I'll add some real world experience of mine with for eveyone's benefit, both good and bad. So anyone getting it knows what to expect.
I had it and replaced it for a 2nd, thinking the CA and purple fringing I was getting with it made it a bad copy (5 to even 10 pixels width; real bad). 2nd lens was identical however (though, $100 less from that seller then the seller I bought the 1st one from). Ok that stinks. Gotta watch out for that.
I tried it inside for interior shots of my home with available light , and was disappointed with that result too (handheld). Even tho it was a sunny day, and I have a lot of skylights,
and the entire back of my house is glass, there wasn't enough light and I had to bump-up the ISO, and was still underexposed (so a lotta noise). But, that was handheld. With supplamental lighting, or tripod, it would have been ok I imagine. I never tried to re-do it since Summer.
Anyway, I wasn't even going to take it to Tanzania. I was very dissapointed. However, I did take it. And once I used it outside in Tanzania to take landscape shots... Holy Cow! You can see the best example of shots in my "In and Out of the Dust Bowl" album in my photo gallery on Fotki, under the Tanzania folder (that being shots taken driving to the Entrance of Ngorongoro crater, into it, and out of it). Click here to go to it:
070815 - [In&Out o/t Dust-Bowl] Ngorongoro Crater Conservation album | m8o | Fotki.com . You really have to look @ the full-rez originals to understand what I'm saying (some montion blur in the foreground of some of them notwithstanding) especially when you notice the huts in the first few and take a look @ them in full-rez 100% crop.
So just saying to all, now that I know you -must- have a lot of light and must stop it down a good deal (needing more light even more important with that), I'm able to get real winners and feel confident that it wasn't money wasted on this gem (yes, I'll even call it a "gem" now).