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  1. #1

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    Spotmatic F with odd meter issues ...

    I just got a Spotmatic F that seems to be behaving a bit weirdly. Stick a super-takumar on the front (not smc) and the meter is reasonably accurate. However if I hit the stop down switch the meter immediately dives by about two stops, even if I haven't stopped down the lens. My understanding was that with the F there was no connection between the stop down switch and the meter electronics so I'm at a loss to understand how this is happening.

    I have a couple of SPs as well so I understand the difference between the operation of the switch in the different models. Anyone any ideas ? I've got to disassemble it anyway to clean it up so I may poke around in the meter electronics at the same time.

  2. #2

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    I've not handled a Spotmatic F but I do have an original Spotty.

    I always thought that when using the pre-SMC Takumars on the F (or ES or ES II) the stop-down switch worked just like that on the original - set lens to Auto, then when you push the switch it'll stop the lens down and turn the meter on?

    I would suspect the film speed selector if your metering is wobbly, both my KM and K1000 (essentially the same mechanism) have problems there.
    Matt

  3. #3
    Ian Grant's Avatar
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    I had a Spotmatic F back in the early 70's and I've had another for about 9 years.

    The stop down switch must cut out the SMC full aperture metering system. I'd expect the meter to read incorrectly with a non SMC lens without the meter switch being used as there's no lug on the lens registering the aperture the lens is set to.

    Ian

  4. #4
    Hatchetman's Avatar
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    I think(?) it may be working correctly. It was designed for an SMC lens, otherwise it works like the original Spotmatic, so when you hit the switch the meter turns off.

  5. #5
    Bill Burk's Avatar
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    It's possible that the meter is "off" until you push the Depth of Field Preview (Meter On) switch on the Spotmatic F.

    I don't have any Takumar's (robbed long ago). But with no lens on my Spotmatic F, I get meter needle all the way to the top - the meter off state. When I move the "Aperture" slider in the body, the meter comes on and responds. This is expected "Always On" mode of the SMCT lens.

    A Takumar or Super Takumar lens will not move the "Aperture" slider. The meter will not be on until you turn on the Depth of Field Preview switch.

  6. #6
    Bill Burk's Avatar
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    In other words, on a Super Takumar lens or Takumar lens, there is a connection with the meter switch and the meter electronics on a Spotmatic F. Soon as you put an SMCT lens on, the meter switch is disconnected and the meter is always on.

    You don't have to disassemble the camera to discover this. Just take off the lens and slide the aperture cam (inside top of lens mount).

    The meter is only accurate with Super Takumar or Takumar lenses when Depth of Field Preview switch is up. The meter is only accurate with SMCT lenses when Depth of Field Preview switch is down.

    With Super Takumar or Takumar lenses, you can use the Manual / Auto slider on the base of the lens as you wish. With SMCT lenses a tiny pin enforces the fact that you must always keep this slider on Auto. If you override this tiny pin and leave the SMCT slider on Manual, you will double-compensate for aperture and the metering will be far-off. (How can this happen you ask? If you also shoot a regular Spotmatic and interchange lenses you might leave a lens on Manual - it's happened to me).

  7. #7
    Ian Grant's Avatar
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    Quote Originally Posted by Bill Burk View Post
    In other words, on a Super Takumar lens or Takumar lens, there is a connection with the meter switch and the meter electronics on a Spotmatic F. Soon as you put an SMCT lens on, the meter switch is disconnected and the meter is always on.
    That's a bit confused

    There's a lug on the SMC Takumar lens that turns the meter on, however it does not de-activate the stop down metering switch which if used then gives false readings. So just trying it with a correct reading of a 30th @f5.6 when the stop down switch is used it claim itneeds a 30th @ f11 (both with SMC Takumar lens).

    I had great difficulty persuading my wife not to use the meter switch on her K mount Pentax with its standard lens, this gave similar false readings.

    Ian

  8. #8
    Bill Burk's Avatar
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    Quote Originally Posted by Ian Grant View Post
    That's a bit confused

    There's a lug on the SMC Takumar lens that turns the meter on, however it does not de-activate the stop down metering switch which if used then gives false readings. So just trying it with a correct reading of a 30th @f5.6 when the stop down switch is used it claim itneeds a 30th @ f11 (both with SMC Takumar lens).

    I had great difficulty persuading my wife not to use the meter switch on her K mount Pentax with its standard lens, this gave similar false readings.

    Ian
    Haaa, You are right. With SMCT lens on Spotmatic F, the Depth of Field switch is electrically disconnected but not mechanically disconnected. You can push the switch up and the needle moves with changes - so you can be misled.

    You bring up an important point: the metering is wrong with an SMCT lens on a Spotmatic F with the Depth of Field Preview switch up. I would say it stinks as a feature in this respect.

  9. #9
    Trask's Avatar
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    I have a Spotmatic, but prefer to put an M42 adapter on my Canon T90 and use my Pentax lenses that way. The best of both manufacturers.

  10. #10

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    The tiny pin to keep the SMC lenses on Auto on the Spotmatic F/ES/ES II is a very clever bit of engineering.

    The lens mounts on these cameras have a groove for the pin to drop into. Mount the same lens on a Spotmatic or earlier Pentax M42 body and the lack of a groove causes the pin to be pressed in, so the lens works just like a Super Takumar.
    Matt

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