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Televue 101

Posted by Ed Moreno   07/15/2008 12:00AM

I recently acquired a Used Televue 101 (Not the NP, but the model that sits between the Genesis SDF and the 101NP).

Since getting Buffy, my 20+ year old 6” f/8 Astro-physics refractor, I have become far more interested in the wide field characteristics of refractors. While so much of the emphasis on these telescopes is on their improving color correction and on-axis performance, what has been attracting me more and more to smaller refractors is their WIDE-FIELD capabilities.. See, in spite of the fact that my 6” AP has a focal length of 1200mm, using it with a 31mm Nagler was an absolute epiphany. The 6” AP was simply the outright BEST WIDE-FIELD telescope I had ever owned. I became much more intolerant of off axis performance issues like coma, field curvature, or field illumination drop-off. The 2 degree field of the old AP was STUNNING as compared to anything else that I had ever used.

And when you give a man a literally PREFECT 2 degree field, what is the NEXT thing he will ask for? He will ask for a perfect 4.5 degree field… LOL.

Now I have to confess that since getting the 6” AP and sitting it alongside of my C14, I have found myself almost blissfully content for the first time in decades as far as telescopes go. As much trouble as it is, I actually ROUTINELY set up BOTH of these telescopes on the same nights to observe. BOTH are SUPERB at what they do, with the Big Al, my C14 being capable of fine Planetary and Solar System performance, and penetrating deep into faint NGC Clusters and Galaxies, and Buffy collecting big expanses of glittering stars.

There are though, some nights when I want to observe, but don’t want to set up even one big scope. Now I am NOT a “Quick Look” kind of guy. I DO have a C5 on a Polaris mount that I leave on the patio set up in Alt-az mode, but it s more likely to look at birds than anything in the sky. The problem of course with the C5 is that it can only provide about a 1 degree field of view, and that field is abberated by off-axis field curvature and uneven field illumination. I LOVE Tiny Tiger though, and I don’t have to worry about something happening to it because well, it isn’t that expensive. I DO use it for the moon from time to time, but not so much. Mostly for birds (and it is SUPERB for that).

So, I decided that I wanted a high quality 4” refractor for nights that I wanted to do some serious observing but didn’t want to haul out one of the large scopes.

I was VERY tempted to buy a new 4” f/7 ED scope, but after owning Buffy, I was going to make wide field performance one of the highest priorities. I asked several dealers (Including Stellarvue) if they had experience with using the 31mm Nagler in their offerings. I wanted to know if they would be good off axis performers. No one would really commit to that though, and rather than take a chance, I decided that I would just go ahead an purchase a “Proven Performer”.

And when you want uber-wide fields, THE proven performer is the Televue Genesis family of telescopes.

My search ultimately yielded a Televue 101. In fact, this was the PERFECT scope for me because it was close to the Televue NP101 in overall performance (I think probably identical), but its slightly larger size and heavier weight kept it closer to the Genesis in terms of pricing. I found a very nice sample for $1400, which included the OTA, hard case, clamshell, AND the ORIGINAL Televue Everbright 2” diagonal.

The sample I purchased was in overall fairly nice condition. Some cleaning and polishing brought it to ALMOST new condition. The only serious blemish (and I choose to believe unknown by the seller) were a couple of paint scars caused by too-long screws being driven into the clamshell. On this point, I was disappointed that Televue does not sell touch-up paint.. I mean these are premium refractors that will last 500 years, and Televue can’t MATCH the paint? Come on, Televue, you can do it, and you SHOULD do it.. Anyway, I was able to find a GM color that was somewhat close (White vs the off with of the TV) and using a toothpick and applying 5 layers, I was able to mostly repair the blemishes. Only the slight miss-match in color gives it away.

The TV 101 uses the glossy anodizing which I prefer to the new Pebble finish. With some light polishing, I was able to restore its original luster.

The build quality is excellent. The Epoxy paint is perfectly applied, and provides a very hard, durable finish. Along with the anodizing and sliding dew shield, the telescope is a very attractive piece.

The focuser is a Rack and Pinion design. It is one of the nicest R&P units I have had on a telescope. I am on record as saying that inexpensive telescope makers should abandon cheap R&P units in favor of Crayford focusers, but this does not mean that I don’t LIKE R&P focusers. In fact, if they are GOOD, I actually PREFER them to Crayford focusers. I feel like a really good quality R&P simply costs more to make than a decent Crayford, but I find that they work better with a wider range of eyepiece weights than Crayfords do. As much as I liked my Moonlight focuser on my Vixen 140, I felt like I did have to play around with the tension adjustment a bit more than with my really good Rack and Pinion focusers. Anyway, the unit on the Televue 101 is well known as being an excellent focuser, and it works well with everything from my 31mm Nagler to my 4mm Ortho.

While Televue calls this scope the “101”, it actually is more like 101.9mm. I am SO happy to have that extra .9mm. The focal length is 540mm. This is VERY fast telescope. I think that the Genesis family is THE catalyst for todays growing popular 4” APO market and for good reason. 4” Telescopes are indeed great all around telescopes.

The Genesis family extends this to make these also ultra-fine camera lenses. Whether you point at the sky, the space shuttle (did you SEE THAT PICTURE!!) or a bird, the Televue 101 is going to give you a border to border PERFECT image. And THAT is why I wanted a Genesis family scope. No scope ever made at these focal ratios has proven better at generating really thrilling wide field views.

Daytime with a 4mm Ortho eyepiece an distant targets provided literally perfect color correction. NOWHERE could I see the FAINTEST INDICATION of any color fringing. It is absolutely the most perfectly corrected refractor I have ever owned. Even my 20+ something year old 6” f/8 AP triplet (no ED or Florite) can't match it in this regard.

Night time star testing shows it to be practically perfect optically. If there is any defect, I cannot detect it. The level of polish matches that on the Astro Physice 6” I own, and it shows no sign of Spherical Abberation, zones, or other optical issues. Overall, I think that is is probably as finely made as is practical.

At night, using high powers on targets like doubles and solar system objects, the performance is consistent with the finest 4” telescopes made. My guess is that only the most experienced and demanding observers would be able to tell if from any new doublet or triplet when aimed at Jupiter. It is essentially perfect. Jupiter shows beautiful detail, the moon is color free and wonderfully detailed, and doubles and colored stars are as compelling as in any 4” scope I have ever seen them though.

Where the TV 101 comes into its own though is in the realm of wide field observing. Here is what I most wanted from this scope, and it delivered in spades.

The 31mm Nagler is perhaps the most perfect eyepiece in terms of off-axis performance that I have ever owned. I could not TELL how perfect it was until I plugged it into Buffy, the old AP refractor. Never before had I seen an 82 degree field that was shown in such utter perfection. I promise you that you have to see it to believe it. In the 6” f/8 AP, the 31mm Nagler yields star points that are as sharp at the field stop as they are at the center of the field. It is uncanny. It is GLORIOUS. It has spoiled me and made me compulsive. Every time I use this combination, I am amazed.

Anyway, the idea was to go from Buffy’s spectacular 2 degree field to a 4.5 degree field using this eyepiece in the TV 101. And it worked. When aimed at the Sagittarius region of the Milky Way, I was THRILLED to see this AMAZING spectacle. The field was both enormous and sharp. Seeing giant sweeps of the sky with this kind of sharpness and crispness is SUCH a delight. The added brightness over an 80mm scope is enough to make it worth the money, and no 80mm scope I have owned was as SHARP off axis as the Televue is using the 31mm Nagler.

Now two things I should mention.. First, I do not think that the TV 101 was QUITE as sharp at the VERY edge of the field as Buffy, the 6” f/8 AP is. At the VERY VERY edge of the field, I can see extremely faint amounts of aberration. My guess is that this is something perhaps coming form the eyepiece. It MIGHT becoming form the telescope, but my guess is that the f/5.4 light cone is so steep that even the powerful 31mm Nagler struggles to bring it to perfect focus.

But this is only at the MOST EXTREME edge of the field. In the 4.5 degree field, I would say that you can only see this in the VERY LAST couple of Arc Minutes. Otherwise the field is extremely sharp.

The other thing is field illumination. Hmmm. You know, I was told for years that people can’t detect slight levels of field illumination dropoff. I believed it. Until I started using Buffy… After Using Buffy, I got to where I could EASILY see field illumination drop-off when comparing fields… For example, I compared a MN56 to Buffy, and illumination dropoff was CLEARLY PRESENT at fields larger than abou 1.9 degrees.. Yes! Buffy, the 1200mm refractor, had a better field than the f/6 5” Mak Newt. The field was brighter, sharper, and better illuminated out to 2 degrees. In repeated comparisons to Buffy at the same power, the illumination dropoff became OBVIOUS. I have since become far more sensitive to it in scopes like my C5, thought the way SCTs start loosing illumination immediately off axis makes it harder to detect than in scopes like reflectors where it starts all at once.

Anyway, Buffy uses a big 2.7” focuser tube. Even the 31mm Nagler is receiving a 100% fully illuminated edge of field. By comparison, the Televue 101 uses a 2” focuser tube. I believe that the front of the focuser tube does indeed very, very slightly vignette the field. I called Televue, and they said that if it was vignetting it, I probably couldn’t see it visually… Hmmm.. Well, that is their story, and they are sticking to it.. But I SWEAR, Buffy has made me a FAR more discerning observer, and I CAN detect it… But as with the edge of field aberration, it is VERY VERY minor, and only occurs in the very last couple of arc minutes of field.

It is interesting to note though that the reason that Televue introduced the TV101is model was because imagers using larger chips were reporting some vignetting at the very corners of the chips. The newer scope uses a bigger focuser. Tube… Hmmmmmmm.

I will say though that once again, I feel like one of the old school “Rules of thumb”, this one regarding field illumination (that you supposedly can’t see minor amount of illumination dropoff), is not really all that valid if you are a serious observer. The more I use Buffy, the more I am coming to realize that a lot of these common wisdom items are bogus. The only question then is how MUCH it bothers a particular observer.

Again, in the Televue 101 both of these are hard to detect. You might look at it and NEVER see the difference. Only a bunch of hours behind the same eyepiece in Buffy has given me such reference point so absolutely perfect as to allow me to see these very, very tiny optical issues. And NO scope that was faster or smaller has ever come CLOSE to the TV 101 in terms of providing such an excellent low power field of view. This bears repeating.. NO scope that was smaller or faster than Buffy has come CLOSE to providing the wide field viewing experience of the Televue 101. And with the edge of field sharpness, that COULD be more the eyepiece than the telescope itself. Maybe at f/5.4, it is reaching the extreme edge of the 31mm Nagler performance envelope. I simply don’t know. Most likely it is a combination of the two.. The telescope might have a very tiny amount of field curvature or off axis abbertion, and the Televue Naglerm might be being pushied to its threashold.. agian, I simply don't know.. I can only say that in the AP working at f/8, the edge of the field is Stunnigly prefect RIGHT TO THE FIELD STOP. SO, lets say the Televue 101, is sharp across 4.48 degrees of the 4.5 degrees you can see in the eyepiece.. It is that good...

The Genesis family revolutionized the perception of the value of small refractors. I think that it is THE telescope that changed the way amateurs thought about refractors. Even the ORIGINAL Genesis (I owned one… I know from experience) is a better wide field and all around telescope than just about any 4” telescopes available today. Their optical perfection is easily capable of offsetting any tiny advantages that a newer scope with less slightly better color correction but slightly less perfect optics might have.

I rate the entire Genesis family as still being a benchmark range of telescopes, and The Televue 101 ranks as the best value among the members of that family, with the optical performance extremely close to the new Televue NP101 but in the slightly larger package and closer to the lower price of the older Genesis (The Genesis SDF is considered by many to be almost identical to the TV 101, so I group them together).

On a scale of 1 to 10? For me? A 9.95. Only my experience with Buffy has cost this scope the .05 point difference. In other words, to someone less “Compulsive”, you are talking an easy 10.

4” APOs don’t really come any better than this. Like my rating above, when you get down to tiny fractions of a Strehl ratio, it doesn’t matter anymore.

If you have thought about one, or thought about a new NP101, don’t hesitate. It still does what it does best better than any telescope made.

My regards.

Semper Fidelis to those that know what it means… I wish it were over so you could all come home. Whether you believe in the mission or not, there is only so much your countrymen should ask you to do, and you have done it, you have done MORE of it, and done it well. Most of us want you home now. Come home, but come home with your heads held high. You deserve it.