Louis D

3 hours ago, RobertI said:

I did examine the on axis views and I couldn’t really say there was an clear difference but perhaps if I knew what I was looking for it might be more obvious to me.

Try using a very bright star dragged across the entire field of both looking for stray light control before it ever enters the field of view, at the edge, and as it crosses the field.  Repeat with Jupiter.  It may well be they behave identically.

Next try viewing a dim star cluster right at the edge of being perceived.  Search along the Milky Way to find some relatively unknown dim ones.  See if there is any difference in presentation between the two eyepieces.  With this, you're testing for sharpness, transmission and contrast.  Dragging it across the field can also reveal vignetting if dimmer members simply vanish from view near the edge.

I would also compare on axis sharpness, contrast, flare control, haloing, ghosting, etc.  You're generally going to do most of your critical observing in the central 50%.

I bought myself a used TS-Optics Photoline 90mm FPL-53 triplet APO for Christmas pre-pandemic just to try something different.  I use it on a DSV-2B mount.  I've really enjoyed its different presentation of planets in particular from my Dob.  They seem sharper and contrastier, if a bit less ultimately detailed.  There's basically no false color in focus even at high powers.

I'd say go for a really good FPL-53/FCD-100 or equivalent doublet or triplet in the 90mm to 100mm range.  FPL-51/FCD-1 doublets show noticeable violet fringing at higher powers in my experience, so that's why avoided them as I moved up in size.  I haven't tried a triplet using these glasses, so I can't comment on them.

You'll need to leave about $500 to $700 for accessories like a 2" diagonal, an alt-az mount, and a sturdy tripod.  The nice part is, all of these can be carried over to SCTs, Maks, and CCs in the future if you want to branch out into catadioptric designs someday.

3 hours ago, Mr Spock said:

The only way to settle the 'what's best' argument, is to have one of each 

Unfortunately, that's all too true.  It's only with back to back comparisons that you start to realize how eyepieces differ from each other, and how each has its strong and weak points.

Bizarre.  It would be interesting to understand how this happens through ray tracing.  Perhaps it's related to SAEP.

2 hours ago, Don Pensack said:

The adapter severely limits the apparent field and causes all kinds of exit pupil aberrations.

I would have thought it would just cause severe vignetting of the field.  How could it induce optical aberrations if it has no optical elements?

I lived for years (at least 15) with a 38mm Rini MPL, 14mm and 5.2mm Pentax XLs, a 9mm Vixen LV, and a 1.25" Tele Vue 2x Barlow.  That was it, believe it or not. 🤫

The slippery slope began when I bought a 40mm Meade 5000 SWA on clearance along with a GSO CC back around 2013.  The combo was so much better than the 38mm Rini that I began to seek out more and better eyepieces.  And the rest, as they say, is history.

Just curious why you chose the 31mm BHA over the 30mm APM UFF.  Was it simply to complete your Hyperion set?

Since mine are from so many different companies, I'd go with a hodgepodge of eyepieces.

No idea, but you get the prize for the longest thread title with the relatively shortest actual post. 😁

4 hours ago, Elp said:

For visual you have to be really nitpicky to have to use a CC

I guess that's me.  Sometimes I forget to put it in the focuser, and put one of my ES-92s in without it and instantly think, "What is wrong with this eyepiece tonight, it's usually sharp to the edge?".  Then I realize I forgot the CC, put it in the focuser, and all is well with the world again. 😁

To be universally adaptable, it needs to have M48x0.75 threads.  My GSO 2x 2" Barlow optical element has this size thread.  Yours appears to be the Chinese made version, so I can't speak directly to its threading.  The upper part of the GSO spacer tube is not M48 threaded.  It's more of an SCT thread, although I've never verified this.

I use a TSFLAT2 substituting for the nosepiece of my GSO 2" Dielectric diagonal.  Since the diagonal has SCT threads, I use an SCT to M48 thread adapter, plus 15mm of M48 tube extension, to attach the M48 threaded TSFLAT2 in front of the diagonal.  This effectively flattens the field of view to unnoticeable levels visually.  I couldn't stand using my 72ED refractor for low power, wide field viewing until I figured out this hack.

That, and the OP hasn't visited SGL since a week after posting the original question.

Did it filter out any unwanted artifacts to make up for the green cast?  I'm guessing it's cutting into the red as well as the IR to cause this color shift.

The 31mm Luminos is going to be much better corrected across the field than say a ~30mm 2" eyepiece of the sub-$100 wide field variety.  There have been reports of kidney beaning or edge of field brightening under certain conditions, but these are probably preferable to vast edge of field astigmatism present in cheaper eyepieces.  The used price is about typical for these; so you could probably sell it on if it doesn't work out for you without losing much, if any, money on it.

I've been using one with a 25mm spacer ring in my f/6 Dob.  It corrects about 99% of the coma in the outer field for eyepieces focusing with 5mm of their shoulder in this configuration.  Perhaps in a faster scope you'd need to be more precise with the spacing.  Just replace the thumbscrews that came with it.  One of them sheared off in the holder tube on mine, and I can't get the remains out.  The screws are made of pot metal.

57 minutes ago, BinocularSky said:

First used binos (my Dad's) for looking at the night sky (actually, for Sputnik) on 4th October 1957. I still use them more than any other instrument for visual. It's not a question of what is right or wrong, just what rocks your boat.  I simply love the portablility and the challenge of hunting stuff with small apertures and low magnification.

I guess it shouldn't surprise me you like binocular astronomy. 😉

I picked up Crossen & Tirion's Binocular Astronomy back in the 90s (first edition) and still have it.  I went through it and used the excellent charts at the back, but I still longed for a telescope.  Once I got my first Dob, I went crazy on astronomy.  It was the increased image scale and light gathering that did it for me.  I do enjoy sweeping the night sky at low powers, but I use 2" eyepieces in short focal length ED/APO refractors instead of binoculars.

I might try to make one of these binocular observing chairs someday, though:

2 hours ago, grjsk said:

It was not my intention to highjack this thread, but I thought it would be relevant to atleast mention that I do in fact have a bit of astigmatism in my observing eye. None in the other though, so I am simply going to try to use the good eye.

 

Thanks for the info @Louis D, I would never have checked it out if it wasn't for your comment!

During naked eye observing, you'll notice star fields will look more pinpoint wearing eyeglasses if you choose to get a pair.  I don't know about Norway, but in the US, there are multiple, affordable online eyeglass makers if you don't feel like splashing out too much money just to correct minor astigmatism in one eye.

Yeah, that's way out of focus.  Next time, turn the focus wheel(s) forward or backward as much as needed to minimize the size of that white spot.  If you center it at best focus (smallest and sharpest image), you should see Jupiter's main equatorial belts and its 4 Galilean moons.  It should look a bit as below through your scope:

Of course, it will appear tiny to your eye:

Mostly better lens polish, coatings, and stray light control.  Most folks positively compare the Leica ASPH to the Pentax XW and Delos lines for sharpness and contrast.  There's also a Zeiss zoom with a wider range that is also well received for similar reasons, if just a bit behind the Leica image fidelity-wise.

3 hours ago, F15Rules said:

And, since I was working then, that was important to me, as I had to often rise early to travel for work. Now, being retired, it's easier for me to have a late night from a commitment perspective, but I'm now 5 years older and struggle more with motivation for late sessions (especially in cold winter nights!)

Right there with you even though I'm a few years from retirement.  Youth is wasted on the young.  They (whoever they are) keep telling us this or that will extend our lives X amount of years.  Do I get to choose which X number of years to tack on, or do I just get X more elderly years?  I think back to 30+ years ago and marvel at what I used to be able to do in a single day.  It makes me tired just thinking about it.  I used to think, "When I'm retired, I'll be able to do all these things I've never had time to do".  I just didn't count on being old and decrepit at that time.  Getting old sucks (pardon my language).

I can see where a Barlow when coupled with low cost, long focal length Plossls could be a good solution, especially if you need to wear eyeglasses due to eye astigmatism.  The only issue I have with some of the long focal length Plossls is that most greatly recess the eye lens, negating their long eye relief.

The 15mm and 20mm Svbony UWA 68 degree Expanse-type eyepieces don't suffer from kidney beaning, just the 6mm and 9mm versions.  The 20mm is great Barlowed in my binoviewer.  I was using a pair of them to observe Jupiter Tuesday night.  Even without a Barlow, they should do well in an SCT.

The two piece tube cap can be used for that, but you'll drastically cut down your potential resolution by masking your aperture.  It can be used to sharpen up the image by making the scope have a longer f-ratio and by making the system unobstructed if it is an off axis opening and you place it between spider vanes.  It can also be used to allow for use of a smaller solar filter.  Try it and see, what's the worst?

Is your scope the National Geographic 76mm Compact Reflector Telescope?