[asahijock]

You can get some fresh 220 Velvia/Provia from Japan or ebay while supplies last. It's probably from the last batch Fuji made in 2017 before discontinuing it. As of 2018, 220 film is not manufactured by anyone.

So yeah, other than that, a 220 insert can only be used for parts to repair a broken 120 one, but that's probably it. Until someone starts making 220 film again.

Thanks for the reply. A bleak outlook. Already on e-bay the 220 inserts considerably outnumber the 120s. The problem with 220 spares is that if you cannot obtain another 120 insert but wish to have a second insert then the vital part of the pressure plate cannot be transferred without alleged potential damage to the motor. No pressure plate then no second insert

asahijock

[kaseki]

I would expect a properly equipped machine shop could plane a 220 pressure plate to 120 plate thickness. The dimpling would probably require fabrication of a special knurling tool. Countersink depth would have to change. All this tooling and effort would only be practical if the price of 120 inserts became astronomical and there were enough demand to set up for dozens of plate modifications. Alternatively, a hobbyist with machining skills and machine access might try experimenting for the fun of it.

[Maxwell]

For information.

I converted a 220 insert to a 120 by changing the plastic tab direction so it winds to the end after 16 frames and replaced the 220 pressure plate with one from a U/S120 insert.

There appears to be no other difference in the inserts and the conversion works perfectly. Just says 220 on the back.................

Be aware that the screws securing the pressure plate are installed with Loctite in the factory and they are not easy to remove. I used a PH000 screwdriver for the little black screws and needle nosed pliers to hold the silver pins, but even then I had to drill out the final screw. Obviously you only need two good pin and screw sets to refit the pressure plate.

[rfom11]

Hi Everyone,

Made an account just for this post. I "converted" a 220 film back to 120 on my pentax 645N and it worked well for the first 13 or so frames but then the motor had a very hard time winding the 120 film, the mirror wouldnt come down and the camera shut itself off and gave a flashing battery sign (had fresh batteries). Took film out and it appeared to have creased the last frames for whatever reason.

Tried it again on another 120 roll in converted 220 insert (in case the original roll had a problem) and same problem.

Tried again on a 120 insert and shot thorough 16 frames with no problem.

So, i'd say that, at least on a 645N, you are better off using the 120 insert. This problem could be specific to my 645N body but why risk it?

[Maxwell]

Hi,

I can only speak of my own experience. On my 645N I am using a 220 back which I converted by changing the pressure plate and the plastic tab and it has worked fine with 120 film, though only 7 rolls of Portra 160 since I did the conversion. Definitely no increase in motor noise, frame spacing is perfect, and winds off correctly at the end.

I am sorry to hear it hasn't worked for you. As you say it may be your 645N body, or it may be the 220 back you used. The symptoms you describe are very similar to those which I have encountered on a worn out 120 back, though that is anecdote rather than evidence.

Of course it is also possible I have the only body and 220 back combination where this conversion works. We really need a few more people to try this experiment.

The conversion is only suggested as working 120 backs are getting harder to find.





.

.

[rfom11]

I think they key here is that you also changed the pressure plate which we agree is different between the backs.

When i say i "converted" a 220 back i mean that i ONLY changed the plastic tab position and left the 220 pressure plate.

My opinion is that running 120 film through a 220 pressure plate is what is causing the problems on a 645N.

Hope that clarifies.

[Smolk]

Thanks for this clarification, which makes a lot of sense! I no longer have my P645N, but I would have taken note despite believing earlier that it would all be fine.

Ok, I know it's an old thread, but it keeps being linked to when there is a discussion about using 220 inserts with 120 film.

I have both inserts and they are, in fact, different! Somehow it's not immediately obvious even when you look at them side by side, but 220 pressure plate has different thickness to accommodate for the lack of backing paper on 220 film. Although it may have no noticeable effect on the IQ, it has other implications to it. If you mod a 220 insert as outlined above and run a 120 roll through it you will immediately notice that the motor sounds different compared to using 120 film in 120 insert. This is because using 120 film in 220 insert puts more strain on the camera motor. This may wear the motor down faster, break it altogether or harm the camera in some other way we don't and can't anticipate.

This claim is supported by Eric, whom I contacted some time ago to seek his expert opinion on the matter:



So yeah, don't do it.

That said, you can probably use a 220 insert in a pinch, but please understand, that you will likely be actively participating in your 645's untimely demise this way. Whether running down a perfectly good camera is worth the price difference between 120 and 220 inserts is up to you, but my personal opinion is it's not.

I'll post photos showing the difference between the inserts later.

[kaseki]

Someone with interest in 645 film cameras and who also has access to a machine shop with a surface grinder might consider reducing a 220 plate's thickness to the 120 plate's thickness and trying it.

[asahijock]

Most of us I suspect and this is certainly true for me will have great difficulty finding (a) a machine shop competent and willing to machine a 220 plate and even if we do find one, it needs to be one that doesn't charge a "king's ransom" to do so.

If the pressure plates are that much different and create motor problems within a few rolls' use then it is indeed a bleak outlook as I said in my earlier post. The 220 inserts are effectively redundant and the 120 inserts on the law of supply and demand are getting very expensive and scarce

Short of a skilled and reasonably priced machine shop in your neighbourhood prepared to have a go, I can see no way round this issue. Sooner or later the problem of parts for out-of-production analogue cameras is bound to arise and this is one such problem


asahijock

[itsdoable]

I posted this a long time ago, and I'm not sure where, so I'll repeat some of it.

My recollection is that the 220 plate was not thicker, but the hard-points that mated with the film gate was machined down about the thickness of the paper, so as people have pointed out, the gap was thinner to accommodate the film without backing paper.



(Previously posted picture by lightproof)

I added tape to the edge of the 220 plate above, so that the machined area at the edge of the plate was now flush with the rest, as in the 120 plate. I used aluminium foil tape. Much easier than machining down a plate.

The reasons for the film gap has to do with keeping the film flat. Film has a curl, which naturally tries to curve down outside the film rails, and helps keep the film flat. Pressing the film against the film rails traps it when it develops a bulge. The other advantage is less friction advancing the film.

... that and flipping the plastic tab.

[asahijock]

Thanks,itsdoable. The conclusion I draw from your post is that using a 220 back you might need a "thickener" on the edge of the plate but it should not make the motor work harder.

How many 120 films have you put through your modified 220 without any adverse effect on the motor? Thanks

asahijock .

[kaseki]

I posted this a long time ago, and I'm not sure where, so I'll repeat some of it.

My recollection is that the 220 plate was not thicker, but the hard-points that mated with the film gate was machined down about the thickness of the paper, so as people have pointed out, the gap was thinner to accommodate the film without backing paper.

(Previously posted picture by lightproof)

I added tape to the edge of the 220 plate above, so that the machined area at the edge of the plate was now flush with the rest, as in the 120 plate. I used aluminium foil tape. Much easier than machining down a plate.

The reasons for the film gap has to do with keeping the film flat. Film has a curl, which naturally tries to curve down outside the film rails, and helps keep the film flat. Pressing the film against the film rails traps it when it develops a bulge. The other advantage is less friction advancing the film.

... that and flipping the plastic tab.

Ohhh! Relative to at least my paying attention to this topic, and in particular the thread where that image appeared, this is the first mention I'm aware of that the 220 plate is the same thickness except at the edges (vs. my previous understanding that the 220 plate was thicker except at the edges). So a surface grinder is not the solution. The metal tape idea seems the easiest so long as it is checked periodically for integrity. Flame spraying would be a more permanent build-up solution but likely overkill for all but the most extreme reliability requirements. Nice!

[itsdoable]

How many 120 films have you put through your modified 220 without any adverse effect on the motor? Thanks
asahijock .

I have not owned the 645 for a number of years, probably pushing 10. I only owned the original 645 (purchased when it was current!), and ran a lot of film through it, both 120 and 220. When 220 became hard to find, I converted that insert over to 120, and since it was a second insert I probably ran less than 50 roll though it. I shot 6x6 and 6x7 for a while, and eventually sold both my 645's as they were not being used much ( I hung on to them as they were really nice machines to use, but I had moved on to bigger negatives). I don't recall ever having any issues with the converted insert - but I only ever used the original 645 (not the "N").

[asahijock]

Thanks,itsdoable. 50 rolls may not be enough to be able to conclude that there is no effect on the motor but what may be more conclusive from an engineering point of view is whether the 220 plate is no thicker. At first glance the fact that it has a lip does strongly suggest that it is the same thickness in the centre as the 120 but it may be that this does not necessarily follow i.e. the centre thickness of the two plates might still be different by a small amount.

Others who may have made the conversion of the 220 and have since put a lot of 120 films through the inserts are what is needed here to help establish if there is wear and tear to the motor but they seem "thin of the ground"

I was not sure from your last paragraph what the lip on the 220 does for 220 film. What does it do that is not required with 120 that has backing paper throughout the film.

Certainly from a manufacturing ease of production aspect it would seem preferable that all the plates are the same thickness and all that has to be done is a small machining job on the edge which tends to lead one to think that the plates themselves are of equal thickness but this is simply an assumption on my part and may not be justified.

asahijock

[kaseki]

In hindsight, I think the "constant thickness" pressure plate makes sense.* Assume a camera/lens with near zero depth of field at some aperture and focal length. Assume that the 220 film emulsion or 120 film emulsion plus backing paper is tight to the pressure plate. There can be only one position of the film plane relative to the lens flange for the viewfinder ground glass and the film plane to be optically equidistant and thereby have the film focus occur where visual focus occurs. With the film tight to the pressure plate, and the presure plate edges tight (metal to metal) to the right and left "rails" of the 645 focal plane stop, it is the OFFSET of the pressure plate edge that rides on the rails relative to the pressure plate surface where the film rides that positions the film emulsion to be the correct distance from the lens flange.
_____
*Given springs etc. pushing the pressure plate to the aperture stop rails, to first order optically it doesn't really matter what the exact pressure plate thickness is. What matters is where the focal point is designed to be relative to the rails, and whether or not the pressure plate edges that fit to the rails are offset or not from the film supporting portion of the pressure plate to assure that the film emulsion is in the correct focal position.