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_nathan
Tinkerer
Username: _nathan
Post Number: 17
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 08, 2008 - 10:06 pm: | 
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Hello. I found a Rollei 35 T the other day and it appears that the meter is underexposing by 2-3 stops. How would one go about adjusting one of these meters? Thanks for any help and replies in advance.
Best,
N. |
Reiner
Tinkerer
Username: Reiner
Post Number: 75
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 25, 2008 - 04:02 am: |
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Underexposure might be caused by an alcaline or a silver oxid cell which have an initial voltage of 1.5 V to 1.6V. The camera was designed for the nowadays banned mercury cells with 1.35V. Take care for the battery you use when you do test exposures. However 2-3 f-stopps off is a bit too much. I expect the effect of the wrong batteries to be approximately 1 or 1.5 f-stopps.
It is possible to readjust the meter. When you do that I strictly recommend to use a silver oxide cell (for ex. SR44) in the Rollei's meter. Their voltage is much more stable than that of alcaline cells. There are 2 potentiometers below the top cap, one for the CdS cell and another for the matching/pointer needle. The potentiometer at the backside of the Rollei is for the adjustment of the meter. The one at the right side (viewed from behind) is to control the linearity of the meter circuit.
I have re-calibrated a meter in a Rollei 35 S in this way. As reference I used my Gossen meter and a known good Rollei 35. To my surprise there was no linearity adjustmend necessary. I took a silde film with it. Pictures in clear light were ok. The pictures made in low light seemed a touch to dark. So maybe a linearity correction would be recommended.
However, even with the original light meter calibration and original batteries I made the experience that CDS cells tend to cause underexposure near the lower end of their range. I made this last experience with different cameras of different types all equipped with standard CDS cells (f. ex. 7sII, 35RD, GIII, Rollei 35 etc). So I think this could be considered as normal.
If you need help how to get the top cap off give a note or do a keyword seach for "Rollei 35". |
Charlie
Tinkerer
Username: Charlie
Post Number: 180
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 25, 2008 - 09:29 am: |
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#675 zinc/air hearing aid batteries are cheap, carried in most pharmacies and put out a stable 1.4 volts. They are slightly smaller than the mercury batteries and may need to be shimmed with a wad of aluminum foil. No recalibration necessary. |
Reiner
Tinkerer
Username: Reiner
Post Number: 76
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 08, 2008 - 10:56 am: |
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675 zic/air cells are a good choice. In the Rollei 35 models they even do not need a shim since the battery compartment supports the 625 types and the 675 types.
However, it the ligth meter is really off and needs a new adjustment anyway it would be wise to adjust it to silver oxide batteries. |
