1.5v battery in Spotmatic?

Leroy77 · 08-01-2019, 05:19 PM

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** · 08-01-2019, 05:36 PM

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

MarkJerling · 08-01-2019, 05:40 PM

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:

Originally posted by rayallen

• 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 · 08-01-2019, 10:28 PM - **1 Like**

Originally posted by Leroy77

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

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

Cuthbert · 08-02-2019, 04:32 AM

Never had an issue in years with my Spotmatics.

pathdoc · 08-02-2019, 08:25 AM

Originally posted by boriscleto

The Spotmatic F is.

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

**boriscleto** · 08-02-2019, 09:20 AM

Originally posted by pathdoc

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 · 08-02-2019, 10:12 AM

Originally posted by boriscleto

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

johnha · 08-02-2019, 11:31 AM

Originally posted by stevebrot

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** · 08-02-2019, 11:42 AM

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** · 08-02-2019, 01:27 PM

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

titrisol · 08-03-2019, 10:25 AM

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

Originally posted by 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

08-01-2019, 05:19 PM	#1
Leroy77 New Member Join Date: Aug 2019 Posts: 2	1.5v battery in Spotmatic? 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

08-02-2019, 10:12 AM	#8
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by boriscleto 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 Last edited by stevebrot; 08-02-2019 at 10:43 AM.

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08-01-2019, 05:36 PM	#2
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,473	The Spotmatic is not voltage dependent. The Spotmatic F is.

08-01-2019, 05:40 PM	#3
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,402	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: Originally posted by rayallen • 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.

08-01-2019, 10:28 PM - 1 Like	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Leroy77 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 Last edited by stevebrot; 08-01-2019 at 10:40 PM. Reason: accuracy

08-02-2019, 04:32 AM	#5
Cuthbert Veteran Member Join Date: Nov 2013 Photos: Gallery Posts: 1,740	Never had an issue in years with my Spotmatics.

08-02-2019, 08:25 AM	#6
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Originally posted by boriscleto The Spotmatic F is. The F has its own peculiar taste in batteries anyway (PX625, IIRC).

08-02-2019, 09:20 AM	#7
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,473	Originally posted by pathdoc 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 $$$.

08-02-2019, 11:31 AM	#9
johnha Veteran Member Join Date: Apr 2012 Location: Lancashire, UK Photos: Albums Posts: 1,155	Originally posted by stevebrot 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.

08-02-2019, 11:42 AM	#10
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,312	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.

08-02-2019, 01:27 PM	#11
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,804	No idea about batteries, so I'll just welcome to the forum.

08-03-2019, 10:25 AM	#12
titrisol Pentaxian Join Date: Dec 2007 Location: In the most populated state... state of denial Photos: Gallery \| Albums Posts: 1,851	I have been using this since the mid 80s.... Originally posted by 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

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