New scope purchase

[multiweb]

Hi guys, I'm looking into buying a new scope for imaging. I'd like to get a Celestron NGT10 F4.7. As anybody had any experience with this model. and can recommend it. I have a G11 and I'm going to piggy back an ED80 and imaging with the QHY8 so I think it should handle the load. The reason I'm moving up in aperture is to go a bit deeper and increase the resolution in my pictures too. Do you think this scope will do it or do you know of better choices for a similer budget? Right now my image scale is about 2.5 arcsec / pixel and with this system I should be closer to 1.4 arcsec /pixel. Thanks for any advice. For the tube only I'm looking at spending $1.5-$2k.

[netwolf]

Marc, Eric Ezystyles used this scope for most of his work and he has produced some excellent images. I think Eric is using the Skywatcher badged version but they are the same scope. But unfortunately due to single distributor monopoloy this OTA is overpriced for what it is. It should be about 500$ but instead its priced around the 1000$ mark, which in my humble opinion is far to much for this scope. At one point this scope was sold sub 500 but i thin it was being imported indirectly and not through the Aussie distributor back then. I would suggest a GSO 10" or 8" would probably be better value for money.

I am considering the 8" version. As i think the 10" maybe a bit much even for the G-11. The problem is not the weight of the OTA but the tube length. The longer the length the more the turning moment Nm (newton meter) is, Force(=mass x gravity or acceleration) x distance. So you need to keep this in mind when considering mount capacity.

[bojan]

Fahim, the tube length does not have detrimental effect to weight capacity of the mount as it is balanced per se
However, the tube diameter does.. bigger diameter, the centre of tube mass is further from RA axis. That means the bigger counterweight (or further away, which is the same thing as inertial momentum is concerned).
On the other hand, the longer tube will pose additional load to worm gear (for the reasons you mentioned).

[TrevorW]

IMO a G-11 will handle the Celestron and guidescope with ease. Opt corp are selling this scope packaged on the equivalent of an EQ5 mount

Cheers

[multiweb]

Thanks for the replies. I agree the Celestron is expensive but wouldn't you think the quality of the mirrors would be better than the GSO? I have a lot of GSO adapters and eyepieces and it's good quality. I never checked their scope though. I was thinking maybe I should get a 10" DOB and use the tube for imaging too when I'm not doing visual. I always wanted to get a DOB eventually so that may be the way to go. Maybe I can push it to 12"? Mike seems to be handling a fair bit of weight on his mount so the G11 could potentially take it?

[netwolf]

The Celestron is made by Synta who aslo make the Skywatcher scope, and as far as i know they are both identical. The GSO mirror based on images i have seen from both, in my humble opinion would be every bit as good as a Synta mirror.

[theodog]

I have a 12" f5.5 (from Bintel) on a G11, works well and I recommend it for the budget.:D

[multiweb]

Cool - sounds good :)


Wow :eyepop: That looks like an elephant on a stick :lol: I can't believe it's on a G11. How much counterweight do you have on the shaft? Tracking alright? Also which model is it on the Bintel site? Thanks for the info mate.

I see you also got a 10" F4.5. Much difference in imaging with the 12"? Worth the upsize?

[theodog]

Hi
The "elephant on a stick" is a little from the perspective. Doesn't look that bad live.
If this link works it will show an early image with the 12, 2nd night.

http://www.iceinspace.com.au/forum/showthread.php?t=31078

http://www.iceinspace.com.au/forum/attachment_browse.php?a=43401

Counterweight is the standard Los counterweight + 8" plastic pipe filed with brickies morter with a 1" center plastic pipe, held on with hose clamps around the counter-bar. To be honest I have no idea of its mass,+ some woodworking clamps.

12" is the BT-302 $1099.00 (Gee'z I payed ~$799 at Easter '08).

The 10" started life as a Meade DS10. All that is left are the mirrors and holders. In its current form the tube consists of two high school science stools welded together end to end. It worked well and was the main scope for years -since '98, in many guises. The mirrors had their coating scratched by removalists so will be recoated and brought back into action sometime in the future.

In summery, the G11 carried the 10" and a 4" refractor guide easily for many years. The 12" is probably as much as I am comfortable with on it. But I have had no trouble and it guides well.

Good luck with you're buying.

[bmitchell82]

that is madness capturing mag 18 stuff. That just goes to show what a CCD or camera is capable of! if only Galileo was alive nowdays he would be absolutely besotted.!:scared:

[multiweb]

The photo angle certainly made the view quite dramatic! :) Thank you very much for all the information Jeff. Saves me a lot of guess work. Much appreciated. :thumbsup:

[gbeal]

Marc,
while I won't pour cold water on the "biggest you can" phase, I reckon the 10" f5 is as big as I would go. I have a home-brew 10" f5, and it is a great scope, perfect focal length, and at f5, digs deep.
It has suffered about 4 tubes so far, and the latest reincarnation is a truss C/F tube.
You capable of fabricating the tube? If so, simply purchase the optics and do the rest yourself. GSO optics are great, I have them in the 16" and had them in an 8" a while back. Can't go wrong, just make sure you don't skimp on the focuser.
Gary

[AlexN]

Marc, Take a look at Clive's "Alchemy" website. He's got a 12" GSO newt + ED80 on a G11 with a QHY8, his images come out brilliantly. I dare say that it will handle the 10" no worries... Also, Spearo uses a G11 with a C14 + WO66 guide scope and images no worries.. :) I think its safe to say your G11 will handle a 10" newt and an ED80! :D

[multiweb]

Yep. Seen it. But it's on a "permanent" setup and he's got a real good shed around it with roll off roof to cut the wind. I think 12" might be pushing it for a "going away" set up.



Thanks Gary. Yeah the idea of buying the optics crossed my mind. But at this stage I think buying one already made up might be fitting my budget better. By the time I'm getting a tube, a mirror cell and all the material not sure if I can match $1k or under.

[AlexN]

Marc, I wasnt saying go and get a 12" I was just saying that the mount will handle the weight of a 12", hence a 10" should be fine, even for a mobile rig.

In response to your reply to Gary, I think buying the complete OTA now is the way to go.. And start designing truss tube setup that you can build as a side project, then move the optics into that later... If you got the 10" optics into a carbon fiber truss setup, you may well cut its weight in half... Not only that, but it would not catch as much wind as a solid tube, and hence, better in breezy conditions.

I have been having urges to convert my C11 to a truss tube... unfortunately the SCT design is a lot less forgiving, if its not JUUUUUST right, things go pair shaped! FAST!

Cheers.
Alex.

[multiweb]

:lol: I don't think the 12" will fit in my Excel . Go buy a scope and come home with a new car? :whistle:

[multiweb]

I did some testing and measuring the past two nights. A 10" F/5 would give me 1.27m FL so I barlowed x2 my ED80 to go to F/15. That gets me 1.2m FL right? Guiding at prime focus through my Celestron with the QHY5 I get an image scale of 1.65 arcsec/pixel and the guiding typically bounces within 1 pixel so +/- 1.7arcsec. I image through the ED80 + barlowx2 with the QHY8. That gives me an image scale of 1.34 arcsec/pixel. Guiding errors show through the imaging scope unless I keep it real tight. I have attached a shot of the full field [ED80 Barlowx2] and although the sampling is good the stars are a little bit bloated. Imaging at prime focus on the ED80 without the barlow is not a problem but the image scale at 2.68arcsec/pixel gives me nice square stars after debayering. Bottom line is that I'm still going to image through my Celestron because at this stage I can't seem to guide good enough to image through a 10". I'll keep practising and meanwhile spend the grand in NB filters instead. :)