great_bear

Ed Ting lists the Mewlon 180 as one of the top five scopes he regrets buying (this link jumps straight to the Mewlon part):

It's because it's cold here. Warm, moist air from your eyeball, is what causes the dewing. Usually the eyepiece is fine until you look through it - would be funny if not so infuriating! On such nights it can help to keep eyepieces in your pocket to keep them warm - but with Delos etc, that's easier said than done!

Where are they the same price as Delites?

I've only just read of the recent passing of the Delos designer, Paul Dellechiaie. Such a sad loss.

I've only just this moment learnt of this - what a sad loss - it was only yesterday that I was singing the praises of the Delos eyepiece. David Nagler of TeleVue said that Paul "never had a bad word to say, and always took adversity in stride by applying logic over emotion. He had one incredible mind. To say Paul was an avid reader is like saying Niagara Falls flows like a bathtub faucet." A loss not only to those closest to him, but to the entire astronomy community.

Hmmm… Could I be thinking of the Pentax XW that I used to have?

Some of you may have noticed that I took a break of several years from SGL before posting again recently. The answer was quite simple: Televue Delos I had been searching a long time for the right set of eyepieces. I started off working my way through nearly every budget model available: various Plossls, the X-Cel's the SkyWatcher/TMB Planetaries, the BSTs, Circle-T Orthos, various budget wide angles, but nothing felt "right". There was always something that bugged me about every model available - hence much discussion in the eyepieces forums both here and on Cloudy Nights. Even when I upped the budget things didn't get much better - I tried the Pentax XWs (didn't like them), TeleVue Plossls (really did not like those!) even some hyped classics like Edmund RKE's and the fabled Brandons. I moved up to some Televue Radians - and was truly horrified at the coloured fringes all over the moon! (what's the point in using a reflector if your eyepiece has CA in spades??). Even making my own combinations with barlows was not working well. I *always* got bad effects from barlows - even with a TeleVue PowerMate I could clearly see internal planetary reflections even with the best quality eyepieces. I decided barlows were out, and didn't know where to go next. Then I bought a Televue Delos, brand new. I froze when I first used it. I was astounded. Everything about Delos was - to me - perfect. Even when performing unreasonable things like shining a high-power torch through it, you could see the internal baffling was perfection too. The build quality is impeccable. What's more, even at the highest powers, stars remain tight pinpricks of light. I sold off various bits and pieces and bought another three Delos - so in total that's the 17.3mm (with Dioptrx), 12mm, 8mm, and 6mm. If you think that's too many of them (especially when using the @Don Pensack magnification scheme) then I'd be inclined to agree with you - I could quite happily collapse the middle two to a 10mm without feeling I was missing out on anything. However I will nonetheless add one final thing: a 5mm Televue Delite. That's to push to 240x on good days (the max possible it seems, in my London skies), to augment the somewhat "safe" 200x of the Delos 6mm (no 5mm Delos exists). I do have some other "keeper" eyepieces that suit various scopes, but my remaining unused eyepieces I will be selling to help fund the 5mm TeleVue Delite purchase. Anyway, all this is just my long way of saying that although "no perfect eyepiece exists", for me, the Delos is as close as it gets! Whilst they are no doubt too heavy for small and lightweight telescopes, for use in my 8" Dob and 6" Newtonian however, they're astonishing. I never thought such a good eyepiece design/build could exist - but it does. Thoroughly recommended. Jeremy.

Would it also make sense that I see no such curvature in the eyepiece that I settled on instead, the Meade 24 SWA?

The TMB Paragon 40mm has become a bit of a classic (also known as the Sky Watcher Aero ED40) - and not particularly expensive either. Unfortunately it's getting harder to find these days. I have one, and it's a keeper; I'm never selling mine (and I'm ridiculously fussy when it comes to eyepieces). https://www.harrisontelescopes.co.uk/acatalog/skywatcher-aero-40mm-ed-eyepiece-2.html (out of stock, regrettably).

I think these guys were probably somewhat more than cheesed off... https://www.latimes.com/archives/la-xpm-1999-oct-01-mn-17288-story.html

Yes - it's worth pointing out that the resolution and contrast ration of the screens in the latest generation of iPhones is incredible. Display technology doesn't stand still...

Well - you can already rent time at high-end telescope facilities remotely. No reason that scheme can't be extended to space telescopes.

It would either have been in the Mak 180 Pro (F15) or the standard SkyWatcher 130P (F5) - I can't remember which.

It was definitely field curvature. You could rack the focuser in/out and the stars in focus would change from being the ones around the edge to the being the ones in the centre (and everything in-between as you racked in/out) I thought it was the Panoptic 24, but can’t rule out being mistaken.

Apologies - I must be getting it confused with something else I had in that focal length that was like the starfield was wrapped on a tennis ball.

I found the field curvature on the Panoptic 24mm unbearable (one of the reasons I sold it on) - does the 41mm also suffer from that?

It often depends on the scope. I got a 30mm GSO SuperView free with my Dob (I think), in which it's really not very good, but nor did I expect it to be. However, it works wonderfully in my Mak 180 (F15), provides the widest field possible, and I've got no plans to replace it with anything else.

I take it you've seen there's one up for sale here on SGL?

Will you do this be by coomparing (e.g.) star distances with a known eyepiece? That's what I had to do with my Mak + binoviewer. The mirror shift required for a revised focal plane that includes the binoviewer, changes the magnification on a mak. in a manner that I knew would be tough to calculate, so I recorded the change in spacing between specific stars. On my Mak180 this gives me: Bino + eyepieces: 1.20 x mono (normal) eyepiece magnification With 1.6x barlow on bino: 1.75 x mono eyepiece magnification With 2.0x barlow on bino: 2.12 x mono eyepiece magnification - although of course on any telescope I would assume that non-parfocal eyepieces would get some slight variance in magnification when using a regular, i.e. non-telecentric, barlow, so I'd always use measurement to get the answer. I wonder what level of magnification the William Optics Bino Barlows provide if screwed directly on the base of an eyepiece, rather than on the binoviewer nosepiece. Anyone know?

As per photos below: You can tell it's a William Optics product - it hasn't been baffled properly! (see above photo) 😊

Sure - will do so later today.

I have both of them. I have no trouble telling them apart - they are different lengths for one thing - the 2x being the shorter one, but the main difference is that if you hold them up in front of your face a few inches away and look at (e.g.) some nearby trees, the 2x will have the wider view. If you are in the dark and want to know which one you have in your hand, with experience you can hold it up to the sky and tell by the aperture which one it is - the 2x having the larger aperture by some margin.

Quality of Q-Tips may be better in USA. Here in the UK “Cotton Buds” (as they are known here) can be quite variable. I used some Sainsbury’s own-brand ones today, and they were shedding fluff all over the lens surface Didn’t affect cleaning much - I just blew it away as it happened using the bulb-blower. My Orion 2” Ultrablock filter is proving tricky. One side is perfect but the other side looks like it has a lot of dust, but in close inspection it’s a myriad of tough surface specks that don’t want to go away. I *think* I’ve made it a bit better, but I’ve stopped before risking it further. is mould-remover safe to try on an ultrablock @Don Pensack or would that destroy the coatings do you think?

+1 for that Baader cleaning cloth. Big fan of that for both eyepieces *and* for mirror spots. When washing (any) optical cleaning cloth, I normally finish up giving them a good hand-rinsing with distilled water. Tap water leaves scratchy limescale powder deposits otherwise. I also find that the cleaning cloths given away with spectacle cases are usually terrible and go straight in the bin.

Unfortunately it *is* important to remove eyepiece dirt because - like cleaning your car - if you avoid it, you can get spots permanently etched onto the surface. But do be *very* careful when using cotton buds and tissue - it's easy to apply too much pressure and scratch the lens due to a trapped dust particle. I've also known some toilet/kitchen tissues to have particles trapped *within* the manufacturing of the tissue itself! For genuinely dirty eyepieces, always use a brushless-bulb-blower first, then visually confirm under excellent lighting that the surface is particle free, and check the tissue/bud is also free from contaminants before slightly dampening with isopropyl or wonder-fluid and wiping, and even then use only the lightest of touches to get the job done. There are some excellent additional tips on the Televue web site. HOWEVER - the best technique of course, is not to get them dirty in the first place. ALWAYS keep them capped (at least the top one) when out, and always bring them indoors with both caps securely on - or they'll quickly get covered in condensation, which can lead to mould spots if then re-capped in that state. Be aware at public events, unskilled observers often fail to see anything due to incorrect eye-placement, and may immediately use their thumb to wipe the eyepiece! It's jaw-dropping when it happens, but they don't know any better. A lot of folks use "junk" eyepieces when allowing randoms to look into the scope for that reason alone. Anyway, if kept clean through careful use, the only eyepiece maintenance required is normally: First a brushless-bulb-blower to remove dust that's landed on them The very edge of a fold of new, *dry* tissue to merely "poke-away" (NOT wipe!) any stuck particles before blowing off the surface with that bulb-blower Then a genuine brand-name lens pen from a reputable dealer - but ONLY if (and where!) there are visible surface marks (again, only the lightest-of-touches) A final blower blast, to remove any remaining lens-pen particles I can't remember the last time mine were bad enough to require any application of fluid... Five years or more? P.S: Avoid using lens brushes on eyepieces in particular. They may appear to work at first, but the dust is often sticky with eyelash-sweat and gets smeared everywhere the next time you use that brush, and the brushes almost impossible to clean after that. Fake lens pens have been common in the past, and are a disaster. Sure they seem expensive when purchased from (e.g.) FLO, but you're getting the real thing - I've had a fake one bought elsewhere before, and believe me, its really not worth the risk!