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03-18-2010, 10:53 PM   #1
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Blog on AF performance of K7

Alunfoto: A practical look at K-7 autofocus

03-18-2010, 11:16 PM   #2
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That's probably the most unbiased article on Pentax autofocus I've ever read. Very insightful.
03-18-2010, 11:43 PM   #3
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QuoteOriginally posted by GoremanX Quote
That's probably the most unbiased article on Pentax autofocus I've ever read. Very insightful.
Agreed fully. Most insightful: all K-7 users should read this blog.
03-19-2010, 12:33 AM   #4
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Interesting but I think there are a few unfortunate omissions:

1) they never say what autofocus type they are using
2) they never say what the canon/nikon bodies they compare to the other people using are (they acknowledge this)

03-19-2010, 01:02 AM   #5
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Jostein Is a swell guy, and you should do yourself a favor and read up on the whole Antarctica trip. Plus some of the older stuff is great too. And see his work in PPG, he has a massive collection of stunning captures.



QuoteOriginally posted by CWyatt Quote
Interesting but I think there are a few unfortunate omissions:

1) they never say what autofocus type they are using
2) they never say what the canon/nikon bodies they compare to the other people using are (they acknowledge this)
On an antarctica trip, I would tend to believe that people bring upper scale DSLR gear. Though some could be older models.

I do think that Jostein sometimes used full AF set-up, and not only center AF. But I'll ask him. He writes more here :
Alunfoto: Southern Fulmar


Here is more on the Better Beamer :
Alunfoto: Days at sea

Jostein also brought the FA* 600mm f/4, which he had bought directly out of Japan.

Here are of some of the Canonites :
http://2.bp.blogspot.com/_VWBjZjc1fI4/SxKXorSHsBI/AAAAAAAAAqA/X1TDBU3zxUM/s1...G0131-Edit.jpg
There were Eos 7D users and others


On his blog there was also a link to the Pentaxian Lenadro Herraiz :
Ushuaia

http://www.pentaxphotogallery.com/home#section=ARTIST&subSection=1471155&sub...=0&language=EN

Last edited by Jonson PL; 03-19-2010 at 04:00 AM.
03-19-2010, 01:34 AM   #6
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First time I'd seen his blog, and was impressed by the images.
Definitely one for the bookmark.
03-19-2010, 04:44 AM   #7
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Wow guys,

Thanks for posting the link to my blog, FunkyMonk. And thanks everyone for commenting. Great to know that some find my ramblings worth reading.

@ CWyatt:
"they" is just me, I'm afraid. Noone to hide behind. The reason I use AlunFoto as sort of a pseudonym is that I live close by a lake called Alunsjøen.

As to your question about autofocus type, I can elucidate:
For birds in flight, continuous mode is the only alternative, really. In particular if you want to rattle off exposure series in hope of catching particularly significant moments.

Further, I found that using the centre sensor gives the best AF result. Even if you have to crop afterwards to get a good composition. The lateral sensors are not of crosshair type, and so tend to miss if the contrast lines in the motif aligns with the sensor. My experience from the Antarctica trip is that using all sensors slows the AF down. I tried all variants over the course of the trip, both matrix, select and single.

Incidentally, this was in line with the recommendation from the pros on board too. Canon ambassador and photographer Ole Jørgen Liodden (Velkommen til Naturfokus), held courses on board and insisted that for all Canon models, the centre sensor was always the best for tracking-AF. He just made a small reservation with regards to the new 7D, which can couple 5 sensors into a sort of giant crosshair (centre sensor + 4 adjacent), apparently without any AF speed penalty. But the centre sensor is still involved.

Hope this answers your questions.

@ Jonson PL:
I bought my 600/4 second hand from a guy in Paris, Texas. In fact, it's the very lens featured on this website: The 600mm f4 Comparison Page for Pentax AF (you may have to click past a full-screen ad to get there). The price for a brand new one from Japan was a bit too steep...
It's a nice lens, btw. The only reason to sell it would be to provide funds towards a 645D...

But first I'll have to improve my finances after the trip to Antarctica. That one certainly didn't come free! But I'd do it again if I could. Worth every penny and more.

Thanks,
Jostein
03-19-2010, 04:58 AM   #8
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QuoteQuote:
I also find the latter attitude to be very counterproductive in terms of what kind of images one attempts, and succeeds, making.
I don't think complaining is entirely unproductive. There is a vein in market focus for Pentax that largely caters to flower shooters, landscape, and even macro to some degree; with exception of the later, lightning fast AF and FPS are largely irrelevant. Who knows if this is why Pentax does not put much emphasis on sports shooting or if they are simply technologically deficient from an engineering standpoint. It is important for Pentax to know though that there are sports shooters out there with an eye on the K-7 (and next-generation) and an eye on the Canikon. Right now, the mouse cursor is hanging over the Canikon for sports shooting.

03-19-2010, 05:41 AM   #9
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I messed with 7D and D300s at local Best Buy stores, it seems K-7 definitely has a little better AF than the competitions
03-19-2010, 05:54 AM   #10
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Interesting read, great to hear that the K-7 has made large advances over the K20D for autofocus performance. I'm definitely keeping my Pentax mount Sigma 100-300 f/4 EX DG for when the next generation pentax bodies have the autofocus systems on par with a D300s / EOS 7D.

QuoteOriginally posted by alunfoto Quote
He just made a small reservation with regards to the new 7D, which can couple 5 sensors into a sort of giant crosshair (centre sensor + 4 adjacent), apparently without any AF speed penalty. But the centre sensor is still involved.
That's correct, called AF point expansion and it's very useful indeed.
03-19-2010, 05:57 AM   #11
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QuoteOriginally posted by luke0622 Quote
I messed with 7D and D300s at local Best Buy stores, it seems K-7 definitely has a little better AF than the competitions
I would absolutely diagree with you on that.
03-19-2010, 06:07 AM   #12
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QuoteOriginally posted by user440 Quote
I don't think complaining is entirely unproductive.
I think you are twisting my argument. By complaining, you do something to your own expectations that will influence your photography also. That's counterproductive, but only in the sense of influencing what kind of images you are inclined to produce; not in the sense of influencing the functions of future Pentax products.

QuoteOriginally posted by user440 Quote
Right now, the mouse cursor is hanging over the Canikon for sports shooting.
That's not just "right now". Pentax was way behind Minolta, Canon and Nikon at introducing AF in the first place. Pentax played catch-up with sports (and all other action-) photography ever since. As a Pentax user, however, there is a lot of progress in the K-7 to enjoy.
03-19-2010, 06:55 AM   #13
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QuoteOriginally posted by alunfoto Quote
Further, I found that using the centre sensor gives the best AF result.
Thanks for your informative blog posting and this additional tidbit, which is something I've been curious about for a while. My K10D is usually "stuck" in SEL mode, and I usually select the centre focus point when using AF.C - and I was curious if this (which subjectively gave me the best results) really is the best solution.

About the sensor types: I don't think you're quite right about this. According to my K10D manual, all central 9 sensors are "wide cross area sensors" - only the two border sensors are not.

AFAIK, the only AF sensor difference in the K-7 compared to the K10D is the secondary light wavelength sensor which helps in tungsten light.
03-19-2010, 07:16 AM   #14
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QuoteOriginally posted by Big G Quote
I would absolutely diagree with you on that.
Well a D700 with a Nikkor 50/1.8G inside a shop (Fnac in Brussels) was so slow I couldn't beleive it

I'm certain, however, that tracking a bird would have been faster with the D700.
03-19-2010, 07:16 AM   #15
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Actually Pentax & Minolta were 1st to offer autofocus

Actually Pentax & Minolta were 1st to offer autofocus, if I recall correctly.

Canon was last to autofocus party.

Minolta abandoned MD mount to offer Alpha

Pentax added screwdrive AF to K Mount

Nikon added screwdrive AF to AiS Mount & has implemented numerous motor upgrades since

Canon abandoned FD mount to offer EOS. And within a decade Canon dominated autofocus most likely due to starting off with a new & larger diameter mount. Ring motors instead of micro motors in lenses.

Thats cool you and Ole shot together. I really enjoy his website and his hands on experiences with Canon 7D.

Made me want a 7D, except I don't want to buy anymore crop format, aps-c dslrs.


QuoteOriginally posted by alunfoto Quote
I think you are twisting my argument. By complaining, you do something to your own expectations that will influence your photography also. That's counterproductive, but only in the sense of influencing what kind of images you are inclined to produce; not in the sense of influencing the functions of future Pentax products.



That's not just "right now". Pentax was way behind Minolta, Canon and Nikon at introducing AF in the first place. Pentax played catch-up with sports (and all other action-) photography ever since. As a Pentax user, however, there is a lot of progress in the K-7 to enjoy.
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