Spotmatic F with odd meter issues ...

[Bill Burk]

I can probably get you one in early December, there's usually a stall at the camera fair I go to which has parts cameras for £1 ($1.55) and postage of a rewind crank would be very low. I bought an SIa for parts but had it working perfectly within 20mins, so had to buy another a few months later but the rewind was missing, The cranks are identical.

Ian

If you see one, great!... I've done the same, bought a parts Spotmatic for the rewind knob and it was mint under patina. Ended up taking the rewind knob and putting a knob from a Canonet on it and gave it to a work acquaintence (I wasn't totally evil, I gave it away with an SMCT 35mm f/2 and Soligor Spot Sensor).

[Ricardo Miranda]

Bill,
Thank you! Incidentally, the Pentax K1000 is the only other Pentax with the same type of "light switch" as I call it. The stop-down lever should be the same as the ES and ES II models.
Many people got confused with that lever, including me when I first got one. I was used to the SP and SP II and had a couple of rolls badly exposed because I was flicking the switch up whit the SMCT lenses. Didn't read the manual until it was too late!

[RichardH]

p.s. Does anyone have a spare "rewind knob" for Spotmatic F? I lost it once then I hunted it down and found it. I didn't put Loctite on it so it fell off again and I didn't notice before the street sweeper came by...

Bill, I sent you a pm.

Richard

[Bill Burk]

Bill, I sent you a pm.

Richard

Thanks Richard,

Ian, enjoy the show but Richard is going to get me a rewind crank. I'm using Loctite this time. Got the bottle of Threadlocker 242 blue out already...

[Ian Grant]

Ian, enjoy the show but Richard is going to get me a rewind crank. I'm using Loctite this time. Got the bottle of Threadlocker 242 blue out already...

Saves me having a wasted Pentax carcus It's this kind of kind of help that makes APUG such a great site.

Ian

[Daire Quinlan]

Thanks for the replies all. I've got it topless (ooer) at home at the moment for a good clean and I'm going to test and adjust the two metering circuits at the same time. I guess I can setup a properly metered scene at EV 8 or 12 or something and adjust the spotmatic from there, both stopdown and open aperture metering.

[Daire Quinlan]

SOOooo ...

I retrieved my SMC 28mm and, fiddling with the two variable resistors at EV16 and EV8 I've gotten the open aperture metering circuit well inside what I'd regard as acceptable readings compared to my sekonic and checked against my F100 with the same lens fitted via an adapter. Not too much adjustment needed either, which suggests that the two CDS cells (or whatever is in the spotmatic) are ok.
The difficulty is with the stop down metering. Even adjusting the seperate variable resistor for the stop down metering to its extreme I cannot get the stop down metering to read at anything other than about 2 stops underexposed. This has me confused because it's the simpler of the two circuits, and it's reading off the same two CDS cells which appear to be just fine. Anyone suggest any possible avenues of investigation ?

Interesting (by which I mean annoying) side note, you have to put the top back on the spottie to actually get the meter to read correctly. That led to some perplexed fiddling and weird erroneous readings until I worked it out

[Bill Burk]

Unscrew the lens 1 turn (to uncouple the aperture coupling) and adjust the stopdown metering to be accurate. I'm pretty sure this stopdown metering is only supposed to be accurate with old lenses.

Don't forget to keep the eyepiece covered when metering, the cells can see through there...

If you find that you can get it to work easily along this line of reasoning... Then I suspect that's what the balance control is for.

[Daire Quinlan]

Unscrew the lens 1 turn (to uncouple the aperture coupling) and adjust the stopdown metering to be accurate. I'm pretty sure this stopdown metering is only supposed to be accurate with old lenses.
.

Sorry, I should have clarified. I was testing the open-aperture metering with a 28mm SMC tak with the proper lugs to engage the aperture tabs on the mount. I was testing the stop down metering with an older 50mm super takumar which doesn't have those lugs (i.e. isn't designed for open aperture metering).

[Bill Burk]

OK so it sounds like a bit of a problem.

To rule out angle of view differences, you could try both with the 28mm - unscrew it (and set the lens switch to Manual) so you use the same lens to do both tests...

For what it's worth, when I tried this Full aperture metering gives two stops overexposure, and Stopdown metering gives one stop overexposure on mine, compared to Sekonic spotmeter...