Spotmatic F -- S.M.C. and Super Takumars reading differently by two stops

kq6up · 09-17-2019, 06:49 PM

Originally posted by stevebrot

Below is a link to a page that has the meter service sheet for the Spotmatic F. I commented it on in a post above, but here it is again.

Pentax Manuals | Service Manuals (PDF password = "Pentax")

It says to adjust one of two sets of potentiometers. I don't know if the mechanical offset is adjustable as well. The manuals for the SPII and K1000 (also on that page) may be helpful as well, particularly since the K1000 meter circuit is similar to that of the SP-F for open-aperture metering.

Steve

Would a pot adjustment affect BOTH the coupled and stop down readings? The stop down metering is spot on in my example.

stevebrot · 09-17-2019, 07:08 PM - **1 Like**

Originally posted by kq6up

Would a pot adjustment affect BOTH the coupled and stop down readings? The stop down metering is spot on in my example.

Different circuitry for each mode. Did you look at the PDF?

Steve

kq6up · 09-17-2019, 07:19 PM

Originally posted by stevebrot

Below is a link to a page that has the meter service sheet for the Spotmatic F. I commented it on in a post above, but here it is again.

Pentax Manuals | Service Manuals (PDF password = "Pentax")

It says to adjust one of two sets of potentiometers. I don't know if the mechanical offset is adjustable as well. The manuals for the SPII and K1000 (also on that page) may be helpful as well, particularly since the K1000 meter circuit is similar to that of the SP-F for open-aperture metering.

Steve

Yes, I see a separate stop down pot. I guess I need to just send it in to Eric, but I wanted to make sure I described the issue correctly. His emails were rather terse (I do understand he doesn't have all the time in the world to go back in forth via emails). I also wanted to make sure it wasn't pilot error. I had just sent him my regular spotmatic. He did a good job on the chipped prism which I wasn't even worried about (only $14), but the light seals look too thin on the back door and I have had one small light leak. I might just do the rear seals myself on my plain spotty. Thanks for all your help guys.

stevebrot · 09-17-2019, 08:55 PM

Originally posted by kq6up

but the light seals look too thin on the back door and I have had one small light leak.

Eric uses doped twine for the light traps on the film door. Twine is considered a craftsman's approach; they should be very effective and should last for decades. If you have a light leak from his seal job, it might be easier to have him do the fix.

Steve

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09-17-2019, 06:49 PM	#16
kq6up New Member Join Date: Sep 2019 Posts: 7 Original Poster	Originally posted by stevebrot Below is a link to a page that has the meter service sheet for the Spotmatic F. I commented it on in a post above, but here it is again. Pentax Manuals \| Service Manuals (PDF password = "Pentax") It says to adjust one of two sets of potentiometers. I don't know if the mechanical offset is adjustable as well. The manuals for the SPII and K1000 (also on that page) may be helpful as well, particularly since the K1000 meter circuit is similar to that of the SP-F for open-aperture metering. Steve Would a pot adjustment affect BOTH the coupled and stop down readings? The stop down metering is spot on in my example.

09-17-2019, 07:08 PM - 1 Like	#17
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by kq6up Would a pot adjustment affect BOTH the coupled and stop down readings? The stop down metering is spot on in my example. Different circuitry for each mode. Did you look at the PDF? Steve

09-17-2019, 07:19 PM	#18
kq6up New Member Join Date: Sep 2019 Posts: 7 Original Poster	Originally posted by stevebrot Below is a link to a page that has the meter service sheet for the Spotmatic F. I commented it on in a post above, but here it is again. Pentax Manuals \| Service Manuals (PDF password = "Pentax") It says to adjust one of two sets of potentiometers. I don't know if the mechanical offset is adjustable as well. The manuals for the SPII and K1000 (also on that page) may be helpful as well, particularly since the K1000 meter circuit is similar to that of the SP-F for open-aperture metering. Steve Yes, I see a separate stop down pot. I guess I need to just send it in to Eric, but I wanted to make sure I described the issue correctly. His emails were rather terse (I do understand he doesn't have all the time in the world to go back in forth via emails). I also wanted to make sure it wasn't pilot error. I had just sent him my regular spotmatic. He did a good job on the chipped prism which I wasn't even worried about (only $14), but the light seals look too thin on the back door and I have had one small light leak. I might just do the rear seals myself on my plain spotty. Thanks for all your help guys.

09-17-2019, 08:55 PM	#19
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by kq6up but the light seals look too thin on the back door and I have had one small light leak. Eric uses doped twine for the light traps on the film door. Twine is considered a craftsman's approach; they should be very effective and should last for decades. If you have a light leak from his seal job, it might be easier to have him do the fix. Steve