Canonet: calibrating meter help

[juggler]

Hi,

I have some Canonets: original Canonet 19, old Canonet QL17 and new Canonet GIII QL17. They all give slightly different exposures when I meter them off the same scene. I had them all set to the same ASA. I am using the original mercury battery, if applicable.

How do I adjust them to have the right exposure?

What I plan to do is to make use of the ASA setting on each camera if I know which one is overexposing or underexposing. Say if I know one is consistently giving me 1 stop underexposure, I will set the ASA to be 200 if I use a 400 film.

To compare this, I plan use my EOS 1N with a EF28-105 lens set at approximately 40mm or 45mm and with the same ASA setting as the Canonets. Then I take their metering off a evenly lit wall.

Assuming the EOS is correct, can I just adjust the ASA on the Canonets accordingly until I get the same exposure reading?

Will this work? Any other way to calibrate the Canonet metering so that it is reliable?

Any help appreciated. Thanks! 🙂

 

[BrianShaw]

Is the difference in meter reading really enough to warrant this much effort? How much difference have you observed?

 

[juggler]

OK, I just tried it using a simple method. No lens hood or filters used. I do not have a light meter to confirm.

At ASA 400, shutter 1/60:

Test 1: Unevenly lit scene:

Canonet 19: f8
Canonet QL17: f8
GIII QL17: ~ f4.5 -- over by 1.5 stops above f8
EOS 1N + EF28-105 @ 40mm: f7.1 -- "evaluative metering"

Test 2: Evenly lit bright wall

Canonet 19: f8
Canonet QL17: f11
GIII QL17: ~f5.6 -- approx 1 stop above f8
EOS 1N + EF28-105 @ 40mm : f8 -- "evaluative metering"

Looks like the GIII QL17 disagree by 1 to 1.5 stops overexposure.
I guess may be not much to worry about on film. 🙂

But do you guys readjust the metering or change the ASA to correct the readings?

 

[Kim Coxon]

Hi,
The adjustment for the GIII is done by removing the top and the trim pot is behind the film transport flag.

There is also a trim resister under the top of the original QL17.

I am not sure about original 19. My service manual is at work. I will look tomorrow and try and post a reply.

Regards
Kim

Hi,

I have some Canonets: original Canonet 19, old Canonet QL17 and new Canonet GIII QL17. They all give slightly different exposures when I meter them off the same scene. I had them all set to the same ASA. I am using the original mercury battery, if applicable.

How do I adjust them to have the right exposure?

What I plan to do is to make use of the ASA setting on each camera if I know which one is overexposing or underexposing. Say if I know one is consistently giving me 1 stop underexposure, I will set the ASA to be 200 if I use a 400 film.

To compare this, I plan use my EOS 1N with a EF28-105 lens set at approximately 40mm or 45mm and with the same ASA setting as the Canonets. Then I take their metering off a evenly lit wall.

Assuming the EOS is correct, can I just adjust the ASA on the Canonets accordingly until I get the same exposure reading?

Will this work? Any other way to calibrate the Canonet metering so that it is reliable?

Any help appreciated. Thanks! 🙂

 

[Kim Coxon]

Hi,
Removing the top is not difficult on the GIII's. I tend to reset for silver cells as it makes life much easier. You couls adjust the ASA setting to give the apeoximate reading. However if the trim is out the error is not linear and will get greater the brighter the conditions. If you trim it, you won't have to remember to offset the ASA either.

Kim

Looks like the GIII QL17 disagree by 1 to 1.5 stops overexposure.
I guess may be not much to worry about on film. 🙂

But do you guys readjust the metering or change the ASA to correct the readings?

 

[ErnestoJL]

Recently I´ve readjusted the meter on my QL 17 (the big one, not the "new") just because I´m using alkaline cells (1.5 V against 1.35 of the originalmercury cell). It was easy as to readjust the trimmer resistor on top of the meter assy, checking it with same target, a stable source of light and using a hand held meter (Luna Pro) for comparison purposes. As the meter is of series design, the adjust isn´t linear, however the difference isn´t bigger half a stop which is adequate for me.

Ernesto

 

[Kim Coxon]

Hi,
You are better off using silver cells rather than alkalines. Silver cells hav a fairly constant discharge curve so the voltage remains stable for most of the life of the battery like mercury cells. Alkaline have a very unstable curve and the voltage will drop about 0.25v or more over their life.

Kim

Recently I´ve readjusted the meter on my QL 17 (the big one, not the "new") just because I´m using alkaline cells (1.5 V against 1.35 of the originalmercury cell). It was easy as to readjust the trimmer resistor on top of the meter assy, checking it with same target, a stable source of light and using a hand held meter (Luna Pro) for comparison purposes. As the meter is of series design, the adjust isn´t linear, however the difference isn´t bigger half a stop which is adequate for me.

Ernesto

 

[ErnestoJL]

Thanks Kim for the advice, you´re right about discharge. I knew about this discharge curve because I use a lot of 625 alkaline batteries for other projects (portable measuring/detection devices). That´s why I´m using them very often (they are allways at hand). It´s allways best to use silver oxide batteries than alkalines, they last longer and voltage is more stable against temperature variations, not to mention discharge curve.
Ernesto

 

[ftw1952]

Canonet using the Eveready 357 battery instead of the Weincell

Canonet using the Eveready 357 battery instead of the Weincell

By using a Eveready 357 battery along with a number 9 o'ring slipped onto this battery it will fit as any 625 battery would. The Eveready 357 is made of silver oxide which has the same characteristics as the outlawed mercury batteries had. Just make sure the positive side of the battery is facing towards the front of the camera on the newer models and facing up to the cap on the older models. I have been installing the Schottky diodes on these cameras so no adjustments are needed to the meter.

 

[Beemermark]

Why not change the ASA setting on the Q17 by 1 stop?

 

[ftw1952]

Why not change the ASA setting on the Q17 by 1 stop?

Some are very forgetful I have found

 

[hap]

Hi,
You are better off using silver cells rather than alkalines. Silver cells hav a fairly constant discharge curve so the voltage remains stable for most of the life of the battery like mercury cells. Alkaline have a very unstable curve and the voltage will drop about 0.25v or more over their life.

Kim

what silver oxide will have the form factor for the canonet battery well?

 

[Mackinaw]

You can buy adaptors (Amazon) that will size a 386 silver oxide battery to fit in a 1.35V-sized housing. The adaptor will reduce the 386 battery voltage from 1.55 to 1.35V.

Jim B.