Some of you may recall my article back from the 2007 Mars opposition with a picture of my astro-dog Max (see “Aperture isn’t everything” by Brian F. Close, March 2008 and the photograph “Summary of the Mars opposition as observed by Brian Close,” April 2008). Well, Mars has come and gone and below is a selection of images from my updated set-up.
As you may recall, my prior set up was a Toucam with a 5” D&G F/12 refractor. I have since switched over to a monochrome DMK 21AU.04 Camera from Imaging Source. This was acquired from Astromart. However, caveat emptor! The camera did not come with software. When I contacted Imaging Source for Software they told me (a) the camera was stolen from a UPS shipment; and (b) I could get the software only by paying full camera price. This was after I had provided them copies of the Astromart ad and the name and address of the seller.
Imaging Source should of worked with me instead of punishing me for buying used and helping them, so I kept the camera and looked for software to run it. (Or at least that’s what I rationalized.) Stark Labs produces a nice little freeware ccd camera control program called “Craterlet.” Stark Lab also produces Ph.D. Guide to run guide cameras and an image processing program called Nebulosity, all freeware (Donation optional). Craig Stark is a great guy and happy to answer questions (see http://www.stark-labs.com).
I don’t know what they are, but Craterlet won’t work with Vista or Windows 7 without additional “codecs.”
Whatever they are, the complete AVI Suite of codecs can be downloaded and installed with a nice freeware program call K-lite CODEC (see http://codecpackguide.com/klcodec.htm).
A monochrome camera requires a filter slide or filter wheel and filters. I’m using a used ATIK powered filter wheel. It’s ok for the price, but if you can afford a USB supported SBIG or other expensive wheel go for it. (My original control box failed and it took me two months to get it back from ATIK in Portugal). I’m using Non-IR Astrodon RBG filters, which are suppose to be parfocalized but are a little finicky.
Here’s my light path stack: Fringekiller® filter on the front of the filter wheel (the D&G is a traditional refractor), 5x ImageMate, filters, then IR filter then the ccd chip. The DMK can take 30 frames per second. With Mars at or below 13”, it can be exposed up to 15 minutes. I take RGB of 4 minutes each, which gives me time to refocus if I have to and adjust exposure. I expose Red and Green at 1/60th a second and Blue at 1/30th. I get about 7000 frames per filter. Frames are then processed with Registax and then color combined with Maxim DL with Green weighted at only 80% of Red and Blue. I got good data until Mars dropped down below 8”.
Next opposition I hope to get color calibration on a white star down so I can get a true color weighting and maybe trade some focal length for light gathering power by using my home built 6” f/6.5 as well as the D&G.
* “Telescope Nut”