The weather at Lake Wallkill continues to be uncooperative, leaving me much time to ponder things such as the astronomer's obsession with glass. Let me preface all of the below with a disclaimer: my knowledge of optics is limited, I only know what I've learned from reading stuff on the internet, in magazines such as Sky & Telescope and Astronomy
, and books like Telescope Optics : Complete Manual for Amateur Astronomers
by Rutten and Van Venrooij. These are just my observations and opinions, which I offer for free with the guarantee that they are worth every cent. If anyone disagrees with any or all of what I have to say, please feel free to write me off as a crank and ignore me; trust me, I won't mind.Eyepiece Forums
On the Cloudy Nights
forum on eyepieces, and elsewhere, one can sit back and watch people pontificate for days in threads such as "Televue 15mm Plossl or Edmund's RKE?", "Pentax 40mm XW versus Tele Vue 35mm Panoptic", " W.O. UWAN 16 vs. Nagler 17 T4 comparo?". This is not really unusual or in any way particular to the eyepiece groups; topics in other groups wander down similar roads ("SCT vs. Mak: Which is better?", "Which Diagonal for AT66ED?", or "G-11 versus CGE" ). Nor is it limited to astronomy - I still bear scars from the "NRD-535D vs. Drake R8" battles long ago on the old GEnie shortwave receiver forums.
I strive to avoid these conversations, in part because I usually have little to offer, but mainly because they are for the most part pointless. It may be social interaction at it's finest, or worst, but I also believe it is simply a manifestation of boredom. On the rare occasions that I allow myself to get sucked in, I always regret it.
That's not to say that I don't enjoy these threads. If you pay attention long enought you soon realize who among the myriad posters actually knows what they are talking about, and once you filter out the nonsense you can learn quite a bit. It's just that I grow weary at times.
I have but a modest collection of glass in my eyepiece case. Some are fairly expensive, some are cheapos. And I'm happy with all of them. Eyepiece snobs might argue that I'm happy because I don't know better, and they may be correct. I''ve no doubt that a Nagler will deliver a finer view than a Chinese mass-market Plossl of similar focal length. My point is, when people start splitting hairs about the pros and cons of different high-quality, high-priced eyepieces, any of which are as good as any other, that's when I tune out. It's no different than arguing about microscopic differences in third-order intercept points of high-end HF receivers, and whether anyone will notice a difference in normal use. It's an argument no one can win.
Trust me, I do not begrudge people their right to buy and compare as many different mega-bucks eyepieces as they like. God bless 'em. I just think it's an unfortunate and largely unnecessary distraction from what is ostensibly the reason we all got into these telescope thingies to begin with - to observe the heavens.My Glass
First, there is my Tele Vue 32 mm Plossl. This was my first "good" eyepiece, purchased back in the early '90s when I first started using my dad's Super C8+
. at the time I only had the stock 26 mm and 7 mm Plossls that came with the scope. The 26 m was OK, the 7 mm was virtually unusable for me because of the tiny eye lens. So I bought the TV 32 mm along with a TV 1.8x Barlow, which gave me magnifications of 62.5x and 112.5x. These two pieces have served me well; I still have and use the TV32P, though I've since moved to a 2.5x Powermate to take the place of the 1.8x Barlow. (No reason; just because. I swear, I did not wring my hands and pontificate over the decision to go from 1.8x to 2.5x on any online forums, I just bought the Powermate on a whim. I've never even compared the two in A/B tests.)
, which I purchased used on eBay, came with a TV 20 mm Plossl and a TV 8-24 mm click-zoom. I don't know if I would have bought them otherwise, but since I got them, I use them. The zoom works well with the C8 to give me a wide range with only two eyepieces, the zoom and the 32 mm.
The rest of my eyepieces are some Celestron Plossls (4, 6, 9, 15 and 32 mm, all Chinese cheapies) that were part of a $99 accessory kit purchased at the same time as my Nexstar 8 GPS; and the Nexstar 40 mm Plossl that came with the scope. The 4 mm and 6 mm are the only ones I use, they are the shortest in my collection and will make do until I replace them with something better.
In 2004 I indulged myself with a set of Vixen LVW
Lanthanum wide-angle eyepieces (42, 22, 17, 13 & 8 mm focal lengths). Like the Powermate, I bought these without hand-wringing and head-scratching. I don't know why I chose them over Tele Vue (well, it may have had something to do with the price, because I'm a cheap bastard). They just seemed like a good fit for my particular likes: wide field of view, long eye relief, and large eye lens. I knew Vixen had a good rep, I liked the specs, so out came the plastic.
Since the LVWs arrived I have not spent much time, as many seem to do, looking at them to find out whether they have angular magnification distortion, field curvature, off-axis astigmatism, or whatever other aberrations. No, I prefer to spend what little time I can muster at the telescope looking through the eyepieces at cool stuff like star clusters, galaxies, and nebulae - much more interesting than looking for flaws in the glass.
The LVWs perform extremely well, and apart from some funkiness that I believe is astigmatism at the edges of the wider pieces (which I only notice when I look for it), I wouldn't trade them for anything. My three most often used LVWs are the 17, 13, and 8 mm. These yield the following magnifications in my two scopes:Nexstar 8 GPS (2000 mm f.l.)
17 mm: 117.65x
13 mm: 153.85x
8 mm: 250xTV85 (600 mm f.l.)
17 mm: 35.29x
13 mm: 46.15x
8 mm: 75x
Adding a Tele Vue 2.5x Powermate increases magnification to:Nexstar 8 GPS (5000 mm effective f.l.)
17 mm: 294.12x
13 mm: 384.62x
8 mm: 625xTV85 (1500 mm effective f.l.)
17 mm: 88.24x
13 mm: 115.38x
8 mm: 187.5x
Admittedly, I have not used the LVWs much with the C8. For one thing, I haven't used the C8 very often since I got the LVWs; my TV85 is the workhorse in my stable. Also, I only have the stock 1.25" diagonal on the Celestron which (a) doesn't work very well with the LVWs, the tension screw rubs against the upper body of the eyepieces; and (b) it doesn't use a compression ring to secure the eyepiece, it has two screws which will mar the chrome barrel, and also appears to skew the eyepiece rather than hold it straight; this can't be good for viewing quality. I've tried using the Tele Vue Everbrite 2" diagonal with the C8 but since I have the Crayford focuser, the whole rear assembly extends so far off the back of the scope it prevents me from looking up near the zenith - and that's about the only place I can look because of the trees at my home. So until I get a new 2" SCT diagonal, it's pretty much Plossl-only for the C8.
I don't use the LVW 42 mm or 22 mm very often with the TV85, but I do love them for cruising the Milky Way in Cygnus on clear, dark nights during the summer. I think I've had about three of them since buying the TV85 in 2004. Otherwise, they are a bit too low power for the stuff I like to look at.
The Tele Vue 2.5x Powermate may be the most valuable accessory in my eyepiece case. It provides a nice range of magnification with a limited number of eyepieces. I especially like the fact that it maintains the eye relief of the longer focal length eyepieces as well as the larger eye lenses - I have a hard time looking through those little pin holes in shorter Plossls. In the course of observing a particular object, I can start with the 32 mm Plossl for a wide view, move down to the LVW 22 mm, then work through the 17/13/8 mm set, before repeating with those three plus the Powermate.What I Need
Just because I'm happy with what I've got doesn't mean I'm through purchasing glass. There's a big gap between my 42 mm and 22 mm LVWs presently filled by only only the Tele Vue 32 mm Plossl. To fill in this range, I am considering a number of eyepieces:Orion Stratus:
35 mm ($199.95) & 30 mm ($179.95). These are LVW clones from what I gather, maybe the most obvious choice to complete my LVW wide-angle set.Vixen LV:
30 mm ($199.95) 2" barrel, 60 deg FOV. But this may be a little too close to my TV32P.Tele Vue Panoptic:
27 mm ($345.00) and 35 mm ($380.00). Both 2", with long eye relief (the 35 mm has an amazing 28 mm e.r.) But you pay for it.William Optics UWAN:
28 mm ($398.00). Expensive, but people are raving about these UWANs. 2" barrel, 82 deg FOV!
To replace the Celestron 4 and 6 mm cheapo Plossls at the short end, I am really hot for the Burgess/TMB Planetary Series
- only $99 each, available in 2.5, 4, 5, 6, 7, and 9 mm focal lengths; they are getting high praise for their contrast on planets. On the other hand, the Tele Vue Nagler 3-6 mm Zoom
might be the better option, at least for the shorter end of the range; that, plus a B/TMB 9 mm might cover it perfectly for planetary observing. I'm just worried about the small eye lenses these eyepieces appear to have. I like picture windows, not peepholes!Resources: