22 replies to this topic

[jerry brink]

Fellow viewers,
I own a Televue 85 and am very seriously considering purchasing a Televue 102 to
upgrade in aperture and magnification ability.

My question is whether a 12.5% increase in aperture is enough to warrant purchasing
a new telescope and will I notice a visual difference going from 85mm to 102mm?

FYI I do mostly visual and view planetary, luner, split stars subjects.
No deep sky yet.

I love Televue telescopes.

Thank you for you're time...and opinions. Jerry

[alnitak22]

Hi Jerry,

 

I’ve had my TV85 side by side with several high end 4” apos including a TV102 and a Tak FS102. The short answer is yes…you will see a difference. The only question is whether that difference is significant enough to warrant the hit in portability you might take. But if portability is not a concern, I know you would love the TV102. 

[Echolight]

You'll likely need a bigger mount.

[radiofm74]

The alternative is coupling your handsome widefield instrument with something with a lot more aperture and small form factor. A C6 comes to mind, or if your mount can swing it a C8. Both are plentiful on the used market and very reasonably priced; both will, in good seeing, offer a massive jump in magnification and detail to your planetary views; both will be great scopes to get started in DSO observing; both scopes will allow you to split significantly closer doubles (let me qualify this… given excellent seeing and collimation… SCTs are less capable than refractors in this compartment IME). 

 

The complementarity will be just perfect. And since both types of scopes use star diagonals, the SCTs will feel familiar in use.

 

If you go the SCT route, let me add two suggestions:

- Factor in the cost of a f/6.3 reducer. It will boost your FoV, and thus expand the objects available for view, and make finding way easier;

- Even with a reducer, SCTs have a narrower FoV than you're used to, and you need to have a good system of finders. My favorite combo is a red dot and a super-light 6x30 RACI (the Orion ones). For planetary and multiple stars, you can mostly just stick to the red dot. 

 

PS: all of the above applies, mutatis mutandis, to a C5!

[areyoukiddingme]

102 is 20% more than 85. It will be noticeable, but whether the increase is worth it for the greater OTA length and weight is something you need to decide on.

 

I also think that something larger to complement the 85 is also likely a better solution. I would go C8 for the aperture in small space--i.e, very likely to mount on the same you use for the 85.

[PJ Anway]

102 is 20% more than 85. It will be noticeable, but whether the increase is worth it for the greater OTA length and weight is something you need to decide on.

 

I also think that something larger to complement the 85 is also likely a better solution. I would go C8 for the aperture in small space--i.e, very likely to mount on the same you use for the 85.

Actually, the TV102 is a 44% larger than the TV85. It would definitely be noticeable at the eyepiece.

Edited by PJ Anway, 19 May 2024 - 04:16 PM.

[SeattleScott]

It sounds like this is for visual?

The TV 102 appears discontinued and only available used. Don’t see them come up often. With patience one could be obtained. I don’t know that I would have a lot of use for a 102 and an 85 unless one was for imaging and one for visual. I would probably just decide which one I liked better and not use the other.

The NP-101 is available new. It is optimized for imaging but can be used visual. It is fairly obscenely expensive for a visual 4” Apo. For the price you could maybe get a 4” Japanese Vixen Apo and a 15” Obsession Dob. Which would be much more practical for a visual observer. Used, a NP-101 can be more reasonable.

For a larger aperture scope to pair with the TV 85, yeah I would forget TV and go with real aperture, like 8” SCT or 10” Dob. Again, a 4” TV Apo would just be a replacement for the 85, not a larger aperture compliment.

[areyoukiddingme]

Actually, the TV102 is 44% larger than the TV85. It would definitely be noticeable at the eyepiece.

 

Depends on what you are calculating. As a diameter, 102 is 20% greater than 85 (i.e., 17/85).

 

By area 85 is 69% of 102.

 

Or, expressed w.r.t. area over the 85, then it's 

 

7225 vs. 10404, or 44%.

[Echolight]

Depends on what you are calculating. As a diameter, 102 is 20% greater than 85 (i.e., 17/85).

 

By area 85 is 69% of 102.

 

Or, expressed w.r.t. area over the 85, then it's 

 

7225 vs. 10404, or 44%.

I came up with 5674 and 8171. Still 44% larger by area.

 

Your calculations look like for a square.

[sevenofnine]

+1 on adding a scope with much more aperture. No matter how "fine" the views are in a TV 101...it's still only 4" 

[areyoukiddingme]

I came up with 5674 and 8171. Still 44% larger by area.

 

Your calculations look like for a square.

We just need a ratio of squares to calculate the relative area. 

 

8.5 squared vs. 10.2 squared. Pi drops out because it's constant.

[Echolight]

We just need a ratio of squares to calculate the relative area. 

 

8.5 squared vs. 10.2 squared. Pi drops out because it's constant.

We could say that the 85 is 16.7% smaller...

if we want to make the 85 sound bigger. 

[SeattleScott]

44% more light grasp is noticeable. But it isn’t like I sit around thinking what ~4” Apo I want to pull out tonight. I think about a 4” Apo versus a 6” Mak or 8-10” reflector. For me only one would remain. I would decide whether or not the added heft of the 102 was worth it for the incremental light grasp. For me, either scope would fill the same role. Grab and go refractor. He really would benefit from having something significantly different rather than something a smidge bigger than what he already has.

[Jon Isaacs]

Actually, the TV102 is a 44% larger than the TV85. It would definitely be noticeable at the eyepiece.

 

The TV-102 was discontinued quite a number of years ago and is only available used.  As has been said you can buy an NP-101 IS for over $4000.  I have a NP-101, a fine scope but demanding when it comes to eyepieces.

 

Both the TV-102 and the NP-101 are 4 inch, 101.6 mm. In terms of aperture and resolution, a 4 inch is 20% greater than an 85 mm. In terms of light gathering, it's 43% greater. Besides the NP-101, I also have 80mm and 90mm apos.  The difference between an 85mm and a 102mm is visible but the views are more the same than they are different.  You will see a little more with the 4 inch but galaxies won't suddenly jump out, globular clusters will not suddenly be resolved, a little bit more.

 

Physically, the NP-101 is a significantly larger, longer, heavier scope.  This is my WO 90mm F/6.2 alongside the NP-101.. 

 

 

By comparison, a 10 inch Newtonian has about 3 times the resolution of an 85mm and collects about 7 times as much light when one accounts for the central obstruction and reflective losses.  It goes over 2 magnitudes deeper, galaxies will jump out, globulars will be resolved, open clusters can take on new life, planets can be bright and colorful. it's a whole new world... 

 

I am a big believer two complementary scopes., a quality 80mm-102mm refractor for the wide fields, terrestrial, for convenience and ease of use, a large aperture scope to do the heavy work.. 

 

Jon

 

 

 

 

[Tony Flanders]

Here's another vote for skipping the 100-mm APO and buying a scope with some real aperture instead. If you've never used an 8-incher or bigger, it will revolutionize your viewing experience. Stuff that's challenging in a little 85-mm scope is obvious in a 200-mm. And stuff that's challenging in the bigger scope is beyond anything you can imagine with the little 85-mm.

 

A 10- or 12-incher might be even better.

[Nov500]

You need  a bigger mount

[daveb2022]

I've got a TV-85 and a NP-101. The 85 is a camping scope and the 101 is my NVD/Ha scope but it travels well too. My 101 using standard EPs in the level of LP I'm subjected to basically confines me to doubles, planets and the moon plus a few brighter planetary nebula.

 

NV has its pitfalls, but it might be another consideration. My 85+NVD does a good job on many DSO's when observing from light polluted skies. If NV isn't an option, a larger aperture might be a better solution. I have an old xt-8 dob that stacks up to my 101 on planets and does much better on DSO's.

[gnowellsct]

I love Televue telescopes.

Jerry

Well then that's your answer isn't it? If you're really in love with the brand stick to it. It happens fairly often with televue.

Greg N

[SeattleScott]

Well then that's your answer isn't it? If you're really in love with the brand stick to it. It happens fairly often with televue.

Greg N

Except he could never own more than a 5" aperture scope.

[Echolight]

Except he could never own more than a 5" aperture scope.

I think there might be an old 140.

[csrlice12]

Al's first hand made telescope was a reflector....

[GGK]

Fellow viewers,
I own a Televue 85 and am very seriously considering purchasing a Televue 102 to
upgrade in aperture and magnification ability.

My question is whether a 12.5% increase in aperture is enough to warrant purchasing
a new telescope and will I notice a visual difference going from 85mm to 102mm?

FYI I do mostly visual and view planetary, luner, split stars subjects.
No deep sky yet.

I love Televue telescopes.

Thank you for you're time...and opinions. Jerry

I too like Tele Vue refractors.  I have a TV-85 and NP101is.

 

If you want a 4-inch Tele Vue refractor for higher power observing, the TV102 looks like a capable scope.  The 880mm focal length f/8.6 APO doublet should show some very nice higher power images and be easy on eyepieces at the same time.  Being only a doublet vs. the quad-lens Petzval design, overall light throughput and contrast should be maximized, showing good details on the moon and planets.  But, it's still limited by the 102mm aperture.

 

I use a larger SCT for high power when aperture matters.  My NP101is is used more for wide field observing, with some high power when that the only scope I have out.  

 

When I had only the TV-85, I was initially using a 30mm eyepiece for scanning, and there were some DSOs that I would not detect under some brighter sky conditions.  I'd scan right over M46, for example without noticing it.  My first step was to add a 21mm Ethos, which kept the same field size, but dropped the exit pupil from 4.3mm to 3mm.  This darkened the background sky and increased the perceived contrast, making it easier to detect those same objects while scanning.

 

I later added the NP101is, and yes, I noticed the increase in aperture both for wide field targets, and for higher power observing of planets, moon and smaller DSOs, but it's not a big difference.  The biggest benefit for me is the increase in exit pupil at the same magnification.  As I push magnification in the small scopes, the image gets more dim than I like, and I appreciate the extra light with the larger 4" aperture.  

 

Also, since my majority use with the refractors is wide field observing, the NP101is 540mm focal length gives a wider maximum field than the TV-85's 600mm focal length, and the NP101is has a wonderful flat field.

 

Gary

[Tony Flanders]

The Original Poster said:
 

I love Televue telescopes.

 
And Greg N responded:
 

Well then that's your answer isn't it? If you're really in love with the brand stick to it.

It depends. The statement "I love Tele Vue telescopes" is impressive from somebody with wide experience. But given that the Original Poster is a beginner -- hasn't even attempted deep-sky observing! -- it's quite possible that Tele Vue is the only decent brand he's ever tried. In which case the statement about loving Tele Vue seems less meaningful. And potentially more restrictive.