I am pleased to share with you my first light image taken with Sigma 500mm/F4:
I knew this is an excellent lens from lenstip.com. (BTW, lenstip.com just released its review on the new Sigma 105mm/F1.4. It's a brilliant lens.) Recently I was really annoyed by the collimation issue of my TAK Epsilon E180ED. So I decided to give the Sigma a try. It has the same focal length, less than 1 stop slower (because of the secondary obstruction of the Epsilon), probably better corner illumination, and probably no need for me to worry about the collimation. So last week I used my mileage to get a free round-trip ticket to fly to Japan and purchased one. Japan's tax-free policy for foreigners saves me a lot on this lens. Even if I include the costs for hotel, food, and local transportation in Japan, I still end up with a huge bargain, comparing with the prices of this lens elsewhere.
Taiwan is now under the strike of a hurricane. However, before it arrived, it brought exceptionally good weather. So I rushed to the mountains to get away from the light pollution and to test this lens. You can see the result above: sharp stars over the entire full frame. In addition, here you can see the illumination pattern:
It's quite good. The light loss is only about one stop in the very corner.
Overall, I am very happy with this lens. I think it is a nearly perfect astrograph.
Edited by whwang, 10 July 2018 - 11:48 PM.