My astronomy project:
Sigma 150mm f2.8 to use on Star Adventurer mount

Content:

1. Introduction, why use this lens?
2. Vignetting test
3. Sharpness in corners with star test * (You are here!)
4. Canon 6D and Sigma 150mm f2.8 mounted on Star Adventurer
5. Photo on M31 and M45

3: Sharpness in corners with star test

Here I have done a simple star test to see how well the lens focus at the edges. When I did my this first star test I couldn't get the live view focus to work. Later when I did a indoor test it worked. I don't think I got the focus where it's best. Anyway, here is my first photo. Canon EOS 6D, 60x15 second at iso800, aperture set to f4.0, position close to M102. This time I used the EQ6 mount, no guiding. To this I used my EQ6 mount is controlled by CdC and EQMOD through ASCOM. No auto guiding this time.

(Click on the image and you get a full resolution image in a new window)

Zoom in, center 1:1 scale

Zoom in, lower left 1:1 scale

Zoom in, lower right 1:1 scale

Zoom in, upper left 1:1 scale

Zoom in, upper right 1:1 scale

For me it looks very promising, other lenses I has deliver much worse result. Remember it's a full frame camera. And I think later I can bring it in better focus. With this small lens I don't have the vignetting problem as I get with the refractor because of the DSLR too narrow body.

If you want to dig a bit deeper in the theory you maybe can find my Web calculators interesting and useful:

• Astronomy calculations: ../../astronomy-calculations/ astronomy-calculations.html