Go Back   Rangefinderforum.com > Cameras / Gear / Photography > Leicas and other Leica Mount Cameras > Canon Leica Screw Mount Film Rangefinders

Canon Leica Screw Mount Film Rangefinders For classic Leica Screw Mount Canon Rangefinders.

Reply
 
Thread Tools Search this Thread Display Modes

Canonet: calibrating meter help
Old 01-11-2006   #1
juggler
Registered User
 
juggler is offline
Join Date: Sep 2005
Location: Singapore
Age: 52
Posts: 56
Canonet: calibrating meter help

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!
__________________
koah
  Reply With Quote

Old 01-12-2006   #2
BrianShaw
-
 
BrianShaw's Avatar
 
BrianShaw is offline
Join Date: Dec 2005
Location: Gone by choice!
Posts: 976
Is the difference in meter reading really enough to warrant this much effort? How much difference have you observed?
  Reply With Quote

Old 01-12-2006   #3
juggler
Registered User
 
juggler is offline
Join Date: Sep 2005
Location: Singapore
Age: 52
Posts: 56
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?
__________________
koah
  Reply With Quote

Old 01-12-2006   #4
Kim Coxon
Moderator
 
Kim Coxon's Avatar
 
Kim Coxon is offline
Join Date: Feb 2005
Location: Lincoln, UK
Posts: 3,363
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

Quote:
Originally Posted by 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!
  Reply With Quote

Old 01-12-2006   #5
Kim Coxon
Moderator
 
Kim Coxon's Avatar
 
Kim Coxon is offline
Join Date: Feb 2005
Location: Lincoln, UK
Posts: 3,363
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

Quote:
Originally Posted by juggler
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?
  Reply With Quote

Old 01-20-2006   #6
ErnestoJL
Registered User
 
ErnestoJL's Avatar
 
ErnestoJL is offline
Join Date: Jun 2005
Location: Argentina-Buenos Aires
Age: 67
Posts: 956
Recently Iīve readjusted the meter on my QL 17 (the big one, not the "new") just because Iīm 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 isnīt linear, however the difference isnīt bigger half a stop which is adequate for me.

Ernesto
__________________
Ernesto Many 35 mm and MF film cameras, some weird cameras... and nothing digital yet!
  Reply With Quote

Old 01-20-2006   #7
Kim Coxon
Moderator
 
Kim Coxon's Avatar
 
Kim Coxon is offline
Join Date: Feb 2005
Location: Lincoln, UK
Posts: 3,363
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

Quote:
Originally Posted by ErnestoJL
Recently Iīve readjusted the meter on my QL 17 (the big one, not the "new") just because Iīm 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 isnīt linear, however the difference isnīt bigger half a stop which is adequate for me.

Ernesto
  Reply With Quote

Old 01-21-2006   #8
ErnestoJL
Registered User
 
ErnestoJL's Avatar
 
ErnestoJL is offline
Join Date: Jun 2005
Location: Argentina-Buenos Aires
Age: 67
Posts: 956
Thanks Kim for the advice, youīre 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). Thatīs why Iīm using them very often (they are allways at hand). Itīs 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
__________________
Ernesto Many 35 mm and MF film cameras, some weird cameras... and nothing digital yet!
  Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tested my Canonet against my Yashica GSN.. Rob Rangefinder Photography Discussion 19 08-01-2007 13:01
light metering FrankS Rangefinder Photography Discussion 75 12-11-2005 17:45
canonet light meter Luf Canon Leica Screw Mount Film Rangefinders 0 08-22-2005 01:51
Battery Light On, Light Meter Not Working lenina Canon Leica Screw Mount Film Rangefinders 4 06-17-2005 19:18
Canonet meter weirdness captainslack Canon Leica Screw Mount Film Rangefinders 1 03-29-2005 16:13



All times are GMT -8. The time now is 09:47.


vBulletin skin developed by: eXtremepixels
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

All content on this site is Copyright Protected and owned by its respective owner. You may link to content on this site but you may not reproduce any of it in whole or part without written consent from its owner.