| NIKON F
Photomic meter ftn also suits: |
August 2004 Mercury battery replacement for PX625 "This replacement is RE-USABLE so you need only buy it once!" |
www.paulbg.com
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| ( this
may well be a solution for others needing a PX13, M20 or PX625 mercury
battery? )
Also see: July 2006 |
"I just recommended your adaptors to a friend here at the office for his Pentax. "As a long-term user of several classic cameras designed for mercury batteries, Paul's adapter is the best yet; it is quick, convenient and inexpensive."
Much of the background to my research came from the excellent work by Robert Decker: "...It appeared to me that the MR9 adapters are of no use for the Nikon F Photomic meter due to the resistance range of 650ohms-156Kohms.This alters the voltage and creates a large error in readings at most light levels." In addition Alkaline PX625A gives 1.5v; which results in a 4 stop error on an ftn meter! Hard to compensate for on the ASA scale setting. Silver Oxide is even worse at 1.55v The use of 2-1.35v cells in the ftn compounds the error from 1.35v to 1.5 to 2.7v to 3.0v also see: |
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Adapter Also fits Zinc Air: PX675 / PX76 / EPX675 / V675PX / MR44 / NR44 / H-C / HC / RPX675 / RM675 / 1128MP / HD675 / MR1154 / H1154 *may still be available somewhere"I just discovered some H1154's (Mercury) from an old PDA, and they fit my adapters"...an almost perfect solution! |
My alternative:
PX625BG
Like many others I discovered the ZA675 zinc-air battery used in hearing aids are 1.35v (even though the packet says 1.4v) and they are the right height ( almost? 0.6mm out) but they are not wide enough! and they are rated at 500mAh ( the PX625 was 450mAh...very close ) A rubber grommet might do the trick..but not on a photomic ftn or cameras that needs a metal to metal contact The top battery makes the + contact on the side of the battery compartment, so the battery casing must touch the side. Irritating isn't it! Also the top must have a 'shelf' for the screw down top. My solution
First of all, I am not a manufacturer (although I did spend 15 years commercially repairing & restoring cameras). and my solution does work, it has 100's
of satisfied users around the world! Meter reading and results: |
battery fit accuracy to +/0.05mm |
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Battery fitted with the 'push on fit' brass adapter. The lower edge of the ring has a bevelled edge for smoother contact in the meter housing. To replace the battery: Push out the old battery from the bottom and push in the new battery from the top.
Buy online with
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The meter is within 0.3stop against my Minolta Dynax meter. I don't know if it would be closer with Mercury batteries...but on a 30 year old meter I doubt it!
If you want it, it goes like this: *There is no 100% replacement for the PX625 Mercury battery, nor will there ever be. *My adapter also allows air to pass.between batteries. In 4 years o-one has indicated any problems "Zinc Air batteries don't last as long as Mercury no matter what you do. (re-sealing the air holes is a myth) When the batteries run out (3-6months is claimed?) you can remove the adapter(s) and fit to new ZA675 batteries! They work out around £3.90 (only around $5 in the US) for a pack of 6 Now! Also Exclusively available in the US from 'Glenn Harrington' (sole US supplier) order directly below. |
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CARRIAGE CHARGE
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"I don't have PayPal, what
should I do?" just follow the PayPal links opposite:Use your PayPal account: Will post to: UK, USA, Europe,
Canada, Australia, Japan Posting: UK: 1st Class Royal Mail USPS: USA/Can/Aus/Jp
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(updated May 2008)
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Choose which quantity you require from the 4 options. (option 2 no longer available) Aug 07: Brass prices have tripled in the last 12 months, I am holding these prices until my current brass stock runs out (v.soon) if you want to beat the increase buy!
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