Pentax Spotmatic F Metering Issue

[Periodista]

Hello to everyone

This weekend I found the Pentax Spotmatic F at a flee market and bought it for $40 dollars with a Zenit Lens (Zenit 44m7 i think... 58mm f2), m42 screw mount

Today I got the 625a battery and with all different speed and F positions the Photometers needle get stuck on the plus side

Is something wrong with the camera? Or maybe the Photometer? Is this lens the right one?

I read something about step down meter, but this camera never move the needle in other way that the Plus side... just move a little when I move the cam...

Any Help?

Thanks!

[Attila]

Welcome! Based on your description , light meter is dead in your camera.
Check your battery voltage, battery contacts is clean or not and how did you put into camera body the battery. If looks every thing correct , meter is dead. Set your camera to 1 sec if it works , all other speeds will be accurate enough I think for B&W and color print print films.

[Periodista]

Mmm... I double check the battery position

With or without battery the needle its on the plus side

:/

[Attila]

No reaction if you keep to dark place or keep to strong light, no corrosion on contacts etc. It is dead in this case.

[visualopsins]

Welcome Periodista!

If battery + is toward battery cap, battery is good, no lens cap, set film speed to ISO100, and set shutter speed to B, meter should be up.

Then point lens opening toward light, move shutter speed to faster speeds, meter should go down by reach 1/500 sec.

In battery compartment, bend contact toward opening sometimes makes battery contact better, meter will work. Other times minor corrosion on adjustment resistors prevent working; turning adjustment back & forth will remove corrosion, meter will work, but then adjustments will need calibration:

Here is pdf of meter circuit with diagrams and photos and how to test and adjust: http://www.k7jrl.com/pub/manuals/pentax/service/spot_f_meter.pdf

edit: password for pdf is Pentax

[peterqd]

Hi and welcome to the forum. I don't think there's anything wrong with the camera.

The Pentax SPF is designed for the later S-M-C and SMC Takumar lenses, which have a lever to tell the camera the aperture setting for open aperture metering. If you use an ordinary M42 lens without this lever, such as your M7, then the camera doesn't know the aperture setting and the needle points upwards nearly all the time.

What you need to do is slide the black switch on the side of the lens mount upwards, in the direction of the arrow. This switches the camera from open aperture metering to stop-down metering like the older Spotmatics, and closes the aperture blades to the setting. Now the camera is simply metering the light and the needle should be more responsive.

You need to remember that this switch on the SPF does not switch the meter on and off like the older models. The meter is on all the time if there is sufficient light to read, so you should keep the front lens cap on except when actually shooting, otherwise the battery runs down quickly.

Hope this helps!

BTW, you can use a modern 1.55v SR44 silver oxide battery in this camera quite happily. It just needs an insulating collar to keep it centred in the compartment and prevent it shorting out.

[visualopsins]

Thanks peterqd, I'd forgotten about the switch needing to be up without lens attached; mine was up when I checked operation for my earlier post...

[Periodista]

wow, I thin i didnt try that...

tomorrow ill see if it works...

thanks for your help