[Leroy77]

Hello pentax world,

I have been doing some research, some websites have been saying that you CAN in fact use a 1.5 volt battery in the pentax spotmatic. Anyone attest to this?

Cheers

[boriscleto]

The Spotmatic is not voltage dependent. The Spotmatic F is.

[MarkJerling]

Have a read here: Replacement battery for Spotmatic SPII - PentaxForums.com
And here: Asahi spotmatic sp battery recommendation - PentaxForums.com
And here: What battery for Spotmatic meter? - Page 2 - PentaxForums.com

This seems to be good advice:

• Silver oxide batteries that work are: Mallory PX-400 or RM-400-R, Varta V394, Maxell SR936W or SR936SW, Renata 394, or any type 392 equivalent.
• Do not be tempted to use alkaline battery equivalents as they have a much steeper discharge curve. The silver oxide batteries have a flat discharge curve similar to the old mercury batteries.

[stevebrot]

I have been doing some research, some websites have been saying that you CAN in fact use a 1.5 volt battery in the pentax spotmatic. Anyone attest to this?

Here is a link to one of my previous posts on this subject...

Replacement battery for Spotmatic SPII - PentaxForums.com | comment #3

As correctly noted on comments that follow on that thread, the meter circuit is a mildly unbalanced bridge that is not voltage dependent except at light values at or below the meter's lower limit of linearity. A more complete explanation as well as an off-site link on the subject (in the past, it had diagrams) are at:

Replacement battery for Spotmatic SPII - PentaxForums.com | comment #6

For the circuit diagram, see page 23 of the National Camera Manual for Spotmatic found at the Pentax Manuals Web site:

Pentax Manuals | Service Manuals


Steve

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Last edited by stevebrot; 08-01-2019 at 10:40 PM. Reason: accuracy

[Cuthbert]

Never had an issue in years with my Spotmatics.

[pathdoc]

The Spotmatic F is.

The F has its own peculiar taste in batteries anyway (PX625, IIRC).

[boriscleto]

The F has its own peculiar taste in batteries anyway (PX625, IIRC).

Yes. Easily replaced by a zinc air hearing aid battery with a rubber o-ring, or a brass ring...

PX625 PX-13 replacement Nikon F Leica, Gossen, Canon

CRIS sold a MR-9 battery adapter with a voltage regulator if you wanted to spend the $$$.

[stevebrot]

CRIS sold a MR-9 battery adapter with a voltage regulator if you wanted to spend the $$$.

They still do, though I was able to buy direct from the maker in Japan for somewhat less.

Kanto Camera | Battery Adapter

It is also good to note that Kanto also makes a voltage reduction adapter for the SP/SPII (H-B model on page linked above) that is built into a replacement battery chamber cover. Given the scarcity of that part, it may be worth the purchase of the adapter just to get the cover!


Steve

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Last edited by stevebrot; 08-02-2019 at 10:43 AM.

[johnha]

They still do, though I was able to buy direct from the maker in Japan for somewhat less.

Kanto Camera | Battery Adapter

It is also good to note that Kanto also makes a voltage reduction adapter for the SP/SPII (H-B model on page linked above) that is built into a replacement battery chamber cover. Given the scarcity of that part, it may be worth the purchase of the adapter just to get the cover!


Steve

Yep I've bought one as one of my Spotmatics had a welded on battery door due to a corroded battery. I managed to find a replacement baseplate without battery cover. The cost of the battery cover is more than the replacement adapter. Haven't had chance to test it yet though.

[pentaxus]

The battery to get is the eveready 387S with spacer ring. It is the same size and shape as the original and works perfectly. They are available on Amazon and ebay. I use them in my 231 Spotmatic, my 23102 Spotmatic and my Spotmatic II.

[Kerrowdown]

No idea about batteries, so I'll just welcome to the forum.

[titrisol]

I have been using this since the mid 80s....

Hello pentax world,

I have been doing some research, some websites have been saying that you CAN in fact use a 1.5 volt battery in the pentax spotmatic. Anyone attest to this?

Cheers