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12-28-2008, 11:20 AM   #1
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K100D: What focal length to enter?

When using a manual lens on a K100D with stabilization turned on, the camera asks what focal length to use. The following describes an experiment to help answer that question. A laser pointer was shined on a wall & a series of photos were taken of the dot:

I observed a few things:
1) Overstating the focal length hurts.
2) Understating the focal length doesn't hurt much if at all.
3) For tripod shots, stabilization on/off or delay doesn't matter much.
4) Tripod shots are not too much different from hand-held stabilized.

The shots were all at about 1-1/2 stop below the 1/focal_length rule & my elbows rested on a table. Maybe later I'll try repeat the experiment with more stops under the rule.


Last edited by newarts; 12-28-2008 at 05:56 PM. Reason: new info & conclusions
12-28-2008, 11:28 AM   #2
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Thanks for doing this. It matches my observations when using my older zoom lens, which is that I seem to get my best image stabilization by inputting the shortest focal length of the range.
12-28-2008, 11:30 AM   #3
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thanx for the test, the only thing is that 2 sec mirror lock up automaticaly disables SR! try to repeat the test with 10 sec mirror lock up, please. Many here say in that case the SR hurts the shots, so let's see...
BR
12-28-2008, 11:36 AM   #4
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QuoteOriginally posted by newarts Quote
3) For tripod shots, stabilization on/off doesn't matter much.
From personal experience, that is false. I spent a whole night this past summer taking shots of a car meet we had, using my tripod. All were focused just right and even rechecked manually. All but 3-5 were blurry. Next day I realized my camera had SR enabled. Next day we drove back out to downtown chicago and took more shots, SR off. Shots came out perfectly...

12-28-2008, 11:44 AM   #5
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Good test newarts! I find sr good on a monopod- bad on tripod. I set my old zooms for shortest length too- my 80-200 I set to 77mm on k10d (80 onk20d) and 70-210 to 70mm 35-70mm to 35mm then later I know what lens I was using by the exif
12-28-2008, 01:09 PM   #6
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QuoteOriginally posted by dave sz Quote
From personal experience, that is false. ....
I don't doubt that your results are inconsistent with mine but I didn't falsify any data or conclusions based on that data. I resent your declaration that I'm lying and/or my data is false.

My manual says that for the K100D the timer function turns off stabilization & my results are consistent with that.

Were you using a different camera perhaps? I thought manually pressing the shutter button while using the tripod might make a difference but I don't see much effect.

Last edited by newarts; 12-28-2008 at 07:13 PM. Reason: new info & comments
12-28-2008, 01:13 PM   #7
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QuoteOriginally posted by axl Quote
thanx for the test, the only thing is that 2 sec mirror lock up automaticaly disables SR! try to repeat the test with 10 sec mirror lock up, please. Many here say in that case the SR hurts the shots, so let's see...
BR
I added the 10 sec timer to the test & it is now shown with the other results.

My K100D manual says the timer function shuts off stabilization; my results are consistent with that statement - 2 sec & 10 sec delays give similar results.

I added test tripod shots without timer delay (shake reduction on) & manually pressed the shutter button; I see little improvement over hand-held, shake reduction on, at focal_length/3 shutter speed.

Last edited by newarts; 12-28-2008 at 05:45 PM. Reason: new info
12-28-2008, 09:24 PM   #8
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QuoteOriginally posted by newarts Quote
I don't doubt that your results are inconsistent with mine but I didn't falsify any data or conclusions based on that data. I resent your declaration that I'm lying and/or my data is false.

My manual says that for the K100D the timer function turns off stabilization & my results are consistent with that.

Were you using a different camera perhaps? I thought manually pressing the shutter button while using the tripod might make a difference but I don't see much effect.
Used friend's shutter cable. I didn't mean to say that you were lying, guess I worded it wrong. My experience just doesn't agree with your findings, that's all...

12-28-2008, 11:33 PM   #9
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Newarts, thanks for posting your findings. I use all manual lenses and not all are represented in the focal ranges provided for selection. This will confirm which way I'll go in making my choice from now on.
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