Chromatic aberration in a reflector

[ste7e]

Hi

OK, I'm new to all this but when I was picking my (first) telescope I read about the different types and I understood that reflectors don't suffer from CA.

Now, when I stack my 10mm eyepiece onto a 2X barlow (two elements) I'm sure I'm seeing CA - unless Jupiter and the moon have both developed a red fringe on one side and a blue one on the other.  I get the same thing when I stick my DSLR onto the barlow (without the eyepiece).

Would you gnarly old experts expect such a thing?  Do I just have a poor quality barlow - I'm using a SkyWatcher 'De-luxe'.

My telescope is a Sky Watcher Explorer 130P on an EQ2 mount.

Attached is a crop of an overexposed Jupiter for your consideration.

Thanks for any helpful (or even not-so) advise

Steve

[Stu]

It does sound like the Barlow is inducing the CA. Have you tried without it?

[michael.h.f.wilkinson]

That is atmospheric refraction; CA of the atmosphere at low altitude. When the planet rises higher it should go. RGB align in Registax can reduce the effect

[Moonshane]

I agree.  could be either depending on the factors. Some eyepieces both cheap and expensive do introduce ca.  it's not generally the scope

[ste7e]

Thanks for the help - I'll check out the RGB align in Registax.  I've been using deep sky stacker - but I'll try Registax instead.

[Peter Drew]

Genuine CA is usually symmetrical round the bright object in view, top and bottom false colour, as already said, is due to atmospheric refraction. Reflectors cannot themselves produce CA but poorly corrected accessories can introduce it.

[beka]

You should also check collimation. The CA of the Barlow or the Eyepiece may show up in this manner if the collimation is off.

[theastrodragon]

You have three elements that can be causing it

The eyepiece, the barlow and the atmosphere.

If its the atmosphere, it will get worse the closer you are to the horizon (looking through more air). Try observing Jupiter when its low and when its high, and note any differences

Try without the barlow; this should show you if its the culprit. You cant do much without the eyepiece...

It could be tricky to pin down precisely - its quite possible its a mix of all three.

[beka]

Damn the atmosphere!