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Irrational lure of Refractors


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I'm not entirely convinced that the choice is irrational. In Spain, the Tal 100rs goes for about €250 which is about the same price as a Skywatcher 150p.

So, I started reading the reviews across the internet (in various languages), and the Tal just kept on coming up trumps: clean crisp views, no star spikes, no coma, no mushy views, scant aberation, pin point stars, no cool down, fantastic optics which are almost as good as ED glass, great for LP city use, no messing with colimation, kind on cheap EPs, and the such.

For sure, the 150p got good reviews, but nothing like the Tal. Then I started coming across articles about the sheer magic and brilliance of the Tal 100rs given by very dedicated stargazers like Astrobaby and Neil English, not to say dozens of other writers here at SGL. In fact, many who owned the Tal were saying things like "if I could keep just one scope it would be this", or "it's my most used OTA", and so on. I could find nothing like that about the 150p.

To really decide where my money would go, I then wrote a post at SGL asking folk to tell me if a 4" frac would give about the same kind of views as a 6" Next and the general consensus by just about everyone who replied was, yes, they will.

Now, given that kind of information for a first time telescope buyer, was it really so irrational to go for the frac?

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I used to have a 6" F/8 Newtonian with very good mirrors, and very small central obstruction (built it in 1979). The views through that scope with a 25mm Ortho (circle T) were just so crisp. Similar s

I don't know how useful it is to cite Damian Peach's images as a measure of the visual performance of a telescope. I could just as well say that if you want to do deep sky observing then an 85mm refra

I've been looking for my second scope, something with more aperature than the 80mm I currently have, and have logically narrowed my selection down to 2, either a 200 dob, or the 200 explorer on an EQ5

You're right, it's not irrational. Refractors do certain things very well, and if you want those things then they're the best choice. Like all designs, they have drawbacks so it's just a question of what's right for you.

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I used to have a 6" F/8 Newtonian with very good mirrors, and very small central obstruction (built it in 1979). The views through that scope with a 25mm Ortho (circle T) were just so crisp. Similar scopes were sometimes called APO-killers (and for a good reason!). I now have an 8" SCT and an 80mm F/6 APM triplet. The former is clearly better than the 6" on DSOs, and has the edge in sharpness (but not in contrast) on planetary and lunar views as well. The 80mm has great contrast, but when going for detail on moon and planets the 8" SCT takes it to the cleaners. For wide-field DSO views however, the 80mm is unrivalled. When I saw the North America nebula with the Pelican in its 5.76 deg FOV (with the Paragon 40), or the entire Veil complex, or the Andromeda Galaxy, M33, or M45 with reflection nebula, my jaw just dropped. At the same time, the detail seen in these same objects with the C8 is stunning.

Don't bicker about scopes, just get the one(s) that suit you and get on looking through them, rather than at them.

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Thats just what I need - a 115mm F/13 "refractor-like views" scope that weighs 80+ lbs!

Joking aside (and there doesn't seem to be enough of that going round in this thread!), how much would a 305mm F5 frac weigh? I've seen the monsterous 9" (?) TMB frac at Scope and Skies and I'm willing to bet my Dob is a grab'n'go by comparison.

I wonder, sidestepping all other dogma, where the attraction of refractors come from? Many of us may well have been into cameras first and so there is still a certain cache associated with large, expensive areas of glass. A Canon/Nikon/Olympus 300mm f:2.8 is, in photography terms, a huge lump of dreamboat lens, that in reality, few of us would be prepared to port around. That doesn't stop one being a desirable piece of kit, even if the reality of it's image quality is best suited to low rez newspaper print, at the apertures it avails. It's big, it's expensive and it's glass - Maybe that's enough to stop you passing one up, if the opportunity arises? It would be an irrational choice...

Russell

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I love the simple elegance of the Newtonian design, but I have to concede that refractors have their appeal. Aside from the issues normally covered, I think it is the low maintenance and durability of refractors that makes them so desirable. With Newtonians:

- The mirrors will eventually need re-coating.

- You may want to clean the mirrors every few years (contentious).

- You have to collimate regularly (not a big issue with practise).

- There is always the risk of disaster, i.e. dropping something down the tube.

I think these factors prevent Newtonians becoming objects of desire, instead they are supremely practical work horses.

I don't have a lot of experience with refractors, but things I don't like about them (apart from the cost per unit aperture) are:

- They are surprisingly heavy which limits their portability and also requires a serious mount.

- The eyepiece location is inconvenient.

- I don't like left/right inversion (I prefer fully inverted).

To me the best refractors are binoculars - the main problem with those being hand shake!

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Here we go again. Refractor versus reflectors, again. I am not knocking refractors or their fans and ultimately this hobby is about what gives you the most pleasure - by definition this is entirely subjective.

However, I get so fed up of refractor fans going on about how superior they are to reflectors. They aren't, they are different and are usually designed for different things. Still the refractor zealots always argue otherwise and then go off comparing a high end AP or Tak refractor against a (probably) poorly collimated low end SCT; well doesn't take a genius to work out which one is "better".

If you compare like-for-like there is much less difference than perceived other than the snob value of expounding the virtues of paying far more for similar performance. You just can't fairly objectively compare an f5 8" reflector costing about £300 (Sky watcher explorer) with a f7.5 5" refractor (skywatcher equinox) costing over 4x as much. Thisgives an interesting read - though no doubt people will accuse him of having a reflector bias.

And just to throw something out if you think that an SCT can't give astounding planetary views go check out Damien Peach's pictures.

I don't know how useful it is to cite Damian Peach's images as a measure of the visual performance of a telescope. I could just as well say that if you want to do deep sky observing then an 85mm refractor is the way to go and here's the proof:

SAG-TRIPLET-HARGB-2SCOPV2-XL.jpg

It doesn't prove a thing, of course, since imaging and observing are quite different processes and you can't see Damian Peach's Jovian details in a C14 just as you can't see my Sagittarian ones in an FSQ85.

Nor do I think we should pretend to know what motivates another person. I have no idea whether or not some refractor buffs are motivated by snobbery or not. My rather enjoyable work means I can use a range of refractors, SCTs and reflectors. There is something special to me about the refractor view and that's that. It offers tiny stars, perfect across the EP, and exquisite contrast. But it doesn't go deep and no-one ever says it does. For that you need aperture and a reflector. And, yes, some reflectors are APO-like. Ralf Ottow's 20th wave PV watercooled 12.5 inch Newt is as good a telescope as anyone is ever likely to use.

I have tried several cheaper apos (Altair Astro Triplets, Meade 127 and ED120) and, to de-bunk the snobbery claim, I'm on record in Astronomy Now and countless times on SGL as saying that they run our TEC140 very close indeed in visual use. And they do.

Can't we just like what we like and not fall out about it?

Olly

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