Posts Made By: Jeff Quinn

Lets face it there are a ton of eyepiece choices these days, and three main types of scopes with a range of focal ratios. A bewildering array of brand names and designs has become available to amateurs in recent times and one of my favorite designs for f/8+ scopes, the Widescan, has finally become more available / affordable. Sadly, faster scopes make a mess of simple classics such as these.

Long story short: nothing compares to the latest Speers Waler line (the WA series) for field sharpness over 80+ degrees in f/5ish scopes in the under $100 price range. They are a cross between naglers, meade uwas, with a healthy dose of propriety thanks to the tenacity of Glen Speers up in Canada who designed them. The optical configuration is a negative / positive group such as the Type I nagler, which allows much more opportunity for correcting astigmatism and coma. You simply can't buy any other genuine negative / positive lens group eyepieces for $90 on the used market, and this design element is the hallmark of full field sharpness over 80+ degrees in f/5ish scopes.

I've had eyepiece fever and owned a few scopes, basically one of each main type other than maksutovs. Nothing changes the eyepiece more than the scope! Good eyepieces in my C102 were so-so in my 152ED and 12 SCT, and downright horrible in a 6" f/5 skyview deluxe Orion eq newtonian. Speers Waler or other UWA style negative / positive lens group eyepieces can deal with any scope and give respectably sharp images over the whole field.

The only exception to this rule is the 18mm SW which is a low cost compromise, in that a true scaled up 10mm SW would be way too large (the old type I nagler syndrome). Even so, in my current f/5 Celestron 8" newt, even the 18mm SW gives 70 degrees of near panopticesque sharpness with eye relief good enough to wear glasses. The additional 10 degrees is there for dramatic effect basically, but the full view is quite satisfying.

It's cloudy tonight and I've got another oddball eyepiece to test (TAL 24) so out of sheer boredem, I thought I'd tell you all that you won't find a sharper ~$100 wide angle eyepice for your f/5ish newtonians than the Speers Waler WA line. Now I've got my set pretty much collected so I can write this, ha. I'm surprised they stay on the used market for so long, they are definately the best bang for buck eyepiece for cheap yet large scopes.

I just pulled out my Meade 152ED (discontinued ED semi-apochromat 6" f/9 refractor from the 90's) and took in Jupiter for the first time in three years. I've had the scope in storage while going to engineering $chool, and have been observing with a Celestron G8n for a while. The G8n is really decent like a good 8" SCT, but I hadn't realized what I had been missing until last night!

The executive summary is that refractors show so much low level contrast, especially if they are of the ED or apochromatic variety, that nothing with an averaged sized central obstruction can ever measure up unless it is double the aperture! Those little wispy layers between the two main bands on the main Gas Giant of our solar system started coming in at times in the 152ED where they never show in the G8n. Just for fun I threw the G8n up on the mount later that night and yikes, BIG difference in detail shown. It was pretty impossible to focus the fine details out of the average seeing in the obstructed 8". Both scopes split castor, the double double, Nu scorpii, and show the three main ring divisions on saturn when it is low in the sky. But that contrast, wow, there really is a reason people pay so much for Apo refractors after all.

So I thought I'd just share this tidbit of observational opinion with you astromarters. The G8n still beats the 152ED on deep sky, where aperture really does win given reasonably corrected optics.

So I got bored and hooked up my 80mm F/7 refractor to my G8N rig with a home made side by side plate. My TAL 24mm UWA gave good images in both scopes, but I needed a dedicated "finder" eyepiece for the little refractor. Thanks to our wonderful (sometimes brutal) capitalist economy, I found myself the new owner of a Chinese clone of the classic 30mm Widescan for $80 shipped.

Here is how it compared to the TAL in the two scopes:

In the 80mm f/7 achromatic refractor, stars were sharper over the full field of view, still a little soft at the very edge but a great effect for showing 4 degrees true field at 19x. The TAL 24mm has a similar effect with slightly less true field, but spike shaped stars toward the edge unlike the Owl 30mm 80*. The spikes were more distracting than the mild astigmatic diamonds seen in the OWL 30mm. The Owl 30mm seemed the better of the two in this scope, and as a bonus it has no amber tone like the TAL.

In the G8n, thankfully the situation was reversed: the more sophisticated TAL handled the weird optical configuration of the Brixner style hybrid Newtonian found in this discontinued Celestron sleeper much better than the Owl 30. In this scope, the Owl shows quite a bit of field curvature, astigmatism, and coma. The TAL hardly shows any astigmatism except for at the very edge, with less curvature but the same coma. I even tried a 27 Panoptic in this scope and preferred the TAL 24 because it almost seems to have some weird coma compensating effect: the coma was not as obvious in the TAL vs. the Panoptic despite the eyepieces having nearly the same true field. Anyhow, the TAL 24 gives a great presentation of 2 degrees field of view and really compliments the 4 degrees seen in the 80mm f/7 with the Owl 30.

Summary: In my fun test with the Knight Owl 30mm 80*, TAL 24mm UWA, and even a 27 Panoptic, the combination of using the Owl in the 80mm f/7 refractor as a 19x80 finder and the TAL 24 in the G8n as a low power star cluster viewer gives a great visual effect. The TAL 24 seems better suited for fast newtonians than the Owl, and even worked better than a 27 panoptic in this particular scope, to my eye.

Have a great day!

The current UO orthos suck, it's the sad truth. I have a 70's era UO 6.5mm konig that is beyond superior to a 7mm UO ortho from the late 90s on any and all planets. Tested in a Meade 152ED that regularly splits Nu Scorpii (~>1 arcsec) and stood up well to an AP155EDT and FS152 in side by side testing.

UO doesn't make 'em like they used to, that's for sure. I'd love to find more classic UO konigs. See _Telescope Opitcs, Evaluation and Design_ for spot diagrams of orthos, plossls, konigs, naglers, erfles, and more. The ortho shows a larger on axis spot diagram than the plossl, and the konig is the smallest of all. My experiences with many UO konigs in practice seems to reinforce these findings.

Tele Vue plossls are my standard for pure 4 element greatness on planets for a reasonable price. They are as good as anything I've ever tested (not counting the zeiss or pentax orthos, or new Tmb monocentrics).

UO orthos work fine, all I was saying in the other thread was that in my scope, they were pretty bad for fine detail on Jupiter and Saturn compared to my UO 8mm and 6.5mm konigs, which I later tested against eyepieces you can actually still find (TV plossls). The TV plossls were quite good, almost as much snap to focus as the konigs and the same contrast. A celestron ultima someone put in my scope was about as good.

Point being, UO orthos performed like $40 eyepieces in my scopes. I seem to have great luck with pre-owned Meades.

The field of view selected depends more on object under observation than scope type in my opinion. Wide fields are just better in every way if they don't bring significant side effects like glare, throughput, weight, cost, or eye relief. The only reason to switch back to a quality plossl or konig is to get the increased contrast and throughput that less glass brings.

In short, for objects where ultimate contrast and throughput don't matter as much as seeing the object of God's grand creation in the context of the immesurable vastness of space, there is no match for 80+ degrees to give you that shocking sensation of the Earth's isolation in the grand scheme of things. For focusing on smaller issues like the cloud detail on Jupiter, any old 30 degree field of view will capture the subject.

Overall it looks a little off center and miscollimated, but that huge slash down the center is really bad. Do you see that when looking at defocused star images, or just during your daytime test?

For $130 I wouldn't bother with plossls if you want wide field low power and largest field of view possible in 1.25" format.

Speers Waler 18mm WA (if you can even find one) is hands down, the best eyepiece to fill this role in that price range. I bought one used for $90 and even in my F/5 G8n, it gives a very pleasing 80+ degree field of view, very comfortable eye relief, sharp to about 65 degrees and somewhat fuzzy beyond that but very dramatic views nonetheless.

Don't believe the hype, there is no comparison to true negative / positive lens group wide field eyepiece. There is simply nothing better for full field sharpness in this price range to fulfill your mission, unless you can find a 20mm Widescan. At f/8, a 20mm widescan (KK or UO brand) will match the speers waler 18mm for sharpness across the field of view, and will also show the full 1.25" image plane giving the widest possible field with your scope.

Ignore plossls, get a real wide field eyepiece! You can do it, troll the eyepiece ads and find an 18mm Speers Waler WA or 20mm KK or UO widescan. I guarantee you will be shocked looking through that soda straw plossl image after getting acquainted with a real wide field eyepiece!

I had a chance to get some more sky time tonight and found that my original impression of these two eyepieces to be reinforced: The TAL 24 gives a better image in the G8N compared to the Knight Owl 30, but in the 80mm f/7 refractor the Owl does better than the TAL, but not by as wide a margin as in the reflector.

It sure is nice being able to instantly switch from a 2 degree true field 80 degree afov to 4 degrees of the same.

Probably the best $300 eyepiece for that scope, for the widest possible views with a reasonably wide apparent field of view would have to be the undisputed standard to which all other wide angle eyepieces are measured: the 35mm Panoptic.

They're not the brightest eyepieces, nor the most comfortable, nor the lightest, nor the cheapest, nor the best looking, nor the most glamorous, but for three hundred bux, a 35 pan would be my vote for the best possible image presentation for low powers (if your eye can take a 7mm exit pupil). Definately one of the sharpest wide angles out there (especially in a f/4.5 newtonian) in that price / field range IMO.