Louis D

I have a TS-Optics 90mm f6.6 FPL-53 Triplet APO that I use visually. It's fine on planets and DSOs, but the limited aperture compared to an 8" Dob is really noticeable in resolution and light gathering. It shows the bands and moons of Jupiter, the rings, Cassini division, and brighter moons of Saturn, the phases of Venus, and the largest features of Mars. The moon shows a wealth of details. However, don't expect to see a wealth of details in Jupiter's bands like barges and whorls or fine details on Mars. Lucky imaging with it might reveal some, but the human eye needs more aperture to pick up such details visually. Here's a comparison image of the moon I took through various sub-6" scopes to give you some idea of visible image scale and details: Ignore the peachy color in some images. That was introduced by the eyepiece (12.5mm APM Hi-FW) that I was using for afocal projection into my smartphone camera. As for a diagonal, I like the various dielectrics made by GSO and sold under such many brands including Revelation in the UK.

I've found my 9mm Morpheus to perform almost identically to my 10mm Delos, just wider in AFOV.

I picked up a BP500 Green-Blue (cyan) filter and tried it out last night in the KUO 152mm. It's very similar to the Hirsch #82B Light Blue (light cyan), just with a bit higher transmission in the middle and with a bit longer tail-off in the red. It paired nicely with the LP470 Light Yellow to create a pale yellow-blue-green filter to eliminate pretty much all false color at both ends of the spectrum, at least to my old eyes. I compared it against the new Lumicon #11 Yellow-Green, Vivitar Light Green #11 (more of an X0), and Hirsch #12A Light Yellow stacked with the Hirsch #82B. On the moon, they all worked pretty well. I'd probably be content with any of them over no filtering. It's remarkable how much crispness each of them added to the image. On the Orion Nebula, the LP470/BP500 stack had the highest transmission with the Hirsch combo close behind. It was no surprise that the Lumicon and Vivitar filters dimmed the nebula a bit because they start tailing off before 500nm in the green/blue/violet end of the spectrum. You don't really need much if any filtering on such dim objects anyway, but I was specifically looking for transmission characteristics. On Orion's Belt/Collinder 70, there is a bit of violet and red fringing still visible on the bright stars, but it is quite tame compared to the filterless view. The yellow-green-blue color cast is barely noticeable after a few seconds. I guess my brain was just factoring it out. Lastly, the Newport BG39 cyan glass is way dimmer than either the BP500 or Hirsch #82B with a much sharper cutoff around 600nm instead of 625nm or even a bit further right. I'm considering retiring from my main filter wallet it as I see no practical use for it. By the way, all of the LP, SP, and BP filters were made by MidOpt in the Chicago metropolitan area.

Check out this post of mine linking to direct comparison edge images of the two eyepieces: If that's not enough to sway your decision, I don't know what would do it.

A bit off-topic, but does anyone recall a 30mm to 32mm Plossl/Plossl-like comparison ever being done? I've always wondered how much better the Vixen SLV, Tele Vue and Brandon are than the budget Plossl lines, Celestron Omni, GSO, Vixen NPL, etc. I'd also be interested how they compare to the vintage Clave, 5 element Meade 4000 from Kowa, etc. The Brandon in particular costs more the 30mm UFF, so it had better do something spectacularly well.

If you don't need to wear eyeglasses at the eyepiece, you might also consider the APM XWA 20mm and its many other brandings. Here in the US, the Astro-Tech version is $247.50 while the Orion LHD 20mm (StellaLyra 80º LER / UWA equivalent) is $299 (both pre-tax prices). You might be able to hunt around and find a reasonably priced version of the 100º 20mm eyepiece in the UK. It's supposed to be very well corrected across ~90% of its field. Since that's way out in your peripheral vision, it's hard to notice when it gets a bit less well corrected unless you go looking for it. Eye relief is certainly less than the 80º 20mm, so taking in the view will be a bit less relaxed. Just another data point for you to ponder.

Not sure what telescope you have, but most folks tend to jump from 30mm to somewhere around 12mm to 13mm. If you start with the 20mm, then you'll probably jump to 10mm, give or take. The difference in view between 30mm and 20mm tends to not be that significant except in very long focal length scopes such as SCTs and Maks.

Did your scope come with a correct image diagonal? If so, I recommend replacing it ASAP with a proper 90 degree mirror or prism diagonal. It will provide a larger clear aperture for widest field viewing without vignetting and provide sharper images without bright star spikes as occurs with correct image diagonals.

What's often most important is what's best for your eyes and facial shape. For instance, I have massive astigmatism in my observing eye, so I need to wear eyeglasses at the eyepiece to get the best image even at high powers and small exit pupils. Thus, long eye relief is important to me. For me, only the 25mm BST Starguider has sufficient eye relief to use comfortably while wearing eyeglasses. I also have deep set eyes, so eyepieces with a broad, flat top don't work well for me. The original 30mm ES-82 with mushroom top has such a broad top that it requires me to tilt my head to the side and swivel my eye in the opposite direction to get close enough to use it properly. The BST Starguiders are all quite narrow across the top, so no such issues with them. The 5mm BST Starguider is a good eyepiece if you don't need to wear eyeglasses at the eyepiece. It should also provide a nice step up in image quality and magnification from your existing 10mm.

I don't know if you read my write up on the BST Starguider/Paradigm line, but here it is if you missed it: It might be worth a read if you want to know how the various focal lengths compare (minus the 3.2mm).

Probably after an exclusive marketing period agreement expires as happened with APM and the UFFs.

If you stick with entry level BVs and lightweight eyepiece pairs, the combo is similar in weight to a large 2" eyepiece like a 31mm Nagler. If your Dob is not balanced for such eyepieces, then yes, weight could be an issue. Cost for such a setup is under $300 in my experience. If you go for a full-on premium BV setup, you can easily spend well over $1000, but weight and bulk will both be high.

By way of comparison, my Zhumell OIII is terrible as an OIII filter. I finally figured out why when I looked at its spectrogram (see my LP Filter thread linked above). It's right shifted so much that it barely captures one of the two OIII lines. However, it nicely captures the carbon lines associated with green comets around 511nm (and possibly 514nm), so it makes for a wonderful comet filter. My two Lumicon OIII filters make green comets disappear, so OIII filters don't normally make for good comet filters. I just don't want people thinking the Svbony falls into that same category that the Zhumell falls into. It's better than nothing as a nebula filter if funds are limited.

Was it night and day difference, or was it more subtle? I've found the difference between my 1990s Lumicon UHC and my Svbony UHC to be subtle. Both improve the image because the Lumicon rejects more background sky glow. However, it is subtle and not mind blowingly better. Stepping up to my 1990s and modern Lumicon OIIIs does show a massive increase in contrast in comparison to either UHC.

The 30mm is actually 73 degrees in apparent field of view with a 69 degree effective field of view due to distortion. The 24mm is 63 degrees in apparent field of view with a 65 degree effective field of view due to distortion. Interestingly enough, both measure to have a 20.5mm edge focal length. They are both right at their stated focal lengths in the center, though ( less than 1% off). The 30mm is world class. It's basically flawless. The 24mm has a soft field stop and slight edge astigmatism in the last 5%. Otherwise, it's an excellent eyepiece for eyeglass wearers who don't get on well with the 24mm Panoptic and have a 1.25" focuser.

Remember, it's the f-ratio that determines diffraction effects. Since most phone cameras have quite fast f-ratios, diffraction effects are pretty negligible.

Off topic a bit again, but here's a group shot of the warming filters on the LED panel: The CC050R is a Color Correcting Red filter of strength 50, where the density ranges from 05 to 50, with 05 being the faintest and 50 being the densest. The #81B is a 52mm I got as part of a larger lot, so not very useful except to hold above an eyepiece. I'm most partial to the CC050R, FL-B and #85B so far due to their more saturated hues. However, they're all quite subtle compared to traditional astronomy colored filters. I never cared for the #21 Orange or #25 Red filters on Mars. They're too dark and in your face. These warming filters are all similar to the very expensive #85 Salmon Brandon filter, but in all sorts of hue and saturation variations. I'll compare them more at the next Mars opposition and report back at that time. I think I paid less than $70 shipped for all seven filters across several different lots.

They thread in perfectly and their outer diameter is such that they are no wider than the eyepiece insertion barrel. It's a wonder to me why 2" astronomy filters are priced so high relative to their 48mm photography dopplegangers. On a different note from blocking spurious violet and red in achromats, look for 48mm warming (81 and 85 series) and fluorescent lighting color correcting (FL series) filters. Being gentle red/orange/brown filters, they help with bringing out some darker features of Mars while not taking away too much light. They tend to be pretty cheap on ebay as old photo stores close out their new-old filter stocks. That, and some come from estate sales in large lots for super cheap.

I'll have to try again with my b/c Optica Green line filter. It passes about a 10nm wide band centered roughly on 525nm. I've also got violet, blue, yellow, orange, and red versions to try as well.

I own a 22mm NT4 and can confirm it is 2" only. That AliExpress deal on the Angeleyes 70 degree eyepieces is tempting. That's way cheaper than Oberwerk's pricing.

I picked up a Lumicon #11 Yellow Green in a 1.25" to complement the Vivitar Light Green #11 in 2" size. It has an almost identical cutoff in violet to the Vivitar, but with higher transmission of blue wavelengths. In that respect, it's a better minus-violet filter. However, at the other end in the red, it has somewhat higher transmission in the red wavelengths than the Vivitar, so less useful as an all around violet and far-red cut filter. This was confirmed visually through my ST80 on Jupiter and the moon. It's barely better than using the Hirsch #12A Light Yellow or LP470 by themselves, which cut no red at all. I took a group shot below with it and some other yellow-green, yellow, and green filters. As you can see, it has just about the same yellow density as the Hirsch #12A and LP470 with just a hint of green to cut some red. I find it interesting that I now have four #11 Green/Light Green/Yellow-Green filters, and none of them match. The Rokunar X1 version is actually closest to the Kodak Wratten spec. The rest are closer to the Hoya X0 spec in that they transmit more blue-violet, have higher transmission overall, and transmit plenty of red. There is no Wratten # equivalent to X0 that I know of.

As I recently said in another related thread, the fairly inexpensive Svbony UHC has performed quite well for me relative to my Lumicon UHC filter. If your funds are limited, I recommend testing the waters with it.

I didn't use 17mm much until I added the ES-92. It's nearly as wide as my 22mm Astro-Tech AF70 (Redline variant). I actually bought my 22mm NT4 from a guy who quit using it after getting a 17mm ES-92. I find I like them both due to the difference in presentation, so no plans to sell either.

If you want to replace those stock eyepieces one for one, you'll first need to measure the focuser/diagonal to see if it is 1.25" or 0.965" inner diameter. You can get a full set of replacement 0.965" eyepieces direct from China on ebay UK here. You can get a full set of replacement 1.25" eyepieces direct from Amazon UK here. The optics will be the same for both. Only the barrel diameter differs. As others have said, they aren't all that great, but they're cheap and they will put up an image, albeit with very narrow apparent fields of view and very little eye relief. If you're in the US, you should be able to find equivalents on ebay, Amazon, and even AliExpress.

Yep, different strokes for different folks.