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05-19-2013, 09:22 AM   #1
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1/6000 Shutter speed

Hello everyone! I just got a SMC-M 50mm f1.7 and trying it out on my K-30 at 1/6000 shutter speed I got this result. At 1/5000 happened again, but with less intense shadow. Do you think it's a mirror problem?

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05-19-2013, 09:26 AM   #2
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My guess is that the M-lens (maybe the aperture lever) is somehow slowing down the traveling hardware during exposure. Re-check with some other DA lens. Inspect the resistance of the M-lens mechanical coupling parts. Older lens tend to stiffen in some ways.
05-19-2013, 09:30 AM   #3
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QuoteOriginally posted by dragra Quote
Older lens tend to stiffen in some ways.
Just like us humans then.

Now, now, before anyone comments further on this, keep it clean it's a family forum.
05-19-2013, 09:45 AM   #4
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Just tried it on my SMC-a 50mm f2 and SMC-M 80-200 f4.5 and it's the same result. Even worse on the zoom. I don't have my 18-55mm kit lens with me right now, but I'll try it ASAP. Thanks for the help!

05-19-2013, 10:17 AM   #5
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QuoteOriginally posted by kerrowdown Quote
Just like us humans then.

Now, now, before anyone comments further on this, keep it clean it's a family forum.
My ankle agrees.
05-19-2013, 11:58 AM   #6
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I'd say it is a slow (lazy) aperture mechanism on the lens. The lens is not fully stopped down at the time the shutter starts its travel, but continues to stop down as the slit moves across the frame. The result is that the photo looks like you are using a gradient filter. In motor drive mode the opposite can also happen where the aperture does not fully open between exposures.

A lazy aperture is not unusual in an older lens and is usually caused by migration of lubricant onto the aperture blades. The fix involves at least partial disassembly to service the mechanism.


Steve
05-19-2013, 12:07 PM   #7
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What happens when you shoot at that speed with the lens aperture wide open?
05-19-2013, 01:15 PM   #8
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You have a defective camera it seems. Unless somehow all your lenses suddenly have broken apertures.

05-19-2013, 01:22 PM   #9
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QuoteOriginally posted by Giklab Quote
You have a defective camera it seems. Unless somehow all your lenses suddenly have broken apertures.
It seems that way to me too...
05-19-2013, 01:30 PM   #10
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QuoteOriginally posted by Giklab Quote
You have a defective camera it seems. Unless somehow all your lenses suddenly have broken apertures.
Excellent observation. We will have to see what happens when the OP tries it with a lens that is less than 30 years old or with the aperture wide open. Lazy aperture is not uncommon, but it does seem unlikely that tests with three different lenses would show the same problem. That being said, I recently took possession of a lot of four lenses, two of which had slow apertures.

If not the lens, then shutter capping would be the diagnosis, though I can't say that I have ever heard of shutter capping with modern shutter. Typically they either work or don't work.


Steve

Last edited by stevebrot; 05-19-2013 at 01:35 PM.
05-19-2013, 01:55 PM   #11
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Seen threads on this at least twice before.

I've had it, at least one other person besides the OP has had it, on cameras from at least the K-x forwards.

Can you show the EXIF at all? I can almost guarantee you were in aperture priority mode.

As best as I can guess, the camera was trying to fire faster than the specs allow it to, and it was catching the shutter.

If you shoot in shutter priority it should (should) not happen.

Also, check your batteries. When I had this crop up before my solution was to get rid of the low-quality AA's I had in the camera in lieu of something else. If its the battery that came with the camera (not AA's) make sure it isn't about depleted. One or both of those solutions worked for me, so its what I can suggest for you to avoid it happening again, or at least minimize it.

Other threads on the subject:
https://www.pentaxforums.com/forums/general-technical-troubleshooting/224480-...ure-bands.html
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/217274-vintage...ds-normal.html
05-19-2013, 02:30 PM   #12
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QuoteOriginally posted by Sagitta Quote
As best as I can guess, the camera was trying to fire faster than the specs allow it to, and it was catching the shutter.
Please explain? I read the two threads you suggested and am still puzzled. The reason being:
  • The shutter curtains should travel at exactly the same speed regardless of the set speed. The only thing that changes is the amount of time between the release of the leading and following curtains. The type of symptom in the OPs photo might happen when the following curtain travels faster than the leading curtain. As noted in the comment above, that would be evidence of a defective shutter and would be present regardless of lens mounted.
  • The lens mounted does not affect the way the shutter behaves, except, perhaps for a totally bound actuator lever and I am not even sure about that case. The two systems are totally independent at exposure time. This is particularly true for non-A contact vintage glass where the body does not even set the aperture. (Actuation is a simple case of open/close.)
  • The spec for the K30 is 1/6000s. This is the case regardless of meter coupling (assuming that the spec your are referring to) ranges. The shutter should fire reliably at this setting regardless of camera mode. Are you saying that Av mode is broken and that actual attempted shutter speed is higher than 1/6000s? Why then the symptom at 1/5000s?
The comment regarding batteries is intriguing, though I don't know enough about the shutter mechanism to comment further.


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05-19-2013, 03:34 PM   #13
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QuoteOriginally posted by stevebrot Quote
Please explain? I read the two threads you suggested and am still puzzled. The reason being:
  • The shutter curtains should travel at exactly the same speed regardless of the set speed. The only thing that changes is the amount of time between the release of the leading and following curtains. The type of symptom in the OPs photo might happen when the following curtain travels faster than the leading curtain. As noted in the comment above, that would be evidence of a defective shutter and would be present regardless of lens mounted.
  • The lens mounted does not affect the way the shutter behaves, except, perhaps for a totally bound actuator lever and I am not even sure about that case. The two systems are totally independent at exposure time. This is particularly true for non-A contact vintage glass where the body does not even set the aperture. (Actuation is a simple case of open/close.)
  • The spec for the K30 is 1/6000s. This is the case regardless of meter coupling (assuming that the spec your are referring to) ranges. The shutter should fire reliably at this setting regardless of camera mode. Are you saying that Av mode is broken and that actual attempted shutter speed is higher than 1/6000s? Why then the symptom at 1/5000s?
The comment regarding batteries is intriguing, though I don't know enough about the shutter mechanism to comment further.


Steve
Interesting thought. Certainly this would only be detectable at very fast shutter speeds (a photography misnomer?) where the trailing shutter curtain actually has a chance to catch up to the leading shutter curtain. It's not that that problem doesn't exist at slower speeds but it wouldn't be perceptible.
05-19-2013, 04:35 PM   #14
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QuoteOriginally posted by IchabodCrane Quote
where the trailing shutter curtain actually has a chance to catch up to the leading shutter curtain.
You are correct in your comment. This problem is actually pretty common with vintage film cameras, particularly those with horizontal-run fabric curtains. My Spotmatic II's shutter is currently out of adjustment and shows a similar symptom, but at the left side of the frame. I don't know that I have seen or heard of this with a modern electronic shutter and would be particularly surprised to see it with a new camera. That is why I thought it would be good to rule out the lens before blaming the camera.

If the problem still exists with the lens wide open or with the newer DA kit lens, it may be time to call Pentax for warranty repair. I am also wondering about Sagitta's comment regarding batteries. Low or inconsistent voltage under load may be a factor. I guess it depends on what moves the shutter curtains. On older cameras, it is spring tension. If the new shutters use some sort of linear motor, battery voltage may be part of the equation.


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05-20-2013, 05:21 AM   #15
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I guess the ultimate test would be 1/6000 with no lens mounted. A few variables less.
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