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Treve
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 01, 2004 - 03:23 am: | 
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Hi there!
The light meter in my camera does not correspond to the readings that I'm getting from my SLR in centre-weighted mode.
I'm currently using zinc-air batteries, so the voltage shouldn't be the problem. I intend to start using SR44 silver oxide cells and would like to calibrate for this while the top-cap is off.
Can anyone tell me how I go about calibrating this camera?
I've had the top-cap off and I can see that there's a variable resistor at the back of the galvanometer(?), just underneath the film travel indicator. This seems to adjust the linearity of the meter, i.e. when I change the shutter speed by one stop, this resistor seems to adjust whether the corresponding aperture changes by one stop. Am I right in this assumption?
I can see various other screws around the galvanometer housing - which one do I use to adjust the meter reading?
Many thanks for your help and advice.
Treve |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 01, 2004 - 04:10 am: |
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You are right concerning adjusting the linearity of the meter.
The absolute values of the meter can be adjusted by turning the galvanometer in its mount. Towards the frame counter there is a tiny screw in the die-cast collar which surrounds the galvanometer. This screw is hard to access - it's much easier after removal of the frame counter assembly which is attached to the main body by two screws only.
Loosen this screw (usually it is secured with a droplet of paint) and gently turn the galvanometer until it shows correct values. On my first QL17 the meter is approx. 1/3 stop off but I prefer to correct this by ASA-setting.
However, make sure that you point both meters at an evenly lighted surface. A grey card would be ideal but any light colored wall will also do. Depending on what your SLR meter sees in its center-weighted area it might give different readings compared to an integrating meter as it is on the QL17. |
Treve
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 01, 2004 - 08:00 am: |
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Thanks Winfried - I was hoping you'd reply!
To help me find this screw, is it oriented vertically or horizontally beneath the frame counter mechanism. Do I go in from the top or the side with my screwdriver? Don't suppose anyone's got a picture?!
So this screw holds the galvanometer in place? I shouldn't touch any of the screws on the galvanometer itself (apart from the linear adjustment screw at the back)?
So I need to loosen this screw, turn the whole galvanometer so that the meter points to the correct aperture value in the viewfinder and finally re-tighten the screw to hold the galvanometer in the new position.
Do this changed galvanometer position have a direct effect on the actual aperture value that is chosen in the lens? I suppose what I'm trying to ask is "do I also need to make a corresponding change somewhere else in the camera?".
Will pointing the camera at a uniform white wall work for calibration purposes? I read somewhere that calibrating under bright conditions is best?
I'm starting to feel quite bold about my new camera repairing abilities. I managed to transplant a whole rangefinder/viewfinder assembly across from a New Canonet 28 at the weekend!
Thanks again.
Treve |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2004 - 12:15 am: |
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The screw which holds the galvanometer is oriented horizontally. Its slotted head is visible on the right hand side (towards the frame counter). Do NOT loosen or tighten any other screws, escpecially not the one covered by the variable resistor - it sets the play of the bearings of the galvanomenter. Of course you may adjust the variable resistor if necessary.
Yes, the position of the galvanometer needle is detected by the sagged blade which swivels in front of it as you depress the shutter button, and transferred to the aperture coupling mechanism. Only thing to adjust here is the fully opened aperture. When the needle points at f/1.7, of course the aperture should be fully opened, and the aperture blades should be barely visible through the lens opening. This adjustment (only if necessary) is done by bending a lever in the transfer mechanism. It can be fine tuned by turning a screw with excentric head which links the swivelling blade to the mechanism. However, if just the light meter is somewhat off, you won't need any other adjustments than the ones described in the first paragraph.
Pointing at an uniform wall will work quite good. Different light meters may have different color sensitivity so the wall should not be colored. As mentioned, a neutral grey card would be the best.
The QL17 is a very complicated camera, so as a (probable) newbie you should not go too deep into it. It bears a couple of not so obvious traps. Remember: Never change a running system!! |
Treve
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2004 - 02:59 am: |
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Thanks Winfried.
I've removed the frame counter mechanism and can now see the screw that you are referring to.
I've taken note of your warning and will probably pass the camera on to the experts before I destroy the thing! It's got a rough focussing mechanism that needs freeing up anyway.
Thanks again for taking the time.
Treve
PS: Anyone know a reliable repair shop in London who can handle QL17s? |
Kent Judiesch
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 27, 2004 - 06:47 am: |
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I read this post with great interest because I also have just received a Canonet G-III QL17 in 'as is' on eBay. Apart from the light seals, which I will replace, the camera is in surprisingly good condition and works like a charm. I did not expect it to operate and I bought it for parts and as a challenge to see if I could get it to operate.
When I compare readings with my X-700, the meter in the Canonet seems to be a bit off, and this, even with a new mercury battery (yes a real one!!!) Matt Denton's repair page mentions adjusting the variable resistor in the back, as opposed to turning the galvanometer in its mount. Does anyone have any feedback or caveats about using this method?
cheers!
Kent |
