Go Back   Rangefinderforum.com > Cameras / Gear / Photography > Classic Film RangeFinders & Other Classics > SLRs - the unRF

SLRs - the unRF For those of you who must talk about SLRs, if only to confirm they are not RF.

Reply
 
Thread Tools Search this Thread Display Modes

Strange metering issue with OM4T
Old 01-12-2020   #1
valdas
Registered User
 
valdas is offline
Join Date: Jan 2007
Posts: 1,540
Strange metering issue with OM4T

I have been always puzzled about some strange metering/exposure issue in my OM4T. In some conditions when the meter in the viewfinder indicates 1/30 or 1/60 I clearly hear that the actual shutter speed is much slower - 1/8 or even 1/4. I thought it was something wrong with the meter or the shutter. However, compared to handheld Gossen those exposure readings were correct. Hmmm. Today I suddenly realized that the actual exposure that camera is using is not what center weighted exposure metering shows in the viewfinder but what spot metering reads. Checked the reading from the spot meter - bingo. So, my OM4T does not shoot using center weighted mode, only spot (except in manual mode). It must be that the previous owner "fixed" this camera or is there anything I am missing in settings?
__________________
My Flickr
________
  Reply With Quote

Old 01-12-2020   #2
Chriscrawfordphoto
Real Men Shoot Film.
 
Chriscrawfordphoto's Avatar
 
Chriscrawfordphoto is online now
Join Date: Apr 2007
Location: Fort Wayne, Indiana
Age: 44
Posts: 9,193
Spot meter should only work after you push the spot button, then the reading will clear and go back to center weighted after you make an exposure unless you used the exposure-lock function.


Keep in mind also that in centerweighted, the OM-4T meter reads light reflecting off the film. If there's no film in the camera, it'll see the black pressure plate and give more exposure than the finder indicated.
  Reply With Quote

Old 01-12-2020   #3
valdas
Registered User
 
valdas is offline
Join Date: Jan 2007
Posts: 1,540
Quote:
Originally Posted by Chriscrawfordphoto View Post
Spot meter should only work after you push the spot button, then the reading will clear and go back to center weighted after you make an exposure unless you used the exposure-lock function.


Keep in mind also that in centerweighted, the OM-4T meter reads light reflecting off the film. If there's no film in the camera, it'll see the black pressure plate and give more exposure than the finder indicated.
Yes, I know all this. Still - meter shows 1/60 (without pushing spot button), I hear exposure 1/8. I measure the same scene in spot - 1/8. So, basically it shoots the exposure measured with spot without pushing spot button. That's the issue.
__________________
My Flickr
________
  Reply With Quote

Old 01-12-2020   #4
p.giannakis
Pan Giannakis
 
p.giannakis's Avatar
 
p.giannakis is online now
Join Date: Jul 2008
Location: Stafford - UK
Posts: 2,546
Can you check the screws to see if the top plate has been taken off? Maybe the previous owner "fixed" it and the spot button is constantly pressed.
__________________
Regards,
Pan


The Monochrome Archives
Instagram



  Reply With Quote

Old 01-12-2020   #5
valdas
Registered User
 
valdas is offline
Join Date: Jan 2007
Posts: 1,540
Quote:
Originally Posted by p.giannakis View Post
Can you check the screws to see if the top plate has been taken off? Maybe the previous owner "fixed" it and the spot button is constantly pressed.
No, that's not the case - the spot function is only activated after pressing the button - only then the spot sign appears in the viewfinder (and it clears with the clear button as described in the manual). It must be something messed up inside.
__________________
My Flickr
________
  Reply With Quote

Old 01-12-2020   #6
dtcls100
Registered User
 
dtcls100 is offline
Join Date: Sep 2010
Posts: 469
Unfortunately, this could be a sign of developing circuit problems, which begin with erratic functions. Hopefully, it could also just be a sign of dirty contacts. Try gently tightening the baseplate screws and clean the battery contacts.
  Reply With Quote

Old 01-12-2020   #7
p.giannakis
Pan Giannakis
 
p.giannakis's Avatar
 
p.giannakis is online now
Join Date: Jul 2008
Location: Stafford - UK
Posts: 2,546
Just to check if I got it right. The meter reading on the viewfinder shows one speed but it shoots with another (that agrees with spot metering)? Can you tape a piece of silver foil and see if the camera shoots on a much higher speed than the one indicated. My OM 2 and 4 can appear erratic when testing them but I have never missed a picture due to wrong reading.
__________________
Regards,
Pan


The Monochrome Archives
Instagram




Last edited by p.giannakis : 01-12-2020 at 12:59. Reason: Autocorrect AI
  Reply With Quote

Old 01-12-2020   #8
valdas
Registered User
 
valdas is offline
Join Date: Jan 2007
Posts: 1,540
Quote:
Originally Posted by p.giannakis View Post
Just to check if I got it right. The meter reading on the viewfinder shows one speed but it shoots with another (that agrees with spot metering)? Can you tape a piece of silver foil and see if the camera shoots on a much higher speed than the one indicated. My OM 2 and 4 can appear erratic when testing them but I have never missed a picture due to wrong reading.
Correct, in default metering mode it shows what appears to be center weighted metering, but shoots the speed what agreed with spot metering. I hear it clearly. In the conditions where spot is the same as average, then it does not matter, but when dark object is in the center then spot is much slower - 2 stops or so. All speeds from 1/250 and slower I can differentiate very well - I was a telegraphist in the army and did Morse code as a sport
__________________
My Flickr
________
  Reply With Quote

Old 01-12-2020   #9
p.giannakis
Pan Giannakis
 
p.giannakis's Avatar
 
p.giannakis is online now
Join Date: Jul 2008
Location: Stafford - UK
Posts: 2,546
For speeds below 1/45 the OM 4 reads of the film. If you put some silver foil and for an indicated speed of about 1/15 it should close the shutter faster (because the foil is very reflective). That will indicate that it works well. Still I think the best way to check it is to shoot a test film
__________________
Regards,
Pan


The Monochrome Archives
Instagram



  Reply With Quote

Old 01-12-2020   #10
retinax
Registered User
 
retinax is offline
Join Date: Aug 2015
Posts: 1,113
Quote:
Originally Posted by p.giannakis View Post
For speeds below 1/45 the OM 4 reads of the film. If you put some silver foil and for an indicated speed of about 1/15 it should close the shutter faster (because the foil is very reflective). That will indicate that it works well. Still I think the best way to check it is to shoot a test film

So if there is no film loaded, wouldn't it expose longer because the pressure plate is probably less reflective than film?
Then if your test, Valdas, was without film, this could be normal behavior.
  Reply With Quote

Old 01-12-2020   #11
valdas
Registered User
 
valdas is offline
Join Date: Jan 2007
Posts: 1,540
Quote:
Originally Posted by retinax View Post
So if there is no film loaded, wouldn't it expose longer because the pressure plate is probably less reflective than film?
Then if your test, Valdas, was without film, this could be normal behavior.

It is not new to me camera, I shot many rolls with it and this behavior is present with the film loaded.
__________________
My Flickr
________
  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



All times are GMT -8. The time now is 14:21.


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.