Originally posted by HermanLee I studied Calculus III and I think this is the hardest problem I ever encountered
BTW, Brothereye, I see in your signature that you own DA*16-50 and Sigma 18-50.
Is the Sigma macro version? If it is, how is it compared w/ DA*16-50.
Sorry, OP, don't mean to hijack the thread.
Thanks,
Hopefully no one will object too strenuously.
The Sigma I have is not the Macro version, and it is not as good as the DA*.
Having said that, it's a pretty good lens for the $260 US I paid for it. Much sharper than the kit lens I have, and faster too.
Due to a bad case of rationalizing lba, I ended up with a DA16-45 then a Sigma 18-50 and finally the DA*. I realized this was ridiculous. Even worse I had an unused DA18-55AL kit lens knocking around in the closet. So I decided something had to go. I kept the DA* because when I sat down and did some informal testing, the DA* performed almost as well as my A 50mm prime, which I've had good results with. The Sigma 18-50 didn't perform as well as the DA*, but it performed better compared to the DA16-45. The testing was done by me shooting detailed subjects in RAW with several lenses under the same light at the same ISO with the same camera body and stopping down about 5 stops, one stop per frame, and repeating this procedure at three different focal lengths, then comparing the frames side by side on my PC to see if I could see any difference(which involved a fair amount of pixel-peeping, which is something I normally don't do.) I was originally planning to sell the Sigma 18-50, but it was pretty sharp, especially stopped down a little bit. It was a real surprise. So I got rid of the DA16-45 which wasn't as good as the Sigma(although it was better than the 18-55 kit lens I'm still trying to sell on fleabay.) The other real surprise was a Tamron 28-200 lens(non-DI) that I was planning to sell. It was sharper than the DA16-45 and even a little sharper the Sigma 18-50, but not as sharp as the DA*. So I kept it as well.
Why did I keep the Sigma when I have the DA*? It seems a little smaller and handier than the DA* and it's easier(cheaper) to buy filters for it. It's basically my kickaround, I'm not planning to take pictures, but I might take pictures kind of bringalong lens. I think it was an excellent replacement for the kit lens, considering that I bought mine new for under $300.
Having said all that, keep in mind these were single examples of each lens, so your results might be different from mine.
The other thing I took away from it was this: at lower magnifications like 50-75%, you might be able to see the difference when comparing two frames from different lenses, but looking at any frame by itself without something to compare it to made most frames looked pretty sharp, even the ones from the kit lens.