Spotmatic F - Sticking mirror

SMBooth · Aug 29, 2009

I have a Pentax Spotmatic F which is in really nice condition except for the meter not working, no big deal and the mirror not returning Mostly when you shoot at 1/8 or slower shutter speeds, but sometimes at faster speeds. Any idea want could be wrong?

Cheer
Shane

Ian Grant · Aug 29, 2009

Could be the damping foam has gone sticky with age. Look inside with the lens off at the front of the focus screen I think there's a piece of foam there from memory, my camera's back in the UK so I can't go check

Ian

SMBooth · Aug 29, 2009

Thanks Ian, I meant to say that if I give it a little help it wants to stay up, if it was sticking to foam I assume once the seal broke it would come down.

ntenny · Aug 29, 2009

I had a problem like this with an SP500. I ended up having to take off the bottom plate (at the suggestion of someone here) and fiddle with one of the shafts in the shutter linkage to get it to come back down. In my case the root of the issue seemed to be with a little L-shaped pawl that needed to be minutely bent with needlenose pliers to change where it engaged. It's worked fine ever since (although I can't get a decent shot with this body---the meter is something like six stops off and I think the focus is a bit out of adjustment, but at least that's a *different* problem).

-NT

jfdupuis · Aug 29, 2009

I had a Spotmatic ES that has this problem once. The problem was quickly solved by lubricating the shutter mechanism after removing the bottom plate. Only one drop of oil from a needle was enough.

Trask · Aug 29, 2009

You don't say if it only sticks when you've used the in-camera meter. I had a Spotmatic in which the mirror wouldn't quite go all the way up because, when you push down the switch to activate the meter, it's the up-swinging mirror that hits a lever in the mirror box to release the switch. It occurs to me that maybe in your case the mirror is hitting the same lever, but is actually getting caught in a "friction fit" with the lever. Easily seen just by pulling the lens and watching the mirror movement.

SMBooth · Aug 30, 2009

Thanks, have solved one problem the meter, it now works. In ever knew I had to use stop down metering on the lens i have. - Operator error, the easy ones to fix...
Might try the oil, when it locks up I have to give a small clog a tiny push and it unlocks, other then that I will send it to repair man.
Trask, there is no meter switch on these camera.

Trask · Aug 30, 2009

Hmm...if it's Spotmatic F, I believe it does have a meter switch. It should be right where the red circle indicates....

SMBooth · Aug 30, 2009

Trask said:
Hmm...if it's Spotmatic F, I believe it does have a meter switch. It should be right where the red circle indicates....

As far as I can tell that's for stop down metering, and it operates the pusher at the bottom of the mirror box, which is quite clear of the mirror. The meter is always on. After read your first post I had to find out what that switch did, and that's what led me to getting the meter working. But operating that switch does not cause anything I can see in the mirror box to jam the mirror up. Do appreciate your help.

Trask · Aug 31, 2009

It's very possible that my Spotmatic is an older model and they changed the internals. In my camera, if you remove the lens, look into the mirror box with the mirror in the normal down position, on the right-hand side of the box up near the focusing screen is a small protrusion. When I push down on the meter switch, this cause the protrusion be stick out. When the exposure is made, the mirror swings up and strikes the protruding device just as it reaches max elevation, and the meter switch is released to return to its original position. As I say, mine is probably an older model.

Ian Grant · Aug 31, 2009

SMBooth said:
As far as I can tell that's for stop down metering, and it operates the pusher at the bottom of the mirror box, which is quite clear of the mirror. The meter is always on. After read your first post I had to find out what that switch did, and that's what led me to getting the meter working. But operating that switch does not cause anything I can see in the mirror box to jam the mirror up. Do appreciate your help.

The Spotmatic F was the first Pentax with Full Aperture metering with the SMC Takumar's, Older Takumars or other screw mont lenses needed to be stoppered down using that switch in the old way.

Ian

SMBooth · Aug 31, 2009

Trask: I your most likely right about the operation, mine does have a small tapered bit that the mirror slides over but on mine it does not move or impeded the mirror. Perhaps its faulty in some way as i need to switch the lever to disengage, it sound like yours automatically disengages the stop down metering when the mirror flips up.

Trask · Aug 31, 2009

If I remember correctly, yes. The camera is sitting in a box in a warehouse in Antwerp, and I'm sitting in the middle of the Arabian Peninsula...

Toffle · Jan 26, 2011

Resurrecting an old thread here. I was just given a Spotmatic F with precisely this problem. In the attached amazing webcam shot, the spring lever A gets caught up on the foot of Tab B and cannot return to its release position C, whereupon the mirror remains locked up.

[/IMG]

The spring lever gets hung up by only a fraction of a millimeter, and a slight pressure on the tab releases it promptly. Through a hundred or so cycles exercising the shutter I have managed to coax it to return to position a handfull of times. Short of bending or filing the tab, does anyone have any idea how to solve this?

[Edit] As it turns out, Tab B was not moving quite far enough because of resistance/friction on the geared wheel just beneath the other end of the tab mechanism near C. A drop of light oil here allowed it to move more freely and not the mirror returns to its proper position. I like it when things work out. (now to find 1.3v batteries)

Cheers,

SMBooth · Jan 27, 2011

Thanks Toffle,
Out with the screwdriver, hammer and light machine oil...Maybe a look-see first

Toffle · Jan 27, 2011

SMBooth said:
Thanks Toffle,
Out with the screwdriver, hammer and light machine oil...Maybe a look-see first

A man after my own heart... my philosophy; bigger problem - bigger hammer.

Further on this, The gear under C has a short post which acts as a cam when the shutter is fired, throwing Tab B, and releasing the spring lever A. Before I oiled it, the cam was sticking just enough so that it did not have enough momentum to completely swing the tab. Too bad I actually had to dismantle the camera about two steps beyond this before I discovered the solution. I was lucky, usually this is the point where I break things worse than they were in the first place.

Steve Smith · Jan 27, 2011

SMBooth said:
As far as I can tell that's for stop down metering, and it operates the pusher at the bottom of the mirror box.

I also think that this stop down lever turns on the meter too. I'm sure it does on my Spotmatic. Don't know about the 'F' though.

Steve.

Toffle · Jan 27, 2011

Steve Smith said:
I also think that this stop down lever turns on the meter too. I'm sure it does on my Spotmatic. Don't know about the 'F' though.

Steve.

That is good to know. This camera is brand new to me and I could see no way to turn on the meter. The manual on Mike Butkus' site states, "Remove the lens cap. Now the shutter circuit is on," which just does not make sense to me.

Steve Smith · Jan 27, 2011

Toffle said:
The manual on Mike Butkus' site states, "Remove the lens cap. Now the shutter circuit is on," which just does not make sense to me.

I wouldn't take my word for it that the stop down switch turns on the meter. I just think it does and I'm sure I have read that it does somewhere.

However on this page: http://www.butkus.org/chinon/pentax/pentax_spotmatic/pentax_spotmatic.htm

Is the Butkus site with the Spotmatic F and it refers to the switch as a meter switch, not a stop down lever. This is because the F does not stop down the lens to meter but meters at full aperture. Therefore, it can only turn the meter on.

4 TURN ON LIGHT METER SWITCH.
Push up the switch button with your thumb, and the small window on the switch button will turn to red indicating that the meter is switched on. Through the viewfinder, you will observe the movement of the meters needle on the right side of the ground glass. Be sure to turn off the meters switch when not actually taking readings

However, that remove the lens cap meter turn on method is correct for the Pentax K1000 (I think).

Steve.

drkhalsa · Jan 27, 2011

I've had a Spotmatic F for about a year now, and my research and experience is that the meter is turned on and off by removing and replacing the lens cap. The switch is for use with older Takumar and other screwmount lenses that need to be stopped down to engage the meter. The SMC Takumar lenses work at open aperture. Also, as I understand it, the Spotmatic F has a bridge circuit and can accept modern 1.5v batteries and adjust to the voltage difference for proper metering. I am not an expert, but from use and reading others, this is what I have come to understand.

Steve Smith · Jan 27, 2011

drkhalsa said:
I've had a Spotmatic F for about a year now, and my research and experience is that the meter is turned on and off by removing and replacing the lens cap. The switch is for use with older Takumar and other screwmount lenses that need to be stopped down to engage the meter.

You could be right but the part in the manual about checking the battery suggests otherwise:

How to check it

1. Set the shutter speed dial to B (bulb) position.

2. Turn the ASA dial to ASA 100.

3. Push the meter switch to "on" position.

Look at the meters needle through the viewfinder. If the needle rapidly drops, the meter battery has sufficient capacity; if it does not, replace the mercury battery.

Just stopping down the lens would not have this effect.

EDIT: I just found this which also suggests a switch: http://forum.mflenses.com/userpix/277_Spotmatic_ligth_meter_schematic_1.jpg

Steve.

drkhalsa · Jan 27, 2011

You're correct Steve, what I mean to say is that for lenses other than the SMC Takumars (which work automatically), the switch needs to be pushed up to engage the meter. The switch in effect stops down the aperture and turns on the meter.

I have 2 Yashinon lenses which require the switch in the up position to activate the meter.

I focus with the switch off and meter with the switch on.

Toffle · Jan 27, 2011

drkhalsa said:
You're correct Steve, what I mean to say is that for lenses other than the SMC Takumars (which work automatically), the switch needs to be pushed up to engage the meter. The switch in effect stops down the aperture and turns on the meter.

I have 2 Yashinon lenses which require the switch in the up position to activate the meter.

I focus with the switch off and meter with the switch on.

I wonder how many times a photographer has said, "the manual wasn't very clear on that..."?

I still don't get it... so if I have a SMC Takumar mounted, the meter is activated by some ??? mechanism that knows that I've lost the lenscap. (never had it, but in my case, it just saves me time) Will the meter run until the battery runs out or until I stick it inside a sock and block the light from the lens? How about the 28mm Opticam Auto, which has a lenscap, or the 35-80 Tamron Macro Zoom, which doesn't have a cap, but a skylight and a rubber hood?

Oh, I'm so confused. Ok, simple but probably stupid question, will any old lenscap work?

I need a nap.

MattKing · Jan 27, 2011

Tom:

It's the light itself that turns the meter "on".

So by making it dark, a lens cap turns it off.

Toffle · Jan 27, 2011

MattKing said:
Tom:

It's the light itself that turns the meter "on".

So by making it dark, a lens cap turns it off.

Thanks Matt, I hoped it was something that easy.

Spotmatic F - Sticking mirror

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