From: "doobisary" <tjp314@pacbell.net>

Date: October 2, 2010 12:00:58 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: Jupiter Image


Hi Alan:


I tried two barlows.  First was a 2x - one of those old ones made with a sink extension pipe with slots cut in it for the eypiece.  The other is an old Meade 3x with a ridiculously long tube that works fine if the lever arm doesn't rotate the OTA in the rotating rings (on the Cave 8", it does!).  I've got an old Televue 2.5x somewhere, but didn't have access to it that night.  And then there's the 5x powermate, which is too much magnification most nights here in LA.


I've gotten some decent color images of planets, but the seeing has to be exceptional, as you describe.  For my 9.25" rigup, I can't use a manual filter wheel and I don't have a motorized one (yet), so it's been color or not at all for that scope.  In other words, the only reason I'm primarily a color camera guy is that I couldn't easily do LRGB with the 9.25" and it was my main scope for planetary when I moved over from webcams to firewire cams and Astro IIDC about 5 years ago.


I bought the Scorpion because it was a good price off ebay, and have only recently added the filter wheel to try with it.  I shouldn't have the same problems with focus on the 10" f/6 I built, because I intended to use it for both planetary with Astro IIDC and DSO imaging with my ST2000/filter wheel combination.  And I will make a sled focuser for it if I need the travel for the SBIG.


...I guess I misspoke.  I do have a motorized filter wheel (CFW-10) with the SBIG camera.  I could put it with a mono planetary camera, but it's heavy and will need additional balancing acts on a Newt.  Also (and more importantly) removing it from the ST2000 and putting it back is a real PITA.  


-Tim.

--- In Astro_IIDC@yahoogroups.com, Alan Friedman <alan@...> wrote:


Hi Tim,


What's the amplification of the tele-extender that you're using? I use a 2x barlow+filter wheel+camera on my f14.6 mak and the image scale works fine in average seeing. At f7 you shouldn't have any problem with image scale using a 2x or 3x barlow in this configuration.


The fine image that Alberto posted was taken in Australia, clearly in very fine seeing conditions. When the seeing is sublime, you could get a good image with a Kodak instamatic. I am not a fan of color cameras. They are so much less versatile than monochrome cameras. But perhaps the biggest loss is the ability to reap the stability benefits of imaging in narrow slices of the visible spectrum. Being able to remove the turbulent blue data from luminance is a big advantage in average seeing conditions. If one were to image all the time, you run the chance of happening upon a few moments of steady seeing when a color camera can shine. But those who image all the time invariably choose a monochrome camera. The color camera is used mostly as a convenience by those who image the planets infrequently, and hence the chances for capturing a fine image tend to be slim from all but the very best locations.


my .02,

Alan




On Sep 27, 2010, at 10:03 AM, doobisary wrote:


Hi Milton:


I thought I'd replied yesterday but my internet connection was flaky and it musta notta gotten in! 


Anyway, I had posted my thoughts about color versus mono cameras. I've only used my Scorpion for RGB imaging a couple of times now, as I only fairly recently purchased an Orion manual filter wheel. 


Problem I have with LRGB imaging is that my old Newts don't have enough backfocus for all the "stuff" in the camera assembly. My 8" f/7 Cave doesn't even have enough backfocus to reach focus with the Scorpion by itself at prime focus. It does reach focus with a barlow in place, though. But to use the filter wheel, I have to put the wheel between the barlow and the camera, which gives me too large an image scale for the seeing.


I much prefer color camera imaging of planets, and am excited to see your results with the Chameleon and the exhad ccd. I've been wondering whether to buy one of those versus a mono or color flea3. Your results have me thinking I might go for a color Chameleon first, and then try the mono flea3 when I can afford it.


-Tim.


--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@> wrote:



On 26-Sep-10, at 5:01 AM, albe albo wrote:




Hello Milton,

nice for a color camera.

I am not able to get good result with my DFK, i don't know why.

The details are always so messed up while with the DMK and the 

filters it seems to go better.


Yes, that's always been the case and has been discussed on this list 

many times. Bayer cameras are lower resolution (by about 50%) over 

Mono cameras. You mix adjacent color pixels together with Bayer 

filters to create the images.


Perhaps it is due to the possibility to process 3 or 4 different 

channels so the averaged result is better.


Yes.


However you also need good seeing for all 3 / 4 LRGB imaging sessions, 

so under my normally mediocre skies (>4+ arc seconds of motion) you 

get worse images that way. Fine details never show up anyhow except 

for maybe 1 or 2 nights a year.


Also with Jupiter's fast rotation, you have to shoot very quickly (or 

only a few frames) or you get rotational offsets between images.


30° above the horizon?


It was 20° when I started taking images and Jupiter only gets to 35° 

above the horizon here maximum, so I'm shooting though nearly 2x as 

much Air turbulence as other people.


Wow...i didn't remember you live so much at north.


Yes I'm at 50.5° N latitude.


Only a question : why did you leave the image so uncorrected 

regarding the white balance?

In my opinion it is pretty cyanotic.


I color balanced using the moon to "gray", when it was about 15° above 

the horizon. Which means it was dominantly red getting though 

atmosphere at that Altitude. By the time Jupiter got to 29°, the Blue 

and Green channels brightness increased.


I played with an automatic white balance (no other corrections) and 

perhaps the result is overcorrected but more similar to the visible 

Jupiter.


http://dl.dropbox.com/u/1094920/ASTRO/Jupiter/Jupiter_20100922_MJA-AWB.jpg


I left it as it's what I shot it as. I'm not 100% sure the real colors 

of most Astro Objects are either.


http://en.wikipedia.org/wiki/File:PIA02873.jpg

http://pds.jpl.nasa.gov/planets/images/browse/jupiter/jupiter.jpg

http://b4tea.com/wp-content/uploads/2010/03/Jupiter.jpg

http://www.solarviews.com/raw/jup/jupwsmap.gif

http://news.nationalgeographic.com/news/2010/05/100514-science-space-jupiter-lost-belt-great-red-spot/


The current crop of images have Jupiter more red than I see it visually.


Later..


Milton Aupperle