Louis D

Budget? I would probably recommend the 17.5mm Morpheus. You shouldn't need much between 30mm and 17.5mm. You may want something around the 13mm mark. There's the 12.5mm Morpheus, 12.5mm APM 84 degree, and the 12.5mm Docter/Noblex. Below 10mm (Delos), I like the 9mm Morpheus. I have the 7mm XW as well. At 8mm, you'd have to go Delos.

The 66 degree 6mm eyepieces are fairly sharp, but suffer from SAEP (kidney-beaning) to some extent. The Skywatcher Planetary line (a generic clone of the original TMB Planetaries) is generally better regarded, as are the BST Starguiders.

I would start with the OIII and add a UHC as funds become available. For planets, a generic Moon & Skyglow filter can help increase contrast. The cheap versions have basically the same passbands as the Baader Neodymium filter, so save your money on that filter and go generic. The generic OIII filters, however, are not very good compared to the leading brands, so don't skimp on it.

Planets are always on the move, so you really need to check Stellarium or an online planisphere to see what's up and when. Their maximum height above the horizon varies over a long period of time (20+ year period?). We're at a minimum for the northern hemisphere right now.

During the summer season here in Texas, we get a high pressure dome that settles over us for months leading to dead stable skies and extreme drought conditions. Every once in a while, a tropical storm or hurricane tries to bully its way into Texas for a few days every month or so, but that's about it. As a result, 200x and more is quite usable with an 8" scope on most nights. I've used 350x with just as much ease with my 15" Dob. It's really mostly aperture limited. During the fall to spring time frame, conditions are generally less favorable, but still better than in the UK.

@johninderbyI bow to your extensive self-centering adapter knowledge.

I would error toward 60 to 70 degree eyepieces. You'll probably find that 52 degree eyepieces feel very constrictive. Since you have an f/10 telescope, there are quite a few affordable wide field eyepieces.

Looks pretty similar to the Antares 2" to 1.25" Twist-Lock:

The 20mm APM XWA is a bit less porky at 23.9 oz. versus 36 oz. for the 21mm Ethos. It's also considerably cheaper and within 90% of the performance of the Ethos. Probably stray light control is the biggest difference. TV really pays attention to the details.

Sounds like a winner this time around.

The DeLites are almost doppelgangers for the Radians, aren't they? Hopefully, they don't have the SAEP of the Radians. I was excited with the arrival of the Radians in 1998, but I couldn't get them to work for me in daylight due to SAEP (kidneybeaning), so I never bought any and stuck with the Pentax XLs.

In Lyra, you've got the Ring Nebula (M57) and the Double Double, both of which are easy to locate because it includes Vega, one of the brightest stars in the sky: The star marked 2 above is Epsilon Lyrae, the Double Double (a pair of gravitationally bound double stars). The object marked 9 is M57, the Ring Nebula. It is practically dead center on the line between those two brighter stars, Sulaphat and Sheliak. The rest are described in this excellent guide to Lyra on Weasner's website.

For emission nebula, an OIII is the most aggressive and often yields the best view. The slightly less aggressive UHC types also show the H-Beta line and sometimes include the H-Alpha and SII lines as well. However, more light pollution is let in due to the wider passbands, decreasing contrast on low surface brightness nebula. OIII passband: Typical UHC passband including H-alpha and SII: Other DSOs don't really benefit much from filtration. Open clusters tend to be "large" and high contrast, so no issues there. Globular clusters tend to be small and compact and do best with high power (200x+) and at least 6 to 7 inches of aperture to start to resolve them into tiny pinpoints. Planetary nebula tend to be compact and benefit from high power as well because that reduces the background skyglow. Galaxies really need dark skies because they emit light across the entire spectrum, so no filter helps to increase contrast with them in light polluted skies.

One of the brands they're sold under in the US is Astro Tech Paradigm Dual ED (possibly the first here). I've got the 5mm to 25mm set as shown below with the Meade HD-60s behind. They are no doubt identical to the BST Starguiders and Astro Essentials.

I don't know about longer eye relief on longer f-ratio scopes, but I do notice much stronger SAEP and CAEP in longer f-ratio scopes as I showed in this thread.

I have the 10mm Delos and 9mm Morpheus, and there's not a whole lot to choose between them other than a wider field of view on the Morpheus. I can't use the NT6s due to needing to wear eyeglasses to correct 2.0 diopters of astigmatism in my observing eye, so I can't give you any advice on them. The APM UFF 30mm is really nice. I highly recommend it.

Off topic, but it seems like everyone in the UK has a "conservatory" which I take to mean an non-heated/non-cooled sun-room or enclosed patio rather than a music room. They're pretty rare here in Texas because it would be over 130° F in there for much of the year. I take it they're much more pleasant there.

I have the GSO coma corrector, and it works great in my 8" f/6 Dob, but I need to take it out for highest power work with planets because it seems to add a bit of spherical aberration on axis. The views are definitely sharper on axis without it. I have noticed the same thing with my TSFLAT2 in my ED and APO refractors. Highest power views are sharper without it in the optical path.

Glad we got that all sorted out so quickly.

I would recommend the 5mm BST Starguider as good step up from the included eyepieces. As far as the phone holder, the Celestron NexYZ 3-Axis Universal Smartphone Adapter gets good reviews here on SGL.

Correct about the total light flux, but the lower powered eyepiece is putting that same number of photons into a smaller area leading to a brighter image per unit area, albeit at a lower magnification. Besides a smaller, bright object image, the background skyglow will also be brighter, washing out low surface brightness objects unless that skyglow can be reduced via a selective filter.

Relatedly, there is the Zarkov Cloud Gun for punching observing holes through the clouds until the cloud filter becomes a reality. Order yours today. 😚

Speers is for Canadian optical designer Glenn Speers. Due to the unfavorable exchange rates between US and Canadian dollars, he wanted to create a home-grown line of affordable wide field eyepieces for Canadians who couldn't afford Tele Vue Naglers.

If you pair the 40mm with a nebula filter such as an OIII, the larger exit pupil may make the nebula appear brighter than it would with the 32mm. This is especially important with longer focal ratio telescope such as CATs that produce small exit pupils with most eyepieces. For example, to get a 6mm exit pupil with an f/15 Mak would require a 90mm eyepiece. 😲 Good luck finding one of those.

Try working your way up to higher powers to see if the image starts to break down instead of jumping from 25mm to 6mm straight away. A Skywatcher/Celestron/Meade zoom eyepiece might be a good option to help gauge the seeing conditions.