Don Pensack

I agree. Its 45° field is a bit narrower than many at that focal length, though.

Other than the Docter/Noblex, and ATC, what European companies actually make eyepieces in the EU or UK? Baader is made in China, as are APM, Omegon, Tecnosky, etc., etc.

I modified your image to show the slight vignetting that occurs at the edge of the field in that eyepiece. Next time, try B&W in the camera for lower noise, and use Pro Mode if you have it and lengthen the exposure a few seconds. I agree--it is a special eyepiece. WAY too low a power for M42, though. Much better on the Pleiades or Beehive.

I don't know about the 26mm MWA in the field. I've only ever seen one in a shop. But I did use the 25mm ES 100° in the field, and I don't think you'd be happy with it: I spent a fair amount of time with the 25mm in my 12.5" under dark skies, too. I also used both a 31 Nagler and a 21 Ethos, in a 12.5" f/5 scope with Paracorr.II. Here is what I found about the 25mm ES100: 1)distortion--obviously corrected for AMD, because RD is noticeable. It's obviously corrected for nighttime, astronomical observation. This is not a negative, just a comment. 2)vignetting--obviously significant, since it's easily visible in both day AND night viewing, starting about 80% of the way to the edge. Not unexpected, since the field stop is a little larger than would be expected in a 2" barrel with this AFOV (probably why TeleVue stayed away from this focal length), but also minimally noticeable at night, and pretty much only if you let the moon drift toward the edge of the field. 3)light scatter--not great. When the crescent Moon is in the field, the light from the lighted part bleeds over to the earthlit part and reduces contrast. Averted vision shows this. When the Moon is outside the field, it's obvious which direction the Moon lies. More aggressive baffling would have reduced the FOV, I believe. Not a great lunar eyepiece, therefore, but since the eyepiece is highly unlikely to be used as a lunar or planetary eyepiece in any scope, this may be a non-issue. Suggestion: use for all purposes except Moon viewing. 4)astigmatism correction--not the best. Even in the Paracorr, star image degradation starts a little more than half-way to the edge and gets suddenly worse at about the 90% point. Going back and forth through focus on a star near the edge, the astigmatism at the edge is obvious. It's better than many 80 degree eyepieces, though. Suggestion: Use as a finder eyepiece for really low power. 5)lateral color. Star images become prismatic near the edge, and moving the eye only partially eliminates this. Holding the eye in the wrong place with an Ethos can do this too, but changing the position of the eye eliminates it. In this case, it can't be eliminated, AND the blue ring at the edge is very noticeable on the Moon; otherwise not at all. Suggestion: Experimenting with eye placement is essential to reduce this effect. 6)internal reflections. With Sirius slightly outside the field of view, there is a semi-circular ghost in the field. The center of that circle is where Sirius is. The ghost is not evident when Sirius is in the field, but it's obvious that reflection from the interior wall of the eyepiece barrel, or the side of a lens, or the filter threads at the bottom, or a modestly bright spacer ring visible near the bottom causes this. It could have been fixed with a baffle, probably, but wasn't, and for the reasons I mentioned above. Suggestion: I would recommend darkening the filter threads on the bottom of the eyepiece and the bottom of the barrel itself. 7)image sharpness on axis and in the center 50% of the field is very good. If a user mainly looks here, it will be an engaging eyepiece to use. Suggestion: Use for objects that can be framed well by the field of view. 8)field curvature. In the Paracorr, I didn't really notice anything that I couldn't eliminate by careful focusing (I was only 62 at the time of this review). But without the Paracorr, though coma dominated the edge, (and astigmatism), I could focus the edge a little better and when I did, it defocused the center. Since my scope has a 1587mm focal length sans Paracorr (1825mm with), I would bet the field curvature of the eyepiece doesn't match the scope and augments it to create a noticeable curvature. It really didn't matter, though, since FC wasn't the biggest issue at the edge, and it was fully eliminated in the Paracorr by focusing partway out from center. Suggestion: Don't focus on a star in the center, but partway out and the entire field will be in better focus. Astigmatism and lateral chomaticism are reduced by having a better focus over the entire field. 9)coloration. Well, I'm pretty insensitive to this. Even if the tint were slightly yellow, my eye would see it as white 2 seconds after looking through the eyepiece. It's one of the reasons I regard any discussion of tint as a "tempest in a teapot". You might notice it if quickly changing eyepieces, like in a turret, but otherwise? It's only important to me if it reduces the ability to see colors in stars or objects. if I see a tint, it's STRONG. But in eyepieces? REALLY subtle. I saw none in this eyepiece, even on the Moon. It would be interesting to see if a simple black ring on the bottom of the eyepiece might eliminate an internal reflection (as it has done on some other eyepieces) or whether simple blackening of the filter threads helps. Had internal baffling been more aggressive, and the FOV reduced to, say, 90 degrees, this eyepiece could easily have earned a better review.

That single line O-III transmission is fine for astrophotography, but not good for visual, since about 25% of the O-III light is lost and the field is very very dark. An 11-12.5nm O-III filter that picks up both O-III lines would be better for visual.

eAFOV is NOT what you see. What you see is the apparent field of view, i.e. what angle the eye has to make from side to side to see the edge with direct vision. ALL eyepieces above about 40° AFOV have distortion, and the wider the field, the more there is. The ES 25mm is a 100° eyepiece (measured 103°), as that is the angle you see, not 94°. I see no purpose to even figure an eAFOV, since it doesn't relate to anything, unless you are merely using the TF = AF/M formula to compute TFOV. And you could just as easily use TF = (FS/Tel.FL) x 57.3 to compute an accurate true field without creating a fictitious eAFOV, since the field stop diameter is known, and this formula excludes any consideration for distortion. Meade 26MWA--44.6mm field stop, ES 25x100--40.8mm field stop. So the 26mm MWA has a larger true field. The SAEP would kill it for me. You're more patient.

£100 + VAT = £120 60% of £120 = £72 It effectively means the eyepiece is being sold for 72% of the pre-tax cost. That's not abnormal in the US, either. It still represents a significant reduction from the new price. A lot of used prices in the US run even higher, at ~80% of the new pre-tax price. It explains why I've always sold used eyepieces in only a few minutes, as I use a 50% calculation for pre-tax price.

I list the actual focal lengths as found on the test bench. Here is what Baader labels them: 17.5, 14, 12.5, 9, 6.5, 4.5mm Here is what they actually are: 17.2, 13.9, 12.4, 8.9, 6.7, 4.8mm Those differences are pretty small--even on the high end, where the difference in my scope is 26x between claimed and actual focal lengths. Cn you tell the difference between 380x and 406x in the field? I don't think I can. Both are "around 400x". The same is true at very low powers. I can see the difference between 50x and 70x if I really try to look for it, but I regard both as a low power for large objects. And if they had the same true field size, it would be even harder to tell them apart. We tend to obsess over small differences. How many times have you seen someone asking about an eyepiece in between, say, 30mm and 18mm when those two eyepieces are only 30x apart in his/her scope? When I said +/-, I was not referring to the measurements of the eyepieces' actual focal lengths, but the idea that someone choosing eyepieces could still follow a progression by modifying the eyepieces chosen by moving up or down to match a series of preferred eyepieces. For instance, if a series progression would be 20mm..14mm..10mm..7mm..5mm..3.5mm in the scope for a mathematical sequence, and the eyepieces came in 21mm, 13mm, 9mm, 6.5mm, 4.5mm, 3mm, then you might simply adjust to pick up the eyepieces offered, even if the sequence was not perfect. There really is no difference in the field between 145x and 155x anyway--they're both around 150x.

8" f/6 dob 1200mm focal length For a set of 50x/100x/150x/200x/250x for generally good seeing. 24mm, 12mm, 8mm, 6mm, 4.8mm For a set of 40x/80x/120x/160x/200x for generally poor seeing. 30mm, 15mm, 10mm, 7.5mm, 6mm. Eyepieces can be +/- of course.

Orion LHD Stella Lyra 80° UWA Founder Optics Marvel Long Perng 80° UWA

I've done PowerMate + Paracorr + 8mm Ethos ( a LONG stack, with 18 elements!) in the dob and had my "lifetime-best" view of Jupiter in full technicolor. 456x and absolutely perfect seeing. I'll never forget it--like a Christopher Go or Damian Peach image, only with a sharper focus.

The 9mm Morpheus is a great eyepiece. I'm continually surprised at its great contrast and sharpness.

Because of needing glasses down to 8mm, my longer focal length Ethos eyepieces went to other observers. I discovered I used the 7mm APM XWA a lot more than the 8mm Ethos, so the 8mm went, too. I simply preferred the 9mm>>7mm jump a lot more. But I still use the 6mm, 4.7mm and 3.7mm. The 6mm Ethos is special--it's as sharp as eyepieces can get and has superb contrast. The 3.7mm is similar, but gets more limited use because of seeing conditions at 500x in my scope. When seeing allows, it is my favorite eyepiece for planetary nebulae. It makes seeing M57's central star no challenge. The 4.7mm is my Uranus/Neptune eyepiece and I value the in-focus longer drift time of the 110° field. Some nights, I want to leave my glasses on, so I do use a 4.5mm (actually 4.8mm) Baader Morpheus, and it is as sharp as the Ethos SX, but the much narrower field means I move the scope a lot more. In a long focal ratio scope, the needs are different. A 13mm Ethos would see a lot of use. I think the 10mm might be just a bit better eyepiece, but it might see less use than the 13mm in the Mewlon. In the dob, though, the 10mm and 6mm make a powerful pairing. The 10mm would spend a LOT of time in the focuser. The 6mm could be a "planet/moon" eyepiece--it's that sharp.

I tried several Brandons in a 130mm f/6.5 scope, and the edges of the fields weren't corrected for astigmatism. I tried again with an 8" f/10 and found the same. They were provided by Questar for long focal length Maksutovs. They might be OK there, but I felt then, and still feel, they should be better corrected for shorter f/ratios to be worth the price of the competitors that are.

Vixen SLVs have 6-8 elements depending on focal length, and are not orthoscopic or Orthoscopic eyepieces. They are also 45-50° apparent field eyepieces. The UFFs range from 60° (10.5mm) to 65° (15-24mm). The Nirvanas (United Optics 82°) are a lot wider. One note: there are a lot of eyepieces sold out there as "Flat Field". These are not the same quality as the "ultra flat field" eyepieces. The Ultra Flat Field eyepieces are sold as: APM Altair Astro Stellalyra Tecnosky Celestron Ultima Edge Meade UHD Svbony SkyRover

One thing to know: The eyepieces have 20mm of eye relief from the glass, but only 12mm of eye relief from the rubber eyecup up. If you wear glasses and wish to use these eyepieces, the best course of action is to replace the rubber eyecup with a regular flip up/fold down type. You then would easily have enough eye relief for glasses use. If you don't wear glasses, the eyepiece is fine as is. Long Perng, the maker, has, I understand, addressed some of the internal light scatter issues they had with the earlier versions from Orion (the LHD), so this has likely improved. Comparing the Orion LHD 14mm (80°) to the 14mm Baader Morpheus (78°), the Morpheus had better contrast and went deeper, but it looked like the culprit was light scatter in the Orion LHD. The issue was communicated to the maker and I've been told that later productions have been better in that regard. Since StellaLyra is a latecomer to the model, it is likely the issue has been addressed.

The ES filters have too wide a bandwidth to be effective: Explore Scientific CLS Broadband Wide 100nm bandwidth Explore Scientific H-Beta H-Beta Wide 18nm bandwidth Explore Scientific UHC Medium Band 48nm bandwidth Explore Scientific O-III O-III Wide 18nm bandwidth Explore Scientific O-III O-III Photographic 6.5nm bandwidth (1 line) The H-ß is about twice as wide as it needs to be. The UHC is closer to a broadband than a narrowband, also about twice as wide as it should be. The O-III visual is too wide for effectiveness. And the O-III photographic is fine, but too narrow for visual use and only picks up one line. The visual filters are cheap Chinese filters and should be avoided.

Take my Eyepiece Buyer's Guide: https://www.cloudynights.com/topic/862337-2023-eyepiece-buyers-guide/?p=12473522 Add a column for price and start looking up prices. I think you'll find well over half of the eyepieces will be in your price range, so the list will contain hundreds of entries. This will not be simple. I used to put prices in the spreadsheet, but it seemed many prices changed every day, so it proved impossible to keep up. Suffice it to say, the huge number of eyepieces in your list will make the task of looking up all the prices and converting to local currency a daunting process that will take you a couple months. Then you will have to go back and do it all again to account for sales and price changes and even currency exchange changes. What would you do if an eyepiece at £147 went to £152? I've just started on the 2024 version, and it is proving to be difficult because many companies seem to have added some new ones since last year.

Baader's O-III filter is so narrow it only picks up the 500.7nm O-III line and excludes the 495.9nm O-III line. Visually, this can result in great contrast for the small bright details, but at the sacrifice of size, as the outer parts of O-III nebulae are fainter, and the 25% of O-III light you sacrifice with a single line filter means it will usually not show the full extent of the nebula. That's why single line O-III filters are usually considered photographic O-III filters, where getting more nebula just means more exposure, while two-line O-III filters are considered visual O-III filters. I experimented with O-III filters from 8.5nm bandwidth to (hard to imagine) 28nm (!) bandwidth, and discovered the really good ones picked up both O-III lines and had bandwidths of 11.5-13nm The 15-18nm bandwidth filters didn't yield the contrast or the full extent of the nebulosity. Needless to say, the ones in the 20-28nm range were simply close to having no filter at all. For O-III, I've seen great results with: Astronomik O-III 12nm (2017 on) Tele Vue BandMate II O-III (2018 on) Lumicon O-III (2005-2011, 2018-2022)

Ed, A good narrowband filter passes the H-ß spectral line at 486.1nm and the two O-III lines at 495.9nm and 500.7nm. Since those lines in the spectrum seem to be emitted by most nebulae, the narrowband filter is the "universal emission nebula" filter. You don't have to know the spectrum of the object to figure out which filter to use. It will enhance just about any nebula that emits light. It likely won't help on reflection or dark nebulae. The important specs are: 22-28nm bandwidth, and >90% transmission at all 3 lines in the spectrum. The filters that do this are: Astronomik UHC Visual Tele Vue BandMate II Nebustar Orion Ultrablock Lumicon UHC DGM NPB Many "UHC" filters have wider bandwidths and enhance the nebula much more weakly. They go by names like: UHC-S, UHC-E, UHC/LPR, UHC-L I suggest staying away from them. So far, I have not seen a filter from China that met the standards of a good narrowband filter, though a few have come close. If you stick to the ones above, you'll do fine. As for size, since the filter will be used below a magnification of 12x/inch of aperture, match your lowest power eyepiece for size. You won't be using it at higher powers due the darkening of nebulae with increased magnification. Where line filters like a dedicated H-ß filter or O-III filter come into play is where the nebula emits primarily energy in one or the other, but not both. A line filter can yield a bit higher contrast. If you find observing nebulae is what you want to do, then add a good O-III filter to the mix, but you can wait on that. Spend a little more money on the Narrowband filter first, because it will get the most use. This summary of what nebula filters are and how they work, and the types might be educational: https://www.cloudynights.com/topic/901098-light-pollution-filter-reviews/?p=13092087

What about AstroBuySell.com/UK/ ?

Mid-range may be determined by your pocket book. I consider <$100 to be inexpensive (Paradigm, X-Cel LX), $100-$200 as average price (Hyperions, BST 70°, UFF), $200-$350 as medium price (XWA, XW, Morpheus), $350-$500 the low end of high-priced (Delos, Naglers), and $500-$1500 as high priced (Ethos, Nikon HW, Leica Zoom). My data for the US puts the median price at ~$100, so the pricing pile resembles a pyramid.

Excellent correction, of course, and smooth in operation, and equally well-corrected at every focal length, and parfocal through the range. Weight limit one kilogram. 2" size. Can it be done? Maybe. Will it be done? Unlikely, as it would have no use in spotting scopes, the home of most zooms.

I'll adopt the use of zooms when they have a constant 80° field from 8-24mm.

Focal lengths are, IIRC, 25mm, 18mm, 15mm, 12mm, 8mm, 5mm, 3.2mm, so no 10mm is available.