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07-02-2018, 01:20 PM   #1
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ME Super: Dodgy Metering

I just acquired a cosmetically-excellent ME Super from eBay and the metering is intermittent. I did the usual things like whizzle the ASA setting, the exposure comp, the selector switch and the aperture ring on the lens I have on (50mm f1.7 SMC). No different. What's happening is when it's set to 'Auto' and I rotate the aperture, I'm expecting the shutter speed display to vary as light varies. It does sometimes, but sometimes it doesn't. Similarly on manual, I'm getting the same shutter speed for a given ambient light irrespective of aperture.

When the lens is removed there's a little spring-loaded tab that engages with the aperture lever on the lens, presumably a detent to tell the camera the point at which the aperture ring stops and hence the f-number. It moves freely and I noticed after exercising this lever, it worked for a bit. So I dribbled a touch of isopropyl alcohol down where the spring-loaded lever goes and it worked satisfactorily for a bit longer.

I've never attempted to open a Pentax MX or ME (I know what I can do and I know what I can't do). Am I on the right track with this fault? Anyone else experienced it? I'm loathe to send the camera back (it is returnable) as it's a little beauty otherwise. Is there anyone in the UK will service it? I used to send my MX to a company at Harrow, but I understand the chap who did the servicing has retired.

07-02-2018, 02:07 PM   #2
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QuoteOriginally posted by Russell W. Barnes Quote
When the lens is removed there's a little spring-loaded tab that engages with the aperture lever on the lens, presumably a detent to tell the camera the point at which the aperture ring stops and hence the f-number.
Yep...that is how the meter is bias by aperture ring position. Yes, you are on the right track.

QuoteOriginally posted by Russell W. Barnes Quote
It moves freely and I noticed after exercising this lever, it worked for a bit.
It is supposed to be firmly spring-loaded.

Question: Is the meter responsive to light when aperture is held constant?


Steve
07-02-2018, 02:38 PM   #3
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QuoteOriginally posted by stevebrot Quote

It is supposed to be firmly spring-loaded.

It is indeed firmly spring loaded.

QuoteOriginally posted by stevebrot Quote
Question: Is the meter responsive to light when aperture is held constant?
Yes. When I point the camera to the TV screen, the lamp, the dark bit under the shelf and a neutral bit of wall, the meter responds accordingly. When I adjust the aperture (on 'auto') there's no change. On 'manual' I get an exposure (no red over or under LEDs) of f5.6 @ 1/60 sec when aimed at the lamp. When I set f11 and repeat, it's still 1/60 second.
07-02-2018, 02:50 PM   #4
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QuoteOriginally posted by Russell W. Barnes Quote
It is indeed firmly spring loaded.



Yes. When I point the camera to the TV screen, the lamp, the dark bit under the shelf and a neutral bit of wall, the meter responds accordingly. When I adjust the aperture (on 'auto') there's no change. On 'manual' I get an exposure (no red over or under LEDs) of f5.6 @ 1/60 sec when aimed at the lamp. When I set f11 and repeat, it's still 1/60 second.
Manual on the ME Super does not work that way. It stays on 1/60 because that is where the shutter speed is set to. Put the selector on "auto" and see if the viewfinder display responds to changes in aperture.

Don't open the camera for attempted repair or squirt anything more it unless you know it is broken.

Link to camera manual (free...password is "Pentax")...

Pentax Manuals | Manual Focus


Steve


Last edited by stevebrot; 07-02-2018 at 02:57 PM.
07-02-2018, 03:43 PM   #5
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I don't know the ME super, but when I first got my SuperProgram I thought the metering was broken, but it turns out that it doesn't work until you have shot and advanced the film two shots (even if there is no film loaded). This was to force a fast shutter speed during film loading even if the lens cap was on. I don't know if the ME super has something similar, but its worth looking into.
07-02-2018, 03:56 PM   #6
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QuoteOriginally posted by stevebrot Quote
Manual on the ME Super does not work that way. It stays on 1/60 because that is where the shutter speed is set to. Put the selector on "auto" and see if the viewfinder display responds to changes in aperture.

Not initially it didn't, no. But when I removed the lens and replaced it it did. And when I replaced the lens I felt the aperture ring offer quite a bit more resistance as I opened it up towards f1.7. Then the meter didn't respond again, staying at the same shutter speed.

Don't open the camera for attempted repair or squirt anything more it unless you know it is broken.

I won't! Don't worry. I only dribbled a touch of isopropanol in on the end of a small bit of wire. Thanks for the link to the manual. When the lens is removed, the spring lever moves smoothly upwards and downwards when I ease off, yet the resistance encountered when adjusting the aperture is quite significant. I observe, when looking at this little spring lever from an oblique angle across the front of the camera, the lever is full forward and follows the curved front profile of the slot.

---------- Post added 07-03-2018 at 12:03 AM ----------

QuoteOriginally posted by abruzzi Quote
This was to force a fast shutter speed during film loading even if the lens cap was on. I don't know if the ME super has something similar, but its worth looking into.
I read about this, and I did wonder, so of course I put a film in it and I'm on frame 4 now. But yes... It's recommended to set 1/125 sec position to advance the film or point the camera at something bright when on auto to advance the film.
07-02-2018, 04:54 PM   #7
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QuoteOriginally posted by Russell W. Barnes Quote
yet the resistance encountered when adjusting the aperture is quite significant.
What you describe sounds like the two tabs are misaligned and jammed against each other. Is there any evidence that either has been bent or mangled?


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07-02-2018, 11:34 PM   #8
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QuoteOriginally posted by stevebrot Quote
Is there any evidence that either has been bent or mangled?
Steve, it's the same with two 50mm lenses and a 135mm lens, both of which work fine in my MX. I wonder if the lever in the camera is misaligned? What you say makes sense and may be a relatively easy fix. If I put a photo on would you be able to tell if it's misaligned or not? I've never seen a working ME Super to compare it to, but I'm guesing it should be the same as on the MX as it uses the same lenses and same open-aperture metering system. Would this be correct?

I have a vernier caliper I can check distances with as well as a visual check.


Last edited by Russell W. Barnes; 07-02-2018 at 11:44 PM. Reason: Further detail added.
07-03-2018, 07:01 AM   #9
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QuoteOriginally posted by Russell W. Barnes Quote
What you say makes sense and may be a relatively easy fix. If I put a photo on would you be able to tell if it's misaligned or not? I've never seen a working ME Super to compare it to, but I'm guesing it should be the same as on the MX as it uses the same lenses and same open-aperture metering system. Would this be correct?
Yes, that would be correct. Compare to your MX.


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07-03-2018, 11:30 AM   #10
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The distances are similar but I don't think that's where the issue lies. On the other side of the ring at the two o' clock position is a tab on an annular ring. On my MX, this ring has springs all around the periphery and moves smoothly and is thinner. On the ME Super there are no such springs visible and it appears graunchy and stiff to move.
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07-03-2018, 12:41 PM   #11
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I understand the correct name for the sticky component is the Diaphragm Coupler Ring.

---------- Post added 07-03-2018 at 09:29 PM ----------

Right. Sorted it (I hope...) It seemed to me like there was a fair bit of 'stiction' between the coupler ring and the aluminium fixed rings that sandwich it. So, using the lead of a 1kilohm resistor I dropped a minute amount of lubricant at three points around the rings 120 degrees apart, fitted the lens set to f22, and very gently worked the aperture ring with the camera in all positions. It now works correctly and the ring returns unaided when either the lens is removed or opened up to f1.7.


I'd like to say I used a fine grade of watch or clock oil, but I didn't have either, so I used a drop of 'White Lightning' cycle oil. I've used this lubricant to good effect on telephone dials and it's good stuff. I suppose lighter fluid might've been better but I have none of that either.

Last edited by Russell W. Barnes; 07-03-2018 at 01:30 PM.
07-04-2018, 11:36 PM   #12
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QuoteOriginally posted by Russell W. Barnes Quote
Right. Sorted it (I hope...)
Good work! Yes, the coupler ring is supposed to slide freely and yes, sometimes it is fouled by grit and grunge. The difference in appearance of the mirror box for the two cameras is to be expected, in part due to the difference in shutters. Despite both cameras being M-series, they are quite different under the skin.

As for lube, I have used small quantities of Tri-Flow, a teflon-infused lightweight oil in similar settings. It penetrates readily (yes use very small amounts) and evaporates to a thin and durable hygroscopic film. It is highly favored as chain lubricant for bicycles. I don't know what approach a camera repair tech might take.


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07-05-2018, 01:49 AM   #13
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QuoteOriginally posted by stevebrot Quote

As for lube, I have used small quantities of Tri-Flow, a teflon-infused lightweight oil in similar settings. It penetrates readily (yes use very small amounts) and evaporates to a thin and durable hygroscopic film. It is highly favored as chain lubricant for bicycles. I don't know what approach a camera repair tech might take.
Thanks. I'll see how it lasts, but I believe Moebius oil might be the stuff to use. We use a PTFE-based lubricant at work but I'm not convinced of its properties. But so far, so good... I didn't see this coupler ring tab until I was a couple of days into the fault: more focussed on the big sticky-out tab at the eight o' clock position which I believe is innocent.
07-05-2018, 09:23 AM   #14
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QuoteOriginally posted by Russell W. Barnes Quote
But so far, so good... I didn't see this coupler ring tab until I was a couple of days into the fault: more focussed on the big sticky-out tab at the eight o' clock position which I believe is innocent.
Sorry for the confusion. My earlier comments were in regards to the coupling that you just now found. The standard K-mount couples for aperture actuation and for open-aperture metering using the quite prominent actuator lever and the much less obvious aperture ring position tabs.


Steve
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