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07-03-2011, 10:21 PM   #16
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QuoteOriginally posted by Class A Quote
That explains it. Even wide open (at f/2.8) the Sigma is sharper than this.
Yes, it is sharper, especially with RAW. although recently, I'm using it a lot at F4 to F7.1, just because I needed depth. I will be posting some new macro shots real soon.

07-04-2011, 12:55 PM   #17
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QuoteOriginally posted by civiletti Quote
I would go for the DA70 if size and build quality are more important to you than macro performance.
Thanks! This made me decide to go for the DA70. I think I'll enjoy its size and build quality over the ability to take macro photos. I'm not too fond of bee and butterfly images and more into street photography. The DA70 will suit me better.
07-04-2011, 04:05 PM   #18
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QuoteOriginally posted by Class A Quote
Note that the two lenses have been measured on two different cameras. The MTF results are therefore not comparable. Even if you normalised them according to sensor resolution, they wouldn't be comparable because of different AA filter strength, different sharpening by Klaus, etc.

Theoretically this may be true, but calculating comparative factors for several lenses tested on various cameras has shown me that results are fairly consistent, enough so that I would put more weight on such MTF comparisons than I would on reduced size JPGs posted on the internet or someone's opinion based on non-technically judged results.
07-04-2011, 06:12 PM   #19
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QuoteOriginally posted by civiletti Quote
Theoretically this may be true, but calculating comparative factors for several lenses tested on various cameras has shown me that results are fairly consistent, enough so that I would put more weight on such MTF comparisons than I would on reduced size JPGs posted on the internet or someone's opinion based on non-technically judged results.
personally, it is still tricky to make lens comparisons done on different systems. PZ for instance wouldn't had done a retest of the old tests conducted on the Pentax lenses on the camera that they used if there is the body has no significant influence on the MTF figures. there is an obvious difference in the numbers between the Pentax cameras used, so we can also think the same with other system. to be more precise, it is better if both lenses are conducted with the same camera. and I don't think we have that data. although from real world use, we can still see the difference (as long as it is not altered). otherwise, what is the point of doing side by side image comparisons. it is not necessarily quantitative measurement, but does support whatever MTF value there is. aside from that, MTF figures are also prone to errors due to other factors involved such a a poor sample.

07-05-2011, 09:01 AM   #20
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QuoteOriginally posted by Pentaxor Quote
personally, it is still tricky to make lens comparisons done on different systems. PZ for instance wouldn't had done a retest of the old tests conducted on the Pentax lenses on the camera that they used if there is the body has no significant influence on the MTF figures. there is an obvious difference in the numbers between the Pentax cameras used, so we can also think the same with other system. to be more precise, it is better if both lenses are conducted with the same camera. and I don't think we have that data. although from real world use, we can still see the difference (as long as it is not altered). otherwise, what is the point of doing side by side image comparisons. it is not necessarily quantitative measurement, but does support whatever MTF value there is. aside from that, MTF figures are also prone to errors due to other factors involved such a a poor sample.

Your concerns are reasonable, but are not supported by reality. Cross-platform comparisons of PhotoZone MTF tests using conversion factors yields fairly consistent results. All it takes is a calculator with division and multiplication functions to check it out. Don't take my word for it.
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