bands of blue, white, and red

[wanderer2011]

Hi,

I've got a 4" reflector.

When I look at planets, my scope splits the light into colors. Blue haze, white planet, red haze. It gets better if the planet is centered, and worse as I sweep the planet towards the edge.

Deep sky objects seem fine. I've really enjoyed the Double cluster in Perseus last weekend.

I have collimated it recently, but I don't think that's the cause because I've always had this problem with Venus and Mars. However I see Jupiter and Saturn ok.

My lenses are dirty and scratched. Should I get myself a new 25mm? Or maybe filters? Might the collimation have something to do with it? What's the cause?

Thanks.

[LukeSkywatcher]

Do you let the scope cool down before using it?. Are you observing through a pane of glass?. Is there any kind of heat source directly between your scope and the area of sky you observe?.

[John]

Venus and Mars are more challenging targets for any scope. Allowing the scope to fully cool will help. Scratched and dirty lenses (eyepieces ?) won't of course.

If you are viewing objects close to the horizon then that won't be helping either as you are looking through more atmosphere which can wreak havoc with the definition of planets.

[wanderer2011]

Yes, I usually leave it outside from late afternoon onwards. But perhaps this last weekend I didn't let it cool at first because I was in a hurry to see Venus. After, I went back to look at it a couple of times before it set so I guess that should have been time enough for the scope to cool.

[wanderer2011]

@John Yes, eyepieces. I think I'll buy myself a new 25mm for Christmas.

Good to know that I'm not the only one that finds Venus and Mars challenging.