Focus for photography

[E_ri_k]

Hi guys, just a quick question...

I have been into astronomy for a few years now, and I'm just getting into the astrophotography side of things of recent. I have a 10 Inch reflector on a HEQ5 mount, and I have done a few piggyback shots with my DSLR, with results I'm pretty happy with for the moment.

When photographing deep space objects by prime focus, like distant galaxies, planetary nebula etc. How do you achieve the best focus, when the object is too faint to be seen by the naked eye? I have looked into bahtinov masks and similar devices, but as far as I can understand they require a bright star to focus on. What about a faint object? Or does the difference in focus for different objects become so minimal because of the great distance they are from earth? Can I just get perfect focus on a distant star and be in focus for a galaxy for exemple?

Thanks.

[bamus]

Hi guys, just a quick question...

Can I just get perfect focus on a distant star and be in focus for a galaxy for exemple?

Thanks.

yeap, if you get perfect focus on semibright star, you will get perfect focus on DS too.

[E_ri_k]

Great, I was hoping that was the case. Thank you.