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Posted by John Taylor on January 21, 2000 at 19:35:47:
In Reply to: Re: Nikkormat FT metering. posted by David Marsh on January 21, 2000 at 17:50:31:
Hi Dave,
Funnily enough, two days ago I checked the voltage of the FT's 625 Alkaline battery with a digital voltmeter and it read 1.53 volts, I then swapped the batteries over with a mercury 625 from my Olympus 35 RC which reads 1.34 volts, but unfortunately the same metering problem persists.
Shame because it's a great camera, but judging by it's external condition, this FT must have been a retired work tool.
I presently use 675 Zinc Air hearing aid batteries in one of my elderly Minoltas, and find them more than satisfactory, and quite good value, ie. GB£2.99 for four cells. I will try to track down 625 Zinc Air equivalents.
Many thanks,
John.
: Good Day John,
: Have you changed the batteries recently? The original battery for the Nikkormat FT was a 1.35 volt mercury cell. The current replacement is a 1.5 volt alkaline cell. This will overdrive the meter circuit and cause from one to two stops of underexposure and sometime affect the linear response of the meter as well.
: I'd suggest using the Wein Photo Cell MRB-625 ($5.99 and in stock) to replace your battery. It's a 1.35 volt zinc oxide cell that has similar characteristics as the original mercury cell. Unfortunately they don't last very long! Once activated by peeling off the green plastic sheet full working voltage is reached in about two hours (although they're usable in a few minutes). Once full working voltage is reached, they start to die. The zinc oxide cells generally last about six months, but hold the 1.35 voltage steady during their short life.
: There are other alternatives as well, the meter can be calibrated to accept the alkaline cells. But this is not practical unless the camera is in need of other repairs. CRIS Camera services (http://www.criscam.com) cells the MR-9 battery adapter ($29.99 plus $3.00 for the battery). It's a container the size of a 625 battery in which you insert a silver oxide "76" type cell. The container has a diode that drops the voltage of the 76 cell from 1.5 to 1.35 volts.
: Sincerely,
: Dave Marsh
: Apex Photo-Technical Services, Inc.
: Manchester, NH
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