieces of tape on the outer rails can re-position the pressure plate farther back in some cases.

Both will guarantee flatness. Pressure plate of 220 back is slightly forward but will be in the same position as it presses against the film rails. Only pressure and counter will be different.

ic-racer · Sep 17, 2012

MFstooges said:
Both will guarantee flatness. Pressure plate of 220 back is slightly forward but will be in the same position as it presses against the film rails. Only pressure and counter will be different.

Maybe I don't follow you. How can it be both "slightly forward" and "in the same position" ?
Neither guarantees flatness
Lack of film flatness is the major limiting factor in medium format photography.

BrianShaw · Sep 17, 2012

I think he means "against the film rails with greater pressure".

markbarendt · Sep 17, 2012

BrianShaw said:
I think he means "against the film rails with greater pressure".

That is the only difference.

lensman_nh · Sep 17, 2012

markbarendt said:
That is the only difference.

And if anyone honestly, truly thinks that spring tolerances in production backs are so good that there is a measurable difference in the pressure applied to the film then I have a bridge to sell you. On a film back that is a decade or 2 old you will see more variance between 220 film backs than between a selected 120 and 220 back. Even new I doubt the difference in pressure is measurable. The only difference in a mamiya 645 120 and 220 film back is a block of metal that triggers a count to 30 in the 220 rolls. Film is registered off the front of the back so the registration distance will not change.

Film backing paper is about 0.002 - 0.004 thou thick. Springs at the price you pay for a brand new Hassy back are not that good.

BrianShaw · Sep 17, 2012

lensman_nh said:
And if anyone honestly, truly thinks that spring tolerances in production backs are so good that there is a measurable difference in the pressure applied to the film then I have a bridge to sell you.

I'm selling the same bridge!

MFstooges · Sep 17, 2012

ic-racer said:
Maybe I don't follow you. How can it be both "slightly forward" and "in the same position" ?
Neither guarantees flatness
Lack of film flatness is the major limiting factor in medium format photography.

Sorry, I was just using your words. Plate is slightly forward when not attached to camera body. When the back attached to the body then the film plane on both backs will be in the same distance from lens flange. Like I said no difference except for the more pressure that is meant to compensate zero point zero xxxwhatever milimetres.

Ghostman · Sep 18, 2012

I use a 220 film back with 120 film on my RZ67 and it's fine. I also use the 120 film back. I have never had any problems with winding, exposure, jamming. Maybe I'm just not experienced enough to notice the difference.

paul ron · Sep 18, 2012

The only differece between 120 n 220 film is the backing paper. The film itself is exactly the same stuff for both!

The film plane is exactly the same for both 120 n 220 backs... otherwise you would never focus a sharp image if you changed backs. The viewfinder is adjusted to match the focal plane of the film, no matter if it is 120 or 220. They both have to agree agree to a sharp image. If you were to have different focal planes for 120 vs 220 one will always be out of focus when changing backs in a shoot. DaHa?

The preasure plates are the same in 120 n 220 backs as are the springs and tensioners. Parts from one can be used in the other but not the counters or the metering mechanisms.

The real differnce in build are the counters n frame metering mechanisms. The 220 mechanism takes into account winding less, no paper, on the take up spool thus metering the frame length differently, by increasing the roll's diameter on the take up using 120 in a 220 back you may have to do some experimenting to see how the spacings fall.

Run a 120 test roll through the 220 back n mark where the frames align?

ic-racer · Sep 18, 2012

MFstooges said:
Sorry, I was just using your words. Plate is slightly forward when not attached to camera body. When the back attached to the body then the film plane on both backs will be in the same distance from lens flange. Like I said no difference except for the more pressure that is meant to compensate zero point zero xxxwhatever milimetres.

Again each camera and back will have its own issues when using the wrong film. I don't want to imply what you have observed on your cameras is wrong (especially if you are referring to the Hassleblad, which has a film gate a little different than just about every other MF camera).
As an example, some cameras (Rolleiflex TLRs and Yashica 124G) put the pressure plate farther back from the outer rails on the "120" setting. For example if you look closely you will see the indentation in the pressure plate where it touches the outer film rails and allows the pressure plate (which of course is a misnomer in that it puts no direct pressure on the film in these cameras) to sit closer to the lens.

Other cameras, like the Rollieflex SLXs, have a fixed film gate depth regardless of the 120 or 220 setting on the film back.

My opinion is that it probably does not make much difference (ie different pressure plate location for 120 and 220) because the film can be wavy and not perfectly flat in the film gate to a much larger amount than the small distance representing the thickness of the paper.

nosmok · Sep 20, 2012

Always late to the party, but it should also be noted that the leaders are different between 120 and 220 film:

220 film leader:

Length of paper = 22.25"
Start mark to film = 7.5"

There's about an inch and a half of unexposed film past the paper, so I'm going to try 8.5" for my start mark to film.

120 paper :

Head to film start: 15-1/2" (from full width paper)
Start Arrow to film: 7"

The tail leaders are different too, but it doesn't matter .

Wayne · Mar 9, 2016

I just ran my first roll of 120 through the 220 Pro SD back I bought for my RB67. The good news is no more light leaks! The tension was worrisome though, it felt very very tight as I advanced it. It went through OK though, and I got all 10 frames. I noticed the spacing was a little bit irregular but plenty of space between each frame.

120 film in 220 back

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