Canon LTM GIII QL17 : Aperture problems in A mode

Canon M39 M39 screw mount bodies/lenses
Looks tight for a soldering iron I may fit the diode to a battery case, instead. I do need to clear the fog in finder for night shooting the patch is bright so it is not critical.

Thanks for the photo, is it Dave?

Noel
 
If one is careful. A 1n4148 diode can be installed in the blue wire in the photo.
The cathode end would point down toward the screw.

Some call me Dave. ;)
 
Dave

I'm real cautious about dismantling unless it is really broken, I'm old like you. The diode in the scrap alkaline is useful, if your name is not Dave, who likes the deer.

Noel
 
Thank you very much greyhoundman! I will give it try throug the weekend, hope I will by able to assemble camera back again :)

Anyway, what is your reason for not making the 1600 ASA modification? I will probably first just calibrate metering, but in future I would like to try thist too, so the potential problem would by nice to know before.

2Xmas - Actually silver oxide cells are absolutely unavailable in Czech republic and as far as I know barely availabe everywhere else. I also red about AgO that it's discharegement curve is not flat too, so there is not much to gain. Just yesterday I tested voltage of my alkaline cell in camera I use about half an year (I don't know how long is actually used, but I got camera with that battery loaded) and it's still 1.5V - very same as the brand new alkaline cell. So I think the alkaline batteries are viable.

I don't know much about what you mean with that diode? It causes to reduce voltage 1.35V and stabilize it through the battery lifespan? Or what exactly?
 
absoluton

Startled that silver cells are not available e.g. the OM4 cameras are very dependent on the e.g. SR44 silver oxide cell, If I travel I'll pack one in future, thanks.
I'll post a battery link next, but in brief the alkaline cells are not like Hg0 or AgO, the diode (a point contact rather then a junction) + AgO cell is an almost exact substitute for the HgO battery, within normal temperatures and current drains. You can either buy adopters which replace the origional cell or alter the camera as Dave suggests above, if you have soldering skills, and have the top off.

You can use the diode and a alkaline cell but the alkaline will drop its voltage in time and your exposure will be dependent, it dependes on the camera how much, and I've still got HgO cells so I've not tried the QL.

Noel
 
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My remark on unavailability of AgO was meant for PX625 only. I think SR44 are not so much problem to obtain in good photographic shops worldwide, but when I travel I always carry backup pieces for my Pentax LX (so I really never had opportunity to use the advantege of hybrid mechanical-electronic shutter :cool: ). It is commonly difficult to get any batteries in the middle of nowhere.

Thanks for info on diode and other solutions anyway.
 
Any difficulties and advice from your recalibration would be appreciated. Dave is too good to see any of the problems which will kill you or I.

Noel
 
So I played with camera for a while... And it's still working :)

But the meter still tends to overexposure when light is not enough. I rather did not turn the barrel of galvanometer (or whatever it's) more, because then the underxposure lock cease to work. I can't imagine 1600 ASA modification, meter just is not sensitive to that low light.

Overally I think the metering error is less bothering now, so it's not the complete fiasco. I will try a roll of film and then will see. But I feel that PX625 adapter with diode is better solution as the really accurate meter calibration doesn't seem possible given my model and used method (resistor and meter position modding).
 
Hm hm, sounds possible.

I just gave it another try and get pretty good accuracy - in constant 1EV ovexposure. Good irony that I began with intention to get 1600ASA and finish with 400 ASA max... :(

I suspect that maybe ISO ring is modded by technician who adjusted the camera for 1,5V batteries before i got it... Is it possible?
 
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