Other than for engineering and making a couple of adapters for this camera, the battle with equipment, collimation, and other excessive vignetting issues should be sorted out.

In many ways, this image is the actual first light for both the camera and the scope.

I wanted to shoot the Markarian’s chain when I had my AT65EDQ, but the wider field that gives the new equipment combination covers most of the Virgo Cluster so that’s what I went after. I could have framed it probably better especially considering that M100 is cut in half, but I’m overall happy with the results. With so many galaxies in the frame, I couldn’t resist and made a montage with some annotations.

I started with some Luminance (10mn at 1×1) before the meridian flip followed by some more Luminance… after 3.5 hours, I started alternating between each of the 3 color filters (5mn at 2×2) until… it was too low and polluted by horrible gradients. Out of practice a little there, I guess I got my maths wrong. I ended up with about 30-40 mn per color. At that point, I pulled the flatbox out and started shooting flats, I was a little anxious about this as I never took any flat with a CCD camera. It’s got a shutter and it typically needs 3-4 seconds minimum. These flats turned out to be decent. I had a good bunch of darks waiting for me at home to start processing.

Here’s the picture (click for full frame):

And here’s the montage with annotations:

• Date: May 11th 2013
• Camera: Moravian Instruments G3-11000 (Sensor maintained at -25 C)
• Exposures: ~ 5 hours of integration time (L: 600 s – 1×1, RGB: 300 s – 2×2)
• Mount: Losmandy G11 Gemini 2
• Imaging Telescope: Takahashi FSQ106EDX III @ f/3.6
• Guiding: Borg 50 mm – Barlow 2x – SX Lodestar
• Calibration: Darks, Flats, Dark Flats
• Stacking: PixInsight 1.8
• Final blending/processing: PixInsight 1.8 and Adobe Photoshop CS6 for the Montage/Annotations

I’ve just QC’ed the part and it’s spot on with my specifications. I’ll have this part anodized sometimes soon along with some other parts (RA and DEC covers for instance, probably some little parts like knobs too).

Next on the to-do list are all the parts for the RA housing (which is made of several thick milled aluminum plates) and the DEC housing. When that’s done, I will be able to start assembly most of the lower part of the mount. I can’t wait.

Front and Rear bearings are not exactly the same size (front bearing has a slightly bigger OD). I am using a SKF bearing to the front and a Timken to the rear. Both are made of two parts: the outer ring and the inner ring plus roller ring assembly.

Each bearing block was machined with tolerance of -0 ; +0.02 mm to guarantee a perfect fit between the block and the bearing outer ring. I still to use lubricating grease to ease the installation but no tool or force was required to slide them in.

It’s only when the RA shaft will be installed that the bearings will be locked in place. I will need to make and assemble parts for the housing and the shaft to complete that step.

While it’s always a waste of a minute or two to refocus when not needed, it has the advantage of being fully automated and will keep you from staying behind the computer to manually launch an AF routine.

I plan on modifying this script later by adding a test on either temperature and/or HFD so that the AF routine is only launched when needed.

Installation:

Extract the *.vbs script file in a known location on your hard drive. You can test the script by using the “run script” function in Maxim (File menu). To use the script to refocus periodically, first create your AutoSave sequence in Maxim and then select the Refocusing script on one of your Sequence Item.

Requirements:

• A camera connected to MaximDL
• A focuser connected to MaximDL
• This script can be edited to change the filter to focus on (Default is Slot 0)

Download

For this reason, I decided to move the focuser about 3″ toward the front of the tube. This will make the camera 3″ closer to the tube which will much more manageable in terms of momentum but it will also be safer as the flange of the Paracorr should be able to mate with the draw tube.

I first disassembled the whole tube which is mainly composed of 4 parts:

• Front ring
• Secondary assembly (spider + vanes + secondary mirror)
• Focuser
• Rear cell (primary mirror assembly)

Then I started taking measurements using a right angle ruler to locate the new spider holes. I am moving both focuser and secondary assembly by 77 mm. It’s important to make sure the new spider holes are well aligned with the original ones. I used a sheet metal drill bit and a hand drill for this job.

I proceeded the same way to measure the 4 mounting holes of the focuser and the large 3″ hole for the focuser itself. The only difference was that I relocated the focuser at 180 degrees from the original hole. I figured cutting too close would weaken the tube too much. I found 3″ sheet metal hole saw which did a very nice cut. I used “regular” hole saw in sheet metal before and using something designed for sheet metal really made a big difference on the quality of the cut.

I cut a 130 x130 mm and 1 mm thick aluminum sheet with 4 holes on a 102 x 102 mm pattern to cover the original focuser hole. While it did fit fine, it wouldn’t comply to the shape as well as I had hoped. So I bent it to shape by hand, very slowly. It took me about 30 mn to get a really nice matching shape. It was then primed and painted white (glossy) on the outside and flat black on the inside.

I then cleaned the tube of any burr before putting it all back together. I finally used my laser and barlow to get it all collimated. On the picture above you can see the tube reassembled with its focuser relocated 77 mm closer to the front. You can also see the original focuser hole (cover not installed). Also note the black rubber grommet on the side of tube. They are covering the original 8 mm holes for the spider vanes.

And on the last image, the cover has been installed.

It is decent enough in my opinion but after using a Moonlite focuser on my 8″ RC it is really difficult to be impressed by the quality of this stock focuser. Considering the weight of the camera that I will be using, I decided to once more go the Moonlite route. This time I chose a 2.5″ focuser with the High Resolution stepper motor upgrade and their “mini” controller which comes with Ascom drivers. I figured it would be nice to start using before the CDK17 is completed.

When ordering I specified a 12″ flange which is close to the OD of the AT10IN tube and also mentioned the model number. Moonlite made custom holes that matched the holes on the tube for a direct fit.

Quality is excellent. The installation of the drivers was trivial. They are Ascom compatible which makes it usable with most capture software which in turn allows for features like Autofocus for example.

I’ve already used and it performed perfectly, it had absolutely no problem lifting the close to 2 Kg camera.

Instead I decided to sell the 8″ and get an affordable 10″ Newtonian which I could probably modify to make it work decently with my new Camera. I went with the AT10IN which is f/4. I picked up directly in OPT in Oceanside, CA.

I got it a couple of weeks before the camera which gave the great opportunity to do some nice visual and get used to this pretty big tube… The G11 mount had no problem handling it. Views were pretty good although seeing wasn’t best. I had great views of Jupiter in the early morning.

The real first imaging light came a month later (10/06/2012). I usually do not go out if weather isn’t almost perfect but I really wanted to check things out, making sure I could reach focus, etc. It turns out the night was clear enough that I didn’t really need to wait for clouds to pass to do some tests which was nice. However, Dan Watt (who is always there to help me figure things out!!) and I realized that this imaging train (camera and Paracorr Type 2) needed to be really far to reach focus. Not only the Paracorr is very (~ 4″) long but it needs 57 mm of back focal distance which is obtained thanks to a custom made aluminum adapter that fastens to the G3 camera with 4 screws and with the Paracorr custom thread on the other side. In addition to this we had to use a 20 mm long extension and the focuser was almost all the way racked out. This obviously created several problems.

1. Being this far from the tube stresses the focuser which could be source of optical problems, collimation and mechanical flexure.

2. The Paracorr T2 does increase the f/ ratio by 15%, but even at f/4.6 it’s still a relatively fast system and being this far from the secondary can be the cause of heavy vignetting.

I was able to do a few 5 mn exposures of M31 and M45 through the clouds. Vignetting was obvious but light was able to get to the 4 corners, still it was some strong vignetting. After analyzing the subs in PixInsight I noticed that the stars were elongated in all 4 corners and it seemed like the elongation was kind of a function of the off axis distance. I have yet to identify clearly what is causing this but as a RC user, it does look like field curvature which is unlikely with a Newtonian. Could it be coma? possible although I’ve checked and the CCD is exactly at 57 mm from the base of the Paracorr which is the distance recommended by Televue, and it starts way too close from the center for being due to the large KAI-11002 chip. Could it be astigmatism due some distortion/flex of the imaging train? I am hoping that I will have the answer to this question soon.

Until then, I’ve started modifying the AT10IN tube by moving the Moonlite focuser by about 3″ to the front. This should substantially reduce the stress in the focuser/tube due to distance between the heavy camera and the tube. But it should also help with vignetting. I will post these modifications within a day or two. I plan on testing this modification on Saturday which should be clear!

I designed a complete drive system around the worms to host the motor/gearbox/encoder assembly, its retention and a spring loading mechanism that is here to insure proper contact between gear and worm with temperature variations.

The following parts composing the drive system are:

• Worm block
• Motor/Gearbox/Encoder assembly
• Motor retention bracket
• Back plate
• Retention frame
• Spring loading block

The worm/motor assembly pivots around one point to ensure a very small clearance on the other side. The mechanism relies on two shouldered screws. The spring block simply pre-loads two springs against the retention frame.

The motors will be controlled a Gemini 2 controller from Losmandy. The choice of the motors was dictated by several characteristics/limitations of the controller. Initially (for testing purposes) I will use the controller of my G11 mount but down the road (and if everything works…) I will get a second controller.

Update: Pinion/Spur are installed (glue in place with high strength thread locker. The motor was then adjusted to drive the spur gear on the worm with zero backlash.

About 3 months ago I had actually pulled the trigger on a Mono CCD but decided to cancel my order and just wait to see how my 17″ CDK project would be coming along. With the 500D not working I decided it was really time for a Mono CCD. I had originally thought of getting a camera based on the new Sony chips but such small chips wouldn’t be a very good fit for the CDK. Instead I started looking at full frame CCD based on the KAI-11002 chip which has much bigger (9 um) pixels.

My 8″ RC, its 2″ focuser and its complete lack of suitable field corrector for full frame cameras was going to be a problem so I ended up selling it and get the 10″ f/4 Newtonian from Astro-Tech.

I considered many different brands carrying a camera based on the Kodak KAI-11002 and finally decided to go with the Moravian G3-11000 with the 7x 50 mm filter wheel option. It has the advantage of having an internal filter wheel, well it’s not really internal but it comes already installed on the camera and you never have to take it off. Plus the Filter Wheel is fully operated and powered by the G3 itself, so no additional cable. Moravian offers MaximDL compatible drivers for the camera and filter wheel. And finally the camera comes with its own capture software package which makes the transition to CCD imaging even more affordable.

The camera came with the FW already installed, in a good quality aluminum carrying case. A high quality USB cable is also included along with an AC adapter, manual, and software on a USB flash drive. Although the aluminum case looks sturdy enough, I will use one of my Pelican case to carry the camera as I am just paranoid about dust.

What I call the “base” is composed of five different parts all made of milled and anodized aluminum. These parts are among the most massive parts of the project as they will support the whole weight of the mounting and telescope.

The “base plate” (or BP) is the bottom most plate and interfaces directly with the pier. It has a large centering hole in which the second part “azimuth adjustment plate” (or AZAP) sits. These two parts can rotate around the azimuth axis for azimuth adjustment. Note that the parts composing the adjustment mechanism are not shown in any picture here and will be detailed later.

Off the AZAP, the two “altitude adjustment plates” (or ALAP) faces each other. In between left and right plates sits the altitude adjustment mechanism.

I will mention again that I am only using my aluminum pier as a solid assembly bench and initial testing. It’s made of a couple of milled aluminum plates and off-the-shelves aluminum T-framing profiles and accessories.