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12-18-2009, 08:01 AM   #1
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K10D + DA*300mm with Tamron 1.4x TC hunts

I have tested my new DA*300 with Tamron 1.4x Pz-AF MC4 TC and irritatingly it tends to hunt every time i try to lock AF on the subject.

Without TC the lens works great.

December is a bit dark month here in Finland as the sun rises only little above the horizon so i haven't been able to test this combination in bright sunlight.

Could it be K10D's or TC's fault? Or could the reason be just that there isn't enough light?

12-18-2009, 08:42 AM   #2
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I use my DA*300 with 1.4 and yes, it hunts sometimes a bit, but nothing much.
But you are right, the less available light turns this combo into the "hunting mode".

I also use the lens with a 2x (going manual) and IQ is OK.

For 2x images with combo, check here
https://www.pentaxforums.com/forums/everything-else/53926-adapter-2x-auto-foc...tml#post848464
12-18-2009, 09:00 AM   #3
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Hello, I also use the DA*300mm and Tammy 1.4 TC almost daily. I find that if I manually give the focus a quick turn so it is closer to the focus point then I generally do not get the hunting. Its faster once you get in the habit of one quick turn left or right to get it closer. Seems to do the trick for me. I don't manually focus it, just get it a half turn in the right direction to start. Not a perfect solution but a definite improvement in my results. Does not seem to dependent on amount of ambient light.

Good luck.
12-18-2009, 09:50 AM   #4
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Joni, osittain ehkä K10D:n heikohkon autofocuksen syytä, mutta oikeesti tähän vuoden aikaan taitaa olla aika turhaa yrittää tuon TC:n kanssa. Ei vaan oo valoa tarpeeksi.

12-18-2009, 09:53 AM   #5
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QuoteOriginally posted by Nitrok Quote
I have tested my new DA*300 with Tamron 1.4x Pz-AF MC4 TC and irritatingly it tends to hunt every time i try to lock AF on the subject.

Without TC the lens works great.

December is a bit dark month here in Finland as the sun rises only little above the horizon so i haven't been able to test this combination in bright sunlight.

Could it be K10D's or TC's fault? Or could the reason be just that there isn't enough light?
I have used the K10D with a sigma 70-200 F2.8 and 2x TC regularly, (same ultimate aperture at F5.6) and it will also hunt in low light a little, I have also stacked a 2x and 1,.4x behind it, and then it really hunts even in bright light.

The bottom line is that all AF will hunt as the light goes down, or as lenses get slower and generally AF won't work with effective maximum apertures beyond F6.7
12-18-2009, 09:53 AM   #6
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Thanks for quick replies!
Maybe I have to wait for spring then.

QuoteOriginally posted by brkl Quote
Joni, osittain ehkä K10D:n heikohkon autofocuksen syytä, mutta oikeesti tähän vuoden aikaan taitaa olla aika turhaa yrittää tuon TC:n kanssa. Ei vaan oo valoa tarpeeksi.
Näinhän se taitaa olla.
Maanantaina alkaa kuitenkin onneksi päivätkin pitenemään.
12-18-2009, 10:36 AM   #7
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QuoteOriginally posted by Nitrok Quote
Thanks for quick replies!
Maybe I have to wait for spring then.


....
Go manual
12-18-2009, 12:18 PM   #8
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QuoteOriginally posted by netuser Quote
Go manual
Yeah, that's other option

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