[sac-forum] Re: CCD imaging guidance needed

Hello Bob,

The DSI is a great camera for the price.

M13 is usually an easy object, but M31 is harder than it looks. Be
sure to take darks and auto subtract them. The AutoStar Software is
very god for the imaging and processing. You can also try stacking
images. For deep sky objects set the Quality and # to zero and 1 and
stack a dozen or so to start. A key for the stacking is to draw a box
around a star to guide the stacking. This allows the software to
precisely stack the images. If you use an Alt/Az mount, draw a second
box and it will de rote the images.

Experiment and ask questions.

As for the focal reducers I use a F/6.3 and F/3.3. I have no
experience with the 1.25" reducers. Best just experiment. While I am
a Mac person I bought a refurbished Dell to use for the imaging. For
$500 you can get a very nice system from TigerDirect and not worry
about taking your Mac out into the elements.

Jeff



At 14:02 -0700 10/12/2007, Bob Christ wrote:

Hi all, need some astrophotographer guru guidance ??

Tim Jones and I fired-up a Meade DSI single-shot color camera last
night - basically our first hands-on experience with
astrophotography. The results were both good and bad. The good; we
can effectively place objects on the chip. The bad: well, the images
(Albireo, M13, M31) could stand improvement to put it kindly. The
seeing wasn't good, but I'll pass on blaming it.

Longer term we plan to image with an f4'ish refractor, but last
night we used a C9.25" SCT, not an ideal imaging platform at f10:

C 9.25" at 2350 mm focal length, alt/az mounted
DSI color camera: pixels = 9.6 microns W by 7.5 microns H
Nebulosity software (Mac w/USB 2.0)
Astro-Physics 2" adapter attached to the SCT threads
2" to 1.25" converter inserted into AP adapter
DSI camera inserted into converter
~ 20 exposures taken of each object - limited to 20 seconds max each exposure

The question: A 1.25' filter format 0.5x focal reducer manufactured
by GSO ($35 shipped) looks viable to use. Does this approach make
sense to implement on the SCT/DSI combination? Would an extension
tube (25 mm offered) help further reduce the focal length (sub f5)?

We could use the original 1.25' visual back to move the camera even
further forward if that is recommended. If yes, again, would the 25
mm extension be of value?  Seems not, but the answer may be
counter-intuitive.

I don't want to go the Meade f3.3 reducer/field flattener + variable
T-adapter route ($150) because most of the imaging will be done
through the RFT.

Feedback regarding the 1.25" .5x focal reducer strategy is most welcomed.

Thanks.

Bob

--
Bob Christ
Executive Vice President
TOLIS Group, Inc.
bchrist@xxxxxxxxxxxxxx
Ph: 480.505.0488 x228
Fax: 480.505.0492
www.tolisgroup.com
The Data Backup & Recovery Experts


--
Jeff Hopkins
HPO SOFT
Counting Photons
http://www.hposoft.com/Astro/astro.html
Hopkins Phoenix Observatory
7812 West Clayton Drive
Phoenix, Arizona 85033-2439 U.S.A.
(623)849-5889
(623) 247-1190 (Fax)
www.hposoft.com

Other related posts: