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Equipment Discussions >> Refractors

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choran
Pooh-Bah
*****

Reged: 12/28/12

Televue 85 vs. Televue NP101
      #5592890 - 12/28/12 03:50 PM

Buying my first scope. This will be for visual use only. I have viewed through televue 85 and televue NP101 and love the wide field views. I'm interested in extreme ease of use, which points to the 85, but after viewing through the 101, I wonder if I'd be giving up significant brightness and detail if I opt for the smaller 85. The weight difference is substantial, even with an increase in only 16mm of aperture. Any thoughts from you folks would be welcome in assisting me in arriving at my decision. Was toying with idea of FSQ85, but price of accessories, waiting time, etc. put me off a bit. Thanks you all very much.
CH


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stratocaster
sage
*****

Reged: 10/27/11

Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5592914 - 12/28/12 04:07 PM

It will depend on many factors that are based on your personal preference.

For me, for my first visual scope I wouldn't go below 100mm aperture, simply because I want to get the most light gathering capability I can without too much hassle moving the scope. However, I don't doubt many would disagree with me on this.

If grab n go is a primary concern I'd consider a 4" scope on a decent alt-az mount at the limit of what I'd consider gng. I have an SV102ED and would not consider it a lightweight on a decent mount. And I believe the NP101 is a heavier scope. With a TV85 you could go with a less beefy mount.

If you're interested in mostly splitting doubles and planetary/lunar viewing, the TV85 would likely be fine. Though there is no doubt you have the potential for greater resolution for planets/lunar with the NP101.

If you want to optimize DSO viewing, then the NP101 would be a no brainer between the two. But again, many would disagree with me on this.


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KerryR
Carpal Tunnel
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Reged: 12/05/07

Loc: SW Michigan
Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5592921 - 12/28/12 04:12 PM

I find one key to pushing the power, under good seeing, of any telescope is rigid mounting. It's a lot easier to rigidly mount the TV 85 than it is the NP101, which is heavy scope for it's aperture, courtesy of the Petzval elements.

So, it'd be worthwhile to think about the mount your interested in buying, and how it's weight and bulk will affect the frequency with which you observe.

I have a Megrez 90, and had a Genesis (predecessor to the NP101). The very slight increase in brightness at 200x in the Genesis was an asset, but it took a much bigger mount to match the stability and lack of focusing wiggles with the longer, heavier Genesis. The Genesis was sold.

Whatever you do, don't skimp on the mount. Alt Az choices will likely get you more rigidity, and thereby lack of focus wiggles, for the money, so consider that route if budget and weight are a concern. I've noticed repeatedly that my perception of sharpness of planetary images at higher powers is directly proportional to the lack of focus wiggles on beefier mounts. Consider 'over mounting' if practical...

I also must humbly submit that neither of those scopes may be the best choice for a first scope-- the lack of aperture tends to punish new observers, particularly on DOS's. More aperture is just about always superior, but depends on where and how you'll observe. Consider-- gulp! I know this is the refractor forum-- an 8" dob for a first scope. Part of your budget will need to be alloted for eyepieces. By the time you get an NP101 and suitable mount, you may not have much left for premium ep's... Not so with the 8" dob...


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5592937 - 12/28/12 04:21 PM

I have both. The 85 is much smaller than the 101. Both are manageable, but if, for example, you see yourself taking the scope and mount, assembled, out into the night to do some quick viewing, then the 85 is much easier. My 101 is the "is" version. I originally bought them "pre-owned" (i.e., "used"), primarily for imaging. The NP101is came later, because, as I got into color imaging, I wanted better color correction. For visual use, this is a non-issue in terms of colored rings around stars or anything like that. But something I rarely see mentioned is that the color of the planets themselves looks somewhat washed-out in the smaller scope. I see this clearly between the 85 and the 101, and the color rendition of both when looking at Jupiter is decidedly inferior to my larger reflectors. Also, even the bright planets are noticeably dimmer in the smaller scope.

Aside from that, I'm not sure that I would recommend either of these scopes if you're just getting into astronomy and don't know what kinds of objects interest you. The optics are very sharp in both, and you don't know what a "clean" star image looks like until you've seen it in a top-notch refractor. OTOH, they are still subject to the laws of physics, and neither is very good for deep-sky viewing. They're just too small to see much. Even for planets, moons of Saturn that are easy in my 8-inch reflector are challenging in the 101 and nearly impossible in the 85. Titan is easy, Rhea a challenge, especially in the 85, and Dione and Tethys nearly impossible in the 85. With the 101, it depends on conditions. All that said, my wife (not an astronomy buff) said that the TV-85 is the one scope she'd keep when I shuffle off this mortal coil.


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Mary
sage


Reged: 01/29/08

Loc: Highlands Ranch, CO
Re: Televue 85 vs. Televue NP101 new [Re: KerryR]
      #5592945 - 12/28/12 04:31 PM

Here is my .02 cents worth. I have both the TV85 and the NP101, if I could only keep one, it would be the TV85. Why..because it is compact and would not require as sturdy a mount as the NP101. The NP101 will definately give you more aperture than the TV85 and has no false color no matter how high you push the magnification. The NP101 truly is the better scope, but if you are seeking grab and go and will be doing any type of travel, the TV85 would be a better choice.

Personally I think either scope is a FANTASTIC first scope. You can always add a dob for aperture later if you decide you really need one, but you will NEVER regret having a TV scope in your arsenal. My NP101 was one of my first scopes and it is still with me and always will be.

Mary


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choran
Pooh-Bah
*****

Reged: 12/28/12

Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5592949 - 12/28/12 04:36 PM

Thank you for the responses so far. I have been viewing for 6 or 8 months with binoculars, and love he wide views, but want a bit more oomph. My thinking was to get a good apochromatic scope for these wide field views, which I truly enjoy, and perhaps later obtain a ten inch dobsonian for seeking out deeper and more faint objects. I would dearly love to see Jupiter's moons resolve to disks, for example, and realize that a 3 or 4 inch scope is not likely to get me there. Still, those wide views..,

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tomchris
professor emeritus


Reged: 12/22/10

Loc: Connecticut, U.S.A.
Re: Televue 85 vs. Televue NP101 new [Re: Mary]
      #5592953 - 12/28/12 04:40 PM

I just always remember that, at the NEAF, David Nagler himself told me that he personally gets more use from his TV-85 than his others scopes.. including a Dob. I agree that, if convenience is a main concern, go with the TV-85. I love mine.

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FirstSightModerator
Duke of Deneb
*****

Reged: 12/26/05

Loc: Raleigh, NC
Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5593037 - 12/28/12 05:53 PM Attachment (103 downloads)

The NP-101 @11 lbs including diagonal and clamshell, 9 lbs OTA alone), 29 in. long with diagonal, is not of itself at all heavy or unwieldy. I often leave mine set up in my garage on a Universal Astronomics lightweight surveyor's tripod and Unistar Light Deluxe mount, and as you can see fron the below picture, it's almost effortless to pick the whole assembly up and carry it outside securely on my shoulder and one hand.

The qualifications are:
1) 11 lbs is right at the limit of many of the sturdiest lightweight mounts, and though the Unistar Light Deluxe functions adequately with an NP-101, it's well short of optimal. The heavier (7 lbs vs 2 lbs) regular Unistar Deluxe mount works much better for higher-magnification viewing and briefer settling times, but even with the extra 5 lbs, the scope/mount/tripod assembly would still be easily portable just on shoulder-and-hand in the fashion pictured.
2) The hard case Televue provides with the NP-101 is the same one used for the significantly larger, heavier NP-127, and this makes the case a bit longer, heavier, and bulkier than it really needs to be for the NP-101. Though the encased NP-101 will easily fit in the seat or trunk of any but perhaps an unusually small car, e.g. one of those 2-seaters frequently used in European cities, it's bulky enough to often require a bit of thoughtful preplanning when loading it wit lots of other gear or suitcases for a trip.

As to any optical advantages of the NP-101 (which is a true apochromat) over the TV-85 (which is an f/7 doublet), from experience I can only compare the NP-101 to my William Optics Megrez-90, also a decent-quality f/6/2 doublet. Even though both the Megrez-90 and the TV-85 are inherently only truly semi-apochromats, i.e. it's technically impossible to bring high (violet), middle (green) and low (red) wavelengths into sharp focus at the same point with a doublet...nevertheless with the Megrez-90 at least, the only noticeable hint of false color I've ever seen with it is a slight yellowish tinge on the limb of the full moon, and that not enough to truly be distracting to my tastes, YMMV. As to resolution, the NP-101 does produce noticeably incrementally sharper images than the M90 and incrementally, though noticeably "flatter" low-power images, though those are not truly fair comparisons since obviously it's not a TV-85 and quite different scope manufacturers are involved.

At 101.7mm aperture, the NP-101 does produce incrementally, though noticeably brighter images and greater depth of reach of objects and can produce a sharp image at moderately higher magnifications than the M90, but NEVERTHELESS four inches of aperture in even the most optically excellent scope on the planet has quite notable inherent limitations. For example, four inches is simply not enough aperture to truly resolve any globular cluster better than to produce a granular "misty" appearance around its edges, with the core region remaining a fuzzball of light. From a suburban light-polluted location, you'll usually only be able to resolve the brighter Messier galaxies, e.g. M81-82, M65-66, M104 etc, and unable to truly see any spiral structure in M51 (just a pair of bright cores surrounded by a small dim halo). It will take really good seeing conditions to resolve E and F in the Trapezium (with a bit of effort), though sometimes you can more often make out the more widely separated E star but not F. What the NP-101 is unparalleled at doing is providing panoramic views of regions densely populated by star clusters within the Milky Way, and also (from a dark-sky site) taking in the whole Veil Nebula at once, albeit rather dimlyand in less detail compared to what is possible seein parts of it at a time with e.g. 12 inches of aperture. By comparison, I've NEVER been able to resolve E or F in the Megrez 90, though perhaps YMMV with the TV-85.

LET'S PUT IT THIS WAY: With my NP-101 available, I almost never use the Megrez-90 any more, except to take it places where I really need its significantly more compact travel case or where I really don't want to risk taking the NP-101, e.g. down into the dunes area near the ocean, or perhaps to a public outreach event of a particular sort where I don't want to risk the possibility of some kid inadvertently knocking over the NP-101 with clumsiness.

Edited by FirstSight (12/29/12 02:37 AM)


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Televue 85 vs. Televue NP101 new [Re: tomchris]
      #5593049 - 12/28/12 06:01 PM

A few thoughts:

For wide field views, one does not need an apo, a good achromat does a good job. That said, for wide field views, the NP-101 is amazing. Other scopes show field curvature, the Nagler-Petzval 101 does not. It has a shorter focal length than the 85.... There's a clue there.

The NP-101 is reasonably light at 10 lbs, reasonably compact at about 26 inches, I consider mine grab and go.

In my view, the NP-101 with its perfect color correction and flat field is an ultimate scope, the TV-85 is not. If you decide against the 101, there are other scopes by other manufacturers that should be considered.

Jon


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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

Loc: Los Angeles
Re: Televue 85 vs. Televue NP101 new [Re: tomchris]
      #5593052 - 12/28/12 06:02 PM

On a contrary note, the NP101 is a magnificent beast, and not that heavy. It's lighter than a lot of scopes, and the mount doesn't have to be that sturdy to use one (the TeleVue Gibralter is a good mount for it, and it is pretty light).
The NP101, though, has a flatter field, less chromatic aberration (none), more aperture (important on everything in the sky), a great focuser, and is just all-around a better scope.
The NP101/Gibralter combo is an excellent Grab'n'Go combination and the image quality is exceptional.
The logical alternative, in my book, is the NP127, but that begins to get pretty heavy on the mounts likely to be used with it.
The NP101 is easily lifted and transported.

As has been said, this is still a pretty small aperture to be an ONLY scope, and would make an excellent companion to a much-larger newtonian. The larger scope would be used when aperture is critical, the smaller scope when field of view is critical.


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FirstSightModerator
Duke of Deneb
*****

Reged: 12/26/05

Loc: Raleigh, NC
Re: Televue 85 vs. Televue NP101 new [Re: FirstSight]
      #5593074 - 12/28/12 06:16 PM

The compactness advantage of the TV-85 lies more with the compactness of its provided carrying case over the unnecessarily long, bulky NP-101 case (the same as provided for the NP-127), and not in any sigificant advantage over the NP-101 in actual field use or setup, once it's out of the case. It's only 11 lbs, including clamshell and diagonal, or only 3 lbs net heavier than the TV-85.

The other advantage of the TV-85 is, as Mary notes, that the NP-101 benefits from a sturdier mount than is truly required for the TV-85. However, in the Universal Astronomics family of alt-az mounts, the NP-101 is quite usable on the Unistar Deluxe Light (2 lb) mount (rated 10 lbs), though it does much better on the full Unistar (7 lb) mount designed for up to 40 lbs. That's a $100 difference in mount price and only 5 lbs.

Whether the aperture advantage of the NP-101 or the lighter-weight/compactness advantage of the TV-85, or the cost difference between the two, are enough to significantly tip the balance is of course a matter of personal taste and situation. For me, the NP-101 wins hands down. For you, that's a matter of your own personal tastes and budget, and perhaps how much the picture I included in my earlier posts is convincing of the degree to which the NP-101 is easily manageable or not.


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Bill Friend
super member
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Reged: 02/16/12

Loc: Maine
Re: Televue 85 vs. Televue NP101 new [Re: FirstSight]
      #5593116 - 12/28/12 06:46 PM

As Jon mentioned, you don't necessarily need an APO for wide-field. There are several 4" f/6-7 achromats out there that would serve you well for low power viewing (the ES AR102 comes to mind). For the price of a used TV85, you could have the 4" achro, a good alt-az mount and an 8" f/6 dob for resolving fuzzies and great lunar/planetary performance when seeing permits.

Cheers,
Bill


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choran
Pooh-Bah
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Reged: 12/28/12

Re: Televue 85 vs. Televue NP101 new [Re: Bill Friend]
      #5593572 - 12/28/12 11:44 PM

Again, thank you all very much for the thoughtful and very thorough answers. I very much appreciate it. Still haven't made up my mind, but you have all given me much food for thought. I'm at the point in my life where I've retired and want the things I buy to last so that they may be passed down to my kids. Whatever way I go on this, I want a high quality item that will outlast me. Solid, heavy duty, with some actual steel in it. LOL Whatever I get, I'm sure I'll enjoy it. Especially if I have the wherewithal to buy one of those great Ethos eyepieces I tried out on both scopes. Just a very pleasing view, to my old eyes. Thanks again, all. I'm sure I'll have other questions, and it's great to find a place with so many knowledgeable folks.
Cheers.


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John Rhodes
Vendor (Televue Rep)
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Reged: 02/21/06

Loc: Torrance, CA.
Re: Televue 85 vs. Televue NP101 new [Re: FirstSight]
      #5593616 - 12/29/12 12:13 AM Attachment (52 downloads)

Quote:

The compactness advantage of the TV-85 lies more with the compactness of its provided carrying case over the unnecessarily long, bulky NP-101 case (the same as provided for the NP-127),




No longer the NP101 & 101is case has been changed dramatically inside and shortened outside:


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Televue 85 vs. Televue NP101 new [Re: John Rhodes]
      #5593767 - 12/29/12 03:34 AM

Quote:

Quote:

The compactness advantage of the TV-85 lies more with the compactness of its provided carrying case over the unnecessarily long, bulky NP-101 case (the same as provided for the NP-127),




No longer the NP101 & 101is case has been changed dramatically inside and shortened outside:




There is also the softcase which is about the length of the new hard case. That's what I use.

As far as a mount, I used a Portamount with wooden legs for a couple of years. It's an Ok mount for the NP-101, usable at 300x through not ideal.

Jon


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Mike W
sage


Reged: 04/30/06

Loc: Upstate NY
Re: Televue 85 vs. Televue NP101 new [Re: KerryR]
      #5594076 - 12/29/12 10:20 AM

The scope that rarely gets set up (too heavy, complicated) v/s an 85-102 mm is the scope that punishes new and old observers! Terrence Dickenson recommends an 80-90mm refractor (at least) on an al-az mount to start with. I've had every kind of telesope in my 40+ years of observing and my Televue 102 on a Gibraltar mount (w/ sky tour, should have bought that years ago) gets used 75% of the time. When I feel the need to look at something crazy faint there's always somebody nearby happy to show it to me in his (her's) large Dob or whatever. It'll be a long time before you run out of objects to look at with an 85-102, and even longer w/ sky tour!( over 2000 objects for small refractors)

Edited by Mike W (12/29/12 10:23 AM)


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la200o
Carpal Tunnel


Reged: 09/09/08

Loc: SE Michigan, USA
Re: Televue 85 vs. Televue NP101 new [Re: Mike W]
      #5594207 - 12/29/12 11:34 AM

I'd go with the NP101. As noted above, unbeatable for wide-field views, but also, with the proper glass at the eyepiece end, just superb for high-magnifcation. The NP101 is NOT a heavy scope and can be mounted easily on a number of alt-az mounts; I have mine on a HH Mark III, but a used Gibraltar at 3 or 4 hundred bucks would do just fine.

The TV85 will be a little more convenient to use, but you'll see more with the 101 and you won't always be thinking, "gosh what am I missing?".

Both are great scopes.

Bill


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tomchris
professor emeritus


Reged: 12/22/10

Loc: Connecticut, U.S.A.
Re: Televue 85 vs. Televue NP101 new [Re: la200o]
      #5594759 - 12/29/12 05:32 PM

Quote:


The TV85 will be a little more convenient to use, but you'll see more with the 101 and you won't always be thinking, "gosh what am I missing?".

Both are great scopes.





I agree that both are great scopes but I also can relate with the OP in that as one gets older, less weight and simplicity become more important. I miss my old Genesis SDF but I decided to keep my 85 (and sell the Genesis) due to the convenience of set up. I didn't feel I'd be missing much more than I was seeing through the Genesis. I later got my 102mm achromatic for increased magnification but the 85 is still the scope I use the most. Although I'm sure the NP101 is better than my Genesis, I gave serious consideration to the TV 102 before buying the Vixen/Orion listed below. Actually, previous Vixen experience and a '4" refractor comparison list' submitted by our own Jim Barnett helped convince me to buy the Vixen to compliment my 85.


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johnnyha
Postmaster
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Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Televue 85 vs. Televue NP101 new [Re: tomchris]
      #5594876 - 12/29/12 06:39 PM

If you are interested in binoviewing, I'd recommend getting the NP101. I had a TV85 for a few years then got some Denk II binoviewers. Within a week the TV85 was sold and I had an NP101, for balance issues alone. Turned out to be a great decision, the NP101 has essentially perfect color correction and I enjoyed mine for years. It not only has that wide flat field but it handles ridiculous magnification.

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FirstSightModerator
Duke of Deneb
*****

Reged: 12/26/05

Loc: Raleigh, NC
Re: Televue 85 vs. Televue NP101 new [Re: tomchris]
      #5595228 - 12/29/12 10:18 PM

Quote:


I agree that both are great scopes but I also can relate with the OP in that as one gets older, less weight and simplicity become more important. I miss my old Genesis SDF but I decided to keep my 85 (and sell the Genesis) due to the convenience of set up.




I'm frankly completely baffled why some folks seem to find the NP-101 awkwardly heavy, unweildy, or inconvenient to set up (especially in comparison to a tv-85), as if we were comparing the merits of 12" vs 8" dobs. It only requires an extremely simple, lightweight alt-az mount, such as the Universal Astronomics Unistar Deluxe, and any needed scope balancing can be quickly and simply done via sliding the OTA within the clamshell, without involving the mount itself at all. I leave a short lightweight 2" rail always bolted to the clamshell of the NP-101, and attach the clamshell to the mount simply by closing the mount's jaws on the rail.

My Megrez-90 (despite being lighter, shorter and of similar size to the TV-85) is actually the more cumbersome and significantly more awkward of the two scopes to mount and balance, because I use rings bolted to a saddle plate to attach that scope to the mount, and I have to first attach the rings to the scope on a flat surface and then attach the saddle plate to the mount. Adjusting the balance requires either loosening the mount's jaws and moving the saddle plate position in the mount, or else loosining both rings, sliding the OTA, and then re-tightening both rings. I find both of these balancing methods cumbersomely awkward, compared to the ease of using the NP-101 clamshell to adjust balance.

BOTTOM LINE: The weight difference between the NP-101 and TV-85 is only 3 lbs. How many of you claimning a significant difference in convenience/weildiness between the two are using significantly different mounts or attachment methods for the NP-101 than for the TV-85? I am not a particularly strong guy, but when I can pick up my mounted NP-101 on a tripod in one hand, sling it over my shoulder and carry it out to my yard (as in the picture I included earlier above)...I am a bit perplexed why one would find that significantly heavy or difficult, unless one's physical condition was such that *either* scope would be challengingly awkward to move and maneuve about. I'm not criticizing anyone who's in that situation, since I'm not so spry or strong myself any more. But if not, I'm not quite understanding what it is you're finding difficult or inconvenient about mounting or manipulating the NP-101, unless there's some significant difference between how you're doing it with the NP-101 vs the TV-85 (or similar weight/size scopes)?

Edited by FirstSight (12/30/12 10:01 AM)


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: Televue 85 vs. Televue NP101 new [Re: FirstSight]
      #5595550 - 12/30/12 04:09 AM

I own both scopes and have used both extensively, for my own observing and imaging, and for public star parties. My ownership of the TV85 goes back to '06, the NP101is to '10. I use them on equatorial mounts, earlier a G11, then a Mach1GTO. Of the alt-az alternatives, I have no experience, but I don't find the prospect of manually chasing a planet at 200x very appealing. A heavier scope means a heavier counterweight. For the NP101is it means a larger dovetail plate and rings. The weight difference of the OTAs multiplies. At my previous home, I often left the TV85 on the mount and carried it out to the driveway for casual observing. The NP101is required some additional assembly to prepare for observing. I now have the 101 on a permanent mount (the Mach1GTO) in an observatory, so the 85 may go back on the G11 for casual viewing. The hard case of the 101 is much larger than the convenient soft case of the 85 (see the longer case in John Rhodes' picture). The 85 is much easier to fit into the trunk of a car. I have to put the 101 on the back seat. I took the 85 instead of the 101 to Utah for the annular eclipse, and the choice spared a lot of room elsewhere in the car. My previous opinion -- which I won't retract or modify -- is my honest judgment based upon my experience of actually owning and using both scopes. The OP can weigh the various comments and decide what he deems important. I'm not sure that either of these scopes is the best choice for a beginning observer, particularly if he access to a dark sky. They are superb at what they do, but you aren't going to be chasing down 13th mag galaxies with either of them, and M42 is going to be disappointing compared to the view through a light-bucket that costs a fraction of these TV refractors. Between the TV85 and NP101is, the brighter image of the 101, even on planets, makes it the clear winner optically. Size matters. But without that comparison available, the OP would be delighted with the 85, provided his deep-sky aspirations are kept in check.

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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5595663 - 12/30/12 08:07 AM

Calypte:

I use my 80mm apo and NP-101 on alt-az mounts with slow motion controls. They are easily transported out through the door and out to the backyard assembled and ready to go. With the slow motion controls, tracking at 200x or even 300x, is not a problem.

But that said, a 3 or 4 inch refractor, no how perfect it might be, is a better second scope than as a first scope. My run of the mill 10 inch Dob provides better planetary views and of course goes deeper into the deep sky.

Jon


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Paul G
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Reged: 05/08/03

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Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5595870 - 12/30/12 10:44 AM

The weight difference is really minimal, a little less than 3 pounds. Either scope will ride comfortably for visual use on a small alt-az mount or a small equatorial mount. To me the decision is easy, the 101 has better color correction and will show a brighter image with more detail.

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Jon Isaacs
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Reged: 06/16/04

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Re: Televue 85 vs. Televue NP101 new [Re: Paul G]
      #5595929 - 12/30/12 11:17 AM

Quote:

The weight difference is really minimal, a little less than 3 pounds. Either scope will ride comfortably for visual use on a small alt-az mount or a small equatorial mount. To me the decision is easy, the 101 has better color correction and will show a brighter image with more detail.






It also is capable of a wider, flatter field.

As I said before, the decision is really the NP-101 versus any one of a number of very good 80mm, 90mm, or even 100mm refractors. The NO-GO101 offers capabilities that are unique, if you want what it offers, it the only choice.

That is not the case with the TV-85, there are other worthy competitors. Myself, I like TV products but I am very happy with my William Optics 80mm F/7 FD, I don't see much reason to swap it for the TV-85...

Jon


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FirstSightModerator
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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5596013 - 12/30/12 12:03 PM

Quote:


But that said, a 3 or 4 inch refractor, no how perfect it might be, is a better second scope than as a first scope. My run of the mill 10 inch Dob provides better planetary views and of course goes deeper into the deep sky.





For visual observation, the most ideal choice is the combination of an NP-101 and a decent 10 or 12 inch reflector. They make perfectly complementary partners, each having respective strengths and capabilities that fill the most important holes in the weaknesses and incapabilities of the other. You want astounding panoramic views and incredibly sharp, pinpoint, perfectly colored stars, the NP-101 cannot be beat. You want the depth of reach and detail only a bit of aperture can give you, to resolve globular clusters and show dimmer galaxies, the 10-12 inch reflector can give that to you.

When observing in my driveway at home, I'll take out the NP-101 three times for every time I'll take out my 12" reflector. When observing away from home at what passes for a dark site, I'll always take both, and go back and forth between them all night. I'll take in the entire Veil nebula in the NP-101 and take in the beautiful intricate detail of individual sections of it in the 12". I'll compare the panoramic view of open clusters in wider context of the dense Milky Way background in the Puppis/Canis Major region in the NP-101, but resolve individual clusters into lots more stars in the 12" reflector. I'll enjoy the view of M33 against a wide stellar background in the NP-101, but begin to resolve its spiral structure in the 12" reflector, and use the latter to go into more ambitous galaxy-hunting. The contextual view of Jupiter and its moons against the background is seemingly more breathtaking and photo-sharp in the NP-101, yet the bigger aperture of the 12" brings out much more subtle detail of the cloudbands than even the finest 4" aperture will ever be capable of doing. It's a real visual treat, a feast, bouncing back and forth all night between the NP-101 and my 12" reflector. Meanwhile, I've got a really nice Megrez-90 doublet which mostly sits on the bench since I got the NP-101. I do agree that it's good that Televue has now redesigned the NP-101 hard case to have a smaller footprint, rather than use the same case as for the larger NP-127. That was always needless overkill for the NP-101 unless you really wanted to make double-use of the case to hold both scope and eyepieces.

Edited by FirstSight (12/30/12 02:42 PM)


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Calypte
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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5596139 - 12/30/12 01:06 PM

Quote:

With the slow motion controls, tracking at 200x or even 300x, is not a problem.



Have you successfully coached a kid at a star party to do this?


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Re: Televue 85 vs. Televue NP101 new [Re: FirstSight]
      #5596825 - 12/30/12 07:45 PM

In my case, I would say that since I had two wide field scopes (the Genesis and the 85), I wanted a scope with a little more focal length for better magnification (hence the Vixen 102mm at FL 9.8). I've put both scopes on separate DUPS plates and thus either is ready to mount on a lighter Manfrotto tripod or DM-4 that I have. The weight isn't that much of a factor but I personally still find the smaller scope easier as a G&G. However, I like your method of carrying your NP 101!!!

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Jon Isaacs
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Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5597464 - 12/31/12 07:14 AM

Quote:

Quote:

With the slow motion controls, tracking at 200x or even 300x, is not a problem.



Have you successfully coached a kid at a star party to do this?




I don't do star parties. 200x is planetary/double star territory in a 4 inch.In public outreach I would not be using the NP-101 to view the planets, a 4 inch is a poor choice as a planetary scope, particularly with inexperienced observers.

The NP-101 does widefield duty. For kids, the wide field of view mates well with a manual alt-az mount because they can quickly learn to sweep the sky, making their own discoveries.

For higher magnification outreach, I use a 12.5 inch Dob. I find that when the line is short and there is time for individual attention, people learn to track quite quickly.

If someone is considering a telescope to be used at starparties and public outreach, the NP-101 is probably not a good choice. As a scope for observing alone, with family and friends, for small groups, it a great scope and the alt-az mount works very well.

But... I am a big believer in the right scope for an object so most objects are better suited to a significantly larger scope so the NP-101 is a companion rather than an only scope.

Jon


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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5597542 - 12/31/12 08:52 AM

IME, complimentary scopes aside, I easily carried my TV Genesis 101 on a Super Polaris equatorial mount with dual drives outside in one trip. If you are reasonably fit, I don't see an issue. I have had 80, 90 and 92mm apos as well, and there is a gain you can see going with the 101. If you want to carry the OTA on an airplane for travel, well the TV 85 would be the better bet or if you simply want a smaller equipment footprint. Personally, I'd go with the 101 if my only scope, I used the Genesis for thirteen years as my primary scope and it went a long way showing me the universe.

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Calypte
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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5598122 - 12/31/12 02:55 PM

Quote:

If someone is considering a telescope to be used at starparties and public outreach, the NP-101 is probably not a good choice.



I used the 85 and then the 101 successfully at public/school star parties for several years. I always got raves over the views, since they were so clearly superior to the usual mis-collimated SCTs. The TV85 showed surface features on Mars during the last opposition, which none of the nearby light buckets was able to do. Using the 85 on a driven equatorial mount helped a lot, too. Public star parties are usually about showeing the Moon and bright planets. Agreed on this point: even the brightest deep-sky objects (M57, M13, M42) are too dim to be effective in these little scopes, but, then, school grounds are rarely dark enough to permit showing deep-sky objects. For schools I now use a Celestron 8SE, which is satisfactorily sharp when collimated. The 8SE has other debits, however, and I may go back to the TV85.

Edited by Calypte (12/31/12 03:07 PM)


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Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5598512 - 12/31/12 06:24 PM

I agree about most DSO's being not so hot with little refractors for obvious reasons, always excepting open clusters and doubles.

Bill


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Jon Isaacs
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Re: Televue 85 vs. Televue NP101 new [Re: la200o]
      #5598535 - 12/31/12 06:36 PM

Quote:

I agree about most DSO's being not so hot with little refractors for obvious reasons, always excepting open clusters and doubles.

Bill:

There are DSOs that are ate best in a smaller scope, there are DSOs that are best in larger scopes. Matching the telescope to the object...
:ubetca:

The same is true of the planets and double stars.. bigger scopes that are properly setup are better suited for viewing the planets than 3 and 4 inch scopes...

Jon

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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5598783 - 12/31/12 09:35 PM

Jon:

Absolutely.

I was responding to "even the brightest deep sky objects . . . are too dim in these little scopes." Some deep sky objects are just great in little scopes. Others, no.

Bill


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Calypte
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Re: Televue 85 vs. Televue NP101 new [Re: la200o]
      #5598886 - 12/31/12 11:07 PM

"...are too dim to be effective in these little scopes." I've successfully shown M57 & M13 to students & parents with my 8-inch reflector, but it requires an enormous amount of coaching to get them to see them in a 4-inch refractor. "See that little fuzzy spot in the middle?..." At a dark-sky site, sure, but, then, I'm not usually going to settle for a little scope if I have a genuine dark sky.

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la200o
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Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5598980 - 01/01/13 12:42 AM

Right: We seem to be miscommunicating. No doubt the bigger scope will make DSO's brighter. My point is that although many DSO's are beyond the capabilities of a small refractor, there are still some that are not. I'd include M42 among those that will cause some oohs and aahs in a 4" refractor, as well as (among many others that would make the list, M6&7 in Scorpius, the Auriga clusters, M2, and so on). Actually, some of the OC's are better in my fast 4" than in my CPC 9.25, with its limited FOV.

Regards,
Bill

Edited by la200o (01/01/13 12:44 AM)


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Calypte
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Re: Televue 85 vs. Televue NP101 new [Re: la200o]
      #5599052 - 01/01/13 01:55 AM

Agreed about the open clusters. A great one for kids at this time of year is NGC 457 in Cassiopeia. It's especially useful (as at a star party recently) when there's no moon or bright planets.

I think the OP probably has enough info by now about the merits of the 85 vs the 101.


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Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5599077 - 01/01/13 03:02 AM

This past summer,on a trip over into western Colorado that was never intended to be astro related, all I had was a small 70mm refractor(A Walmart Special that I paid $10.00 for in an ARC store) that I keep in the rear of my small car during the summer and had just one chance on one night under truely dark skies to use that telescope. Despite having no choice as to grabbing a larger aperture scope,I wouldn't trade the experience that night away,period. The sky stability was probably close to a Pickering 8.0 that late May night.

We all do what we have to do,and if given no other option, using a small aperture scope under a dark sky ain't too shabby a proposition IMO and IME. If that little telescope was all I owned and I also lived and could observe 275 miles west from where I ordinarily do so,count me in for 15 to 20 a nights a month doing just that.

Enjoyment of this hobby comes in many forms,so I don't need the "best" or "largest" telescope in the "perfect" viewing location to have a good time. As always,YMMV.


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RogerRZ
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Re: Televue 85 vs. Televue NP101 new [Re: KWB]
      #5599154 - 01/01/13 07:06 AM

Quote:



Enjoyment of this hobby comes in many forms,so I don't need the "best" or "largest" telescope in the "perfect" viewing location to have a good time. As always,YMMV.





Right. I would say 90% of my observing is done in 2-5 minute chunks, using my 1x7 (probably 1x6 by now) binoculars. They are never a let down...


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skullpin
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Re: Televue 85 vs. Televue NP101 new [Re: RogerRZ]
      #5600104 - 01/01/13 06:33 PM

I vote for the TV85 as a first scope, providing the will to afford it. It is a great introductory scope for many reasons...

1. There is much for a beginner to find with 85mm.
2. For a beginner, visually there is not a large difference between 85 and 101 mm.
3. The TV85 is light, easy to mount, and quick to use with a fast cool down.
4. The TV85 compact enough for easy travel. Out to the cottage, camping, around the world, etc. Compact size (remember to include the mount and tripod) matters if you are travelling with the family, the dog, and a cooler.
5. The TV85 can double as a birding/daytime scope. Not quite backpacking friendly, but adequate at the campsite, marsh lookouts, etc.
6. Both scopes can be displayed/stored in the living room. Fraser* appreciates his 4" scope in this capacity. The TV85 might have a slightly better "spouse acceptance factor" if your house is cramped.
7. If you get serious about astronomy, you will get a larger scope in the future. Then, you will be more knowledgable and able to select a larger scope that meets your needs. Walk before you run with a small refractor, they are a lot of fun.
8. If you do eventually get a larger scope, the TV85 will always be a lovely compact second scope.

Sure, some of these points apply to many refractors up to and including the NP101. Though some points need to be evaluated so you get the most use out of their purchase. Getting the NP101 for its slightly better views might result in less viewing overall.

My $0.02, Keith

* Fictional character of uncertain astronomical hobby background.


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Jon Isaacs
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Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5600349 - 01/01/13 09:13 PM

Quote:

"...are too dim to be effective in these little scopes." I've successfully shown M57 & M13 to students & parents with my 8-inch reflector, but it requires an enormous amount of coaching to get them to see them in a 4-inch refractor. "See that little fuzzy spot in the middle?..." At a dark-sky site, sure, but, then, I'm not usually going to settle for a little scope if I have a genuine dark sky.




I am not quite sure why we are discussing what an inexperienced observer can see in these scopes, it seems to me we should be discussing what an experienced observer can see.

Even an old codger like me can see 11th-12th magnitude galaxies in an 80mm if the skies are reasonably dark...

Jon


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Jon Isaacs
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Re: Televue 85 vs. Televue NP101 new [Re: skullpin]
      #5600351 - 01/01/13 09:18 PM

Keith:

As you point out, there are good reasons to purchase an 80mm-90mm apochromatic refractor. But if that is one's choice, I am not sure that a TV-85 is the wisest choice, you can get similar capability and quality for considerably less money from other vendors.

If someone were to ask me about whether they should buy a TV-85 or the NP-101 as a first scope, I would invite them over to my place and set up three scopes, my 80mm William Optics FD, my NP-101 and my 10 inch GSO Dob. Then I would point them all at Jupiter. After that, M42. After that, M35...

I do some birding with my NP-101 but then there are times when I do birding with my 12.5 inch Dobsonian.

Jon

Edited by Jon Isaacs (01/01/13 09:30 PM)


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BillP
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Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5600412 - 01/01/13 10:01 PM

Quote:

This will be for visual use only. ... love the wide field views. I'm interested in extreme ease of use, ... I wonder if I'd be giving up significant brightness and detail if I opt for the smaller 85.




OK...you really want ease of use...but you are having aperture fever which is obscuring things for you

Go back to your primary need...super easy. So smaller is better. I would consider the TMB 92. Splits the difference on aperture and is super small.


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Calypte
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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5600606 - 01/02/13 12:52 AM

Quote:

Even an old codger like me can see 11th-12th magnitude galaxies in an 80mm if the skies are reasonably dark...

Jon



I confess that I've never seen a 12th mag galaxy in my NP101is.


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Jon Isaacs
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Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5600760 - 01/02/13 06:36 AM

Quote:

Quote:

Even an old codger like me can see 11th-12th magnitude galaxies in an 80mm if the skies are reasonably dark...

Jon



I confess that I've never seen a 12th mag galaxy in my NP101is.




J. Reynolds Freeman completed the Herschel 400 with a 55mm refractor... I am 64 years old and my eyes are not what they used to be, that is never going to happen.

I used 11th-12th magnitude because the magnitudes vary with the source. For example, the brightest Galaxy in Hickson 68 is NGC5350, Cartes du Ciel lists NGC-5350 as being magnitude 11.3 but Sky Tools lists it at 12.3. The Blue Flash Nebula NGC-6905 is listed by both as magnitude magnitude 12.0, I have observed the Blue Flash with my William Optics 80mm F/7 FD from our place in Boulevard.

Obviously a 3 or 4 inch refractor is not the ideal scope for such targets, they are much more easily seen in a larger scope. But sometimes I'll be observing and I get the hankering to see if I can find some favorite in a smaller scope. It is pretty amazing what can be seen in a small refractor.

Jon


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choran
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Re: Televue 85 vs. Televue NP101 new [Re: BillP]
      #5600956 - 01/02/13 10:26 AM

Bill, is the 92SS of similar build and visual quality?
Thanks,
Chuck


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Jim7728
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Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5601010 - 01/02/13 10:52 AM

I had the Genesis SDF and compared to the TV-85, the cool down time is significantly longer in the Petzval, than the TV-85.

Also of note: Field curvature is noticeable in the TV-85 when using a 21mm Ethos and most definitely in a 90mm f/5.5 ED doublet that I also own and would think the AT/ 92SS will have the same optical trait, depending how old your eyes are.

Quote:

I would dearly love to see Jupiter's moons resolve to disks, for example, and realize that a 3 or 4 inch scope is not likely to get me there. Still, those wide views..,




I personally need a 5" APO to start seeing Jupiter's moon's as disks in a light polluted location and to also have a wide view then it's a NP-127.


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Starman1
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Re: Televue 85 vs. Televue NP101 new [Re: Jim7728]
      #5601064 - 01/02/13 11:13 AM

Quote:

I would dearly love to see Jupiter's moons resolve to disks, for example, and realize that a 3 or 4 inch scope is not likely to get me there. Still, those wide views..,



That's the point, isn't it? Each type of scope has its own purpose.
A TeleVue NP101 will give you astounding, wide views. My 12.5" dob, at 456X, sees each Galilean moon a different color, making identification fairly easy, and at 608X, I thought I saw albedo markings on Ganymede in exceptionally stable seeing.


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johnnyha
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Re: Televue 85 vs. Televue NP101 new [Re: Starman1]
      #5601159 - 01/02/13 12:22 PM

Quote:

I would dearly love to see Jupiter's moons resolve to disks, for example, and realize that a 3 or 4 inch scope is not likely to get me there. Still, those wide views..,




My 4" FS102NSV when I had it, easily resolved the moons of Jupiter as discs, each an individual size and color, and I could easily see them cross the face of the planet. Shadow transits looked like fresh bulletholes.


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t.r.
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Re: Televue 85 vs. Televue NP101 new [Re: johnnyha]
      #5601196 - 01/02/13 12:44 PM

Just for clarification on resolving Jupiters moons read the quote by EdZ from a previous post on the topic titled "Jupiter's Moons"...

" What affect does scope diameter have?
Scope size determines the smallest object that can be resolved. The smaller the scope, the larger the object needs to be for it to be resolved. A 6" scope can resolve down to about 0.8 arcseconds, enough to see all the moons resolved. A 5" scope would see the smallest moons only as the visible disk within Airy disks. These are not resolved. A 3" scope has an Airy disk so large that it would would bloat the smallest moons to nearly double their resolved size. A 3" scope would bloat even the largest moons to a visible disk that does not represent a resolved disk. Sure they would look like resolved disks, but actually they are large visible disks within the Airy disks."

" How big are the moon's
Well that varies with the distance to Jupiter.
Jupiter is 88,700miles in diameter. At 5AU its disk would appear 39.3 arcsec.
The sizes (at 5AU) and the magnitudes of Jupiter's moons are:
Ganymede 3,270 = 1.45 arcsec, mag 4.6
Callisto 2,980 = 1.32 arcsec, mag 5.6
Io 2,260 = 1.00 arcsec, mag 5.0
Europa 1,940 = 0.86 arcsec, mag 5.3 "

" Except perhaps when Jupiter is at it's very closest, and only then for Ganymede, none of Jupiter's moons can be resolved with a 80mm scope. But even in an 80mm scope variations in magnitude can make one moon look larger than another. None-the-less, that is not resolved.
Ganymede and Callisto can probably both be resolved in a 100mm scope, and potentially, for the most eagle-eyed, at powers as low as 100x, but probably for most people closer to 125x-150x.
To resolve the smallest moon, you'd be safe in your expectations by using a 6" or larger scope at 160x to 200x"

Most people with smaller scopes are really reporting seeing the airy disk created by the moon and not a true resolved disk.


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Calypte
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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5601724 - 01/02/13 06:39 PM

Quote:

J. Reynolds Freeman completed the Herschel 400 with a 55mm refractor... I am 64 years old and my eyes are not what they used to be, that is never going to happen.



I'm 68. I once was proud of my ability to see faint DSOs. I considered the Horsehead "easy" in my 12.5-inch f/5 Newt and "there" in my 8-inch f/6. This was from sites like Blair Valley in Anza-Borrego Desert State Park, which I know you're familiar with, Jon. A day came when I went to show the Horsehead to a skeptic, and it wasn't there for me. That's when I threw in the towel and turned to imaging. But I have to say that I considered mag 12 galaxies (the unlabeled ones in Atlas Coeli 1950.0) to be about my absolute limit with the 8-inch. Maybe I gave up too easily on fainter ones simply because no atlas I owned showed them.


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Re: Televue 85 vs. Televue NP101 new [Re: Calypte]
      #5601917 - 01/02/13 08:38 PM

Quote:

But I have to say that I considered mag 12 galaxies (the unlabeled ones in Atlas Coeli 1950.0) to be about my absolute limit with the 8-inch. Maybe I gave up too easily on fainter ones simply because no atlas I owned showed them.




I am not saying I can see every 11th or 12th magnitude nebula or galaxy but there are some I can see... But I start with ones I know already in a larger scope.

At 64, I am afraid my eyes are not what they once were, that's one reason I hunt these things down, it gives me a little reassurance that there is still some gas left in the tank..

Jon


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Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5602707 - 01/03/13 10:41 AM

Quote:

I would dearly love to see Jupiter's moons resolve to disks, for example, and realize that a 3 or 4 inch scope is not likely to get me there. Still, those wide views..,



I use the NP-101 with an Ethos SX 3.7mm. Adding Jon's 2x GSO barlow lens (without the extension) gives about 220x. I see Jupiter's moons clearly as nice round discs, not points
Personally, I think unless portability is an issue, go with the NP-101. It does fabulously wide views (I don't think there's any scope out there than can match it for widest-sharpest-field ) If cash is an issue, then truly other scopes would be better than the TV-85.


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Re: Televue 85 vs. Televue NP101 new [Re: cloud_cover]
      #5602769 - 01/03/13 11:21 AM

Quote:

Quote:

I would dearly love to see Jupiter's moons resolve to disks, for example, and realize that a 3 or 4 inch scope is not likely to get me there. Still, those wide views..,



I use the NP-101 with an Ethos SX 3.7mm. Adding Jon's 2x GSO barlow lens (without the extension) gives about 220x. I see Jupiter's moons clearly as nice round discs, not points





The difficulty is that stars do not resolve to points but rather round disks and this can be clearly seen in a 4 inch scope at 220x. The Raleigh Criteria for a 4 inch scope is 1.36 arc-seconds, about the size of Jupiter's largest moon. The additional difficulty is that the size of the disk depends on the brightness of the object. Consider an unequal double star like Castor, both the primary and the secondary are points sources but the secondary is about 1.4 magnitudes dimmer and when magnified, the Airy disk appears smaller.

In a 4 inch scope, a point source like a star resolves to a disk about the size of Jupiter's largest moon, a moon is seen as something larger than this, but it is dependent on the brightness. Thus, seeing disks of varying size is not sufficient to "resolve" the moons of Jupiter.

Jon


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Re: Televue 85 vs. Televue NP101 new [Re: choran]
      #5603345 - 01/03/13 04:41 PM

Quote:

Bill, is the 92SS of similar build and visual quality?
Thanks,
Chuck




Would put its build quality a notch lower than the TV as TVs are built like tanks. But the build is still excellent on the TMB. Optically I would say they are all very good. TV85 is a doublet and some folks report they can coax a very little color out of now and then. NP101 essentially color-free. TMB had a little color as it is a super-fast triplet. NP would be a more complicated re-collimation given it's dual doublet design, other two perhaps a bit simpler if needed (TMB is meant for user collimation, TVs are built for it to be done at factory).

NP is really in a class of its own and should IMO be considered as such due to its optical design - Petzval. It produces a flat field whereas doublets and triplets do not. You might gets some field curvature visible at the eyepiece for low power ultrawides with the TMB, not with the NP. If optical performance were the ONLY deciding factor then would go with the NP as it has the unique flat field, very fast focal ratio. But since portability and simplicity are prominent goals for you, and aperture as well to some degree, the others come into the mix. For me, if just a choice between the 85 and the 92, I would go with the 92 because smaller and wider field and more aperture...simply more versatile than the 85. Plus the TMB92 (not the L version) has Starlight focuser which puts most focusers to shame, and still $350 less than the 85. If you go with the L version then $850 less than the 85. So could get the 92L with a battery of fine eyepieces and have more TFOV and more aperture than just the 85. To me, the choice is between the 92SS and the NP101. If I was going to make the refractor I buy my only largest refractor, then would probably opt for the NP101 if could afford. If I anticipated getting a 120mm or 130mm APO in the future, then that would steer me directly to the 92 as would never need an 80mm for travel since the 92 is so very small and a 101 is IMO just too big to keep with a 120 or 130 APO also. It is s always more about other things than purely optics.

Edited by BillP (01/03/13 04:49 PM)


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Erik Bakker
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Re: Televue 85 vs. Televue NP101 new [Re: BillP]
      #5603384 - 01/03/13 05:06 PM

Quote:

It is s always more about other things than purely optics.




Very true Bill


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John Rhodes
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Re: Televue 85 vs. Televue NP101 new [Re: BillP]
      #5603889 - 01/03/13 11:25 PM

Quote:

NP would be a more complicated re-collimation given it's dual doublet design,



Tele Vue scopes only need tilting of the front cell to collimate... like most scopes, the rear elements cannot move in their cell.


Quote:

if just a choice between the 85 and the 92, I would go with the 92 because smaller and wider field and more aperture...simply more versatile than the 85. Plus the TMB92 (not the L version) has Starlight focuser which puts most focusers to shame, and still $350 less than the 85.




All Tele Vue scopes come with custom Starlight Feathertouch 10:1 Rack & Pinion focus assemblies... except the TV 60 "is"


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Mark9473
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Re: Televue 85 vs. Televue NP101 new [Re: Jon Isaacs]
      #5604145 - 01/04/13 06:46 AM

Quote:

In a 4 inch scope, a point source like a star resolves to a disk about the size of Jupiter's largest moon, a moon is seen as something larger than this, but it is dependent on the brightness. Thus, seeing disks of varying size is not sufficient to "resolve" the moons of Jupiter.




Well as long as I'm seeing dimmer Callisto as a larger dot than the brighter Io and Europa, you're not convincing me that I'm not seeing the size differences between the jovian moons. Did this in a 90mm achromat many years ago, and more recently in my 107mm apo. But it helps to be close to opposition, when the moons are just a bit larger.


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