Barlows

[reconair]

I'm looking for opinions on what are the best color corrected barlows currently on the market. I'm currently doing some planetary imaging of Saturn and I'm using a Meade 5X TeleExtender. What I'm finding is a subtle spectral gradient across the Saturn image. The gradient is yellowish on one side and blue on the opposite side, most noticable at the edges. I'm wondering is this just an unavoidable artifact of increased magnification or are there barlows that are better color corrected than others.

I would be interested in hearing from Televue Powermate users and Astro-Physics barlow users.

Will an APO barlow make a difference or is this just a marketing ploy?

My primary instrument for planetary imaging is a Takahashi TOA 130 and a ToUcam Pro II (840k)

Thanks for your comments.

[tvuejohn]

Reconair,
It sounds like Chromatic Aberration ( CA ) and several things
can cause it. I really doubt the TOA is the problem, so this leaves
the Barlow, seeing conditions & focus. All three can cause this.

I'm leaning toward the seeing & focus because if the TOA is decent
the Barlow just can't bend the light enough to cause this much CA.

Remember the atmosphere is a lens and only rarely a good one.

A top of the line Barlow or Powermate sure wouldn't hurt and would probably sharpen the image.
Here is a link to our Powermates Page : http://www.televue.com/engine/page.asp?ID=42

Make sure you very steady skies and really check the focus.

[BT Technologies]

I would tend to agree with John regarding the seeing being more of an issue than the quality of the Barlow.

I have not used a Meade barlow so I can not comment on how well it works or does not work with the TOA. I can tell you that either the Televue Powermates, Takahashi TOA Extender or the AP Barcon are EXCELLENT barlows and will provide you with the best possible image providing the atmospher is cooperating!!

Originally Posted by reconair

I'm looking for opinions on what are the best color corrected barlows currently on the market. I'm currently doing some planetary imaging of Saturn and I'm using a Meade 5X TeleExtender. What I'm finding is a subtle spectral gradient across the Saturn image. The gradient is yellowish on one side and blue on the opposite side, most noticable at the edges. I'm wondering is this just an unavoidable artifact of increased magnification or are there barlows that are better color corrected than others.

I would be interested in hearing from Televue Powermate users and Astro-Physics barlow users.

Will an APO barlow make a difference or is this just a marketing ploy?

My primary instrument for planetary imaging is a Takahashi TOA 130 and a ToUcam Pro II (840k)

Thanks for your comments.