This is what I did with my grey Luna Pro and Canonet. It works well. But since I don't care for the Canonet I seem to have a rather expensive spare part bouncing around in the bottom of my camera bag just waiting to get lost.
Originally Posted by tchamber
when I tried using 1.5 volt batteries in my Leicaflex SL the response was non-linear, i.e., an exposure compensation that worked in bright light was way off in low light and vice versa. I finally bought 10 mercury batteries to tide me over.
Gossen USA equippped my old Luna Pro S with an adapter that allows me to use L44's, and they work fine.
As a sucker for any rangefinder camera, particularly ones branded Yashica, Konica, or Canon, (but I'm not really choosy - as long as the camera is a rangefinder) I snap them up whenever I find one at a garbage sale. Batteries for them? No problem, if you're in the U.S.. Just go to "Batteries Plus." They've always had suitable replacements for the old mercury jobs. I checked with the local store (Salem, OR) and they told me they have over 200 stores across the U.S.. Sure beats messing with soldering guns, expensive adapters, etc.
A couple of thoughts on this:
1) If you're shooting slide film the latitude should be plenty wide enough to compensate for the relatively minor difference in readings from a 1.5v vs. 1.35v battery.
2) Probably okay with most other film too.
3) Do some side-by-side comparison readings b/w your "overpowered" RF and a more recent camera or outboard light meter and see how far "off" you really are. A slight adjustment in the appropriate direction of your f/stop on the lens may result in a more "accurate" compensation than changing the ISO/ASA setting on the camera.
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When I restore my old Konica Auto S2, Autoreflex T series and other cameras, I usually recalibrate the meter to give accurate reading with silver oxide cells (if the camera is designed for 1.35V) or lithium cells (if 2.7V). In the case of Auto S2, there is a potentiometer on a small PCB on the meter unit, right behind the rangefinder mirror that is linked to the lens cam. It's shown in the fourth picture of this link:
Just blow it up and see the pot with green and black wire. One goes to the meter, and the other go to the CdS wire (connected right next to the battery well). The camera is + ground as you see the red wire grounded in the picture.
I had to restore one of my Auto S2 the other day, and this camera had many small problems evrywhere (I hate that!) I had to take pretty much EVERYTHING apart. So I decided to make photo documentation... though some parts I was too into fixing and didn't get to take much pictures. (well, wait until next time I pick another one up!)
Anyway, the top link is this:
CdS cells have only approximate linearity (conductance roughly proportional to irradiance intensity) and there is need to compensate for this. Also, if the meter indicates the correct aperture, what's displayed is also logarithm of the irradiation intensity. Some sophisticated meters use multiple CdS cells in combination to alleviate this, and a simple meter circuit like Auto S2 compensates for this by varying the spacing for each stop difference. For example, check the space betwen f/4 and f/5.6 (wide), and f/11 and f/16 (narrow). This is due to multiple factors, such as the minimum (residual) resistance of CdS cell, resistance of the meter and the series resistor, as well as the nonlineariy of the CdS cell itself. In lock-needle exposure automation like ones used in Konica cameras, the meter deflection is transferred to aperture driving lever. In this camera, the nonlinear relation between the deflection and f/stop value is mostly compensated at this level. (In cameras for interchangeable lenses, the lever angle and f/stop must be well standardized, and often must be linear, but for fixed lens cameras, they can design just for one lens.)
So what happens if you use a battery of higher voltage and compensate with the film speed? The problem is that the sensitivity offset is not constant at f/2 end and f/16 end. That's the problem. If you set the offset for one end and the other end may be a stop off. Yes, only a stop. Not a big deal. But I prefer to eliminate this offset error. The offset is greater in the f/16 end, so people who routinely shoot in f/1.8 to 4 range may not notice much.
Match needle cameras have simpler mechanism and of course their solution is also simpler.
Last edited by Ryuji; 08-01-2006 at 08:35 PM. Click to view previous post history.
As with the Rollei 35S cameras, the meter can also be adjusted for the change from the 1.35 V Mercury to 1.5 V Alkaline battery by a repairman. If you are comfortable enough and you have the tools and reference, you could make the adjustment yourself.
These are 1.4v batterys,#675, made for hearing aids. Thier almost identical in size to lr44's (see scans attachment below) . I bought some, but I haven't tried them yet. Has anybody tried using these. I was going to use them in a konica c35 but the cameras battery holder wants a battery with a smaller negative contact diameter like a wein cell or the original battery. But I think they would work with other cameras that have a battery holder that can use lr44's.
I know this is useless information for most average end users. But I thought to say that it's very often an easy matter to recalibrate meter. No need to have diagrams or service manuals, although they are certainly helpful.
Originally Posted by naturephoto1
Most cameras can be recalibrated, and it's easy to follow the circuit to get the metering circuit diagram. (Most, if not all, competent repairmen keep a notebook and pencil handy during work.) Based on this diagram, anyone who has basic knowledge of circuit theory can figure out which pot needs to be turned to which direction. The amount, however, has to be calibrated against known standard...
The above doesn't apply to electronic shutter cameras, such as Yashica Electro's. I'd hate to work on those cameras. But even those could be worked on...
Zinc air cells are good in terms of voltage stability... but they don't last long once used. I prefer to use silver oxide or lithium cells (alkaline is inferior in terms of discharge property). Those lithium cells allow me to almost forget that the camera used battery!
Using OM cameras with slide film I do find a just noticable underexposure using 1.5v batteries, although it's only very slight. I bias the meter to overexpose by 1/3 of a stop and that gets it pretty much right. With B&W and col neg, the difference falls into the noise, but I still tend to leave the bias on as it does bring up deep shadow detail a bit.