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The AstronomersCassegrain
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Which telescope to buy?

Below are some of the telescopes I've used in recent years, ranging from ~30 -3000 dollars. (shortened for YTs character limits) Price $35 76mm reflector dobsonian mounted (Celestron Firstscope) Weight ~ 1kg (a couple of pounds) Setup time ~0 East of Transport 1 Short focal length- wide angle field of view. Finder not really necessary. Ultra cheap, good views of Moon, Jupiter Venus, rings of Saturn, bright, wide separation double stars, and brighter deep sky objects such as M13. I was not particularly impressed with the optics on mine, but for 35 bucks, you cant complain too much! Price $200 90mm Maksutov-Cassegrain, dobsonian mount (Orion Apex) Weight ~ 1kg (a couple of pounds) Setup time ~0 East of Transport 1 Longer focal length means smaller field of view for comparable eye pieces. I was impressed with this scope on the planets. It vastly outperforms the Firstscope on optics. The scope comes off the dobsonian mount on a quick release and can be mounted as a spotter scope (the main reason I got it). The dobsonian mount here (one arm) is exactly the same as the mount for the Firstscope. These are sort of the poor mans refractor. Great views of Moon and all the bright planets. Picked out Titan (brightest moon of saturn) with ease. I got this telescope for two reasons, firstly for outreach, in that you can just grab it and point it in seconds, zero setup time. Secondly I can mount it piggyback on the CPC11 (see below) and use it as a spotting/ guide scope. The Maksutov has the 'nice' feature that its a closed tube(helps keep dust out). The Mak. will have the edge on planets/ guidescope etc due to its longer focal length, but the Newtonian will be more all around bang for the buck. Price $600 10in Newtonian reflector, dobsonian mount (Celestron Starhopper) Weight ~ 15kg (~30lbs) Setup time ~10 mins to carry parts outside, 10 mins + cool down. East of Transport: Telescope is about the size of a small child (although not that heavy). It is big and awkward. Difficult to handle for the small. Almost the biggest telescope you can fit in a compact car (the reason I got it). The long open optical train requires periodic alignment (columniation) if it is frequently transported. Powerful deep-sky scope. Near zero photographic potential, but fantastic views of nebula, globular clusters and galaxies. Great scope for planets too. At this size the moon is getting too bright to look at for any length of time. Like most big newtonians, short focal ratio, which pragmatically means you get quite wide angle views. Again well suited to deep sky observing. Price $1500 90mm (3.5in) Stellarvue apochromat, -no mount, tube only (Apo Triplet) Weight ~ 4kg (~8lbs) East of Transport: The telescope is small and easy to transport. Comes with a bag that will go on an airplane as hand baggage. Worth the price for the aperture? Probably not unless you are in a fairly specific niche. This makes a great wide angle lenses for guided photography. As a guidescope its focal length is kind of short. That basically means the field of view for a given eye piece is wide. You need a very short focal length eye piece to get good magnification. I found myself using a 4mm eyepiece to look at planets, and even at that the image was small. As a finder scope though, that wide field is great. The other thing that these scope gives is absolutely beautiful stellar images. The stars just fall into incredible pin pricks. Beautiful contrasty flat views. I found the use of the short focal length eyepieces annoying for planetary use. Lacks the light gathering for versatility as a deep sky instrument. I only really ever used this as a piggybacker for the CPC11 below. Price $2800 11in Schmidt Cassegrain, driven goto alt-az fork mount (CPC11) Weight ~ 30kg (~65lbs) and thats just the top section. Tripods another 15 kg I think. Setup time ~30 mins to carry parts outside and align, 20 mins + cool down. East of Transport: It will fit in a compact car. To carry the telescope any distance really isnt an option unless you are strong. The ergonomic design is very good though. I always found mounting up the scope a bit of a bitch. Aligning it is relatively easy as the scope mount has a GPS in it that means you dont have to plug in these numbers and the time. Alignment is quite easy. I found the scope slips relatively easily unless the clutches are done up very tight. The scope can carry quite a burden (although of course when the scope weights this much extra, it does need to be well balanced). At this level it is an excellent photographic platform. It yields amazing views of almost everything. It's photographic potential is probably as good as you can get from a portable platform. This is the instrument I used to do the full rotation of Jupiter, although there the primary limitation was the stability of the sky.

Channels: Observational astronomy 

Added: 1763 days ago by Ordonomundi

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