I have been imaging now for a while with a 120mm Orion EON ED refractor. I had an old Orion 6" ST F5 750mm reflector sitting in the corner of the garage. Knowing that many reflectors won't come to focus with DSLR cameras I had not given it a try. Just out of curiosity though, I decided to give it a shot 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 adapter on the silver part of the focuser tube.
This is another view of the whole rig. This is the mount I used for imaging here on this thread and is also my quick grab and go mount. I used an EQ 5 clone. I will modify it for guiding later in this thread.
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 750mm. The Moon image came out sharp and well focused with no chromatic aberration. I also shot the Dumb Bell nebula with it but can't seem 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 (Focal Length). In this configuration it can only be used at F5 750mm. 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.
20" F5 Obsession, OMI mirror .987 Strehl. 10" F4.7 reflector OTA. 6" F5 ST reflector. 120mm F7.5 EON. 80mm F11.3 guide scope. TeleVue 31mm T5. 27mm Pan. 22, 17, 12mm T4's. 8mm Ethoes. Baader Hyperion 21, 17, 13, 8, 5mm. TeleVue 2X 2" Powermate. Zuhmell 2" ED Barlow. SkyWatcher EQ-6 SynScan GEM. Vixen Polaris GEM, DA drive, mod for ST4 guide port & Celestron CG5 2" leg tripod. Canon T1i. Orion SSAG. Logitech 300 w/ MOGG 1.25" adapter.
johnjohnsonLow 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.
Have A Nice ...
Find me on Google PlusEquipment:
Orion XT10 Classic, Celestron C6 R-GT (CG5 GT mount), C80ED
Canon EOS 350D, Canon EOS 50D, Meade DSI II Color CCD, Phillips SPC900NC
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".
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 5 ( 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.
I found the image of the Dumb Bell M 27 nebula that I took with this scope. It was on the EQ 5 clone 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 are probably elongated in Declination. I just wanted to see how well it would wide field image.
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 EQ 5 clone 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!
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 EQ 5 mounts. using dual axis controllers. The clone mounts can be found on Ebay by typing in the following search description.
CG-5 type Dual Motor Equatorial Telescope EQ Mount
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.
Got another chance to test out this rig. Shot from backyard in town. 60 images of 45 seconds each. Canon XSi at prime focus, ISO 800. Guided with SSAG and PHD through a 60mm Celestron refractor. 6" Orion short tube reflector. No flats, No darks. processing was DSS, Gimp. PS.
Back in June I took an image of the Sun and spot group 1019. Single shot With XSi. Image cropped to show group. processed with PS elements 6. False color added to enhance spots.
pretty cool shots JJ. I've always wanted to use one of my reflectors with my DSLR, but focusing remains a problem. I even purchased a zero profile adapter, which didn't help. I thought about maybe adding a low profile focuser, but didn't want to spend the money when there's a chance it won't help either. So I just keep using the refractors for imaging. With the skies the way they've been this year, there hasn't been much imaging going on anyway!
"Good friends are like stars, you don't always see them, but you know they're always there."
Equipment (so far): C6R-GT, C 80ED, Orion XT8, Orion XT10, Coronado PST, Zhumell 20x80 Binos
Have you tried Barlowing your reflector? When imaging with my refractor, which has graduations on the draw tube, I all ways right down the settings for the different optics. I found that at prime focus and barlowed, there was a difference of 3 cm of out travel provided by the barlow. This could quite make the difference you need to focus.
I have done FOV indicators in The Sky 6 and my Canon XSi has a very equivalent FOV to a 27mm Panoptic. I therefore use the Pan to center and adjust my field. That is the equivalent to a low power EP. We know that Barlows extend the eye relief of low power EPs, so it should do the same for the camera. I have not tested this on a reflector but it could be true.
You didn't need the Shoestring interface box with the Orion SSAG, right? The SSAG can conect directly to the RG cable from the hand controler and to the computer USB?
I want to do that to a Vixen DD1 and Shoestring shows a picture of the solder points for that controller.
That's correct. The SSAG cable hooks Directly up to the new port just as if you were connecting it to the guide port on any other mount. You will have to set your hand box directional slew speed to it's lowest value, in my case 2X. I found it to be a very easy mod. You will have to work on your mount to get as much backlash out of it as you can.The motors themselves have plenty of built in backlash! I would not want to image with this mount at much over F5 or 750mm due to the backlash.
Good luck on you mod.
That's what I thought. One of the reasons I got the SSAG was because of the opto-electronic circuit. My split ring uses a Losmandy G11 controller and they need the SBIG relay or an isolated circuit in the guide camera. I'm using Vixen MT1 motors on a CG-5 mount because it has a little more capacity than my old Vixen GP, be nice to hook up an auto guider to it.