CCD imaging

Re: Imaging on a shoestring budget

johnjohnson — Sat, 04 Jul 2009 18:53:35 GMT

Modifying an Orion dual axis hand controller for an ST4 guide port. This is a real easy mod to do and guides very well at short focal lengths. The hand control has to be used in the 2X sidereal mode for guiding. The mod was described on the Shoe String Astronomy web site. This mod can apply for the EQ3 / EQ4 mounts. using dual axis controllers.

http://www.store.shoestringastronomy.com/eq_mod.pdf

This is the modified hand control and all parts were bought at Ace hardware. A six line phone line and coupler. Make sure to use the end that gives the straight through connections to keep the color coding correct. This works perfect with the Orion Star Shoot Auto guider and it's cable.

Re: Imaging on a shoestring budget

johnjohnson — Sun, 28 Jun 2009 18:50:39 GMT

Last night 6/ 27/09 I had another excellent chance to try out this rig. I imaged M56. This is 256 images of 20 seconds each. This was done from down town Sioux Falls SD. Images stacked using DSS, and processed with Gimp and PS elements. I am real pleased with it as I modified my Apogee EQ4 mount with dual axis drives to have an ST4 input and guided it with an Orion SSAG. Not to bad for one of the crummiest mounts in history! The mount cost $150 brand new! This link explains how to modify an Orion dual axis controller.

http://www.hodgsonobservatory.org/?p=454

Re: Imaging on a shoestring budget

johnjohnson — Thu, 25 Jun 2009 11:56:50 GMT

I found the image of the Dumb Bell M 27 nebula that I took with this scope. It was on the EQ 4 mount unguided. I don't recall the spec's for ISO or number of images stacked as it was a while back. The stars are a little elongated but a perfect image was not my goal that night. I did not do a very good polar alignment either so the stars a probably elongated in Declination. I just wanted to see how well it would wide field image.

Re: Imaging on a shoestring budget

johnjohnson — Thu, 25 Jun 2009 11:09:41 GMT

I got a chance to try out the 6" reflector on a DSO. This was taken at 4:00 am so dawn was coming and beginning to wash out the sky.This was 16 images of 10 seconds each at ISO 1600. Canon EOS XSi at prime focus. EQ 4 ( Sky View Pro clone) mount unguided. I used the 10 second self timer to eliminate the shakes. I just wanted to see if the reflector would focus easily and take faily good images. There was some vignetting so I croped it off. Processed with DSS, then GIMP, then PS elements.

This is what the images looked like before processing. I was surprized how the main images came out.

Re: Imaging on a shoestring budget

johnjohnson — Thu, 25 Jun 2009 03:52:34 GMT

tkerr,

Yes the upper inch and a half of the focuser draw tube simply unscrews and the T-ring can be threaded directly to whats left. I also noticed that the secondary is quite large. It's to bad the focuser is only a 1.25 inch model but that is common for apertures less than 8".

Re: Imaging on a shoestring budget

tkerr — Sun, 21 Jun 2009 15:06:44 GMT

That's interesting to know that you can thread the draw tube directly to the T-Ring. Essentially it's the same as using a lower profile focuser with a zero profile T-Adapter. Certainly a lot easier than modifying the tube to move the primary mirror.

Re: Imaging on a shoestring budget

galactic_photog — Sat, 20 Jun 2009 23:46:46 GMT

johnjohnson:
Low and behold the thing actually came to focus with room to spare.

Newts, at least properly configured newts, make great imaging scopes. I've been using a newt (originally an 8", followed by a 10") for galaxy imaging. The 10" newt focus point is 5-6" out of the tube, no problem for the mono ccd plus filter wheel (with the Baader coma corrector inside the focuser.

A primary mirror move (and upsize of the secondary) would easily allow for a Wynn reducer/corrector to be used in place of the simple coma corrector (the approach used on the expensive ASA and Orion Optics f/2.8 to f/3.8 newt astrographs). Don't discount the newt, it can work well for photography.

Robert

Imaging on a shoestring budget

johnjohnson — Sat, 20 Jun 2009 00:46:05 GMT

I have been imaging now for a while with a 120mm Orion EON ED refractor. I had an old Orion 6" F5 reflector sitting in the corner of the garage. Knowing that many reflectors won't come to focus with DSLR cameras I had not tried it.Just out of curiosity though, I decided to give it a try one night. I noticed that the upper part of the focuser could be removed and a T-Ring could be screwed directly on to the silver part of the focuser tube. This is it with the upper part of the focuser removed.

This is another view of the whole rig. This is not the mount I use for imaging but my quick grab and go mount. I use an EQ 6 for serious imaging.

The night I tested the rig to see if it would come to focus the Moon was out and a little past half. I decided to use it as a target. Low and behold the thing actually came to focus with room to spare. It makes a great wide field imaging scope at F 5. The Moon image came out sharp and well focused with no chromatic abbe ration. I also shot the Dumb Bell nebula with it but can't see to find the image any more. Here is the Moon shot though. It has been cropped as I could probably get 3 Moons in the field of view.

I picked this scope up used for $150 for a grab and go. It does do a fine job for what it is. The only draw back is with the upper part of the focuser removed, you can't use a barlow to up the magnification. In this configuration it can only be used at F5. I don't think there is enough in travel left on the focuser to use a reducer. Those on a tight imaging budget might consider looking for one of these used.