….well I had promised to follow up on my my AG Optical iDK 10 inch F/6.7 and its long past due. I received the scope last May and between weather, glitches, day job and life, I have had little time to use it or report back.
As I previously noted, I had ordered the scope after speaking with Dave Tandy back in late 2014. It arrived in May 2015 and I set out to mount it and configure it on my MYT……
https://catchingphotons.wordpress.com/2015/05/26/oh-what-a-beauty-and-a-preliminary-review-of-ag-optical-i-dk-scope/
….fast forward and quick review.
-the scope weighs in around 32 pounds. It is sturdy and gorgeous to look at. Even my wife who does not relish my insomnia associated hobby remarked that it looks like a work of art! The carbon fiber charcoal black look contrasts beautifully with the machined red.
-mine was the first 10 inch truss model made and you can see it on AG Optical’s web page. During the time that I ordered it, Dave was not supplying the optical reports that he is now issuing with each scope. I wish I knew what my mirrors strehl is but they seem to be well corrected.
-The MYT required approximately 40 pounds to balance the scope when outfitted with the camera, OAG, and adapters. The mount seems capable but you are close to the limit and I found that for perfect balance I needed the extension bar. My MYT saga is long and protracted and I will not delve on it here. In the end, I ended up upgrading it to an MX+ and now in retrospect this scope is much better suited to a heftier mount such as the MX+.
For those interested in this scope, I am not stating that an MYT or Mach-1 cannot handle it but just be aware you are close to the limits.
So after a frustrating fall of sorting out issues and trailing stars I finally mounted this scope on the MX+ and immediately saw that it was happy on its new home.
I will outline my setup in the next few paragraphs and relate some of my experiences:
SETUP
The scope is easily lifted by one person using its side dovetail plates. It slides easily onto the versa plate of the MX+. I find that with my setup using a QSI 683 wsg-8 and ST-i auto guider and spacing adapter, that the scope balances easily just slightly forward of center on the versa plate. I still have ample room forward on the versa plate, and in fact the front retaining bolt does not even engage as the dove-tail on the AG Optical is short. The middle and back bolts secure the scope easily and securely. RA balance is easily achieved with about 50 pounds (I use two 20 pound weights all the way up on the counterweight bar and s smaller 10 pounder slightly farther down).
The TCF-S3i focuser is hefty and very solid. you will need some sort of spacing adapter to reach the focus plane which is about 11 inches back. There is a lot of back focus which is good if you plan on adding a rotator and such. I use the Optec large 3 inch spacing adapter which is secured by three large thumbscrews and then attached to my camera with another three thumb screws. This works but you have to be careful to keep everything centered with all the thumbscrews. I will probably have a precise parts adapter made that will thread onto the camera and thus eliminate one thumb screw junction.
I had a Dewbuster made special with some 5.5/2.1mm 12 V ports. It sits on the top dove-tail plate and I plug-in the two dew heaters (primary and secondary) as well as the fan into it. I am mac based so I ordered my scope without the thermal control system and simply rely on the dew buster. The dew buster is powered via powerwerx power pole distributor. This is the small version that has 4 ports. I have a 12 volt line running through the mount that supplies power to this distributor. This in turn supplies 12V to the dew buster and supplies power to my QSI 683. I also have two USB runs through the mount, one for the guider and the other for the camera. I connect the TCF focuser via a small RJ12 cable to the USB port on the versa plate. The focuser is also powered by the 12v port on the versa plate. In the future I will add a rotator that can connect to the other versa plate USB port and draw power from the dew buster.
I connect the two USB lines from the cameras and one from the mount to an Icron Ranger and then run 150 feet of CAT5 from it to my desktop computer inside. I can control everything from the warmth of my home office.
As an aside, the MX+ is actually surprisingly portable given its capacity and heft. It is an easy thing to simply carry it out on my ATS pier from my basement to my patio. I then add the counterweights and scope and proceed to polar align, T-point model, etc. I can leave the setup outside under a tele gizmo cover for weeks on end without issue or change in my polar alignment.
COLLIMATION STRUGGLES
….full disclaimer. This was my own fault and let it serve as a warning for any fellow OCD sufferers out there. PLEASE WAIT UNTIL YOU HAVE AN IMAGE UNDER THE STARS BEFORE YOU MESS WITH THE COLLIMATION!
You will need to unscrew the primary baffle in order to collimate with a laser or tak scope as it prevents a clear look back on the the corrector lens. Use a Tak scope and laser if you like but keep in mind my experiences below…..
When my scope arrived, I set everything up and used my Howie Glatter laser to check the collimation and alignment. Here are a couple of issues….the slip in nature of the laser does not result in a very repeatable position despite a compression ring. Be careful if you use one, that it is not leaning downward due to gravity as you secure it. This was my first mistake….secondly, it is pretty bright and it is difficult to really see if you have the laser falling back on itself (supposedly there is now a dimmer for these lasers, probably something I will pick up at some point).
So with my laser in hand I noticed things seemed off so I decided to center it all up. All looked good until I got out under the stars….my spider vanes now showed a splitting diffraction spike??? I wasn’t sure what was wrong until I spoke with Dave and then made the acquaintance of one great guy Dan Wilson! Dan has become a great friend and I look forward to sharing a drink with him someday. He has been patient and really helped me with a lot of issues. Dave would confess that Dan really knows these scopes. He tinkers with them frequently, and I am sure he has taken them completely apart!
Turns out that when I was re-centering the laser and I adjusted the spider vane centration, I was actually mis-aligning the opposing spider vanes. The fix required carefully measuring the distances until I had them all equal.
With that fixed I went ahead and finished the collimation with my laser but yet my images under the stars were still elongated, particularly in my upper left corner.
Next I resorted to a Tak collimating scope. Using it was fairly easy and I believed everything was lined up; yet when I checked with the laser they now did not agree at all. What was up?? I could not figure it out…no matter what I did the Tak and the laser would not agree and the stars looked worse! Dan to the rescue…he suggested I loosen all the truss rod connections and actually move the ring until I was well centered using the Tak scope. So as scared as I was, I went ahead and did this with the help of my son. He would adjust the ring while I was looking in with the Tak scope and then I would quickly begin tightening while checking with the Tak scope and he holding everything steady. Once secure I now finished collimating with the Tak scope. Now I checked with the laser and things were very close in agreement. Good enough! I would not do another thing until under the stars.
Dan had shared with me a document he was involved with on Collimation. It can be found here:
http://www.deepskyinstruments.com/truerc/docs/DSI_Collimation_Procedure_Ver_1.0.pdf
I studied this carefully and armed with it in hand, my collimation screws labeled and marked, my large 27 inch iMac taken outside I proceeded to start collimating under the skies. I used the SKYX 3D star profiler to look at the energy levels of my out of focus donuts. I also used a little freeware program written by a fellow paramount user that would create concentric circular overlays on the stars. Using these I was able to really see on the iMac the subtle changes I was making to my stars. I started with collimating the primary which needed barely a tweak. Next the secondary..gradually making the appropriate changes as described in that document and then bringing focus tighter. Re-check the primary, then continue to with the secondary until it looked as good as I could get it.
FINALLY! perfectly round stars in all corners. I used pixinsight to measure eccentricity on a 10 second exposure and it was .36!! Success and relief.
MINOR ISSUES REMAINING
I have a few outstanding issues that are not related to the scope. I have noticed occasional internal reflections particularly on the bright stars. Looking at my Flats particularly using an HA filter one can see the internal reflections that appear to be coming from my imaging train. I also have some pretty bad dust motes on the CCD screen.
At Dan’s suggestion I purchased some Rustoleum ultra flat black camouflage paint and painted the inside of my extenders and adapters. I’ve also gone ahead and cleaned my cameras CCD window. The new Flat looks much better…
I will admit that dust has been a problem for me. Dave supplies a shroud and fabric shower caps that cover the secondary and primary baffles as well as the outer ring. Unfortunately when mine was made there was no primary bucket cover. It appears he now includes this with these scopes. I have asked to purchase one for my scope although it will not secure well due to the design of my scope. He has added threads to the primary ring of more recent models so that this cover will fit secured. I will figure out a way to secure it with velcro and hopefully keep the dust off of the primary. It should be here in a few days.
THE REAL FIRST LIGHT
So after all the issues sorted out, a new capable mount underneath, and a couple clear nights in December I finally was able to acquire a few hours first light with this baby. These two images were just 3-4 hours in Ha and will be completed next season but what I have more than pleased me.
Stars were round and crisp, details sharp and contrast great. I’m happy and ready for some good nights of imaging this spring (if the New England clouds and weather ever cooperate).
CONCLUSIONS AND OBSERVATIONS
The scope is a real winner. I am very pleased with the finish, construction, and in particular the light weight. Once my collimation woes were sorted out, I have not needed to touch it again. It has been several months without any change in the appearance of my stars or collimation. This, despite transporting the scope in and out of the house.
I do not have the Temperature compensation module but using a simple dew heater I have not had any issues with dew.
The fans work quite well bringing the scope to ambient quickly. I have noticed that with the fan at anything other than the lowest setting, my guide star really jumps around. Perhaps there are some gradients or tube currents coming across the primary or secondary but in any event setting it to the lowest setting takes care of it.
I use @focus to automate my focus runs. The TCF-S3i works perfectly with it. In fact I have noticed that the focus barely changes despite significant drops in ambient temperature. These scopes are very thermally stable.
Lastly, Dave Tandy has been great. I have emailed him quite a few times and he has always been patient and responsive. He is a great guy and makes a superb product. This 10 inch Truss iDK that he was more than happy to make me even though the design was closed tube at the time, is exactly what I was looking for…. reasonable aperture, relatively fast and very wide imaging circle that I can grow into.
Clear Skies!
