Atmospheric Dispersion Corrector (ADC)

[Hans Tucker]

Noticed that views of Jupiter from Melbourne are not going to be ideal this year.. sooo... I am thinking about investing in an Atmospheric Dispersion Corrector (ADC) but at 329 Euro they are rather expensive. Anyone using one of these for visual and imaging and can offer their 2 cents worth as to the performance.

[DarkArts]

Hi Hans,

Firstly, I've never used an ADC ...

Visually, I've never found dispersion to be much of an issue, providing you wait until near the "high point" of the evening - even on humid nights it only seemed to affect me in the lower 20-25 deg or so. Even with colour imaging, it wasn't toooo bad - Registax's RGB Align feature worked OK for me on the occasions I needed it. Your experience may be different of course, but I personally wouldn't rate the deficiency of dispersion at 350 Euros' worth for the average viewer.

For imaging, it may be more cost-effective, and indeed may produce better results altogether, to use a mono camera and RGB filters, and you'll also have the opportunity to focus each colour optimally. Theoretically, dispersion will also occur in mono/RGB-filtered imaging and an ADC should sharpen single colours as well, due to the "broadband" RGB filters used - and they're necessary to grab enough light for the short exposures we use in planetary imaging. But, I've personally never noticed a dispersion problem in mono/RGB. Then again, perhaps I've not imaged at high-enough resolution to encounter the problem.

2c.

[algwat]

best seeing and imaging is when your location has low water vapour.
see this link, darker the better. rgds, alan
http://realtime2.bsch.au.com/wv_sat.html

[Shiraz]

even with mono, it is still worth having an ADC at low altitude, particularly for the blue channel. I have one and use it because I have it, but the performance gain is almost always marginal due to poor seeing at low altitude - it only made a real difference on two sessions over the past couple of years.

another issue is that they are not all that easy to set up on a Newtonian scope - I guess that it would be a simpler procedure on an SCT.

[Exfso]

I have a pair of these I purchased from Adirondak at least 10 years ago, they work a treat.

http://www.iceinspace.com.au/forum/showthread.php?t=119458