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02-14-2008, 08:56 AM   #16
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The shake reduction function, at least on my K10D, remains activated even with a teleconverter attached, but, as others have noted, the focal length does not reflect the added teleconverter. My 100mm lens with a 1.5x teleconverter would have a focal length of 150mm, for example, yet the camera continues to read 100mm. So, I guess a good question at this point would be how much a teleconverter actually impacts the SR function?

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02-14-2008, 09:26 AM   #17
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The greater the TC multiplier the greater the SR deviation. Perhaps I should test it with TC or A lens with false focal length input.
02-14-2008, 10:43 AM   #18
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QuoteOriginally posted by Matjazz Quote
The greater the TC multiplier the greater the SR deviation. Perhaps I should test it with TC or A lens with false focal length input.
I have thought about this but unless you can have the camera on a constant vibration source, I think the results would be unreliable or inconsistent.
02-14-2008, 12:49 PM   #19
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QuoteOriginally posted by Lowell Goudge Quote
I have thought about this but unless you can have the camera on a constant vibration source, I think the results would be unreliable or inconsistent.
Enough samples and you could extrapolate believable data via statistical analysis but yes a repeatable vibrational sequence (not necessarily constant) would provide unambiguous conclusions.

02-14-2008, 04:06 PM   #20
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Hi distudio

QuoteQuote:
Enough samples and you could extrapolate believable data via statistical analysis but yes a repeatable vibrational sequence (not necessarily constant) would provide unambiguous conclusions.
Erm, could you speak in plain language from now on, 'cos my head is starting to spin slightly and I'm beginning to feel rather dizzy......

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Richard
02-15-2008, 04:53 PM   #21
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QuoteOriginally posted by Confused Quote
Hi distudio



Erm, could you speak in plain language from now on, 'cos my head is starting to spin slightly and I'm beginning to feel rather dizzy......

Best regards
Richard
Your head hurts because we have been shaking it too much with our test theories.

What we are discussing is the following.

Is there any way to realistically test the effectiveness of shake reduction, as a function of the error in focal length setting that results on KAF lenses when you use a teleconverter, due to the failure of the camera to compensate for the change in focal length.

the problem I raised is that unless you had a machine introduce the vibration, it would not be consistent enough frame to frame, in order to get repeatible results. Distudio is suggesting that if you do enough tests at each focal length error, you could draw a conclusion from the average value of the measured error.

Maybe this is possible but we would then need to determine how to measure the error?
02-15-2008, 05:12 PM   #22
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Hi Lowell

So if I've understood this discussion correctly, although the actual SR mechanism in the body of the K10D continues to function (despite the insertion of the TC), because the electronic information between the KAF lens & the DSLR body has been 'broken' (disconnected) by the TC, the SR mechanism is unable to compensate correctly because it has no idea what the focal length is of the lens being used, particularly in the case of a variable super-zoom-lens for example ?

Best regards
Richard

Last edited by Confused; 02-15-2008 at 05:23 PM.
02-15-2008, 05:22 PM   #23
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QuoteOriginally posted by Confused Quote
Hi Lowell

So if I've understood this discussion correctly, although the actual SR mechanism in the body of the K10D continues to function (despite the insertion of the TC), because the electronic information between the KAF lens & body has been broken by the TC,
the SR mechanism is unable to compensate correctly because it has no idea what the focal length is of the lens being used, particularly in the case of a variable super-zoom-lens for example ?

Best regards
Richard
close but not quite. if the data link was broken, then the camera would prompt you for a value, just like what happens on a K mount lens, Unfortunately the TC just passes the lens data streight through, so you are locked into the data the lens sends, with no option for change. It is not that the camera does not know the focal length, it does!, it just does not know about the glass you inserted in between the camera and the lens.

02-15-2008, 10:24 PM   #24
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QuoteOriginally posted by stewart_photo Quote
(snip)... So, I guess a good question at this point would be how much a teleconverter actually impacts the SR function?

In an effort to at least partially answer my own question, I tried SR with a couple of AF lenses (the longest 250mm) and a 1.5x teleconverter. It does appear SR continues to perform somewhat beyond the point I expected to see poor results from camera shake. Of course, quick tests like this obviously don't say much since they don't establish how effective SR is at any given point or how many stops before SR might fail, but it's a start.

So, at this point, I would trust SR up to a stop, or perhaps two depending on the amount of shake, beyond the point where I normally expect to see camera shake in the final image. Anyone else getting better or worse results with a teleconverter added?

stewart
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