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05-12-2015, 08:08 PM   #1
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Spotmatic shutter timed incorrectly at 1/15th only, what could be causing this?


I have an old Honeywell-Pentax Spotmatic that was my first camera like 15 years ago, and belonged to my dad before that. I recently pulled the camera out of storage at my dad's house, and everything seems to be working correctly save the shutter at one speed only.

All of the speeds slower than 1/15th look at sound accurate(the slowest speeds I actually "timed" by putting my phone with the stopwatch running on one side of the camera and firing the shutter with the back open), and the faster speeds look and sound like they should. 1/15th, however, holds the shutter open for about 3/4 of a second and I do not know why. I have not had the camera professionally serviced yet, and hopefully there is a simple solution to this problem. Aside from that all it needs are new light seals, and I can do that myself.

If anyone has any ideas on what could be causing this, or how to fix it, I'd appreciate it a lot.


05-12-2015, 08:38 PM   #2
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Age and disuse are the most likely culprits. Lubricants dried out and becoming stiff, springs losing tension etc. Best solution is the have the camera CLAed (Cleaned, Lubricated and Adjusted).

In the US Eric Hendrickson is the go to guy for servicing Pentax manual focus cameras (linked below):

05-12-2015, 08:52 PM   #3
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The slow speeds 1/30 and below) will probably come back in line (or close to it) after you exercise them a bit.

Just curious: do you really need 1/15? You'll probably be getting vibration blur at anything below 1/60 anyway--at least handheld.
05-13-2015, 03:02 AM   #4
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The faster shutter speeds are probably off too. The light seals and mirror bumper will most likely need replacement.

05-13-2015, 09:19 AM   #5
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It is lack of exercise ... camera muscles need to move too!
05-13-2015, 06:20 PM   #6
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If the oil has outgassed from the grease no amount of exercise is going to re-emulsify the grease - it will just displace the clay or other substrate and you'll have bare material wearing against each other (gear tooth to gear tooth etc.) without lubrication.

No amount of exercise is going to add tension to springs that have been stretched or compressed long enough to lose tension. Same for the ribbons on the rubberized shutter curtains as these models are pre-vertical metal shutters.

My 45+ year old Minolta Rokkor 58mm f/1.4 focus was stiff because the helicoid grease had dried out. By working it it got less stiff but you could feel "play" in the action especially when reversing direction. I finally obtained some helicoid grease and found disassembly instruction to take apart the helicoid. There was no grease left on the threads at all - just little piles of clay on the extremes where I had exercised the dried up grease out of the helicoid threads. Re-greased it is as smooth as new, with no play or slop.

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