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03-23-2014, 11:36 AM   #16
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QuoteOriginally posted by awaldram Quote
Any lens should be calbrated at between 25 and 50 times its focal length anything else will lead to surprising and disapointing results.
Interesting.

I've been trying moiré based AF micro adjustments, so 50xF, and liveview, max zoom to confirm etc.

What's the terminology, for the zooms being in micro-AF-alignment; at their shortest and longest focal length?

Example: 60-250
Also, does most zooms exhibit the same characteristics? I set a global adjustment of (-3).
Then this (-3) works the best at [60mm] and [250mm]?

It moves the opposite direction up, to about: half the focal length, and back again. [60mm] (-3) then [125mm] (+3)
and back towards (-3). [150mm] (-2) [190] (0) etc to (-3) at [260].

So, with firmware hacking, maybe we’d write calibration files to the memory card?
Then you could read calibration, and apply them to specific focus lengths, and even more.
Calibration + focal length +WB, as different lightning “probably" yield different results.

Sorry OP, for the hijack. I'm just making sure I understand the theory.

03-23-2014, 03:00 PM   #17
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So I have been out all day shooting on all distances and the TC with K-3 and DA*300 is not good. Soft images all over the scale. The manual says that 2 stops may be needed sometimes which means I have to stop down to f/11 and that is to dark for my taste. Shifted to my Kenko and the results was good. I will send it back and have a beer to drown my dissapointment.
04-02-2014, 02:22 AM - 1 Like   #18
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I got a replacement TC from Pentax and I feel it performs much better than the first one.

These pics are with DA*300 + Pentax TC and the second I have added my Kenko as well.



04-02-2014, 10:22 PM - 1 Like   #19
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Much better!
I have just ordered the Pentax converter. It's nice to have an idea of the difference between a good one and a bad one.

04-03-2014, 02:52 AM   #20
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QuoteOriginally posted by awaldram Quote
Given your examples it apears your camera is only just inside the DoF with the da*300+HD converter

As this is visible at close focus it will deteriate further for distance.

Have you by chance calibrated you lens at close distances as this will almost certainly be wrong if you were closer then 50M.?

For 300mm ideally more than 75M

and for 300mm+converter 105M
I just realised that your numbers are ten times larger than they are suppose to be. The 300 should be calibrated at 7.5 to 15 meters and with the converter 10.5 to 21 meters . Not 75 and 105.
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