Monday I took delivery of a GSO Truss Newtonian through Bintel. I thought it might be worth advising people what I thought of my initial impressions.
First up, the price is very good for what you are getting and the delivery was very prompt.
Next the box for this thing is huge. I could just get it through our front door. The telescope is well supported by polystyrene packing and the box is two thicknesses of cardboard. See the photo
Whilst the scope is large it is easy to lift. In fact it is easier to lift than the 12" RC that GSO make. The build quality looks great. Everything is well machined and put together nicely. The back supporting plate is one piece and appears to be quite rigid. It has three fans which are placed 120 degrees apart. The primary is a conical mirror which will aid cooling. It appears to be adhered to the back plate. Collimation is done via three sets of screws with one moving the assembly and the other acting as the locking screw.
The back focus is about 180mm from the plate which supports the focusor (ignoring the focusor will aid in getting adapters sorted if you intend to use an Atlas). That plate seems to hold the focusor really well and helps stabilise the secondary assembly. The secondary assembly seems quite rigid with supporting poles inside the secondary cage. It will be interesting to see if it supports my STXL sometime in the future.
After some collimation I took an image of a water tower 5 km away from our home across the valley whilst the scope was sitting on a bench. The resolution is pretty reasonable I think, of course star testing and imaging will confirm my thoughts on the matter. See photo.
One thing I have noticed though is that the truss needs a shroud as light can be seen entering into the focusor from bottom of the secondary assembly. It's not a big problem and it can be alleviated really quickly.
Another thing GSO could do to improve this scope would be to install a secondary heater. I would expect the secondary will dew up quickly without a dew heater. Kendrick make a dew heater which I am expecting delivery of in next day or so which will sort that problem.
Those minor things aside I am expecting this scope to be as good as their RC's. Bang for buck is going to be high and I am looking forward to imaging with it. It will be a light bucket compared to RC and I am hoping it will perform every bit as good as that scope.
Thats awesome Paul looking forward to hearing your opinion of it. Ive been looking at 12" newt options myself although ideally I would rather an f5 . The tube version of this seems to have a lot of structural issues and flexure so hoping this solves some of the issues otherwise my next options are a big jump price .
Thank you for sharing your first impressions Paul. The telescope looks very impressive. I have been entertaining an idea of going a similar path (a fast Newtonian for imaging) so I will be following your journey with this beast
Looking really good Paul! The GSO optics have been top notch for quite some time, just been waiting on their mechanics to catch up
What corrector are you planning on using?
Colin I have been an advocate for GSO optics ever since they were first sold here. I had one of the very first 8" RC's and despite all the negative talk about them I got some nice results.
I am awaiting a Baader MPCCIII. I will also consider a Wynn if that does not work.
Quote:
Originally Posted by spiezzy
hi Paul congratulations on you new scope I have the 10" version and it is great I love mine to death the only issue I have was the collimation but but with a little exploring I managed to solve the problem quite simply see image .
the secondary housing in mine had some flexure and when pointed in different areas of the sky it would loose collimation so a quick trip to bunnings and $45 bucks later it is as solid as a rock I can flip it upside down and the collimation does not budge that was with my scope this might not be the same with yours I also added a moonlite focuser to mine but the original focuser is quite solid
can't wait to hear your first light experience with it
cheers Pete
Quote:
Originally Posted by John K
Hi Paul,
thanks for sharing your initial impressions. I was looking for feedback on this scope in this thread so what you have posted is useful,
- Just wondering if you can confirm the 180mm back focus (is that without a focuser?)
- What coma corrector do you plan to use?
- What are your initial impressions about the rigidity of the top cage assembly where the focuser is?
Clear skies.
John K.
John, that 180mm is what I measured to my sensor from the mounting plate, not including the focusor.
The top cage looks ok to me but imaging will soon tell me what is going on. I did not feel any loose components at all but taking a look at spiezzy's mods it could be on the cards. Time will tell.
I received my 12" scope from Bintel yesterday over the ditch here in NZ. It's a beast! See image attached compared to my 10".
Pretty much agree with everything Paul has said. However I wish the front section was beefed up a little. eg as per the SkyVision or Hercules newt astrograph design.
I will be using my GPU corrector rather than my Baader MrkIII. I tend to get smaller tighter stars with the GPU.
Moonlite focuser is now attached with a adapter from Ron.
Dave, did this have a straight fit or did you have to do some cutting? The flange kit looks bigger than the hole to me. See photo of my base plate?
Quote:
Originally Posted by DaveNZ
Hi Paul, which secondary dew heater did you purchase.
I'm struggling to find something the correct size.
Thanks Dave
The one I was initially sent did not fit but I believe the Kendrick R200SS does fit correctly or is very close to fitting correctly. I'll let you know how that goes.
[QUOTE=Paul Haese;1319099]Dave, did this have a straight fit or did you have to do some cutting? The flange kit looks bigger than the hole to me. See photo of my base plate?
No cutting. The adapter is made for our GSO truss newt.
You remove the GSO ring with the four screw holes. The Moonlite adapter fits in the hole and has a screw ring which screws in from underneath and clamps the adapter in place. the top section of the Moonlite adapter is wider than the GSO focuser plate.
Paul, I noticed that there are several tapped positions for the dovetail mounting plate but none inline with the focuser/imaging train. This causes an issue with balance. Your balance changes as you move across the sky through the zenith.
Seems a design issue. Probably need to shift the focusing plate/focusing position.
Paul, I noticed that there are several tapped positions for the dovetail mounting plate but none inline with the focuser/imaging train. This causes an issue with balance. Your balance changes as you move across the sky through the zenith.
Seems a design issue. Probably need to shift the focusing plate/focusing position.
I rotated the entire secondary assembly and recollimated. All fine now. That puts the focusor in line with the RA shaft in the traditional park position. Took about half an hour to sort that.
I rotated the entire secondary assembly and recollimated. All fine now. That puts the focusor in line with the RA shaft in the traditional park position. Took about half an hour to sort that.
I would be interested to know exactly how you did that. Did you remove to top section from the truss and rotate ?
I undid the bolts from the truss which hold the cage in place and rotated. It all matches so rotation is easy.
Thanks, I just popped out to the observatory and had a look.
I have some Bobs nobs and springs but I think I'll just use the GSO set in the mean time.
I'm rather impressed with the conical mirror. I wasn't expecting that. This means a simplified cell design. You would think GSO would advertise this as a point of difference.
