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01-01-2009, 02:22 AM   #16
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QuoteOriginally posted by GaryM Quote
FWIW, I use that same trio with the K200D, and have no focusing problems. The Km/K2000 should be at least as good.
Cool. I have $200 from Xmas, when I find a good deal on the DA 21, I'll pick it up!

01-01-2009, 08:58 AM   #17
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QuoteOriginally posted by pcarfan Quote
So, one plausible reasoning is methodology. I would have assumed that both methods are close enough to not give this much of a difference, it is like testing two different lenses ?, but I could be wrong.

I was also wondering whether the different bodies (K100D vs K10D) used for the testing, would show this much difference as well.


I am not trying to figure out whether this lens is good or not, or which of the tests is correct. Ignore the lens and even ignore the absolute results. I am just wondering what are plausible reasons for such a difference of the same lens between two tests, that's all.

-Methodology
-Camera body
-sample variations

etc.

Thanks.
I suspect that when comparing tests from different sources, that any ir all of the above could come into play as there are no real control elements to baseline against. The objective parts of the testing will be difficult to compare and on top of it the interpretation of those results, as written up,
tend to reflect the reviewer's subjective opinion.

Personally, I have found this lens to give very pleasing results when used with a k20. Dave
01-01-2009, 05:55 PM   #18
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QuoteOriginally posted by Stratario Quote
Recently I purchased another used copy of DA 21 to complete my DA series. I also have the Tammron 17-50. As I was testing the KatzEye I happend to take similar shots between DA 21 and the Tamron 17-50. Nothing scientific but in this test the DA wins. However, I think the results of the Tamron could be improved by manual focusing. These shots were taken with AF.
Taken with "AF" doesn't do much to tell us an apple was compared to an apple. You didn't tell us the aperture/ISO setting used on either. You need to compare aperture to aperture at minimum, ISO is next important, where shutter speed can be dynamic to give you the same exposure (as long as it's not too slow to introduce blur from shake if you're not on a tripod).

Also, odd on your conclusion. I find the Tamron shot to be far sharper in the corners & edges. Note the electrical lines and tree near it. Being a proud and satisfied Tami 28-75/2.8 owner, I'd be happy to be a 17-50 owner based on that shot, over the 21.
01-01-2009, 06:20 PM   #19
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QuoteOriginally posted by m8o Quote
Taken with "AF" doesn't do much to tell us an apple was compared to an apple. You didn't tell us the aperture/ISO setting used on either. You need to compare aperture to aperture at minimum, ISO is next important, where shutter speed can be dynamic to give you the same exposure (as long as it's not too slow to introduce blur from shake if you're not on a tripod).

Also, odd on your conclusion. I find the Tamron shot to be far sharper in the corners & edges. Note the electrical lines and tree near it. Being a proud and satisfied Tami 28-75/2.8 owner, I'd be happy to be a 17-50 owner based on that shot, over the 21.

Sorry about the omissions. Following are the details. And yes, you're very observent. The Tamron shot is indeed sharper on the left side by comparing the telephone pole.

The first shot with DA 21mm was at F3.2, ISO and also 1/4000 Sec
The second shot with Tamron 17-50 was at F2.8 , ISO 100, 1/4000 Sec

I love Tammy 28-75 more than the 17-50. They both front focus. But the 28-75 works very well across all focal lengths with a -60 focus adjustment on the K10D. But to get the best out of the 17-50 I start with -40 at 17mm and increase the amount of adjustment gradually more to -140 by 50mm. This is the only lens that I have that shows this kind of characteristic.

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