Atmospheric Dispersion Corrector - Any one using?

[SnakeyJ]

Just seen a listing for an AstroSystems Atmospheric Dispersion Corrector (ADC) on ABS, as I've not heard any mention of these thus far I was initially a little cynical, but a quick google brought up the details from Astrosystems web site . A quick search of SGL for ADC does reveal that they are being used, though seem to be the reserve of more serious PIs at larger appertures.

As the product claims and acompanying images look rather bold/impressive, I just thought I'd ask if anyone here is using these for LRGB imaging (particularly planetary)? My cynical nature says no gain without pain, so other than the purchase price are there any imaging dissadvantages? And finally, are any improvements likely to be worth the effort with my 8" newt?

[x6gas]

These were reviewed (both the concept and, if I remember correctly, so specific devices) in Sky at Night magazine last year or possibly in 2011... I'll see if I can dig out the reference...

[umadog]

Dispersion depends on elevation so the example is surely at low elevation. Anyway, here's a really good detailed review:

http://www.skyinspec...DC(2587060).htm

Interesting idea, though. I wonder how much it would help visually...

EDIT: ah, sorry, I see I just found on Google the link that was already in the advert. Anyway, it's still a good link

[emilf]

Hello!

I also use an 8'' reflector with ASH ADC on a color camera and I consider useful for planetary images at low altitudes as Saturn.

I did a little experiment with 203/1200, Bresser 3x SA Barlow (telecentric), ccd DBK21AU618as and UV-IR cut filter with and without ADC.

I've got two pictures taken in the same conditions (just remove ADC), first (45) made ​​on 4/14/2013, 1:21 pm local time at altitude 31 degrees with ADC and the second at 1:31 pm local time at altitude 32 degrees without ADC processing we used the same algorithm also identical in both cases.

I noticed that the without ADC tints appear blue top and red at the bottom and also a degradation of contrast compared with adc pic due atmospheric dispersion.

We have here a very useful article on ADC:http://www.skyinspec...DC(2587060).htm

[emilf]

Sorry, I wanted to write 01:21 am and 1:31 am .

[x6gas]

Overview of what ADC's are all about is in the November 2012 issue of S@N, page 62. Quite a detailed and interesting article.

The upshot seems to be that they are useful if you are imaging a planet that is low in the sky; has low surface brightness; better for colour cams than for monochrome, but monochrome are improved too, especially (and not surprisingly) when imaging through a blue filter; also improves the experience when visually observing...

Course that might all be hype!

[SnakeyJ]

Dispersion depends on elevation so the example is surely at low elevation. Anyway, here's a really good detailed review: http://www.skyinspec...DC(2587060).htm Interesting idea, though. I wonder how much it would help visually... EDIT: ah, sorry, I see I just found on Google the link that was already in the advert. Anyway, it's still a good link

Thanks Umadog - this is an excellent article and explains the concepts very well - I have read it twice, but probably need a third bash to finally let it sink in.

Hello! I also use an 8'' reflector with ASH ADC on a color camera and I consider useful for planetary images at low altitudes as Saturn. I did a little experiment with 203/1200, Bresser 3x SA Barlow (telecentric), ccd DBK21AU618as and UV-IR cut filter with and without ADC. I've got two pictures taken in the same conditions (just remove ADC), first (45) made ​​on 4/14/2013, 1:21 pm local time at altitude 31 degrees with ADC and the second at 1:31 pm local time at altitude 32 degrees without ADC processing we used the same algorithm also identical in both cases. I noticed that the without ADC tints appear blue top and red at the bottom and also a degradation of contrast compared with adc pic due atmospheric dispersion. We have here a very useful article on ADC:http://www.skyinspec...DC(2587060).htm

Thanks also emilf for posting the image comparison taken with very similar equipment to mine - the effect is definitely noticeable, though not so pronounced as the advertising blurb. Though much will also depend on general seeing conditions as well. Very interesting though and it certainly looks valuable if I want to seriously do Jupiter next January (by which time I should have also have a better camera to go with this).

[SnakeyJ]

From my read of the Astronomy & Sky article, it seems to me that the benefits may be more apparent on OSC imaging, presumably for RGB you are only imaging a narrow band for each channel. Obviously imaging with the L filter would be improved by re-converging RGB channels, although currently I am trying to use IR-PASS filter to provide my luminance channel as this seems to provide better results in poor seeing and at higher magnification due to the longer wavelengths. Once the separate channels are stacked and LRGB aligned, the alignment errors are removed n'est pas?

Well I've certainly learned something new, but probably need to pay close attention to the information posted accompanying images of Jupiter, Saturn - especially on similar equipment to mine. With the low elevations that we're blessed with at 50 deg N, this may really prove to be very useful.

[cgarry]

I have one and can't understand why every planetary imager in the UK does not use one (well apart from the cost!), especially with Saturn being as low as it currently is. I see so many threads about seeking out that last bit of detail in planetary images, yet hardly anybody talks about ADCs which can actually make a genuine difference.

Cheers,

Chris