Quote:
Originally Posted by andrew
One thing though, a problem I have at the moment is being able to accurately focus on the stars with what I use. Will I have any such difficulties if I purchase this lens? I wouldn't expect so given what I've been reading, I guess I just need some reassurance  |
Focusing will still be an issue. It's always an issue and always difficult to get right. It's always something you should spend a lot of time on at the start of your imaging session. Nothing worse than taking a whole run and when you get them back on the computer, realise your focus was slightly off and you have blobby soft stars everywhere.
Take some test exposures (ISO1600 for 10-15 seconds) and zoom in on the LCD to check the tightness of the stars. Go back and forth through the focus repeating the test until you get the smallest tightest stars.
You can also hook your DSLR up to a laptop and use software like DSLRFocus, ImagesPlus and others to do effectively the same thing, but it's using maths to determine the quality of the focus and you just look at the numbers as you go back and forth through focus until you find the lowest number (tightest focus).