I have a fever!!!

[cloud_cover]

After all those shifts, overnight at Puggai, I came down with afever. Doc says its APERTURE FEVER!!!!
As you guys know, when I went to Punggai I said I'd wait a year before a scope purchase, and I was eyeing at Astrotech 8" Newt on a CG-5 goto type for lots of astrophoto work (and some visual) - After reflection on my horrible behaviour that night (I spent a lot more time behind my camera and Orly's mount than I did actually look through a scope. In fact I hardly looked through the scopes..... ), I think my instinct when I see something nice is to whip out my cam and have a go.

So I guess when I think of a scope, this is what I want:
1. Reasonable budget. Up to USD 2000 give or take a little, inc shipping and Joo Beng's profits.
2. Good, versatile photo platform. Mods like coma corrector acceptable
3. Good viewing platform with bright views and contrast. This tends to come with increasing aperture size.
4. Reasonably mobile - at least can fit in standard car boot for field trips.
5. At least 8" aperture in a good quality reflector. Need for collimation acceptable provided its needs be done once per session or occasionally twice, not every hour or every movement.
6. Reasonably rapid set up: Unlikely to have much field trips so quick setup at near home location for an hour or two's peeping is probably going to be the most frequent mode of operation. Long cooldown SCTs/Maks are out.
So I was doing some "market research" when I came across these options:

Celestron 8"Newt on CG-5 Goto (C-8 NGT) USD 1099 or
AT 8" Newt on CG-5 (Can do for around the same price, slightly heavier)
f4-f4.7, fl generally 800-1000mm
Pros: Cheapest setup, my original idea. OTA (16-20lbs) within load limits of mount (35lbs) for astrophoto with space for adding DSLR (3lbs), future guidescope + autoguider. Lightest setup, may be marginally considered grab-and go. Known to have good images with coma corrector. EQ mount allows long exposures. CG-5 may allow use of camera alone as a tracking mount for wide field long exposure.
Cons: Smallest aperture. AT scope bigger central obstruction than Celestron.

Celestron 10" Newt on CG-5 (C-10 NGT) USD 1299
Pros: Bigger Aperture. If 8" can do good pics, 10" should be able to achieve at least similar result. Same pros for independent use of CG-5 as tracking mount for camera.
Cons: Heavy for mount! OTA (36lbs) alone heavier than specified load for mount (35lbs). Plus camera, guider etc etc. Reviews show pics possible but vibrations a big problem and even a breeze is a killer.

Orion SkyQuest 12XTG (12" GOTO DOB) USD 1599.
1500mm, f5. (something)
Pros: Biggest aperture, value for money considering aperture. GOTO mount, still car transportable (marginally). GOTO allows some extended exposure times but will not allow for field rotation.
Cons: Non-EQ mount will result in field rotation, unable to use for extended exposures. Lack of removable mount means no "grab and go" tracking mount for camera only (used for wide field). Long focal length (1500mm) means large targets like M31 and the whole of Orion will be too large for its field, even with 0.75x reducer (which introduces vingetting). Not designed with photography in mind: Not sure about possible vignetting, sufficient back focus to focus on DSLR sensor plane.

HELP!!!!!!! (And to think this is just pre-research research!)

[Gary]

I had the same concern about cool down time for Maks. Consulted a few local experts and the answer is that this is a non-issue in countries without much drastic temperature changes from indoors to outdoors. Tried my Mak in Singapore and Punggai and have proven this to be true. I don't remember waiting for anything to cool down. By the time (a few minutes) I finish setting up my scope, I can use it immediately. So my advice is to reconsider SCT/Mak in your research unless you intend to bring your scope very frequently overseas to colder climates.

You have not own your very first telescope yet, so this is not considered fever. Don't worry. It will come after you own one. So much for waiting for a year.

[orly_andico]

hi kelvin

the mount weight rating is usually over-stated for the Chinese mounts. And, if you want to do imaging, you must use HALF or even less of the weight rating. So a CG-5 (claimed 35lb) would only be good to about 15lb for imaging.

Also the Chinese mounts are not too well-made, so you would need to autoguide them. That means you need a computer and power.

As I mentioned in Punggai, for astro-imaging its the numerical aperture (the f-number) that matters, not the actual diameter. Thus the most usual imaging scope is a fast refractor. A 50mm f/2 will take images in less exposure time than a 200mm f/4, even if the 200mm has twice the diameter of the 50mm.

If you're after diameter / aperture because you want to observe visually, it's a whole different story. Imaging and visual don't really mix.

If I were you and were going to spent USD 2000, I'd get the best mount I can buy, say a Vixen Sphinx or GPD2, and use whatever's left for a refractor, you'd have probably USD 500 left over. Get an Astro-Tech 102mm or something.

If you really want a big scope and still do imaging, I'd suggest a Sphinx or GPD2, and the 8" f/4 imaging newtonian. Make sure to buy the Baader MPCC for it.

Or the Vixen VC200L (more upscale!) but it costs a whole lot more. Whatever you choose, for the love of all that's holy get a good mount. :-) You can re-use and re-use the mount even as you change scopes, but an under-size mount will have to be gotten rid of, when you get a bigger scope.

[timatworksg]

Hi cloud cover

I like your style for whipping out your cam! Makes for great shots..really!!

It's hard to come to a compromise on a scope for both visual and imaging at the same time with a comfortable size and weight. Personally I find the Maks/SCT's great for visual where they are 5" to bigger! Imaging with these scopes are tricky and may end up more frustrating with their focal range which can deter the unsure beginner imager.
Refractors/Reflectors are great for Imaging. A 3" to 4" (80-120mm) refractor makes a good imaging scope with reasonable wide FOV and enough mag to pull in the DSO. Visual wise they won't show the full splendor of the Jewel Box, but since you are imaging, the pic will show this to you...though not 'in your face' zoom! However the clarity from an image on a 80mm scope will show alot. Which is why I hardly look through my C8..as the image shows what I need to see if I were to!
Larger size refractors come with seriously Heavy and long loads!! Making it not practical for solo work...lol! Hence the Reflector...but size makes the scope grow...but lighter! Maks and SCT's are hybrids of the 2 but though not entirely unsuitable for imaging...just not fully built for it in it's entirety. Some have gotten good pics...so it's alot of trial and error.
Through the time I have gazed upwards...I resolved, personally, that a Good quality mount (GP or GPD2) is great for a 3-4" refractor with DSLR and guidescope set up for imaging. Leaving a 6-8" and above Compound scope (Mak/SCT) for pure visual. Even with a mount capable of a 8" you'd still need weight on the scope to balance it as Maks and SCTs are bottom heavy!
Unless you have huge cases and can lug everything by a car to and from a car park to Ob site...then no prob if large mount and scope!!
And don't forget the biggest spoiler of imaging....lug everything, set up, point north, perform 30-45mins of aligning, adjusting, find subject....CLOUDS...tons of them!!! Then,..reverse procedure and head home....sob sob...been there done that!

Well my 2c...Sharing the experience to not help decide but give you a perspective of what you could expect.

[cloud_cover]

Thanks for the replies!
Sorry, I've been at work every since posting and very "shack"
I get the idea that the mount is very, very important. Unfortunately there's a very steep jump from a CG-5 to an Atlas EQ-G/CGEM then on to a CGE!!!!!
Shall pen further reply once I get my brain functional again, preferably after a long, long snoozing session!

[orly_andico]

hi kelvin

that is true.. the big mounts are fantastic but cost a lot and weigh a ton.

I think the best buy is the GP-DX or Sphinx SXW.. good to about 16lb - 20lb (so use half that for imaging). somebody was selling a Sphinx SXW some months back for $1800 SGD.

If you can buy 2nd-hand, I just saw a Losmandy GM-8 for $800 USD, although it had no tripod (I passed on that one).

[Chris]

The Sphinx is an awesome mount from experience, but will take a team of beefed up water polo players to carry. As for the VC200L, collimation is a headache, and is POOR for visual.

A mak is advisable, but will result in soft stars due to the >33% central obstruction.

As Ming Lee and other professionals always suggest, get a good 4-5inch apo instead. There is a new contender in the market called a mak-newtonian. Excellent for visual, as well as good performance for astrophotography. You can also consider that, only problem is cool down, but a cooling fan will be easy to install.

As for the mount, get it off Singastro. I have been trying to look for mounts all over the place and the most cost effective/ convenient place to get it is here. However, you will have to be patient and lie in wait for a good offer.

[cloud_cover]

Thanks for all you comments! Now that I'm more lucid.....
I now understand that mount is actually more important than scope.
I'm thinking of a CGEM. I've always wanted GOTO and it seems the computerized controls are better than the Atlas and does not need Polaris to be visible for a reasonable alignment, even though the Atlas is quieter on slewing. Of course I'd love to get a CGEPro/G11/SPD2 but I can't quite spring for that much cash.
I'm eyeballing the Orion 8" f/4 imaging newtonian with Baader MPCC as its short (28" !), light (16lbs) and has a CO 28% (AT has 34%. Maybe that's why it needs contrast enhancing baffles). I still am twitchy for a 10" though..... must be so nice.......
Orly: I agree f ratio is very important for exposure times although higher apertures give greater resolution. And yes, get a good mount ;)
Tim: Thanks for the advice on SCTs and Maks. For me though I'm thinking of newtonians due to the f ratio since the high f ratio on SCTs and Maks (not to mention long focal length) will require very lengthy exposures. Refractors are nice but I want some aperture too! If I can only have 1 scope I'd like it to produce nice visuals as well as nice pics. A tradeoff, yes.
Chris: Mak Newtons are nice but they do cost a premium. A Newtonian with MPCC is far cheaper, size for size.
Now does anyone have a CGEM to sell?

[orly_andico]

CGEM is a good choice, but most people would go for the Atlas. Reason..? CGEM still has teething problems, just last month someone on the CN mailing list ordered a new CGEM and it was busted on arrival.

Now sending it back to Celestron is not a huge deal if you're in the US, but if you paid $500-odd to ship it to Singapore, getting a busted CGEM would really get your goat.

There's this shop called "available astrogear" in HK -- maguro77 tipped me off to it -- they have a Takahashi EM-10 (non-Temma) currently for sale at 10,500 HKD which is about 1800 SGD. It is not GoTo, but it is a Takahashi. EM-10 is rated for 16lb imaging, so although on paper it is less capable than a CGEM, in reality I would go for it rather than the $1300USD CGEM.

And I agree about the imaging newtonian -- an MPCC will fix the coma problems and it's relatively short unlike the %$^%$!! long SCT's and Maks. Orion makes a 190mm Mak-Newt though for $1200, which is like 4X the price of the AT8IN. So I'd go with the Newtonian definitely, also usable for visual because it's 8" aperture.

As for resolution -- it's not as important as you think. Most DSO's are large (unless you are gunning for Arp galaxies or the Pillars of Creation). And normally the atmospheric seeing limits resolution to about 2 arcsec, so having a scope with more resolving power than 2 arcsec will be wasted most of the time\. a 130mm refractor would already hit that 2 arcsec resolution with normal-size sensors (about 6 - 8 micron per pixel). That's 5" -- so something like a 7" Newtonian would be about equal. Any more than that.. you'd be paying the price of huge weight and not getting any more resolution.

A big scope carries along with it an even bigger mount, to the point that observing becomes a huge chore.

Note these observations are for imaging.. for visual, bigger will always show more detail and a brighter image.

[cloud_cover]

CGEM is a good choice, but most people would go for the Atlas. Reason..? CGEM still has teething problems, just last month someone on the CN mailing list ordered a new CGEM and it was busted on arrival.

Now sending it back to Celestron is not a huge deal if you're in the US, but if you paid $500-odd to ship it to Singapore, getting a busted CGEM would really get your goat.
.

*ahem* Astrobargains *cough!*