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05-08-2009, 01:49 PM   #1
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New 60-250 able to use K-7 contrast AF?

Mr. Mabo mentioned in an earlier post I saw about the need to make changes to any lenses that will use the new real time contrast detect AF sytem and only SDM line will be adaptable. Anyone care to speculate if the 60-250 which was just released was already designed to use the new contrast detect AF system? Maybe this was already answered - I could not find it.

- Tom

05-08-2009, 02:22 PM   #2
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QuoteOriginally posted by Photomy Quote
Mr. Mabo mentioned in an earlier post I saw about the need to make changes to any lenses that will use the new real time contrast detect AF sytem and only SDM line will be adaptable. Anyone care to speculate if the 60-250 which was just released was already designed to use the new contrast detect AF system? Maybe this was already answered - I could not find it.

- Tom
The marketing of this lens took longer than we expected just to insure that it would be compatible, I think.
05-08-2009, 04:14 PM   #3
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I hope so. With the 60-250 I can get by with just 3 lenses for 90% of my shots. I like the concept of the K-7 from what I hear about is so far from unofficial information. Not sure how much I would use video, but you never know what opportunities it may bring. I hope Pentax comes in with a winner so I can afford to keep my RZii kit and still do some film.
05-09-2009, 01:21 AM   #4
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For optimum performance of the contrast detect AF, lenses needs prepared prepared focus motors (do note that Olympus has issued upgrades for their existing lenses to give better functionality with contrast detect AF) or they will focus slower than what is actually possible with the system. The 60-250 has been delayed so long and when it comes now I would be surprised if it wasn't designed with "the new K" in mind since 60-250 would propably be a popular choice among the target users for "the new K".

05-09-2009, 04:08 AM   #5
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QuoteOriginally posted by RMabo Quote
For optimum performance of the contrast detect AF, lenses needs prepared prepared focus motors (do note that Olympus has issued upgrades for their existing lenses to give better functionality with contrast detect AF) or they will focus slower than what is actually possible with the system. The 60-250 has been delayed so long and when it comes now I would be surprised if it wasn't designed with "the new K" in mind since 60-250 would propably be a popular choice among the target users for "the new K".
Do you think older SDM lenses can be upgraded so than people that have just bought DA* lenses can benefit from these advances?
05-09-2009, 04:42 AM   #6
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I think Olympus lenses needed update because they actually have a firmware [i.e. some software on it]: i don't see why a normal electric motor shouldn't be precise and fast enough.
05-09-2009, 06:30 PM   #7
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QuoteOriginally posted by lol101 Quote
Do you think older SDM lenses can be upgraded so than people that have just bought DA* lenses can benefit from these advances?
so far all Pentax SDM are micromotors (essentially screw drive with the motor located in lens' body instead of camera's body), not ring type motors, so they are too slow to ensure a fast CDAF.
05-10-2009, 01:53 AM   #8
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QuoteOriginally posted by deejjjaaaa Quote
so far all Pentax SDM are micromotors (essentially screw drive with the motor located in lens' body instead of camera's body), not ring type motors, so they are too slow to ensure a fast CDAF.
That would also include the 60-250 in that case.

AFAIK, this lens features the same AF mechanism that previous ones.

Plus, if SDM is inherently too slow for fast CDAF, what can possibly do Pentax to claim that they needed to upgrade lenses? They certainly did not upgrade them to ring USM did they?

05-10-2009, 02:24 AM   #9
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QuoteOriginally posted by deejjjaaaa Quote
so far all Pentax SDM are micromotors (essentially screw drive with the motor located in lens' body instead of camera's body), not ring type motors, so they are too slow to ensure a fast CDAF.
Another pure speculation? There is no reason why micromotors cannot be made to be as fast as ring type.
05-10-2009, 05:45 AM   #10
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QuoteOriginally posted by deejjjaaaa Quote
so far all Pentax SDM are micromotors (essentially screw drive with the motor located in lens' body instead of camera's body), not ring type motors, so they are too slow to ensure a fast CDAF.
I still think the chokepoint is still in the AF algorithms in place than the hardware itself. Non-ring type Canon lenses are still able performers in AF speed. Not world-beating speed, but still capable.
05-10-2009, 07:54 AM   #11
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QuoteOriginally posted by nosnoop Quote
Another pure speculation? There is no reason why micromotors cannot be made to be as fast as ring type.
the only speculation here is underlined above
05-10-2009, 08:02 AM   #12
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QuoteOriginally posted by vinzer Quote
I still think the chokepoint is still in the AF algorithms in place than the hardware itself. Non-ring type Canon lenses are still able performers in AF speed. Not world-beating speed, but still capable.
yes, performers - with PDAF - where you can predict where to move and calculate how much you will need to move the focusing group of optical elements with one measurement... one measurement - one movement (some systems are doing double check though)... now enters CDAF where this is not possible (you need several iterations) and put on top of that AF-C... as for performers, sure - we even have screw driven lenses that can focus fast... with PDAF
05-11-2009, 10:27 AM   #13
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FWIW: the lens was tested on a Pentax MZ-5n and it appears to be fullframe. See here for the results: Pentax 60-250 SDM Samples: Pentax SLR Talk Forum: Digital Photography Review
06-09-2009, 08:04 AM   #14
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Won´t screw driven on body motor support contrast AF??
Why...??
06-09-2009, 08:27 AM   #15
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it will.
I consider it just a myth that the 60-250 was delayed for some special reason, codiac2600 also mentioned this that "they had plans for it" but I see no special reason why the 60-250 should be delayed it doesnt have any special feature that the other DA* has
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