curtis_hedman Posted February 3, 1999 Share Posted February 3, 1999 I've had my 6x7 repaired twice in the last three months for film transport problems (overlapping and/or large interframe gaps). The first time the camera came back, I noticed that the wind lever "free-wheeled" effortlessly after cocking the shutter; I seem to recall that, before the repair, it basically locked after returning to the rest position after the cocking stroke -- am I wrong in that? Anyway, after the second repair, the wind lever ALWAYS cocks the shutter, so long as the back is closed - film or no film. The shutter cocking mechanism NEVER seems to disengage, even after 10 exposures (as though the film selecter was mis-set). Also, the frame counter dial cannot be moved with the standard "push down and twist" approach. The shuter can be cocked with the back open using the little round key. Unfortunately, in neither repair attempt did the inconsistant film transport problem get solved... in fact, based on measurements from three rolls of film, the gap variation has stayed pretty much constant throughout (in all honesty, it looks like the overlapping frames are gone). Anyone have similar experiences? I'm tempted to leave well enough alone, since it appears that I now can consistantly get nine exposure per roll! I'm disinclined to give the repair shop a third shot at it, given their track record to date. Link to comment Share on other sites More sharing options...
allan_jamieson2 Posted February 3, 1999 Share Posted February 3, 1999 I have experienced frame overlapping problems with my first Pentax 6x7 camera about 4 years ago. I took it to a good repair shop and they overhauled the winding mechanism and after that it seemed to be fine. However, both that camera and my newer Pentax 67 do tend to be a bit erratic in the spacing between each frame, sometimes there is a big gap and at other times a minute gap. I don't think that the film advance system is all that great to be honest, and that is nothing at all to do with the age of the camera. Maybe, that aspect has been improved a bit on the new 67II model. If I were you I would be looking for a refund from the repair centre that you took your camera too. If they are an approved Pentax repairer a complaint directly to Pentax might not do any harm either. Also, if you paid for the repair by credit card you might be able to get a refund from the card company as the work carried out has obviously been sub-standard. Try to find a good repair centre Curtis and take your business there. I wouldn't take the camera back to the other place again ! Link to comment Share on other sites More sharing options...
gene_crumpler6 Posted February 4, 1999 Share Posted February 4, 1999 Curtis: Considering the cost of a new p67 body at B&H of $995, maybe you should consider cutting your losses. Unever frame spacing is a characteristic of the p67, but has not been a problem for me. Link to comment Share on other sites More sharing options...
chris_toomer Posted February 4, 1999 Share Posted February 4, 1999 I have an odd thought on this. If the frame spacing gets wider as the roll is used, could it be caused by the diameter of the take-up spool getting larger as more film is wound onto it? Or are cameras designed to compensate for that? Chris Toomer clt@alpine-cons.com Denver, CO Link to comment Share on other sites More sharing options...
gene_crumpler6 Posted February 4, 1999 Share Posted February 4, 1999 You know, I've not been able to figure out how the p67 counts frames. All of the other MF cameras I've used have/had the knurled wheel pressing on the take up spool and the mechanics seem straight forward. I've look in the back of the p67 and I can't seem to figure out what roller does the counting! Is it the roller at the edge of the shutter next to the takeup spool??? Link to comment Share on other sites More sharing options...
curtis_hedman Posted February 4, 1999 Author Share Posted February 4, 1999 You've got it, Gene --- the rubberized roller just before the take-up spool does the measuring. In theory it turns freely just the right number of turns as the film is pulled by it, then locks. A clutch on the takeup spool is supposed to slip so the rest of the stroke necessary to cock the shutter can happen without the takeup spool turning (or maybe there is a'disengage' mechaism in the winder). I'm beginning to wonder if part of the problem could be that the roller has hardened over the years, so that the film "slips" across it a little, meaning more than the right amount of film moves by before the rollor does its thing.... or the declutching doesn't quite let go. Anyone else have any thoughts? Curt Link to comment Share on other sites More sharing options...
gene_crumpler6 Posted February 5, 1999 Share Posted February 5, 1999 With that arrangement, its a wonder that the spacing is a good as it is!!! Link to comment Share on other sites More sharing options...
david_flater1 Posted February 5, 1999 Share Posted February 5, 1999 $1K on a new camera doesn't buy you much, does it? I would expect incurable film transport problems from junky, worn-out used cameras, but from a new one, I'd be hopping mad. Link to comment Share on other sites More sharing options...
michael_heal Posted February 5, 1999 Share Posted February 5, 1999 <p>Frame spacing becomes uneven on many medium format cameras if the film is not wound tightly on the takeup spool. Some overlapping frames may be caused the film slipping on this spool. When you load the camera, try applying a little drag (using one of your fingers) as you start winding.</p> Link to comment Share on other sites More sharing options...
curtis_hedman Posted February 5, 1999 Author Share Posted February 5, 1999 Just to clarify -- this Pentax 6x7 is 25 years old! It is the original version, non-MLU, none of the running improvements to the transport mechanism. It has not gotten heavy use in those 25 years (I have used it in cycles - with it sitting on the shelf for years at a time), and it was only this Fall, when I decided to get active in photography again that the problem surfaced. This is the model that Pentax no longer supports, either for repair or, it would seem, parts. The repair technician (we had a heart-to-heart talk yesterday) tried to make do with modifying parts from the currently available inventory, with varying success. He has put a lot more parts into it than I have paid for, and is willing to have me present when he makes one final attempt to adjust the mechanisms. He says that there are four critical adjustments amoungst the various cams and pawls..... Anyway, I'm going to take him up on his offer Saturday; we shall see how it comes out. Incidently, prior to this Fall, I never experienced any sort of transport problem with the camera, using both 120 and 220 film. One other question on the words about how other MF cameras determine film motion.... if the system essentially counts the turn of the takeup spool, wont the frame spacing grow as the diameter of the takeup spool increases due to the spooling up film layers? And if the camera uses a wheel that rests on the film (to measure true linear motion) does this do any damage to 220 film, which has no paper backing? Come to think of it, I guess a small ruber "tire" might not do any more damage than the full width Pentax "roller" I have a factory service manual (old) coming (from an ebay auction) - maybe it will enlighten me on all of this, particularly after a chance to witness "surgury" first-hand! Curt Link to comment Share on other sites More sharing options...
gene_crumpler6 Posted February 5, 1999 Share Posted February 5, 1999 In the rollies and maimya C series, the wheel presses against the outside of the take up spool. Thus it measures the length of the film moved, not the number of turns of the spool. As the spool fills up, the wind stroke on these cameras becomes shorter. It works perfectly with leaf shutter cameras. With focal plane shutters, it becomes a bit more complicated. Link to comment Share on other sites More sharing options...
curtis_hedman Posted February 6, 1999 Author Share Posted February 6, 1999 Latest update -- the technician readjusted the linkage in the winder while I watched (the mechanism is complex but elegent, and nothing look flimsy to me), and now the camera film transport seems to work properly. It was interesting to note how small an adjustment (on a small interlock pawl) was needed to make the whole mechanism shift its behavior from incorrect to correct. It was also interesting to note that some of the screws, locking collars, etc. had left-handed threads. The technician clearly know the mechanism by heart (he mentioned he has worked on hundreds over his career), and I feel good now that the camera is as close to new as a 25 year old camera can get! Link to comment Share on other sites More sharing options...
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