A bit of a scare!

Started Dec 4, 2008 | Discussions thread
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Jim King
Jim King Veteran Member • Posts: 8,588
A bit of a scare!

I recently acquired a Tamron SP 17-50/2.8 from Prodigital2000 at a bargain price (used MS Cashback rebate), as I had read a number of reports claiming that it gives better IQ than the Pentax DA*16-50/2.8 and I wanted to see for myself whether this was the case.

One of the first shots from the Tamron, taken yesterday at 17mm and f2.8 with my K20D, yielded the following (100% crop, center, no PP):

Needless to say, I shot it again, and when I saw the same result I figured I had a bad copy. Oh well, time to send it back for a replacement.

Today I was shooting some more images to see if I still had a problem (I did) and noticed that my battery indicator was at half charge. Hmmm - I remembered that others have commented on poor AF under low battery conditions, so I installed a fresh battery. Lo and behold, I now saw the following:

Moral of the story - if you are having unexpected lens IQ issues be sure that your battery is well-charged before concluding that the lens is at fault. My K20D seemed to focus and shoot properly at "half-charge" but obviously it did not.

BTW, I later shot some comparison images with my DA*16-50 and concluded that the Tammy is about equal to the Pentax in the center of the image but is a bit better in the corners, esp. at 16-17mm. As it is a lot lighter I'll carry it when weight is an issue and weather resistance/QF/SDM are not important.
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Jim King - Retired Colormonger - Suburban Detroit, Michigan, USA; GMT -4h (EDT)
Pentax user for over 45 years. Photo gear and collection listed in my profile.

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A fanatic is one who can't change his mind and won't change the subject.

  • Sir Winston Churchill

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The difference between genius and stupidity is that genius has its limits.

  • Albert Einstein

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