Buying a farm was supposed to get me some local permanent dark sky access, but between work, family and the farm the 16" has seen little work until recently. It has been so long that some of the sky looked foreign to me.
I made the changes to the dec drive and now it's pointing accuracy gets galaxies on the 1.4MP chip with half sky slews. That is very handy when you are lost and star hopping is a struggle.
I also made some changes to the moving secondary cage, to make focusing a little more accurate but I haven't exposed that to photons yet.
Astrofest next week, but I won't be taking the horse shoe this year as I won't be staying there long enough to justify moving it. Observatory is next on the cards.
Love the mount Justin, similar to something I made.
How did you make the horseshoe? It looks like your getting pretty good tracking, at 50x I can only get around 1 minute subs, think I need better polar alignment
The main ring is made from two pieces of 50x3mm flat steel bar and bent on a roller for curving steel and then held in a jig, brought up to a hot temp (nothing too accurate I just used an oxy flame reduce heating a cooling flexing) and welded with a 6mm gap between them to improve stiffness.
The photo is of the early stages of construction and testing but you can see the ring more clearly with the primer on it.
It has been a journey but finally having great results. Tracking and pointing are superb. I just need a better camera to let it stretch it's legs. Currently using a Meade DSI ProIII at prime focus, slewing halfway across the sky routinely getting the target object on the main imager. 10 min subs are possible but I go between 1 and 5 min depending on the object and the seeing.
Got the focuser sorted and passing photons proof with a shot of the Trifid Ned with 15 sec subs (the wind was really blowing at the farm four days ago). The old focuser was causing me issues with pointing as it was moving during slews and made alignment at bit off. Also caused slightly non round star images as can be seen in the Eagle Neb photo. You can see parts of the old focuser beside the dirty mirror.
Now I just need to clean the mirror it is hard to see under the dust, but it proves that you don't need perfect optics to get a reasonable image, but the fuzz around the stars is a bit of a give away.
In that I will hold off cleaning a bit more until I get a cleaner place to leave the scope, cross fingers, wrapped and trapped are not doing great in the shed at the moment.
Got the stepper drive working on the focuser now and works a treat. But there was some hurdles along the way. It wouldn't be an ATM project without a snag or two.
Remoting the filter wheel next.
Got the guiding working properly now, I had it set too aggressively and now it only needs a nudge every 10 sec or so. It was a mystery at the time as it was acting like it had pec error, but the band drive has almost no backlash and minimal pec error. When I turned guiding off the pec error went away and I could do 1 min subs with nice round stars. Presto software issue identified.
Three of the Grus quartet, very happy with the mount.
Some shots of the focuser system that I have put on top of the truss frame as well as the RA (third picture) and Dec (forth picture) drive systems for those that are interested.
It was a bit of a challenge to get the focuser to move smoothly but now it is going well. The band drive is fantastic, no noticeable PEC, pointing is reliable and no backlash, each step of each motor in either direction gives instant scope movement.
The whole point of the different focuser system was to reduce the distance from the secondary to the eyepiece or camera, hence reducing the need for a larger secondary and get a little bit more light onto the front of the camera and increase contrast. It has four tensioned pulley systems (first picture) around the top cage and two stepper driven actuators (second picture) on each side to move the whole thing in concert.
All of my recent posted images where taken with this scope and mount, with the old modified DSI Pro III you can see in the back ground of the focuser top image.
The next step is is to get it into and observatory and remote it from the house, bring on Sound Stepper.
I have now replaced the stainless steel drive bands with a synthetic minimal stretch bands that are used in industrial cardboard folding machines.
The old stainless bands were getting about 500 hrs of operation before cracks in the band caused failures and usually just before the end of an imaging run. (Murphy's Law)
The RA drive has improved a bit and the Dec has stayed the same, and to date it all works much better for reliability. Now guiding has become an unneeded with 2 min subs as the brighter objects max out the wells in the QHY23.
The moving secondary cage has had bigger springs placed in the pretensioning system which has greatly reduced backlash in the focusing system.
Proof is in the pudding and here are a couple of 10x60subs luminance to make sure I'm on the right track.
I'm about to start a 16" ATM project of my own, just wondering what f-ratio your scope is and your thoughts on the imaging fov you get with it? Do you wish it was wider/narrower or happy as it is?
The mirror is a 403mm GSO f4.5 and I started building it hoping that one day Sony would bring out a wider and better ExviewHad and presto they did in the 814.
These shots are unguided 60 sec subs and are 2x2 binned which matches the seeing most nights. The field of view is just what I was after as I can image galaxies at 1x1 with guiding and longer subs and get good detail if the sky plays nice.
Cheers Justin, I haven't decided on an f-ratio yet and this info helps.
I have been thinking about f5 with my 0.73x Wynne corrector which would end up pretty well corrected and approx f3.6 and 1460mm, a good compromise on fl and speed, but this is not set in stone yet.
good to hear it's all going well.
