Louis D

3 hours ago, Stu said:

I did have a 30mm ES eyepiece for a while, but it wasn’t quite in the same league, and showed noticeable field curvature in my current Genesis, defeating the object of such a widefield.

Interesting.  I have one of the original mushroom top 30mm ES-82s, and it is dead flat of field to my presbyopic eyes.  What I can't stand about it is the CAEP that causes the ring of fire.  It also causes extended objects like planets to split into a red and blue copy slightly separated from one another near the edge.  If you simply concentrate on the center, it's hard to notice this, so it is good for sweeping rich star fields.

Enjoy your Terminagler/Genesis combination!

15 minutes ago, GKA said:

Yes i did, and I think it's great value, i also bought the Baader continum filter from Flo to go with it, great combination. 

Only visual for now. 

Good to hear.

Did you buy through AliExpress or directly from Hercules?  Any issues with the transaction?

The only time I got tripped up with all these inversions and flips was when I was using both a refractor and a Newtonian at an outreach event on alt-az mounts.  As I moved each to reposition the object after letting it drift though the field of view, I kept getting mixed up which way was up/down and left/right in each.  The refractor is upright, but reversed left/right.  The Newtonian is rotated 180 degrees, so inverted in both directions.  I eventually got the hang of it.

@GKADid you ever get a chance to try out your Hercules solar wedge?  If so, what are your thoughts on it?

KUO is making some splendid eyepieces like the APM UFFs and likely the Aero ED, WO/Nirvana/TS UWANs, and maybe even the Orion LHD and APM HDC-XWA lines.  If any Chinese eyepiece maker can pull it off, they're mostly likely to be able to do it.

1 hour ago, amaury said:

The APM Ultra Flat Field 30mm have been reported to be eyeglasses-friendly when the eyecup is folded down. Still not anywhere near the 22mm of eye relief they state in the specs. 

It's still quite comfortable to use with eyeglasses.  In use, it feels more like the 18mm of eye relief that my Pentax XWs and 14mm Morpheus have.

Maybe I missed it in the video, but how does it compare to the 9mm APM XWA HDC Hyperwide?  Is the 9mm ES-100 worth $250 more ($549 vs $299)?

I just remember how long it took for the 17.5mm Morpheus to finally hit store shelves.  Wasn't it several years of delays?  And that was pre-Covid.

1 hour ago, paul mc c said:

I done that,but its so close it looks like 5mm and a second look it looks like 4mm......i have found somewhere that sells them so will order a pack of each size.

It's a good idea to keep these screws around for other unforeseen needs in the future.  They're used in a lot of astro equipment.

Okay, I now understand you're trying this photographically.  Can you try it visually to see if a Barlow/eyepiece combination can reach focus?  I'm much less familiar with photographic applications.  My guess is that you need to rack your focuser inward to reach focus, not add more extensions.

Are you sure you don't need more in-focus?  Is a star image getting smaller after inserting the Barlow at the original focus point when moving the Barlow/eyepiece combination toward or away from the visual back?

Generally M4 or M5 screws, depending on the brand.

7 minutes ago, Don Pensack said:

Even then, the issue with the 14mm seems to be scope-specific.

In my 12.5" dob with Paracorr II, (1826mm effective focal length) the 14mm seems to only deteriorate right at the field stop.

And who looks at anything right at the field stop?

With slight refocusing near the field stop (last 10% of field, let's say) in all of my scopes, I see a bit of astigmatism in my 14mm Morpheus that is utterly absent from the 9mm Morpheus, 10mm Delos, and 14mm Pentax XL (which has loads of field curvature, but no astigmatism).

I look at planets near the field stop as I let them drift across the field to maximize dwell time looking for details.  There's no degradation in the 9mm Morpheus or 10mm Delos across the field that I can detect using this technique.

A 2" Barlow will severely vignette/cutoff longer (22mm+) widest field eyepieces.  You're better off going with a telecentric magnifier as @johninderby suggests above.

If you want to go cheap but good and are willing to deal with loss of field, the GSO/Revelation/etc. 2" 2x ED Barlow is hard to beat, especially used.  They typically go for about $60 used here in the states.

Alright, I'll come to the defense of 40mm SWA eyepieces at f/6 under Bortle 6 skies.  I enjoy maxing out the field of view while viewing large objects like the Pleiades or Collinder 70.  They're bright enough that the brighter sky background isn't distracting at all.  They're also enjoyable for sweeping rich star fields.

Yes, they're marginally useful for detecting smaller DSOs due to the low contrast with the brighter sky background, so higher power and wider field of view eyepieces are more useful.

Probably an M3, possibly an M4, screw.  Take one down to your local big box home improvement store and screw it into their thread sizer mounted on a column in the fasteners aisle to find out for sure.

I've been using a Celestron 94108 90° correct image diagonal for 20+ years in my 60mm finder scope to good effect.  I can't seem to locate it at any retailers these days, though.

From what I've read, the 4.5mm and 6.5mm Morpheus have less eye relief than the longer focal length ones.  As a result, you need to get your eye closer to the eye lens to take in the entire field of view as you found out.  Try removing the extension ring and see if the vignetting goes away.

As for the difficulty holding the view in them, it sounds like SAEP (Spherical Aberration of the Exit Pupil) or kidney beaning.  I've experienced the same issue with the 12mm and 17mm Nagler T4s.  It wasn't until I took images through them using a 127 Mak and a slow, extreme wide angle phone camera that I figured out they had SAEP.  The two together seem to really expose undiagnosed SAEP.

Try using those two Morpheus eyepieces to look at the full moon, and see if you get fleeting kidney bean shadows midway to the field stop.  Also, try using them on a bright day terrestrially to expose the issue.  The key thing is, your eye's iris must be significantly stopped down from wide open to see it.

Here's an image I composited of SAEP as seen through various eyepieces using the technique above.  By holding the camera perfectly centered and at the exact exit pupil, SAEP is revealed to be a continuous ring shadow.  It explains why a lot of folks don't get on well with the 12mm ES-92, but do fine with 17mm version.  Notice how within an eyepiece line that SAEP grows worse with decreasing eyepiece focal length.  This might be what's happening within the Morpheus line as well.

I find it interesting that some eyepieces have a shadow in the dead center as well as the ring or in lieu of it.  I have yet to find a good explanation for that phenomenon, though.

The rainbow rings are caused by CAEP (Chromatic Aberration of the Exit Pupil) where different wavelengths of light focus at different distances behind the eye lens.  This leads to the "ring of fire" effect.

I don't think it's possible with the maximum field of view of an 8" SCT being about 1.4 degrees and the Pleiades being about 1.8 degrees.  Even in an 8" Dob with a 1200mm FL, it's a bit of a tight fit.

You can't combine an F/R with a 2" diagonal and widest field 2" eyepieces without severe vignetting.

The cheapest route is generally the F/R if you've already got a 32mm Plossl or 24mm SWA eyepiece.

32 minutes ago, Second Time Around said:

Here's an extract from a comprehensive review by author Bill Paolini on diagonals.  Here he's comparing various prism and mirror diagonals at f/6.25, where the received wisdom is that mirrors will do better.  Quite illuminating!

"..........After completing observations of Jupiter in the Celestron 80mm APO with the prisms, the various aluminium, silver, and dielectric mirror diagonals were tested.  First impression when moving from observing with the prisms to the mirrors was, "wow...more scatter!"  I felt this was a rather obvious tell.  I was also surprised that the details on Jupiter were definitely softer through the mirror diagonals than they were when using the prism diagonals. As example, the NNTB was not showing though the mirror diagonals, and any structure within NEB and SEB was only hinted at as a nondescript albedo differences.  Changing out the mirror diagonals to prism diagonals, and all the NEB and SEB crisp definition and structure reappeared, as well as the ethereal NNTB..........."

For the complete article go to https://www.cloudyni...omparison-r2877

Of course, in Japan, this might be one reason why straight through viewing is popular.

There's the GSO diagonals sold under the Revelation and iOptron brands in the UK as well.  I really like their 2" diagonals, but have no direct experience with their 1.25" diagonals.

One advantage to prism diagonals over dielectric diagonals is lower scatter.

3 hours ago, amaury said:

Would you say the ES68 24mm performs better that the APM UFF 24mm? they are priced fairly similar

Not having looked through an ES68 24mm, I wouldn't know.  I have strong astigmatism, so I wear eyeglasses at the eyepiece; and the ES doesn't have enough eye relief for me to view the entire field while the APM does.

From what I've read online, the APM is at least as good as the ES, just not as good as a 24mm Panoptic.

It's my neighbors' back porch lights that light up my backyard.  There's not much I can do about them other than asking them to shut them off when no one is in their backyard.  Some are sympathetic, others feel safer keeping their yard floodlit at night and refuse to change their ways.

Not always obvious to newbies, but a planisphere is easiest to use by aligning it with the sky by holding it over your head so E/W/N/S on it align with those of the sky instead of two being flipped.

I would avoid any alt-az mount that places the load above the alt axis.  They tend to tip over backward above about 45 degrees due to the imbalance.  That rules out the first two.

EQ (specifically, GEM) mounts can be frustrating for beginners doing visual only.  Their only advantage for visual is you need turn only one knob to keep an object in view once roughly polar aligned.  They also tend to be over-taxed in these beginner kits and can be very wobbly/shaky as a result.

There are quite a few really good alt-az mounts out there, but they are mostly out of your price range before you even add a telescope OTA.

That leaves you with the 6" Dob as your best bet, though shipping to DR could be quite high due to its size.  You'd want to also get a cheshire tube or similar to check and perform collimation on it.