Originally posted by Matchete Notably focusing wise.
Simple answer
Bahtinov mask. I made one out of a 3" PVC pipe cap for my old 300mm f/4 super takumar and it fits this lens too. It is substantially snugger on the hood of the sigma 300mm f/4 APO but it just needs to stay put long enough to get it focused. You will need to focus it manually and once you get it nailed switch the lens to autofocus and switch the camera to manual focus so you don't accidently change it. Or at least that is what made the most sense to me on how to set things.
To make it I
created a template for the lens that was sized for the
3" PVC pipe cap, and using a saw attachment for the dremel cut slots in it.
Originally posted by Matchete Do you have any advice for DSO photography with this lens btw ?
Some form of tracking is almost necessary. I went out last night and forgot the O-GPS1 for the K-3 so I was limited to .8 to 1 second exposures to avoid noticeable bad trails and with the humidity, and smoke there wasn't much up. I did manage a respectable picture of Jupiter and the Galilean moons with a little bit of a trail when view at 100%.
With the massive light pollution where I live even at midnight when I went back out I could only see 3 stars unaided. The wind is changing today so what is blowing in from canada goes away and I am heading to my lake with is much darker so I will really get to exercise it.
---------- Post added 08-11-18 at 12:50 PM ----------
Here is a sample of what this lens is capable of for astro even at F/4
Shot last night with Jupiter being fairly close to the horizon (about 15 degrees up I think) through a lot of humidity and smoke blowing in from canada. Still managed to get all 4 Galilean moons without the trails being too bad. This is a 100% crop and jupiter is still tiny.
4 x 1 second exposures stacked
ISO 1600
F/4