120 film with 220 back?

I have a Pentax 645, but only a 220 back. Can I load and shoot

120 film into it?> and what will happen?

Lane,

<p>

I, too, have a Pentax 645 and love it! Anyway, to the best of my

knowledge, the 220 film is thinner than the 120, hence the need for

either separate backs or an adjustable back (like the Pentax 67).

The 220 film in a 120 back would likely leave the film not 'pressed'

completely against the back, leading to possible out of focus

pictures. Worst case scenario would be 'wavy' pictures where parts

were in focus and other parts out of focus.

<p>

Chris

Worst case scenario: You will have to keep track of the exposures

you make for a while, as the camera will wind up exposing the paper.

<p>

I have both backs, and the look identical. The presure plates feel

identical. The load identical.

<p>

The only thing there are some little studs on both backs which have

no discernable purpose. I guess they are for telling the camera what

kind of back is there. One of these days I'll take out my multimeter

and ohm them out just to see.

<p>

Go ahead and try it out. It can't jam, and you'll answer an age-old

question equivalent of "How many licks does it take to get to the

center of a Tootsie Roll Tootsie Pop?" :)

I'm not familiar with the 645 film path, but the question involved

running 120 through a 220 back. The 120 film plus paper backing will

be a bit THICKER than 220, where you have film or paper but never both

together. Also, on my practice roll of 220 (TXP) the film itself is

about 0.050 inches/1.25mm narrower than the paper leader. If the

tolerances within the film channel are tight, I can imagine that you

might indeed jam something running thicker film/paper through it.

Also, if the width of the channel is just right for the film only, I

can imagine that there would be no problem putting slightly a wider

paper leader and trailer through it alone, but that things might jam

up on the sides when you run that wider paper through along with a

thickness of film.

<p>

OTOH, unless the back is particularly delicate, it ought to be tougher

than some film and paper, so the worst that might happen is that you

tear up a roll of 120 finding out if it will work.

<p>

Let us know what you find out if you decide to try it.

Lane,

<p>

I was in your position once (Bronica instead of Pentax though) and got

conflicting answers to this question. I did try a roll of 120 (Fuji

slide film) in my 220 back and was successful. OTOH, some responses

I've seen stated that you may run the risk of damaging either the

film, or less likely the back, for the reasons others have stated

here. I didn't want to run that risk so I got a 120 back. I now have

two 120 backs and use them both constantly. My advice is get a couple

more back as soon as you can (I think 120 backs are most useful, but

that's up to you). Having the ability to change your film mid-roll

(i.e. color to B&W, or 100 to 400 ISO) and back again is one of the

great things about these cameras. Good luck.

Here in Germany it is not very easy to get second-hand magazines for

the Pentax 645. A few months ago I was lucky to get a used 220 mag.

Mostly I use 120 films and so I tried to use them in the 220 back: It

worked, the pictures taken are of exellent sharpness. The only problem

that occurs is that you have to watch the counter. It is possible to

take more than 16 "pictures"...;-)