Louis D

45 minutes ago, KeithP22 said:

are the celestron omni good eyepieces. 

They're decent, but probably no better than the Astro Essentials Super Plossls or the Revelation Plossls.  Some are made in China, some in Taiwan, but in the end, all the lenses may be sourced from the same supplier.

These all get high ratings:

1.6x 1.25" Nikon EIC Barlow

3.0x 1.25" Televue Barlow

2.4x 2.0" Vernonscope Dakin Barlow

2.0x 2.0" AP BARCON (BARADV) Barlow

2.5x 2.0" Siebert Telecentric

2.0x 1.25" Carl Zeiss Abbe Barlow

You can just pull the rubber eyecup straight off.  Perhaps then the adapter would work:

5 hours ago, steveex2003 said:

Apologies for being dim. What does the term; close to the shoulder mean?
Thanks.

Sorry about that.  How about we hold a contest for a more intuitive name for the "reference surface" than either that or "the shoulder"?  Neither is very good I'll admit.

You could check with Martin Pond over on CN.  He loves to take apart vintage binocular eyepieces and create new, home-brew eyepieces from the lenses.

Agreed, most Pentax, Morpheus, and ES (JOC) eyepieces focus very close to the shoulder.  All Tele Vue eyepieces focus further in or out relative to the shoulder except for the 17mm NT4 which also focuses right at the shoulder.  I really notice swapping in my 10mm Delos because I have to rack it 1/4" out to reach focus.  The 12mm NT4 was so annoying at being 20mm below the shoulder that I added five 4mm thick O-rings and a 20mm 2" extension ring to the bottom to nearly parfocalize it.

The 8mm, 12mm, and 18mm BST Starguiders would work well in your scope without breaking the bank.

6 hours ago, michael.h.f.wilkinson said:

it focused at the same point as my XWs, something the Delos 14 won't do

Yep, you'll need to invest in a Tele Vue In-Travel Adapter which will run you about another £43 or so to parfocalize it somewhat.

5 hours ago, Barry-W-Fenner said:

Hi Louis

That's spot on what  I am getting. The stars are fine points that turn more tear drop and a have a point at the bottom as they drift to the field edge.  Regarding coma corrector, what would be the best option for a 12" dob?

The best option without doubt would be the Paracorr T2 at 495 GBP.  However, if your pockets aren't that deep, the GSO/Revelation CC is quite good for 65 GPB.  I use it in my Dob to good effect.  It does need a 25mm spacer tube between the optical section and the eyepiece holder.  As long as all your eyepieces focus within 5mm of their shoulder, coma will be corrected to within about 95% or better of optimal.  I only had to parfocalize one eyepiece, my 12mm Nagler T4 because it focuses 20mm from its shoulder, so coma was noticeable with it without parfocalization.

I've found it to be plenty good enough that I've never felt the need to upgrade to a Paracorr.  It does need removed for highest power work because it contributes a bit of spherical aberration visible only under those conditions.  It's my understanding the Paracorr T2 does not, so there is that.

The GSO/Revelation requires 11mm of in-focus, which is similar to the Paracorr.  The ES HRCC requires 31mm, IIRC, which is a lot more and beyond what I have available.

On 29/07/2020 at 14:42, Kyle Allen said:

Check out M17, M8, M20, and M22. 

Definitely M17 and M22 are easy in light polluted skies (at least this far south they are).  I just enjoy sweeping the Milky Way to see what I see from time to time.  There are plenty of random open clusters and star associations and asterisms along it to marvel at.

If you have a coma corrector that also flattens the field, it is possible to see that the 14mm Morpheus has a very slightly curved field in the last 15% of the field.  I also confirmed this in a field flattened ED refractor.  By comparison, the 17mm ES-92 is dead flat to the edge in the same scopes despite being significantly wider.  You can confirm this for yourself by moving a bright star from best focus in the center to the edge and seeing if it needs refocused there.  However, if you don't have a flat field scope, you won't be able to be certain where the field curvature originates from.

The 14mm Morpheus also has slight astigmatism at the edge (unlike the 17mm ES-92).  Again, put a bright star at the edge and rack it through focus from inside to outside of best focus.  If the star changes from a radial to a tangential line (flattened oval) on either side of focus, that's what astigmatism looks like.

It's likely, though, that coma could be what you're seeing a the edge, especially if you're not using a coma corrector in a Newt.  It will make a bright star look like a pointed tear drop with the point aimed at the center.

I would cross import the 35mm Aero ED from FLO rather than getting the two low power ES-70 eyepieces.  It is both cheaper and better performing.  There's no VAT, sales tax, or import tariffs, just shipping charges.  The difference between 58x and 68x does not justify two eyepieces.

A 56mm Plossl would be a better option to get a larger exit pupil for using an OIII filter on nebula.  The true field won't be any larger than with the 35mm Aero ED, though.

The Veil nebula is all but invisible in my skies, but easily visible with an OIII filter.  It's simply a matter of increasing the contrast by eliminating non-nebula emitted light from light pollution.

With the Orion nebula, which is quite bright, it simply allows a greater extent of the faint filaments to be seen.

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.

On 29/07/2020 at 10:04, Shaun Sr said:

so get an oIII?  I deal with lp. But I travel to dark as well

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.

On 28/07/2020 at 12:33, Tenor Viol said:

I agree with the above comments - very high magnifications are unusable. You will be lucky to even get one night a year where you could even think of using it for a start. Planets are small - and that's the end of it. You will find that most of the time you use low to medium magnifications and very occasionally in very good conditions you will get to use a higher (e.g. 200x) magnification. 

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.

2 hours ago, johninderby said:

Wish FLO would sell the StelaMira twist lock adapters seperatly. Work well and have a 20mm wide clamping area.

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

3 hours ago, Dantooine said:

I did consider the 21 ethos however, the panoptic is about £500 less, but the main reason was the 21 ethos is around 20oz more weight than the 6 & 8. This would have gone against my ideas about weight range. 

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.

1 hour ago, Don Pensack said:

The Delites do not.  No one seems to have any issues with eye placement except the inevitable person who doesn't use glasses and doesn't adjust the eyeguard up and experiences blackouts by getting inside the exit pupil.

Color presentation is also more balanced--no one describes the Delites as "warm" in tint.

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.