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03-22-2009, 08:59 AM   #1
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Is it the lens or the brand?

I bought my K200D with the Pentax 18-55 II kit lens. I wanted some more zoom capabilities but a versatile lens, so I just bought the Tamron 18-200 . Today was my first day using it and it did not focus nearly as well as my pentax DA. I tried both auto focus and manual focus and then I put my pentax lens back on and I could focus...it was a fairly macro shot. The Tamrom focuses fine for distance. So I'm wondering, should I expect poorer focus with the Tamron because it has a greater zoom or is it because it's the brand?

Also, Since changing my lenses I have a black dot in my viewfinder. It's not showing up on my images so I'm not sure where the dirt is. I tried wiping my viewfinder and using the camera's dust removal function.

TIA!

03-22-2009, 09:10 AM   #2
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I don't use auto focus lenses, so I cannot really answer your questions about the tamron. as for the black spec on the in the viewfinder, it is dust dirt or debris that got inside the body when changing lenses and has stuck to the viewing screen. this wont impact your photos because it is not on the sensor, it will just bug you when you look through the viewfinder. I would suggest getting a blower to try and dislodge it from the screen. however do not under any circumstance touch the screen as you will likely do more damage by touch than whatever is stuck to it oculd possibly do. were you changing lenses in a windy or dusty enviornment?
03-22-2009, 09:11 AM   #3
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Black dot could be dust on your rear or front element. As for lense quality, i just see what images guys produce and follow those for selection. The Tamaron got some good reviews and with a K200 in one of the earlier threads, my personal preference so far are Pentax only lenses.
03-22-2009, 09:14 AM   #4
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QuoteOriginally posted by Clicker Quote
Black dot could be dust on your rear or front element.

also a possibility. is the dot still visible in the viewfinder with no lens attached? im thinking its on the viewing screen, not the lens.

03-22-2009, 09:16 AM   #5
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The dot is still on the viewing screen without the lens...I was in my house when I changed the lens.

I should also add, that even when I tried to do some manual focusing, the fine focus ring was at its maximum and my image was still not in focus.
03-22-2009, 09:21 AM   #6
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QuoteOriginally posted by LoveofJoe11 Quote
The dot is still on the viewing screen without the lens...I was in my house when I changed the lens.

I should also add, that even when I tried to do some manual focusing, the fine focus ring was at its maximum and my image was still not in focus.
then its on the viewing screen. you mention some 'macro'. were you closer to the subject than the lens can focus? ie: beyond the minimum focusing distance. if you weren't, then it could possibly be a problem with the lens. is this a used lens?
03-22-2009, 09:24 AM   #7
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I probably was closer than the minimum focus area...just looked it up, yes I was quite closer than the minimum focus area...good to know, thank you!
03-22-2009, 09:27 AM   #8
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QuoteOriginally posted by LoveofJoe11 Quote
The dot is still on the viewing screen without the lens...
Use an air blower (like the popular rocket blower) on the focusing screen (above the mirror). But don't worry about dust on the focusing screen, since it doesn't affect your photos and will drive you crazy if you do start caring.

03-22-2009, 09:43 AM   #9
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QuoteOriginally posted by asdf Quote
Use an air blower (like the popular rocket blower) on the focusing screen (above the mirror). But don't worry about dust on the focusing screen, since it doesn't affect your photos and will drive you crazy if you do start caring.
I have several 'spots' on the screen of my MX. I also just ignore them. though I could likely get rid of them or even just change the screen.. never bothered with it.

QuoteQuote:
I probably was closer than the minimum focus area...just looked it up, yes I was quite closer than the minimum focus area...good to know, thank you!
glad to see that was the problem and the lens is fine. the 'macro' feature on most of these zoom lenses can only be described as 'close up' and not true macro in any way, so the closest it can focus is still much farther away than any macro and most prime lenses. usually the 'macro' is on a 1:4 scale where as true macro is 1:1 or larger than life size and can have a minimum focus distance as close as a few centimeters.

also AF speed will be somewhat slower on a zoom lens with a longer end focal length because of the distance of travel between wide and long. just something to keep in mind.
03-22-2009, 07:06 PM   #10
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QuoteOriginally posted by séamuis Quote
the 'macro' feature on most of these zoom lenses can only be described as 'close up' and not true macro in any way, so the closest it can focus is still much farther away than any macro and most prime lenses. usually the 'macro' is on a 1:4 scale where as true macro is 1:1 or larger than life size and can have a minimum focus distance as close as a few centimeters.
Agree, sounds like this is just a case of trying to focus on something too close.

QuoteOriginally posted by séamuis Quote
also AF speed will be somewhat slower on a zoom lens with a longer end focal length because of the distance of travel between wide and long. just something to keep in mind.
I wouldn't generalize about AF speed vs. focal length. The lens designers decide on how long the focus path will be--how far the focus ring will have to turn to go from infinity to minimum focus. On a macro lens they'll usually allow long focus paths to improve manual focus characteristics. A darker (slower, with smaller minium aperture) may hurt AF speed as well, as might a lens with larger, heavier elements to move.
03-23-2009, 10:15 AM   #11
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QuoteOriginally posted by séamuis Quote

glad to see that was the problem and the lens is fine. the 'macro' feature on most of these zoom lenses can only be described as 'close up' and not true macro in any way, so the closest it can focus is still much farther away than any macro and most prime lenses. usually the 'macro' is on a 1:4 scale where as true macro is 1:1 or larger than life size and can have a minimum focus distance as close as a few centimeters.
Actually, though, I was surprised and pleased to see how close the kit lens can actually get, having been very used to writing off what they call 'Macro' on a zoom lens, very useful. (I'm by no means a serious macro shooter, mind you, but considering I got the kit lens for free, this is at least some real nice utility I don't have to buy. )

(cutting out some stuff as I realize the poster's concerns are entirely about the 'macro' distance. )
03-23-2009, 10:31 PM   #12
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I'm one who will always stick up for the 18-55 kit lens. I love mine and it has excellent IQ throughout the range. I'm not really sure what you mean by poorer focus. Is it just a little slower or do your shots look out of focus? I don't have the Tamron but I do have a Sigma telephoto zoom and it does tend to focus slower and hunt more but the IQ is good as long as I stay in the sweet spot. If the photos look a little blurred then it may be due to motion with the longer and heavier lens. Shake reduction is great but it has limits and you need a pretty fast shutter with a long lens.
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