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08-06-2021, 06:39 AM   #1
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LX Getting Specific With Shutter Speed

Hello All,

I photograph moving water; creeks, rivers, small waterfalls. Very slight variations in shutter speed produce vastly different looks to the water.

I've been a digital shooter of this subject heavily for the past six years, and I'm working to translate this into film. I know my Pentax LX has an electronic shutter capable of doing a near infinite fraction of every speed printed on the dial. I utilize Automatic shooting to approximate them via bracketing. This is far too messy for what I need.

Is there some long forgotten about device that attaches to cameras of this vintage of camera to allow very exact control of bulb mode? I do hope to be able to shoot my LX. Every other feature of its outstanding and all I need. If it's not possible, which later camera body would be best suited to my purpose? I'm alright with swapping the body out, though yes it would be a shame. The LX is the apple of my eye.

I would appreciate any direction. Just back from a photo camping trip, and I'll be leaving on another in just over a week. Your advice will be implemented immediately. Thank you.



08-06-2021, 07:01 AM - 1 Like   #2
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QuoteOriginally posted by Wesley Snaps Quote
Hello All,



Is there some long forgotten about device that attaches to cameras of this vintage of camera to allow very exact control of bulb mode?
A cable release and a stop watch.
08-06-2021, 07:31 AM   #3
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I shoot in the 1/15th of a second to a 1/3rd of a second range. I feel like I could shoot a whole roll of film and if I'm lucky one shot would be the specific speed I'm attempting. I don't think it's physically possible to only activate the cable release for 1/15th of a second, but 1/10th and slower with practice may be possible.

08-06-2021, 08:13 AM   #4
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QuoteOriginally posted by Wesley Snaps Quote
I shoot in the 1/15th of a second to a 1/3rd of a second range. I feel like I could shoot a whole roll of film and if I'm lucky one shot would be the specific speed I'm attempting. I don't think it's physically possible to only activate the cable release for 1/15th of a second, but 1/10th and slower with practice may be possible.
Frankly, you are asking too much of the equipment. It was never designed to give that kind of accuracy. If you put the camera on a shutter speed tester, you will find that the shutter accuracy is, at best, ± 1/3 of a stop from the set speed, and that is if it's been freshly serviced. This means it could be out as much as 2/3 of a stop from exposure to exposure when the dial hasn't been moved. The same with the lenses, they can be out significantly on a shot to shot basis.

I don't know why you think you need that kind of shutter speed accuracy for landscape work, especially the type of work you showed in your OP, but that's your business and I'm not really interested. I can tell you that pursuing it with a camera of the vintage you are using is a fool's game.

08-06-2021, 09:08 AM   #5
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1/15th to 1/3rd of almost a 2 stop range. The LX was a pro standard body and if I remember correctly from reviews at the time had an accurate shutter so clearly was designed to give at least 1/3rd stop accuracy.

Your subject matter has rapidly changing highlights which would make metering very variable. Add in that the LX meters during exposure and you will never get the same result twice. The obvious solution is to use manual mode and set the shutter speed you want.
08-06-2021, 10:32 AM   #6
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QuoteOriginally posted by Wesley Snaps Quote
I photograph moving water; creeks, rivers, small waterfalls. Very slight variations in shutter speed produce vastly different looks to the water.
Such has not been my experience at exposure times greater that about 1/5s. I suspect that for "B" mode shooting you will not see much difference between 1s and longer exposures. If you need finer control than a stop watch for longer than 1s, a different camera might be in order, though even then, the increments would likely be 1s or greater.


Steve

Last edited by stevebrot; 08-06-2021 at 10:45 AM.
08-06-2021, 10:46 AM   #7
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Thanks for the replies.

I'm now researching which cameras can accept a 2.5mm connector for an intervalometer. Potentially I'll buy a Pentax MV-S to use with my K glass. I'm digging around to find out what the connector is for the shutter release socket on the MV-S.

Does anyone reading this happen to own an MZ-S?

Thanks


Last edited by Wesley Snaps; 08-06-2021 at 01:27 PM.
08-06-2021, 10:48 AM   #8
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QuoteOriginally posted by steephill Quote
1/15th to 1/3rd of almost a 2 stop range. The LX was a pro standard body and if I remember correctly from reviews at the time had an accurate shutter so clearly was designed to give at least 1/3rd stop accuracy.

Your subject matter has rapidly changing highlights which would make metering very variable. Add in that the LX meters during exposure and you will never get the same result twice. The obvious solution is to use manual mode and set the shutter speed you want.
This is all true. The LX shutter was very accurate for it's day at ±1/3 stop. However, this means as much as 2/3 stop variance FROM SHOT TO SHOT at discreet shutter speeds.
Obviously, they get more accurate as things slow down, below the sync speed, the shutter is probably accurate to within 1/10 stop, for an exposure variance of as much as 1/5 stop from exposure to exposure.

I suspect you have hit the nail on the head with your comment about OTF metering during exposure. There is no practical way of keeping the LX being run in automatic from making fairly wild exposure variances in normal use. If the light change at all, the exposure will be affected.
Note this only happens when speeds fall below sync speed. At sync speed and above, the metering is done off the leading curtain and exposure is locked in at the moment the button is pushed..
08-06-2021, 11:51 AM   #9
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QuoteOriginally posted by Wesley Snaps Quote
Does anyone reading this happen to own an MV-S?
To be honest, I am completely unfamiliar with that model. There was an MV and an MV 1, but both of those use a standard mechanical cable release.


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08-06-2021, 12:07 PM   #10
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Might this thread be helpful?

Intervalometer for LX - PentaxForums.com


Steve
08-06-2021, 12:52 PM   #11
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QuoteOriginally posted by stevebrot Quote
Might this thread be helpful?

Intervalometer for LX - PentaxForums.com


Steve
Wow, definitely interesting. That's not out of the question. My good friend is a retired electrician and would be interested in helping me rig something up

08-06-2021, 01:19 PM   #12
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QuoteOriginally posted by stevebrot Quote
To be honest, I am completely unfamiliar with that model. There was an MV and an MV 1, but both of those use a standard mechanical cable release.


Steve
MZ-S perhaps? Different series from the MV's.
08-06-2021, 01:22 PM   #13
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Yes, MZ-S, I'm sorry, that's the one I was getting at. I have edited my above post. It seems like a very nice camera. There's an intervalometer specifically for it too.
08-06-2021, 03:06 PM   #14
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QuoteOriginally posted by Wesley Snaps Quote
I shoot in the 1/15th of a second to a 1/3rd of a second range.
Sorry for not noticing this sooner. The LX supports 1/15s, 1/8s, 1/4s, and 1/2s as manual shutter speeds. It looks like the camera has you covered.


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08-06-2021, 03:46 PM   #15
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QuoteOriginally posted by stevebrot Quote
Sorry for not noticing this sooner. The LX supports 1/15s, 1/8s, 1/4s, and 1/2s as manual shutter speeds. It looks like the camera has you covered.


Steve
My guess is he is trying for 1/12, 1/6, and 1/3 as well. Today's DSLRs are far more refined in this regard than old film cameras.
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