Issues with Pentax 645N Film back and loading film

Megan Eagles · Oct 23, 2021

Hi there,

I have been using my trusty Pentax 645N for a while with no issues then suddenly I had an issue locking the film back on (it felt slightly stiffer than usual). After that when I pressed the shutter to advance the film I had loaded it made a different noise (although definitely wound something along) and then I got an E message on the LCD.

I have changed the batteries, tried reloading the film a few times and no success in fixing the error message.

Any ideas? Could it be a connection issue between the film back and the camera? I dont have a spare film back but I could see if I could borrow one from somebody..

thanks
Meg

LimeyKeith · Oct 23, 2021

Try pressing the mid roll rewind button non the bottom of the camera. Hopefully the camera will spring into life, rewing the film and clear the ERR message. If it doesn't rewind then try taking out the film and repeating this procedure. If the ERR message clears inspect the back and camera housing for any signs of obvious damage before trying a reload. What film are you using? I ask because my 645N hates Fomapan 200 and jammed every time I tried to use it.

pentaxuser · Oct 23, 2021

LimeyKeith said:
Try pressing the mid roll rewind button non the bottom of the camera. Hopefully the camera will spring into life, rewing the film and clear the ERR message. If it doesn't rewind then try taking out the film and repeating this procedure. If the ERR message clears inspect the back and camera housing for any signs of obvious damage before trying a reload. What film are you using? I ask because my 645N hates Fomapan 200 and jammed every time I tried to use it.

Good advice. Did you ever discover what it might have been about Fomapan 200 that differed sufficiently from other films to create this problem and was it literally ever time and only Fomapan 200 and not say 100 or 400 or was 200 the only Fomapan used?

One day I might consider Fomapan for my 645N but do not want to risk the problem you had

Can I ask others here with 645Ns who have used Foma films if they have had similar problems?

Thanks

pentaxuser

drmoss_ca · Oct 23, 2021

Old thread at pentax forum about the issue: https://www.pentaxforums.com/forums/48-pentax-medium-format/40937-645n-err-lcd-yikes.html

I had a 645n and a 645nII. The battery holder contacts were not always reliable, and I ended up using some hot glue to fix them in place, and some stop bath concentrate (ie strong acetic acid) to clean off corrosion. Very reliable afterwards.

roamandclick · Oct 23, 2021

I have a 645Nii and shoot quite a bit of Foma 100 with the occasional roll of Foma 200 peppered in from time to time and have never had any issues. Could be because it's a more recent model though... The Foma films seem thinner than Kodak or Ilford stocks and I would think the camera would favor that.

This Foma 200 jamming issue raises some curiosity though... I'll keep an eye on it next time I load up a roll!

Megan Eagles · Oct 23, 2021

Thanks for this advice - I pressed the mid-roll button and then reloaded a test film which did load correctly and I shot through the roll successfully so thank you so much. Is the mid-roll button a bit of a re-set for this kind of issue?

I do definitely think there might still be an issue with my film back as its still quite stiff and now quite hard to remove. Do you think these could be coincidental issues or that the film back connection might be affecting it?

FYI, i was using Portra 400 so I don't think it was the film affecting it.

LimeyKeith · Oct 23, 2021

pentaxuser said:
Good advice. Did you ever discover what it might have been about Fomapan 200 that differed sufficiently from other films to create this problem and was it literally ever time and only Fomapan 200 and not say 100 or 400 or was 200 the only Fomapan used?

One day I might consider Fomapan for my 645N but do not want to risk the problem you had

Can I ask others here with 645Ns who have used Foma films if they have had similar problems?

Thanks

pentaxuser

Perhaps you've forgotton this post Pete: https://www.photrio.com/forum/threads/pentx-645n-repairs.159486/#post-2073032

LimeyKeith · Oct 23, 2021

Megan Eagles said:
.....Is the mid-roll button a bit of a re-set for this kind of issue?

......I do definitely think there might still be an issue with my film back as its still quite stiff and now quite hard to remove. Do you think these could be coincidental issues or that the film back connection might be affecting it?

FYI, i was using Portra 400 so I don't think it was the film affecting it.

The trick with the rewind button seems to be a panacea for many ills but I have no explanation why - unless perhaps the mechanism gets itself out of sync sometimes and this resets it all.

What part of the removal is stiff? Is it the locking lever that is hard to rotate to lock/unlock the back? Is the back difficult to insert into it's housing?

Late Edit: Fomapan 200 is the only film I have had the issue with so I don't use any of the Foma films in this camera.

pentaxuser · Oct 23, 2021

Thanks, Keith and yes I had forgotten that original thread. There might be an issue with Foma 200 and if so then logically this is likely to be true for all Foma films and not just the 200. Pity that there are not a lot more of us using Foma in P645Ns to really know for sure

Meagan, as far as your " stiff and hard to remove insert" is concerned I have just had a look at mine. Once the back locking mechanism has been released by turning it 90 degrees then turning it a little further moves the " metal hooks" on either side down enough to clear the part inside the actual space into which the insert goes and allows it to be pulled out. There is a little resistance when you turn it a little more ( internal spring resistance? ) but it should not be enough to make it really stiff. If the two hooks go lower each time you twist then they should clear the parts in the space to which they engage quite easily

Try gently to twist the unlocking mechanism a few times to see if this frees up the movement. As far as I can see this mechanism to secure and free the insert has no connection to the film loading mechanism and your problem in #1 but you may have reached the same conclusion so my last sentence may be redundant

pentaxuser

LimeyKeith · Oct 23, 2021

Just a final word from me. Since I had my original problem back in 2018 I have put dozens of films through the camera without any problems at all in both 120 and modified 220 inserts, mainly Ilford HP5+ and FP4+ (I hope I'm not tempting fate here ). Earlier I dug out the Fomapan 200 films that caused the original problems and which I developed to get the usable frames and they are still as springy as ever despite being stored in files and binders. Remarkable and although I love Fomapan 200 in 5x4 format the 120 version will never meet my 645 again.

Megan Eagles · Oct 28, 2021

LimeyKeith said:
What part of the removal is stiff? Is it the locking lever that is hard to rotate to lock/unlock the back? Is the back difficult to insert into it's housing?"

Both! Locking lever is stiff to turn and now the film back itself is very tricky to remove. Perhaps it got damaged by my forcing it? I've had a look at the locking mechanism and can't see anything too untoward but am worried I will have the same issue next time I load film and will waste another roll. Do you think the issues could be linked?

LimeyKeith · Oct 28, 2021

I think your film back my be distorted in some way because the film back is a very loose fit when inserting into the camera until the final 5mm or so when you have to turn the locking lever a few degrees anti clockwise to allow the locking latches to engage with their sockets and the back itself to mate with it's housing, then you turn the lever 90 degrees clockwise to lock the back in place. Although I don't do video I just did a quick one to show how easy it is to fit a back into my camera but flickr just mangles it and makes it all jerky so I removed it. If you want to see it, PM me your email address and I'll send it vai WeTransfer - you just click on the link they send you and it will download the file.
Do you have, or can you borrow a second back just to check whether it is the back or the camera causing the problem?

Megan Eagles · Oct 28, 2021

LimeyKeith said:
I think your film back my be distorted in some way because the film back is a very loose fit when inserting into the camera until the final 5mm or so when you have to turn the locking lever a few degrees anti clockwise to allow the locking latches to engage with their sockets and the back itself to mate with it's housing, then you turn the lever 90 degrees clockwise to lock the back in place. Although I don't do video I just did a quick one to show how easy it is to fit a back into my camera but flickr just mangles it and makes it all jerky so I removed it. If you want to see it, PM me your email address and I'll send it vai WeTransfer - you just click on the link they send you and it will download the file.
Do you have, or can you borrow a second back just to check whether it is the back or the camera causing the problem?

That's what I thought, it was always so smooth to turn before. I did manage to get hold of another film back today and compared the two and the locking mechanism on mine was not moving causing the issue. New film back works beautifully and the film wound on perfectly. Issue solved! And seems likely the two issues were linked. Many thanks for your help and advice!

LimeyKeith · Oct 28, 2021

Thank goodness the problem was with the film back because camera repairers for the 645 are almost impossible to find.

Happy shooting.

Issues with Pentax 645N Film back and loading film

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