Unusual Spotmatic problem

oreston

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Hi,

This is only my second post ever on the APUG forums, so please be gentle with me I wonder if anyone here can help with an unusual shutter problem?

Recently I won an ebay auction for a Spotmatic SP. The attraction was that the camera had a Super Takumar 85mm F1.9 attached to it, although the seller didn't seem to have much idea about what they were selling and the description was minimal. For once I took a chance, got lucky and managed to snag it for a very OK price.

Anyway, the camera itself is a well-used example of the motor drive model (just the body, no motor drive unit) and as such is moderately rare if not especially valuable. I haven't film tested it yet but it seems to work pretty well in most respects. The battery cover was frozen due to corrosion. Once removed, cleaned-up and replaced with a new button cell the meter came up trumps. Curtain tension seems fine and the shutter appears to fire correctly on all the timed speeds (no capping on 1/1000). The light seals and mirror bumper need replacing and the meter switch is sticky - but that's all par for the course and can be dealt with.

The one thing that's got me scratching my head though is the "bulb" setting. Basically it doesn't work and fires as if it was an instantaneous speed. This isn't a huge problem in practice as I probably wouldn't use it very often. If I keep this Spotmatic (which really is visually a little bit beat up) it would be as a "take anywhere" street camera, so I really wouldn't be making many long exposures with it. I do like things to work properly though, and as much as anything I'm simply curious about the bulb issue as it's not a shutter defect I've encountered before (except once years ago on a Russian rangefinder).

So does anyone have any idea if this is something that could potentially be fixed easily? Yes, I know I could send the camera away for a full CLA but for an otherwise smoothly working unit it's something I'm not eager to do just at the moment. I view the camera effectively as a freebie that I acquired to get the lovely portrait lens that came with it - and anyway I already have a CLA'd Spotmatic to use.

Thanks in advance for any suggestions!
 

cliveh

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I will try and be gentle with you by asking when, if ever are you going to use bulb flash and if so where are you going to get the flash bulbs from?
 

Sirius Glass

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Welcome to APUG.

You could call or write for estimates for shutter adjustments. Then you can decide to use it as it is, send the camera in for the adjustment, or wait to have the problem corrected when the camera needs other work.
 

tony lockerbie

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Welcome to Apug. Unusual problem indeed, and I have many SP bodies and have never encountered this problem. BTW Clive, the B setting is not for bulb flash, but for holding the shutter open for long exposures. If you want to do long exposures, ie, more than one second, just do multiples of one second...works well.
Probably not worth a CLA unless the camera is in exceptional condition, cheap bodies are always available these days. As you say, that 85mm lens is really worth having, you will really like it.
 

shutterfinger

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Yes, a CLA is what the doctor orders.
Google Spotmatic Service Manual and http://www.pentax-manuals.com/manuals/service/servicemanuals.htm is at the top of the list.

Open the camera back, set the shutter dial to B, and open the aperture to its widest opening.
Cock the shutter. While looking through the back trip the shutter. Does both of the curtains actually move?
Now set the speed dial to 1 second. Position a clock or watch so you can see its second hand and the back of the camera at the same time.
Cock the shutter. Trip the shutter just as the second hand reaches a second mark then note where it is when the shutter closes. It should be within the second hand width of the next second mark.
Set the shutter to 1/2 second and repeat. The second hand should be half way between second marks when the shutter closes.
If these are not correct the camera needs servicing.

And yes you got a nice lens with a parts body attached.
 

cliveh

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The OP refers to it as a bulb setting and so that's what I thought it was.
 

MattKing

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MattKing

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cliveh said:
What does the M stand for?
Click to expand...

M is for medium speed flash bulbs.

The other common flash synch choices are X for electronic flash and FP for focal plane bulbs - the ones that burn for a long time.
 

cliveh

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Thanks Matt, I now understand.
 
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oreston

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Oren Grad said:
http://en.wikipedia.org/wiki/Bulb_(photography)
Click to expand...

Yep, I was referring to the B shutter setting (B as the conventional abbreviation for "bulb" as explained in the linked article). As I said, it fires instantaneously at a high speed (may even be around 1/1000 sec. as that's next to it on the dial) rather than staying open for as long as the shutter release is depressed.

Flash bulbs? I agree there's not much call for them (and certainly no need!) but I believe you can actually still find them as old stock if you look.
 

abrosig

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The "M" stands for medium and relates to only the old magnesium flash bulbs.

I'd probably film test the camera before doing anything else. If the rest of the shutter speeds do prove out to be correct (or at least close enough for film latitude), then I'd happily shoot with the camera. It's possible (probable?) a misfunctioning bulb setting may mean problems with the mechanism itself.

Try this: cock the shutter, then set the speed dial to bulb. Test fire, holding the release down. If shutter doesnt remain open, cock the camera again, then jiggle the shutter speed dial to be sure it's seated correctly. I have a couple of older cameras I have to monkey with the speed dial to make them function correctly in bulb. They're FSU's, though, so may not relate to the Japanese models. Hope this helps.
 

AgX

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oreston said:
Flash bulbs? I agree there's not much call for them (and certainly no need!).
Click to expand...

If you are very restricted on space but only need a few flashes, bulbs are the outcome, especially if you need about GN(m) 40.
 

ambaker

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No need for flashbulbs? Talk to spelunkers, folks who explore caves. Flash bulbs are still popular with them. Lots of light in a very light package. If you need to take lots of shots in the studio, strobes are it.

If you are going some place remote flashbulbs pack a bunch, are light, and do not require heavy battery packs. The tiny AG-1B flashbulb is rated at 140 (in feet at ASA 100 x-sync at 1/30 of a sec.)

Slow for action, but for something like the afore mentioned cave, quite handy. The bigger boys go much, much higher.


Sent from my iPad using Tapatalk HD
 

Bill Burk

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I wonder if maybe it's an intentional design, part of the alteration to support the motor drive.

Was reading in Petersen's Honeywell Pentax System 1974 which covers models up to the ESII / F.

The chapter describing the motor drive doesn't specifically say the regular B is disabled... But describes a switch setting for B. That makes me think something special makes "B" happen and it comes from the Base.
 

Sirius Glass

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M synch refers to M class flashbulbs which have a different illumination pattern than X synch or F/FP synch.
 
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oreston

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Well I don't know much about spelunking, still less about cave photography, but that's just my ignorance
 
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oreston

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Thanks - very interesting.

You know I wondered if it might be something like that (on the basis that firing the shutter on B while using the motor drive might not be good news). However I'd dismissed such a notion because the Spotmatic SP shutter is 100% mechanical and I reasoned that an electronically operated interlock on the B speed was therefore perhaps unlikely. Also, if there was such a function, wouldn't it logically only kick in with a motor drive unit attached to the camera? Unless of course something has simply got stuck on this rather battered example.

It's worth exploring though. Later on today I'll unscrew the base plate and see what I can see.
 

Bill Burk

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Pentax had a funny way of implementing features back in the '70s

Like full-aperture metering, and how they implemented backwards compatibility with Super Takumar lenses that didn't have the aperture block. You had to always use "depth of field preview" switch with those lenses... or else... And new SMCT lenses had this baffling tiny pin that locked the Manual/Auto switch on the lens itself. If you had a mix of old and new bodies, and left the lens in Manual mode by mistake and used it on an F metering body, your exposures were hosed.

There were some things you always have to learn and remember with Pentax.
 

Chan Tran

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I don't know either but tend to think that it's possible. But reading the manual for the motor drive and the B setting has to be set also on the drive I think the camera isn't different from the regular one. My original thought is that they compromise and make the B position not working at all and thus if you accidentally set on B the motor drive won't hang up. But I don't think it's the case.
 
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oreston

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I had a look at the manual too (you can find it at http://c758710.r10.cf2.rackcdn.com/files/support/manual/168_1314744930-48025547_manual.pdf). I does explicitly say that, "The basic operating manual for the standard Spotmatic camera applies to the Spotmatic Motor Drive." On that basis I would be inclined to think I have a faulty shutter, since there doesn't seem to be any mention anywhere of a modification to the B setting on the camera itself, or any indication that it wouldn't work without the motor drive.

Then again, the motor drive unit itself has a "B switch" which has to be set to "B" if you want to make long exposures. Interestingly, you can also obtain T (Time) exposures by turning the main C/S (continuous/single frame selector) switch on the motor drive to its "off" position while pressing the trigger with the "B switch" set to B. (To end the time exposure you simply turn the C/S switch back to its "S" position.) This ability to do time exposures is definitely non-standard Spotmatic behaviour, so who really knows? Unless someone is able to chime in who has both the camera and the motor drive unit, or who used them back in the day
 
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oreston

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I take your point, but from what I've read other manufacturers' solutions to implementing open aperture metering in M42 weren't any better or worse than Asahi's - particularly with regard to backwards compatibility.
 

Chan Tran

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What I think is this. The motor drive has no knowledge of whether the shutter cycle is completed and ready for winding so it simply wait for you to release the trigger button on the motor to advance to the next frame (or wait a specific amount of time). In B it has to wait a little longer after you release the trigger to start closing the shutter.
 
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