Downsizing from 102mm Refractor

[bond19]

I currently own a Tele Vue 102 and 12" OOUK dob

As John (mod) alluded to, I am increasingly using my dob for all my observing and finding my TV sits unused. I guess for visual aperture rule.

So my question is, if I downsize and sold the TV, what scope should I get to replace. Bear in mind I love the high quality optics of the Tv, plus the robust construction and the marvellous engineering (it just works out the box) so my new scope has to meet these criteria. Here are my requirements for the new scope

1. Wide fields for sweeping milky way views

2. Robust build

3. Well engineered (no tinkering needed to make it work)

4. Price £1000 (max)

5. Enough aperture to be useful and give pleasing views

So folks please can you help?

Chris

[Joves]

TV85 or TV76 if you like the views and sturdiness of your current quality-built doublet, but simply want a smaller version. Both will provide sweeping wide fields, significantly more than your current scope does, actually.

I know the general consensus is that 4" is the minimum useful aperture for visual observation, but I have had many enjoyable nights with the TV76. Under dark skies, it's an absolute little workhorse!

[John]

Personally I find 102mm as small an aperture as I care to go however if I was to look for something smaller I might be interested in something like a Takahashi FS78 or one of the Vixen Flourite 80mm or 90mm's. The TV 85 seems incredibly compact and well built as well. I had a WO Megrez 90 for a while which seemed quite a sweet scope but it's probably not in the TV or Tak league.

[Stu]

Given your criteria, I totally agree with Aaron. I have had both TV76 and 85 (still have the 85), and they are lovely scopes. Built like tanks, beautifully engineered and wonderful Widefield views under a dark sky.

The 76 will give you a wider FOV and is more portable, I find the 85 to be more capable of higher mag so is great on doubles and capable on planets. With a Herschel wedge it is also fabulous on the sun.

Another option might be one of the Genesis/101 variants. You talk of 'downsizing', but this could be in terms of focal length. These scopes are either f5 or f5.4 and will give you your 4" aperture, TV build quality plus those fabulous Widefield views. I have regrettably sold my Genesis now but it gave a 5 degree field with a 31mm Nagler and easily fitted the whole Veil in, fabulous from a dark site. NA nebula wonderful too.

Worth considering a feathertouch Microfocuser upgrade for any of these scopes, it makes the most of the buttery smooth TV R&P focuser but with the dual speed for accuracy.

[damnut]

It is a shame to see an instrument like the TV 102 going unused. If you have the funds (and selling the 102 would provide them) then also if you like the TV scopes then the TV85 seems like an ideal compromise. Somewhat shorter than the TV102 might provide you with an ideal compromise.

Some info found ---

With TeleVue's 2" focuser and a matched wide angle ocular the 85 reveals its extraordinary wide field of view ability showing up to 4.6 degrees at 11X to reveal the entire "Messier Catalog" of deep sky wonders, or to be employed for panoramic viewing of a seashore or countryside. Imagine a telescope that at a dark sky site has the combination of resolving power and field of view to sweep the Milky Way, see the Double Cluster in Perseus (NGC-869), find the Andromeda galaxy (M-31) and see it's ellipsoid shape, and see the form of large Nebulae such as the Veil and North American Nebulae! With a 55mm Plossl our TeleVue 85 can reveal all three stars of Orion's belt, closer in it reveals the jewel like stars of the Trapezium - a birthplace of stars, with a sweeping wisps of greenish gas clouds surrounding it. With a higher magnification M13 (the Hercules star cluster) takes on a "salt and pepper" appearance even from suburban skies on a clear night. By the time one finds a large enough aperture catadioptric, reflecting, or achromatic refractor to see similar detail, then one can only see a fraction of their area due to the relatively high focal length of these competing telescopes; imagine trying to observe the night sky through a straw!

The 85 compares favorably against many telescopes in field of view:

• 1.9 at 22X for a common 80mm achromatic refractor,
• 1.4 at 31X for a common 8"f6 reflecting telescope,
• 1.3 degrees at 32X for an 8" Schmidt-Cassegrain (operating with an optional telecompressor lens)
• 1.3 degrees at 32X for an 3-1/2" Maksutov-Cassegrain.

Good luck with some very difficult options to exclude!, but a nice task ...

[ronin]

Cannot really see any point in going smaller for your situation.

If you sold the 102 and bought a 76 then I cannot see you getting a scope plus a handfull of cash as I guess (no idea) that the used price of the 102 would match, or be very close to, the new price of a new 76.

You do not say the 102 is too big, heavy, inconvenient, difficult or has a problem so why would you pick up a 76 to go set up outside when you do not take a 102 to set up outside. You could actually end up finding that the reflector shows so much more that using a 76 is used less then the present 102.

[Stu]

Cannot really see any point in going smaller for your situation.

If you sold the 102 and bought a 76 then I cannot see you getting a scope plus a handfull of cash as I guess (no idea) that the used price of the 102 would match, or be very close to, the new price of a new 76.

You do not say the 102 is too big, heavy, inconvenient, difficult or has a problem so why would you pick up a 76 to go set up outside when you do not take a 102 to set up outside. You could actually end up finding that the reflector shows so much more that using a 76 is used less then the present 102.

I think the point is that the 102 is a longer focal length refractor which doesn't do anything particularly different to the newt, and is outperformed by it.

A 76/85 etc have much shorter focal lengths and offer a completely different perspective in terms of Widefield views that the newt can't do. They become complementary rather than one out doing the other

[bond19]

Nail on the head BigMakStutov. I'm looking for something to compliment my big dob and I love to sweep starfields and the like. 

I think the point is that the 102 is a longer focal length refractor which doesn't do anything particularly different to the newt, and is outperformed by it.

A 76/85 etc have much shorter focal lengths and offer a completely different perspective in terms of Widefield views that the newt can't do. They become complementary rather than one out doing the other

[John]

Nail on the head BigMakStutov. I'm looking for something to compliment my big dob and I love to sweep starfields and the like. 

Thats where my litte Vixen ED102SS comes in. It's F/6.5 so my 31mm Nagler gives a 3.8 degree true field. The best that my 12" dob can manage is 1.6 degrees.

I guess for low power observing one of the short tube achros would do a decent job but the build quality won't be anywhere near anything so far discussed.

[scarp15]

Nail on the head BigMakStutov. I'm looking for something to compliment my big dob and I love to sweep starfields and the like. 

Perhaps yet another alternative might be to consider a pair of Helios Apollo 15x70 binoculars mounted on a trigger head / mono pod.

[ollypenrice]

BigMakSutov makes a good suggestion regarding the F5 4 inch TeleVues which are not too costly second hand. Within budget anyway. You get the aperture plus the 500mm focal length. This was the best rich field scope I ever used and I miss it. I have a very inexpensive old Pronto which does a good job of filling in but that's from a very dark site. I can see the whole Veil and whole Rosette with it, for instance, but they were better in the Genesis.

I also splashed out on some second hand Leica 8x42s and I won't be making the mistake of parting with those... When the imaging rigs are running perfectly (or rather IF they are running perfectly  ) I settle into my lounger and am in heaven.

Olly

[Chris]

This has just popped up on ABS:

http://www.astrobuysell.com/uk/propview.php?view=94851

Someone wanting to trade an APM 80 for a TV102

No affiliation of course but thought I would make you aware of the option

I have no idea about premium premium Apo's so might not be what you had in mind?

[ronin]

Just read that and thought that is damn convenient.

Chris got the link in first.

And APM are good scopes.

Maybe the change was meant to be for both of you.

[bond19]

Ohh, thanks I'll take a look

[NickK]

Have you considered a 0.6x reducer?

I have a 105mm APO, 670mm fl and something that would give wide field and f4 would really be a hoot.

The SDP's primary role is with a camera, looking through it is good and has some good points (M42 and others) but you don't get 'oooooo' as you do with a big aperture for visual.