Don Pensack

Here is the spec sheet from Vixen Japan:

I have 14 eyepieces in my kit box and one coma corrector. The 2" adapter for that CC, and the 3 eyepieces with undercuts all got the treatment with copper tape to fill in the undercuts, and now slide right in and out. The copper tape technique works quite well.

They've been around for several years, so many on-line reviews if you search.

I think 3 companies have had 4 element telecentric Barlows: Tele Vue Optics, Harry Siebert Optics, and Jing Hua Optical( sold as Meade, Explore Scientific, Altair, and others). There may have been others, but I am not aware of them.

Yes, They produce very very large numbers of glass for phone screens every year. Also eyepieces, scopes, mounts, etc.

ES designed 3 other focal lengths in the 92° series several years ago, but they haven't been released. They told me they've been put on hold due to production scarcity. I was told by their sales manager that they place orders for eyepieces a year in advance and that the factory, a cell-phone glass manufacturer, makes the eyepieces in two large production runs per year. if they get all they ordered but make an error guessing what will sell and what won't, they can make changes in the next production but can be out of stock for 6 months to a year. And they have been. That was before Covid19. Now, they have to contend with raw materials shortages, factory shut downs, standing in line to get on a ship IF a cargo container is available, and a shortage of drivers to deliver the container. Factory to warehouse shelf used to be 3 weeks, but now it can be 3 months. Add that delay to other delays, and they can only pray their planning department guessed exactly right on product demand. Most companies saw a 300-400% increase in sales during the pandemic, and though sales have declined since the peak, they aren't back at pre-pandemic levels. So, shortage of materials, long delays, and increased demand--a perfect storm condition that creates empty shelves.

This is an industry that can't standardize filter threads. Standardize eyepiece barrels? ¡Buena suerte, amigo!

It sounds a lot like astigmatism. Cause #1, if it rotates in angle with your head, is you own eye. If it goes away at high powers, but is worst at low power, that is a good sign it is in your eye. Cause #2, if it doesn't rotate with the head , is in the optics of the scope. That could be the star diagonal or the objective. You can eliminate the star diagonal by using/borrowing another and seeing whether the problem goes away. If it doesn't, it is likely in the objective. I have seen tons of small refractors (50-90mm) with serious astigmatism in the lenses, so that would not be surprising.

Eye relief is the distance from the top center of the eye lens glass to the exit pupil. It is the industry standard. However, there are factors that affect how useful that eye relief is: 1) the depth of the eye lens below the rubber eyecup. Many long eye relief eyepieces have their long eye reliefs destroyed by a too-deep eye lens. 2) Whether the eye lens is concave, flat, or convex. Some older designs seemingly have no eye relief but are still usable because of convex lenses. Some more modern designs seem to have less eye relief due to concave eye lenses. 3) The shape of the top of the eyepiece. If a folded-down eyecup still sticks up several mm, that will reduce the effective eye relief. Effective eye relief is the distance up from a folded down eyecup to the exit pupil. I have seen effective eye reliefs really bite into the mfr's eye relief significantly. The 24mm APM Ultra Flat Field eyepiece has a 29mm eye relief, but the effective eye relief is only about 18mm because the eye lens is deep in the eyepiece and the rubber eyecup doesn't fold completely flat. Even with that, the 18mm effective eye relief can be too long when the eyepiece is used by a non-glasses wearer (see Badhex' post). 4) Some companies have tried to measure the effective eye reliefs of their eyepieces and post those figures because it is relevant for glasses wearers. But this figure, if not also quoted in combination with the mfr's eye relief, is misleading to those who view without glasses. Take that APM 24mm. If all you saw was 29mm, then most would think the eye relief was excessive. But it's only about 18mm for glasses wearers, and some glasses wearers couldn't use it. And non-glasses wearers might still find the 18mm excessive, or be scared away from the eyepiece altogether by seeing the 29mm figure. I advocate that all eyepiece companies advertise both actual and effective eye relief figures, which would help all of us decide if the eyepiece is suitable for our uses. But, as they say, if wishes were horses, beggars would ride.😄

I've shipped many thousands of orders via UPS and USPS. USPS has not lost one package, though occasionally it takes an extra week or two to arrive, and I have had one misdelivery (which the homeowner delivered himself). UPS has lost about a half dozen boxes and damaged a few others. Still not a large number, but it is annoying. FedEx has not lost a package, but they are very expensive. I don't know about the UK, but shipping services in the US allow you to purchase insurance for the value of the package when you ship, and if you can show the value of the item shipped (which requires a paper trail), you do get reimbursed (at least I always have been). None of the orders lost had been delivered, though.

Huh? The rubber is glued to the threaded ring, and there is no grease at all.

I reply above, in between your lines.

Yup. Baader Morpheus, Pentax XW, Baader Hyperion--all 43mm underneath (Hyperion also has a 54mm).

The Hyperions work fine at f/8 and longer. Come to think of it, most eyepieces work great at f/8 and longer.

It is not unusual, in fact it is ordinary, for people who don't use glasses to find the eye relief of long eye relief, glasses-compatible, eyepieces to be excessively long when used without glasses. Many eyepieces have roll-up, or slide-up, or click-up eyecups to pull the eyecup out farther away from the eyepiece to help hold the head in place at the longer distances to the lenses. Others, like the Morpheus, include an eyecup extender, and yet still others sell an after-market extender. There is nothing unusual in your having a bit of difficulty holding your eye in place at a large distance from the eyepiece. Many amateur astronomers have been getting steadily older, and the number of posts criticizing eyepiece makers for not having enough eye relief for glasses has been steadily climbing over the years--to the point where, now, it is almost folly to introduce a new line of eyepieces that are not compatible with glasses. The makers, though, do need to address usability by the non-glasses wearers. Even with glasses, there is a profound difference from person to person, and some glasses wearers can use as little as 16mm of eye relief, and others need up to 24mm. How deep-set your eyes are and how far away the lens is from the eye enter into the picture of a need for eye relief. Even a lot of people who do not wear glasses complain about short eye relief eyepieces being "uncomfortable". Make sure you observe while seated--that makes holding your eye in place much easier.

It is held in place by the knurled ring. You need to unscrew the ring to remove the rubber eyecup. That will expose the M43 thread.

It is true that TeleVue has switched to single-sided caps on most of their eyepieces, so it is possible the dual-sided versions are no longer being used. However, a lot of stock still has the dual-sided caps. Only a call to TeleVue will provide the truth of that.

TeleVue only sells these direct to consumers. It's possible there is a distributor in the UK, but I don't know if there is or not,

Your issue is Seeing. The magnification you seek to achieve requires exceptionally good Seeing, and a mount that can deal with such a long focal length and still track smoothly. I regularly observe where there is excellent seeing, but even then, the planetary imagers take a hundred thousand images to get 500 good ones for stacking. You might be better taking a video and then using software to reject the images that are too far from average focus to combine. And that assumes your scope is cooled down, which might be the issue. If it has sat out the entire night and you are taking images after many hours of the scope sitting outside, the optics are probably cooled. If not, heat in the scope itself could be blurring the image. And when was the last time you checked collimation in the scope? A very high power star collimation might help. And, were the planets being imaged still low in the atmosphere, or did you wait for Saturn to culminate (cross the meridian)? Because getting a sharp image when the planet is below 30° altitude is iffy, and below 20° is just plain unlikely. But, all that being said, try every morning for many days in a row, and you may find one of those mornings has better seeing. Take a lot of images, then.

I think having the red transmission, when the red is the brightest emission from the nebula, makes the nebula appear larger and allows those of us with exceptional abilities to see reds and long wavelengths, to pick up reds in the nebulae. M42 is so bright it damages my night vision, so no surprise I see multiple colors there. M8 and M17 are not as bright, so it is an exceptional night where even a filter that passes reds allows reds to be seen (or maybe I should call it "pinkish-grey"). I've also see red in M20 and M16, but due to the low surface brightness, the colors could be spurious. To wit: under extremely low light conditions, two grey areas immediately adjacent, one of which is ever so slightly brighter than the other are seen as greenish-grey (the brighter) and reddish-grey (the fainter). The colors aren't real, but are filled in by the brain. It's always wise to distrust the colorations. However, I have seen a yellowish-beige in M42 adjacent to the central region, and marked it on a crude drawing. Later, I verified its reality on color photos of the nebula. So sometimes the colors seen are real. I'm also at 35°N, so these nebulae all rise much higher in the sky for me. M8, for instance, culminates at +30-31° for me. So I see a brighter nebula against a darker sky.

Thanks for the clarification. I guess I never saw the "improved" version of the filter. I'm not all that sure the red transmission is what has the effect in making the filter a good one. My Lumicon, TeleVue, and Astronomik are all 26-27nm bandwidths, while my DGM is only 21nm in the blue green. That is a substantial difference in bandwidth. It may simply be the narrower bandwidth that yields the high performance level, though red coloration in M42, M8, and M17 are a lot easier in the DGM. I have a 2010 Lumicon UHC with a 22nm bandwidth and no red transmission at all. I should compare the two more extensively.

My DGM must have been an original because it has the triple looped red-orange-to-red response. Stars appear basically red as the 21nm bandwidth in the blue green is insufficient to add a blue green coloration. I didn't know they had changed the spectral response of the filter. The narrow Blue-green and the single peak at H-α will not color stars red--they should appear blue green since the eye's H-α response is well below 1% at night. DGM still shows the triple loop response on their website: http://www.npbfilters.com/spectral.html and the NPB filters tested here: https://searchlight.semrock.com/?sid=a08a1af9-84ee-49d2-959d-153d7e7c0eb8# all have the triple loop response. Here is the spectral curve provided by the filter coater: https://www.omegafilters.com/product/4384 So I have to ask, where did the "Improved DGM NPB" curve come from?

yes, add a second extension (they are available from Baader), or, simply unscrew both the extension and the eyecup a mm or so and leave them that way. There is no risk of them falling off because the threads are quite long, and you can dial in the extension you need. if you are concerned about the looseness, maybe add a drop of green loctite to the threads so they can still be threaded with a bit of resistance.

Pentax was owned by Pentax, then Hoya, then Ricoh. All those companies are Japanese. How something is classified is, I believe, determined by the preponderance of the manufacturing. A US made car uses parts from many countries, and may be assembled in Canada from US-Made sub assemblies and still be considered a US-made car. In the case of the Pentax eyepieces, Ricoh has plants in the Philippines that assemble camera lenses and binoculars, which is probably why they have them assembled there. I was told they were assembled there, but I doubted it until I started getting all the eyepieces from the Philippines in boxes marked "Philippines". We live in a multi-national world.

The US has a 25% tariff on Chinese goods.