Skymax 90 - Diffraction rings around stars?

[jdg600]

I find when I view stars through my Skymax 90 I always get a slight diffraction pattern around stars. Its not very distracting but is always definitely there and I cannot focus it out. My question is: is this normal for this type of scope? or does it point to some problem with the collimation?

I'd be most grateful for any help on this.

[dweller25]

It's normal and an indication that you had good seeing

[Alkaid]

Yes, with an obstructed scope design you will see a larger diffraction pattern than you would with say, a refractor. This is due to the central obstruction.

Do you get a sharp view of the moon? If so, it's fine.

[jdg600]

Thanks for the replies guys. I thought (or least-ways hoped) that that was the case but I just wanted to check. As I say, the effect isn't too distracting, indeed I find it often lends a bit of impact to the view of bright stars, though occasionally it can make faint secondaries difficult to pick out.

[John]

You get this with refractors too and the diffraction ring can make tight binaries harder to split to if, as you say, a faint secondary is sitting right on the diffraction ring.