From: Len Fulham <lfulham@tpg.com.au>

Date: December 28, 2010 2:04:50 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Narrowband Imaging with Flea2


Jim


I have a keen interest in your conversion of the Schmidt camera, and would like to have some further contact as your project develops, particularly with regards to the DSLR dissection and the eventual image quality with a simple plano convex lens.


I am just beginning a project to modifiy my 8" Schmidt to digital and would be interested to see your results. I have not been able to find any examples of the Celestron Schmidt modified to digital with a large sensor. Do you know of any examples? 


I am aware of several home conversions at f3-5 - 4 with simple plano convex lenses, and APM with faster system with a compound field corrector. 


The subject of digital Schmidt cameras is somewhat off topic, so unless others disagree perhaps we could communicate privately if you wish to.


Cheers,


Len.




Posted by: "jimchung2338" jim_chung@sunshine.net   jimchung2338

Mon Dec 27, 2010 5:53 am (PST)

I finally got a chance to try out my second experiment last night because it was finally clear (that makes three clear nights since midNovember).


I placed my Flea2 inside an old 8" Celestron Schmidt Camera with a Baader Ha filter and also jumped the terminals for long exposure. That resulted in a disappointing maximum exposure of only 40s! I'm hoping to turn the Schmidt camera at f/1.5 into an astro outreach/star party scope that can do DSO narrowband imaging from within the city within say 2 minutes. 


http://dl.dropbox.com/u/4852049/m42flea20x40.jpg


M42 is a fairly bright Ha target so the 40s subs look like the stacked image just noisier. The focal plane of a Schmidt camera is curved hence the star aberrations starting to show on the margins of the image. I attempted the Horsehead Nebula but the small pixels of my Flea2 even binned 2x2 could not clearly show it with only a 40s exposure. I had much better success with my Starlight Express Lodestar guider ccd and exposure control is also much easier. But both these ccds are really small and do not take advantage of the Schmidt camera's ability to deliver a large flat coma free image. So my next step is to dissect this slightly broken Canon 10D camera with its APS sized sensor and create a remote CCD sensor head to place inside the Schmidt. Unfortunately I'm getting slightly off topic with this forum!


Happy New Year to all!


Jim