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Gave my Asahi Pentax Spotmatic-F an outing with Colorplus
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Posted: Sun Oct 12, 2025 12:43 pm
Post subject: Gave my Asahi Pentax Spotmatic-F an outing with Colorplus
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Posted: Sun Oct 12, 2025 12:43 pm
Post subject: Gave my Asahi Pentax Spotmatic-F an outing with Colorplus
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I gave my Asahi Pentax Spotmatic-F Gift Camera an outing with a 1.5 V battery to see how it performed instead of the Mercury 1.35 V
I loaded with 2005 dated kodak Colorplus 200 found in my film fridge and processed in 'well-used' C41 ---
24mm f3.5 SMC Takumar



50mm f1.4 SMC Takumar


28mm f3.5 SMC Takumar


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Posted: Sun Oct 12, 2025 10:02 pm
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Posted: Sun Oct 12, 2025 10:02 pm
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Like 1

The old Kodak film is stil usable!


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Posted: Mon Oct 13, 2025 12:03 pm
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Posted: Mon Oct 13, 2025 12:03 pm
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1.5 Silver oxide batteries work great in the SP-F. I havent seen a significant difference under normal shooting conditions


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Posted: Tue Oct 14, 2025 1:32 am
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Posted: Tue Oct 14, 2025 1:32 am
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If I recall correctly the Spotmatic F metering circuit is "balanced" -- the voltage difference make no difference in exposure readings.

Very nice film results! Takumar colors pair well with the Kodak film too.


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Posted: Wed Oct 15, 2025 12:53 pm
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Posted: Wed Oct 15, 2025 12:53 pm
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visualopsins wrote:
If I recall correctly the Spotmatic F metering circuit is "balanced" -- the voltage difference make no difference in exposure readings.

Very nice film results! Takumar colors pair well with the Kodak film too.

A long long time ago, in a galaxy far away there was the Spotmatic yahoo-group
Among the gems that came out of it was a document about the batteries for the Spotmatic.
I cant attach the pdf, but says this about the SPF:

Quote:

SP F.
• Mallory PX625, Duracell PX625A, Excel Z625PX, Eveready E-625N.
• The Spotmatic F uses a dual coil meter movement that, like the
bridge circuit, cancels out battery voltage variations on the
level we are dealing with here. So it is immune to the
difference between 1.35v and 1.5v, too. The original battery
for the Spot F was a mercury type. In this case, Pentax used
the identical circuit in the KM and K1000, without any
electronic changes. They substituted the silver types with NO
ALTERATION at all.


My SPF belonged to my father in law, he bought it new in 1974 or 75 and the battery compartment is for SR44


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Posted: Tue Oct 21, 2025 4:43 am
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Posted: Tue Oct 21, 2025 4:43 am
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Beautiful photos! Thank you for sharing!


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Posted: Tue Oct 21, 2025 5:16 pm
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Posted: Tue Oct 21, 2025 5:16 pm
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@ pentaxpete: Thank you for sharing these images !! -

@ titrisol: I wasn't aware of the "stabilized" circuit of the Spotmatic; that's a very useful information indeed - especially since my Minolta SR-T cameras really need mercury batteries ...

S


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Posted: Sun Apr 19, 2026 3:49 am
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Posted: Sun Apr 19, 2026 3:49 am
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Looks like a very sharp lens!
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