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K10D focus issue


david_kelly13

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Earlier this year Carl Weese reported in The Online Photographer that the K10D

had a problem focusing the DA21mm f3.2 on narrow vertical objects. He had

Pentax send him a second lens to make sure it wasn't just a QC matter, and his

tentative conclusion was that the AF sensor was much broader than indicated in

the viewfinder, and therefore might sometimes favor a contrasty background

object. He wrote that the problem didn't occur with the 40 or 70mm DA's, just

the 21.

 

I"m about to buy a K10D and would like to make the DA21 my first lens for it.

Has Pentax addressed the problem Weese identified (and several other users

confirmed)? I can't fall back on manual focusing because my left hand is

impaired -David Kelly

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Only a few moments ago I got a return auth# from B&H for the exchange of my new DA21

for another. It just isn't sharp. I know about the AF problems. I've tried MF'ing the lens

but I just can't focus like I used to plus often what you are focusing on is very small

anyway.

 

I di some tests at 3.2-8 and it was soft (well not biting sharp) until F8. At that point

maybe DOF covered the fault. I need this lens to be as good as possible wide open. I know

it is no ultra super sharp WO lens but it really has to be better than mine sems to be.

 

BTW a Nikon D2 series camera can and will also be fooled by something high in contrast

right near where you want to focus.

 

I may be expecting mroe than the lens can deliver. I am comparing it to the 43,50 and 77.

It isn't close to any of those.

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I never let the camera choose a focus point. I have the camera always set to let me put it where I want it. The camera does have 9 cross type focus sensors afterall so the center one isn't the only "good" one like many other cameras. But center sensor or not ISO 100, 5 ft away from a near frame filling texture filled piece of wood in good light and a shutter speed over 1/1000 and the image isn't sharp?

 

I did the same test with a $100 28mm A-SMC MF lens and it is far better than this 21 I have. I hope the exchange lens is better. I need this length and I don't want a zoom to get it.

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Neil, you have hijacked this thread to discuss quite another issue, but as long as you have: if there is a QC problem with the lens you'll find out right away and please let us know. This lens is not the only reason I want a K10D but it is a big one. I'm experiencing Nikon withdrawal symptoms as i realize i can't simply go to KEH.com and grab an EX grade 20mm f2.8 for 300 bucks anymore.
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David sorry you feel I took the point of your thread away. I just wanted to add that while I

had read of Carls focus problems and also of others that I had what mught just be a bum

lens. I though my post might prove timely.

 

i did the tests I did to rule out the focus sensor just plain missing my target. Now I hope

the lens was just a bad copy. I really like the view and the size.

 

I also have a Nikon system. I have seen and now know when teh af sensor will be fooled

and miss focus and I'd say that yes the Pentax could do the same thing.

 

I will report back on wether or nor 21 #2 is the same or better than the one I have.

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I agree (money), I did pay 'full wack' for my 20mm FA f2.8 a little over a year ago. I have to tell you, it was worth it. I just (8 months ago) got a 35 FA f2.0 for my K10d, and it is the only lens that has ever been on it, again no problems. I use, like someone said here or maybe someplace else, the single spot meter AF mode.
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