Louis D

I paid about $65 in shipping costs to the US; but on the plus side, FedEx got it here in 3 days. Since I didn't pay the 25% special tariff, 8% regular tariff, or 8.25% sales tax, I was still paying about the typical used price for them in the US ($170).

I measured 11mm of usable eye relief using the flashlight projection method. The eye lens is recessed 7mm, so 18mm of design eye relief. Believe it or not, but I've had no issues seeing the entire AFOV in the 40mm Lacerta ED with my eyeglasses on. They do have to be in contact with the fully retracted eye cup, but it works just fine for me. I reverified this Saturday night. I can't explain this result any more than being able to see the entire AFOV of the Svbony 3-8mm zoom at 8mm with eyeglasses pressed lightly against the rolled down eye cup. It has a bit less measured, usable eye relief than the Lacerta. For comparison, I have to really cram my eyeglasses really hard into my 27mm Panoptic to see its entire AFOV, and it claims to have 19mm of eye relief, though I've measured just 14mm of usable ER. The eye lens is barely recessed, so it must be down to its concavity. I even scratched an expensive eyeglass lens on the exposed, metal retaining ring on the eye lens of that eyepiece. I have had no qualms retiring it in favor of the 30mm APM UFF. Had the UFF existed in the late 90s, I would have never bought the 27mm Panoptic in the first place. That concave eye lens versus flat eye lens may be part of eye relief usability despite what the ER numbers say. Eyepieces with steeply converging eye rays from concave eye lenses may be more difficult to use with eyeglasses than those with more gently converging eye rays from relatively flat topped eye lenses.

I have used a Moon & Skyglow (Urban Skies) Neodymium filter to slightly cut light pollution to enable better seeing of comets in the past. Lumicon made a comet filter that passed the carbon lines associated with many comets. Since they are just to the right of OIII lines, a UHC or light pollution filter like a CLS or similar might help as well. As far as color filters, perhaps a light green or blue filter might help. The problem is, you want a teal or cyan filter that cuts out yellow/orange/red light. I don't know of a commercial astro teal or cyan filter. It would sort of be the inverse of an orange filter (which cuts violet/blue/green light, the colors of most comets). You really won't know until you try each on a particular comet.

Try Budapest Telescope Centre. They show low stock rather than no stock. I've bought from them before without any issues.

I've found that if I add 15mm of extension to a GSO dielectric 2" diagonal along with an SCT to M48 thread adapter, I get pretty close to perfect results in either my 432mm 72ED or 600mm 90mm APO. I tried removing the 15mm extension for the latter as suggested by the separation table, but the results were worse.

It's the same as the APM UFF line which includes 10mm, 15mm, 18mm, 24mm, and 30mm versions: It could be that KUO makes the ED line as well as the UFF line, thus the similarity in appearance that you noticed. You may also be confusing the 30mm ED with the 30mm UFF which are not the same design at all. The 30mm and 40mm EDs were originally TMB Paragon designs. The 35mm was introduced later after the death of Thomas M Back under other labels. I see @badhex beat me to the punch, but on the next page of responses.

That is so weird that you consistently get these results with your copy, and I get my results with my copy. It doesn't matter which scope I use it in or how much edge refocusing I do, the Trapezium clearly loses its distinctive shape nearing the edge in my 14mm Morpheus while the 17mm ES-92 at an even lower power and wider AFOV continues to show it perfectly to the edge without any focus futzing. I even tipped my head to look straight at the edge to make sure my eyeglasses weren't causing the issue by inducing chromatic aberrations by looking through them off axis, but the view remained the same.

35mm variant of which? The UFF series stops at 30mm and the ES-68 series has 34mm and 40mm members. I have both the 35mm Aero ED and 40mm Lacerta ED versions of these eyepieces. The 35mm has a wider AFOV, slightly smaller TFOV, and poorer outer field correction than the 40mm. In fact, last night, I went back and forth between my 40mm ED and 40mm Pentax XW-R, and I think the ED had less field curvature and basically the same level of field correction. The Pentax does have a larger AFOV due to greater distortion, but basically the same TFOV. I thought about bringing out the 35mm ED last night, but the tighter eye relief and poorer correction put me off that idea. I had lots of other comparisons of newer equipment to make that had been queued up for a while, so my time was somewhat limited for revisiting the past. Basically, I'd say skip the 35mm ED and get the 40mm ED. The difference in exit pupil and sky brightness is minimal. I'm pretty sure you've seen my write-up of all of them, but it bears worth repeating for those who haven't:

Tonight I compared my new Svbony UHC to my vintage Lumicon UHC on the Orion nebula. The difference was very slight. Both helped to bring out nebulosity in my Bortle 6/7 skies. My new Lumicon OIII performed about the same as my vintage Lumicon OIII except that it didn't leak any red, so stars were simply green, not green/red, which was less distracting. Either Lumicon OIII worked better than my Zhumell OIII, but not vastly so. Stacking them darkened the background even more. Any of the OIII filters brought out more nebulosity extent than either UHC from the background sky. In short, the Svbony is a great tool to have in your astro toolbox for a great price. The Lumicon OIII is also a best buy at its current closeout price with the moving sale discount code from Farpoint.

I just got in from using my 90mm TS-Optics FPL-53 APO (f/6.7) with TSFLAT2 flattener on the Trapezium region, and I could only detect the very slightest amount of astigmatism and field curvature in the last 15% of the 30mm APM UFF's AFOV. The 30mm ES-82 had vastly more astigmatism, and wasn't nearly as sharp on axis. I had difficulty splitting the Trapezium anywhere in the field with the ES-82, but could split it everywhere except in that last 15% with the UFF. My only two eyepieces that were absolutely sharp edge to edge without refocusing were the 12mm and 17mm ES-92s. The 12.5mm APM Hi-FW was close behind losing just a bit of sharpness in the last 5% of the field. The 14mm Morpheus had a bit more astigmatism and field curvature nearing the edge. The 22mm NT4 was had noticeable astigmatism and some field curvature. The 26mm Meade MWA was noticeably sharper on axis and held onto more of that sharpness nearing the edge without refocusing.

Give the ES HR CC a try with the 30mm UFF sometime, and see if both issues are minimized. Most CCs not only correct coma, they also help to flatten the field. If you can live with both issues, and the imbalance issues with the CC outweighs the sharpening effects, then definitely continue using the UFF straight into the focuser.

You don't say which coma corrector you were using with your f/5 Newtonian. I've found my 30mm APM UFF to be sharp to the edge with a GSO CC in my f/6 Dob. I've measured its AFOV to be 73 degrees. It's eAFOV (to plug into TFOV calculators) is indeed 70 degrees due to slight distortion.

Glad those filters worked out for you. I've been experimenting with various yellow filters trying better understand what density of yellow is needed to suppress unfocused violet light in my 80mm f/5 refractor. So far, it appears that lighter is better on less bright objects, but brighter objects require a denser yellow. I think it's because our eyes simply can't perceive dim, unfocused violet; but can when it becomes brighter. That yellow filter you bought should be just about appropriate for planets in fast achromats without introducing a noticeable yellow cast. I think it's close to a Yellow #8.

Let us know what you think of it once you get a few nights use out of it.

I believe the GSO has a 75mm +/-5mm separation requirement. So, if you're roughly in the ballpark, you're good to go. Since most of my eyepieces focus within 5mm of the shoulder, I've found that adding a 25mm M48 spacer ring between the optics section and the eyepiece holder removes 95%+ of all visual coma for nearly all of my eyepieces. The lone exception is my 12mm Nagler T4 which focuses 20mm below the shoulder. I could clearly see residual coma, so I did the following to parfocalize it using five 4mm-thick, 48mm-ID O-rings and a 20mm M48 extension tube: I say visual coma because a camera would most likely still detect some uncorrected coma, but our eyes are not so adept at noticing slight ovalness to stars in the far outer field. The Tele Vue Paracorr II and ES HR CC both have tunable tops, but I think their designs are less forgiving of being off a few mm from the correct spacing. That, or their owners are less forgiving of slight imperfections. I will warn you to remove the pot metal thumbscrews GSO supplies with their CC and replace them with M4 steel cap head hex screws. One of their cheapo screws sheared off in one of the two thumbscrew holes and I can't remove the remnants without drilling it out and retapping the threads, so I've been living with using a single steel thumbscrew since then. Why do they do that? A dozen steel screws bought in bulk would probably cost no more than a dollar in Taiwan.

Here's a nice thread on CN about these Vixen made short tube 80s. Seems like you picked up a vintage winner.

Coma is one of those things that you don't notice until it's gone, and then you notice it when it's back. I went without a CC for 15 years in my Dob quite happily. Then, a GSO CC came up for sale on CN classifieds for $75, so I went for it since it was a fraction of what I was paying for individual eyepieces during that period of upgrading. BOOM! The outer regions of 70+ degree eyepieces were noticeably sharper. When I removed it, I couldn't unsee the slight unsharpness I had been living with. Admittedly, if your eyepieces have loads of astigmatism or field curvature in the outer field, you won't notice a difference. This was the case for me prior to my eyepiece upgrading spree. You also might not notice with long eye relief eyepieces with powerful Smyth lenses that slow down the incoming light cone for the image forming upper group(s). This is the case with my 10mm Delos. I absolutely cannot detect any change in the image with or without a CC. This is not the case with the 12mm ES-92, however. It desperately needs a CC for best performance. Low power eyepieces like Panoptics and their clones probably benefit the most from a CC. I've also found that some long focal length eyepieces have sharper field stops with the CC than without. I have never been able to pinpoint what is the optical cause of that artifact.

I use a GSO coma corrector with a 25mm spacer tube between the optics nosepiece and the eyepiece holder. With my ES-92 eyepieces, it's quite obvious even at f/6 when I forget to put the CC in the focuser. However, at high powers, I have to remove it because it induces a bit of spherical aberration on axis which turns fine planetary details to mush. The Tele Vue Paracorr II reported doesn't have this issue.

Are you referring to these offerings? Altair 70 EDQ-R F5 Quad APO Astrograph TS-Optics 70 mm f/5 Quadruplet Flatfield Apo with 3-Element FPL53 Objective TS-Optics 61EDPH - 6-Element Flatfield Apo 61 mm Aperture F/4.5 TS-Optics 5-Element Flatfield Photo Apo Refractor - ED61PHD

I picked up the Svbony UHC since it's already wider in passband than a typical premium UHC, so it's closer to a light pollution filter already. The CLS is getting too wide to be of much use at all.

The usable eye relief of the original mushroom top 30mm ES-82, which is slightly better than the 31mm NT5, is just too tight to be comfortable panning around with eyeglasses. Both have about a 30mm diameter eye lens, which is simply not enough for an 82 degree field to be comfortable to use with eyeglasses. It's doable, but not easy. Here's a size comparison of my 29mm ES-92 (labelled 12 obviously) with my decloaked 30mm ES-82 and 40mm Pentax XW-R: I don't use the 29mm ES-92 regularly, but instead break it out occasionally to liven things up a bit.

Right there with you. Your eyepiece journey with the NT4s and ES-92s exactly mirrors mine. I do have the 29mm ES-92 unicorn eyepiece. It started out as a 12mm ES-92 missing its field (Smyth) lenses that ES sold in a large lot of warranty returns. I've always wondered how it got in that condition. I pieced together a couple of hard-to-find step rings to reduce its in-focus requirements from 40mm to 21mm. If I screw my GSO CC nose piece directly into the filter threads, I can reach focus even in my Dob. It has a lot of chromatic aberration starting not far off axis, but if you look straight at the center, it's not that noticeable. Its much better than the vintage 30mm Kasai Super WideView 90° in this regard. The measured AFOV remains at 93° as with the original 12mm ES-92. It is remarkably free of edge astigmatism despite lacking its Smyth lenses. Usable eye relief remains about the same as for the original 12mm ES-92 which I also have. The measured field stop using photography is 48.4mm despite measuring 51mm with calipers. The FS being well above the top of the 2" barrel allows for this. The internal field stop is now fully accessible for direct measurement just like in a Panoptic. It is a hoot to pan around star fields with. The window into space effect is full blown. Without the Smyth lenses, there is no SAEP (kidney-beaning) at all, so holding the view is a breeze while panning, even with eyeglasses. I've compared it to my 30mm ES-82, 30mm APM UFF, 30mm Widescan III clone, 26mm Meade MWA, 29mm Rini MPL, and the 30mm Kasai SWV 90°; and it is in a league of its own for low power, wide field panning with eyeglasses. If ES would offer this as a product with some sort of chromatic aberration corrector instead of the Smyth lenses, it would sell like hotcakes.

It seems like you'd want to keep the Masuyamas for the lightweight set given how big and heavy the new XW-85s are.

I've gotten a couple of new filters (Lumicon's second most recent OIII that they're clearing out for $30 with their MOVINGSALE2023 code and the Svbony UHC), but no time at night to try them out yet. I imaged their spectra through my spectrograph and came up with the following: The Lumicon UHC and OIII Old both date to the late 90s. The Zhumell barely does anything for OIII being too far right of the lines, but might work as a comet filter and the C lines. The new Lumicon leaks an unnoticeable bit of red, so a major improvement over my vintage filter. In fact, the vintage Lumicon OIII is more of UHC with no H-beta line. The Svbony UHC is more of a light pollution filter than a true UHC filter. It might also make a decent magenta filter on Mars. I hope to try them all out on the Orion nebula in the near future.

I use the nosepiece of a vintage Meade 140 2x Barlow which operates at 3x in my Arcturus binoviewer to reach focus in all of my scopes. My Dob is setup with maybe 25mm to 30mm of in-focus from its focus point. The Meade nosepiece results in very sharp views.