First attempt on Jupiter with my ETX!

[acc]

In English please?

Aiyoh...what he means is to buy TMB or AP apo to solve the problem! :-)

What problem? Catch no ball leh... heheh

[Meng Lee]

Hmmm, but I thought most of the fringing in almost all the planetary images is due to atmospheric dispersion? (refraction in short)

The lower is the planet, the worst it is. You can use the RGB realign in Registax to correct for quite a bit. There is even a 2 prism corrector for it. I think its called PDAC with rotatable prism to correct for the dispersion.

[cataclysm]

The ETX Mak uses a relatively thick correcting meniscus frontal lens, which leads to longitudinal chromatic aberration. Unless it is a two-element achromatic corrector (which is expensive), the residual CA cannot be nullified completely. Such a corrector can only be paraxially achromatic which means the light rays very close to the optical axis will have the same focus for different colour wavelengths. However, once the light rays come on near the outer zones, this will not happen similarly, thus as a result of this (called spherochromatism), longitudinal chromatic aberration will still occur, particularly in the outer zones. Thus if one were to correct for this, an additional lens element can be placed in the front of this corrector, but if one were to completely eliminate residual spherical aberration at the same time, you will have to make the lens apheric too (which in turn has a further consequence, the resultant colour-free FOV is even narrower).

Huh???!!
Rocket science!

[hommel]

I think what remus said is that the mak is still not colour free (unlike a sct) due to the single element, curve, thick meniscus lens, so only the centre region is, sort of, colour free, outer region will still have chromatic aberration.
But visually the CA in a mak is virtually undetectable.

[acc]

But visually the CA in a mak is virtually undetectable.

This I understand and definitely agree with. The Meade ETX is excellent optically and fantastic for planetary use.

[jiahao1986]

Jiahao, can you sort of provide some of the settings you play with to get from your pre-processed (registaxed) pict to your final processed pict? You are very good in adjusting these settings.

Thanks.

I cannot remember the exact number I set to each channel and I only adjusted the first and third channels, the first is about 10 and the third is about 30; other adjustments were all done in Photoshop

[mrngbss]

Yes, I was referring to Photoshop.. Did you use Curves, Levels or Hue, etc?

[jiahao1986]

I mainly adjusted Levels and Brightness in Photoshop, and I used auto color adjustment and found it turned out OK, plus a liittle color balance adjustments to yeild the final result~~~

[mrngbss]

I see, i see, thanks a lot! Looks like the webcam is performing very well!

[jiahao1986]

yeah I'm actually surprised by the result, especially that details in the GRS and three festoons are visible~~~