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Classic Camera Repair » Archives-2006 » Canon AE-1 - views sought on projected modification for metering problem « Previous Next »

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Frank McLean

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Posted on Wednesday, March 08, 2006 - 11:03 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I have an AE-1 with the classic 'twanged tungsten wire' problem, whereby the pulley wire that attaches the ASA dial on the right side of the camera ALL the way across the camera to the pulley on the rewind crank that moves the resistor that actually registers the speed to the internals, phew, has snapped. So the meter always says underexposed. What a great design.

So, replace the wire y'say. On a camera that cost me $8, that I want just as a picture taker, I'm spending $20 plus shipping plus time removing top cover, overhand knotting, feeding wire through various rollers, under, over, all round about? Hmm. I'm thinking along the following lines. Bear with me. Purists look away now...

If all I need to do is be able to rotate that left hand resistor, can I: remove the rewind crank and covering bits, attach a dial to the resistor, make some tiny standoffs to raise the rewind, erm, black plate thing, enough to let the dial turn freely, replace the rewind bits. I would then have a way of adjusting the film speed by turning the dial I created. Calibration should be simple, since there is an index mark on the resistor for 100 ASA, so I have my starting point. Point at static light source, then move the dial till aperture is one stop more closed in meter = 200 ASA, etc.

Advantages as I see: Actually quite fun, cheap, would get the camera working, would also add exposure compensation functionality (in abitrarily variable amounts). And I'd have the only one there is. :-)

Disadvantages: It might not work (why I'm here), it might look God Awful (but camera pretty much already likewise), I might get assassinated by Canon's maintenance department.

Ladies and gentleman, I await your replies. Remember, there are 2 'I's in 'idiot'. :-)

Thanks,

Frank
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Ed

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Posted on Wednesday, March 08, 2006 - 12:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

You've taken the shutter speed setting out of the equation when making settings--when you turn the dial as it is you're making a shutter speed/asa combination--with your setup the shutter speed setting would have no effect. Also, feel that all the work you're going to, it would be simpler to replace the tungsten wire.
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Frank McLean

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Posted on Wednesday, March 08, 2006 - 02:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Holey Moley. Ah yes, I see how the shutter dial pulley also moves the left hand resistor when turned purely for speed. My word, how wonderful. How wonderful a bummer. Then I guess I would need to effectively have a copy of the existing shutter/film speed dial planted over the resistor, which, I guess, is simply what the pulley gives you. What a bunch of arse. Have any other Canon's got this feature?

I suppose one of my main beef's with replacing the wire is that it strikes as such a horribly designed system, prone to breakage, which makes me loathe to put it back that way. It surprises me, as everything else in there looks well thought out. This is almost literally a 'trip wire' for the unwary. Before I found out about the wire, I saw many, many posts from people saying, 'I have this wierd problem with my AE-1, where the meter (etc) - everything else works really smooth.'

Anyway, thanks Ed, I'm glad you were there to point out my problem. I may still tinker with my dial, just for the heck of it. (I'm actually not just a penny pinching miser.) So, I'd need an outer, fixed ring with ASA,then an inner movable ring for shutter speed, then the actual resistor contact pointer. Sounds like a deep dark drawer project... :-)

Thanks again, that would've been a mistake,

Frank
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Glenn Middleton

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Posted on Wednesday, March 08, 2006 - 03:37 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Do not know what all the fuss is about and anyway wire or 'string' drives are not unique to Canon. The system has worked well for years and replacement, if needed takes less than an hour. I have found that most breakages occur on cameras that have had a less than professional CLA. Follow the manual and the camera offers no pitfalls to the repairer, professional or amateur.

I have one of the first AE-1s into the UK and it still has its original tungsten wire, even after a hard working life in the laboratory.

The tungsten wire, behaves in a similar fashion to fresnel focusing screens when they are cleaned/washed. I have cleaned many screens over the years - no scratches, marks or other damage ever. Yet for other people they seem to disintegrate as soon as they touch them. Same thing for the tungsten wire. Know the product and handle accordingly and you will have no trouble. Nick or stretch it and you might as well replace before you put the top back on.
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Frank McLean

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Posted on Wednesday, March 08, 2006 - 07:16 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hi Glenn,

So you're saying that I should be aware of this potential string issue on lots of camera models? Thanks for the reassurance on the ease of replacement. If this is a common feature, I guess I'll have to live with it.

"Nick or stretch it and you might as well replace before you put the top back on." - see, to me, that means this is going to break ALL the time. People with stuck advance levers WILL, probably very gently, take the levers off to see if it's anything obvious, very gently lift the dials, and very gently nick, stretch or break this wire. OK, I know they really should keep their hands to themselves, unless they've bought the repair manual and the proper tools, but is that realistic? Is that fun? If this is common design, then I'm going to be a lot more wary of buying secondhand cameras.

Thanks again,

Frank
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Glenn Middleton

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Posted on Thursday, March 09, 2006 - 09:02 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Frank,

It really is not difficult to replace on the AE-1.Lots of models is perhaps pushing it, but Canon is not unique
- as a search of this Forum will show. I fully understand where you are coming from. With the AE-1 the problem is compounded by the fact that there does not seem to be a free download of the manual. Well I have not found one; but I knew I could buy a good hard copy for £10, so did not burn the midnight oil looking.

The knack with these 'string' drives is to make sure that you have set the correct combination of shutter/film speed or aperture/film speed etc. In most cases this will give you a wire with little tension in it - so you can carefully remove the top or whatever is required.

Canon used a tungsten wire because it does not stretch, thus the calibration of the system stays constant. However as you and many others have found, the lack of give and the very small diameter is a breakage waiting to happen.

I personally always like to read the manual before starting to repair an unknown model. Obviously it depends on the degree of complication, but even on something that looks simple the manual often reveals setup procedures that are not obvious. The Canon 35-70/f3.5-f4 is a good example. This little lens almost falls apart in your fingers, it is that simple to strip and reassemble. However reading the repair manual, you soon realise that to get this compact design to perform properly requires more than just a makeshift collimator. You need the correct test kit, so there must be an awful lot of these lenses that have had their performance ruined by well meaning DIY.

So buy the manual, yes. As for tools, this really depends on if you want the camera to remain looking unopened. Should you just want to repair a charity shop find, use the proverbial Swiss Army Knife. On the other hand a mint M2 in need of a CLA, is worth the investment in proper tools from Microtools catalogue.

Glenn
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Frank McLean

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Posted on Thursday, March 09, 2006 - 12:53 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hi Glenn,

Yes, I agree with you wholeheartedly for cameras which do not fall into the charity shop category (as this one does - it's rough).

I have a Nikon FE in superb shape with an auto-releasing shutter that I *AM NOT* planning to 'mod' in any way, shape or form. :-) Nope, just waiting on the info, then it's on with the gloves and softly softly.

Since getting my old Pentax ME Super working with simple instructions from this site, after having 4 'experts' at the local camera shop tell me I'd be better off junking it and buying a new one, I've gained a lot of respect for the older manual/ semi-automatic SLR's. And a lot of great pictures. It pains me to think of the number of 'experts' in specialist camera shops throwing away beautiful pieces of engineering every day.

Anyway, I just hope this FE doesn't have a string...

Cheers,

Frank

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