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Pentax DSLR Discussion Talk about Pentax Digital SLR technique here, including the *ist D series, the K100D series, and the K10D, K20D, and K200D models.

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Old 10-13-2007, 10:43 PM   #1
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K10D and Green Button Manual Lens Shutter Speed

Hi All, I use a K10D V1.3 software with a number of Manual Lenses, 24, 40, 50 135, 28-85 plus A or FA lenses using the aperture ring instead of A. For all of them in the Manual Setting at ISO 100 I am restricted to a slowest speed of 3 seconds using the Green Button. Metering is OK until the shutter speed reaches 3 seconds and then any further reduction in aperture or light, has no effect on Green Button measured shutter speed.

Have done some tests and the maximum shutter speed follows EV, ie ISO 100 = 3s, ISO 200 1.6s, ISO 400 .8s, ISO 800 .4s and ISO 1600 1/5s. I have tried different Custom Settings etc but no change. Can't be sure but I think the situation didn't arise until I loaded V1.3 software.

I can adjust shutter speed using the e dial so can still use the manual lens. But why the Green Button shutter speed limit tied to ISO is my question?

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David
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Old 10-14-2007, 01:04 AM   #2
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I think that you're hitting the bottom of K10D metering range.

Try to enable Auto EV compensation in Custom menu (it's off by default).
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Old 10-14-2007, 01:06 AM   #3
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My guess would be that it has something to do with the lower limits of the light meter's sensitivity. That is, it just can't measure light at a level that requires more than 3 seconds of shutter time.
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Old 10-14-2007, 07:20 AM   #4
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I'm not sure of the absolute limits at each ISO setting, but I have run into this a couple of times doing exposure tests.

As others have stated, it seems to come from the limit of metering
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Old 10-15-2007, 01:41 AM   #5
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Oops, you are all quite correct. A quick check with my FA 28-105 f3.2 confirms that when 3 seconds is displayed for shutter speed the A setting is in excess of 30 seconds. Thanks for the prompt advice, I thought I had a camera problem for a while. To compensate the ego I have just ordered a FA 43mm limited.

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