Louis D

Just now, Alan White said:

That's where some of next doors lights are with me.
Light up trees and a tasteful* Giraffe in the tree, they light up the whole sky North and North East for me sadly.

*tasteful - as in not!

Luckily, my neighbors are using low wattage solar charged lights only in their front yard that are fairly innocuous.  They were shining into our master bedroom window until I asked them to redirect them.  Even low wattage was annoying in our darkened bedroom.  Our houses block that light from being a problem in the backyard where I observe.

5 hours ago, Don Pensack said:

Yes, cell phone cameras don't require as much eye relief as DSLRs.

And DSLRs are extremely difficult to use for afocal projection.  Generally, the entrance pupil of most DSLR lenses lie deep within them, making it difficult to get it to coincide with the exit pupil of the eyepiece unless it has very long eye relief.  Zoom lenses just compound the problem by burying it even deeper than with prime lenses.

@Ruud Your next animation should be to explain chromatic aberration of the exit pupil, and how it causes the ring of fire in the 31mm Nagler and 30mm ES-82.

7 minutes ago, globular said:

Or maybe I'll get ES92 17mm and ES92 12mm as skip 14mm altogether..... 

I rarely use either of my 14mm XL or Morpheus eyepieces in favor of my 12mm and 17mm ES-92s.  The exception would be in 1.25"-only usages.  That, or where a light weight eyepiece is necessary.  I know, many folks don't consider 12 to 13 ounces light weight, but it is in comparison to the ES-92s.

56 minutes ago, RickEm said:

Does it matter if eyecups are up or down?

You may have to flip the eye cup down to be able to get the camera close enough to properly couple with the eyepiece's exit pupil.  The eye cup being up may help block stray light, though.  You'll just have to experiment and see what works best.

Having taken all of those afocal images of my eyepiece apparent fields of view in this thread, I've found it is possible to couple cell phone cameras into eyepieces with as little as 3mm usable eye relief.

Here's a new one I haven't previously released.  It's of a generic 6mm Huygens I got with a $25 70mm x 300mm refractor off of ebay with just 3mm of usable eye relief:

This was with the AT72ED and a Galaxy S7 rear facing camera.  It is actually not that bad of an eyepiece at f/6.  It shows that with skill, it is possible to use eyepieces with very little eye relief.  I was hand holding the camera using my finger edges to maintain alignment with the eyepiece.  It's an acquired skill.

1 hour ago, Don Pensack said:

The Pleiades really look best when the field of view exceeds 2° and even better at 3°.  This is the realm of the short focal length refractor (480-750mm focal lengths).  It's pretty close to the only object that large that you might care to look at, and it is fantastic at 15x in a short 80mm refractor.

Collinder 70 (Belt of Orion open cluster) is another large favorite of mine at low power.  15x70 binos show both it and the Pleiades rather well.

3 hours ago, Mick_1960 said:

It will be great if I can use my laptop to see what the telescope is seeing rather than looking through an eyepiece but I would like the option of the eyepiece.  The laptop will just make it easier if I take the family out.

I remember at another star party that an imager was stacking deep space object (DSO) images in real time on his laptop using a dedicated astro camera in the focuser.  In about 10 minutes, faint nebulosity that was invisible to the human eye was readily apparent.  I can't say that it was a very exciting experience.  You might as well download professional images off the internet if you're going to stare at a laptop screen at a dark sky site.  I much prefer gathering ancient photons with my eyes.

For that kind of money, you can get into some seriously heavy rigs.  How much weight are you willing to lift?  How much space do you have in your vehicle to haul a scope and mount?  How much storage space do you have at home?

As far as my recommendation, I'll relate a recent experience I had.  There was a newbie at a star party here in Texas with a brand new Celestron NexStar Evolution 8" EdgeHD.  He was happily, wirelessly controlling it with a tablet running planetarium software.  With a 10mm Delos, it was providing an excellent image of Jupiter and other targets that night.  It was super easy to select targets within the planetarium software on the tablet.  Once selected, the mount quickly slewed to the new target and kept it perfectly centered.  The Starsense made alignment a cinch as well.  This rig would be easy to store, setup, transport, and use.  It would also leave plenty of money from your budget for eyepieces and other accessories.  8" is a sweet spot for astronomy.  Big enough to provide good views of most objects and yet not so big as to put off using it due to inconvenience.

44 minutes ago, RobertI said:

Hi Louis, I was using in the 102ED-R (hiding in the title of the thread! ) - I was particularly interested in trying it on this scope as I was not sure how it would work (I'm confident it will work in the C8). It's good to know you can get focus in your dob, it might be that I can use the binoviewers in my 150PL in that case. Interesting that your 2x barlow becomes 3x, whereas my 1.3x barlow becomes 5x!! I guess all barlows would behave differently in this setup? Never quite got my head around barlows!

I figured you mentioned it somewhere, but I wasn't looking in the thread title, just your posts.  It's not the first time I've missed pertinent info mentioned only in the thread title.  🙄

It will definitely work in your C8, but it will requiring moving your mirror forward which will increase the focal length a few hundred millimeters I believe.  It will also induce a bit of spherical aberration by moving the mirror well away from the optimal design position.  It might be visible at high powers or it might not.  Some people are sensitive to it while others are not.

The longer the Barlow is originally, the less effect lengthening the working distance in BV usage has on the magnification.  The Meade is a "mid-length" Barlow like the 2x Tele Vue 1.25" Barlow.  Your Baader Q-Barlow would be classified as a "shorty" Barlow.  I do have a "long" Barlow (6 inches or so), but it does not have a removable optics section.  If it did, it would be terrific for BV work.  I'll have to see if I can swap the optics into a spare Meade 140 nose piece I have someday.  It will all depend on lens diameters and the combined spacer/lens depth of each.

Which of your many telescopes were you using the BVs in?

I get 3.0x magnification with the optical nose piece of a vintage Meade 140 2x Barlow screwed onto the front of my Arcturus (similar to OVL) binoviewers.  I have no trouble reaching focus in my limited in-focus Dob with this combo.

I have the 22mm Nagler T4 now.  Does the 31mm Nagler have the same usable eye relief as the 22mm NT4?  I'm using the 30mm ES-82 mushroom top right now because the eye lens is basically flush with the top and I can just take in the full FOV with eyeglasses.  I've wondered over the years if it is worth upgrading to the 31mm NT5 for its better correction.  Although I wouldn't do it if it doesn't have at least as much usable eye relief as the ES.

My TV gear includes all the NT4s, 27mm Panoptic, 10mm Delos, 2x 1.25" Barlow, and PBI.  They're all fantastic.

Adding @Don Pensack re: 31mm vs 22mm Nagler usable eye relief question.

29 minutes ago, Don Pensack said:

Camera step-down or step-up rings.  These are available in a plethora of sizes to adapt camera lenses.  You could find one to press-fit to the lip under the eyecup and attach the eyecup to the outside of it.

There's also the possibility of a rubber lens hood with the lens-end inner diameter similar to the widest part of the ES-17's upper barrel.  That would allow it to be slid up or down somewhat to adjust the height.  Once fitted, it could be cut down to custom fit the hood to the user's facial shape including wing shaped.

43 minutes ago, John said:

David Sinden ?

Henry Wildey ?

Peter Drew ?

Rob Miller ?

Dudley Fuller ?

David Lukehurst ?

Edit: maybe better discussed in another thread though ?

Definitely Peter Drew.  I'm less familiar with the others.  The fact that he's active on SGL is truly awesome.

It would make for an interesting thread of great past and present individuals in amateur astronomy around the world.

1 hour ago, merlin100 said:

Sorry, I've never heard of the gentleman.  No disrespect intended, but being relatively new to the hobby, many of these names mean nothing to me.😲

No problem.  He and Al Nagler of Tele Vue are practically treated as demigods of astronomy gear over here.  I wonder who the UK equivalents would be. 🤔

1 hour ago, johninderby said:

Oddly enough while the value of an second hand AstroPhysics refractor stays high in the US in the UK they depreciate much more. US buyers could pick up a bargain by buying a used AP scope in the UK.

Interesting.  So, something like this 23 year old Astro-Physics 155EDFS on CN classifieds might go for half this or less in the UK?  I'll have to keep that in mind if I ever decide to go after an AP scope.

7 hours ago, merlin100 said:

I also occasionally sell on eBay, so I know how it works. I always believed that once something has been bought new, that it's value depreciates by around about half.

Not for Astro-Physics refractors.  However, if Roland catches you profiteering by immediately reselling one of his scopes, he won't sell to you ever again.  He knows he could ask for much more for each of his scopes, but he doesn't as a matter of principle.  He simply sells them for what he considers a reasonable profit to keep his business going.

Dielectric just means multilayer vapor deposition creating a 99% reflectivity (at 45 degrees) mirror.  They also don't tarnish like an aluminized or silvered first surface mirror.  I like my GSO/Revelation dielectric diagonals quite a bit.  I would skip the quartz substrate option, though.  I've got both and can't detect any difference.  The cheaper diagonals also tend to not be as well made mechanically, I've found.  You get flex with binoviewers or heavy eyepieces.

If your pockets are deep enough, the 12.5mm Nikon NAV-HW might be worth a look.  Most CN reports rate it as slightly better in most ways with regard to the 13mm Ethos (sharpness, immersiveness, contrast, eye relief).  With its EiC lens, you get a 10mm as well.

Time to convert the basement/garage into a woodworking shop, I guess.  Totally weather independent hobby. 😉

I didn't take up astronomy until I moved from New York to Texas.  I lived with 30 miles of New England's western edge.  They don't call in NEW England for nothing.  The weather is pretty similar, if a bit snowier.  Astronomy was never much of an option there due to the weather and both air and light pollution. 🌧️

3 hours ago, Don Pensack said:

It depends on the scope.

  In my 12.5" with coma corrector, the 14 Morpheus is sharp to the field stop.  The CC flattens the field slightly and eliminates coma, something many mistakenly confuse with astigmatism.

When I wear my glasses, I see zero astigmatism in that eyepiece in the f/5.75 (CC corrected) scope.

I'll go back this fall/winter and have another look at the 14mm Morpheus in several different telescopes.  I'll try them out in my new to me 90mm TS APO as well.  I have a TSFLAT2 dedicated to it as with the 72ED.  I'll even rotate my head around to make sure it's not my eyeglass prescription causing it.

Sometime over the last couple of years, I distinctly remember going back and forth between the Pentax XL and the Morpheus to determine which would be in the A-Team case.  Even in my field flattened 72ED, there was curvature in the Morpheus and slight astigmatism (racked on both sides to confirm tangential/radial swap at best focus) as compared to the XL which had stronger curvature but zero astigmatism, none, once refocused.  In the end, I decided that the larger field and milder curvature of the Morpheus were preferable to the XL's stronger curvature yet perfect edges once refocused.  I even increased the TSFLAT2 distance by attaching it to the end of the original diagonal nosepiece and pulling the eyepiece and 1.25" adapter upward out of the diagonal to vastly increase the flattener's working distance to over-correct the scope's field curvature.  The Pentax XL eventually was perfectly flat and corrected across the field.  It was magnificent.  It's a shame Pentax didn't add a dedicated field flattener somewhere in the design to achieve this same result.

Lest you think the scope was causing the curvature, my 17mm ES-92 wasn't showing any curvature, nor was my 10mm Delos or 9mm Morpheus.  I can't recall if the 12mm ES-92 showed any curvature or merely a tiny bit of edge astigmatism.  I do distinctly remember that the 12mm is slightly disappointing compared to the 17mm.

5 minutes ago, Jiggy 67 said:

Maybe it’s my understanding of eye relief which is lacking, I assumed that by increasing the distance between eye and outer most lens that would increase the eye relief but I bow to your better knowledge John 😀

Eye relief is the fixed distance behind/above the eyepiece's eye lens where the image forms.  All the rays should converge to a fairly tight circle/point at that distance.  You need to put the lens of your eye at that distance to take in the image.  Adding a spacer ring merely pushes your eye back a bit.

56 minutes ago, Jiggy 67 said:

What @Barry-W-Fenner said......It’s important to note that the Morpheus eye relief is around 20mm (I think) but can be increased with the supplied spacer ring which I’ve done with all mine. I’ve got the full range and, like Barry, I’m very pleased with them

Make that decreased eye relief with the supplied spacer ring.  One came with my 9mm Morpheus.  It's nothing more than an M43 spacer ring (think empty filter ring).  It works the same as the Tele Vue eye cup extender, only it attaches differently.

12 minutes ago, John said:

The Delos uses a system where the whole top section of the eyepiece slides in and out and is locked in place by twisting the top and bottom of the eyepiece in opposite directions.

Actually a bit more complex than that.  It's the top and bottom of the upper/outer barrel of the eyepiece.  The lowest part of the eyepiece that resides in the focuser plays no part in the adjustment.  Thus, it is a two handed operation compared to what can be a single handed operation for the Pentax XW as you stated.

To revisit the difficulty of capturing field curvature with a small camera lens, here's an extreme example of the camera lens's ability to flatten an otherwise very curved field.  The 30mm WideScan clone below (Agena UWA second from right/bottom) has vast amounts of field curvature.  So much so that most folks describe it as entering light/warp speed.  But, it looks pretty good here, having only mild astigmatism:

I've measured the 14mm Pentax XL and Morpheus to both have 18mm of usable eye relief.  My 7mm and 3.5mm Pentax XWs also have a measured 18mm of usable eye relief.

My 10mm Delos has 21mm of measured, usable eye relief.

36 minutes ago, globular said:

Thanks @Louis D.

How do I interpret your images?  It looks to me that the Morpheus has more curvature than the XL. But when combined with the curvature of the scope being used I imagine things change... and may be the extra curvature in the lens cancels more of the opposite curvature in (some) scopes?  But isn't the Edge HD supposed to be relatively flat compared to other scopes?  So the Morpheus might look more curved in my scope than the XL / XW? .... May be I'm getting this all wrong? 

You're not going to be able to see field curvature in these images because the camera's lens has more than enough depth of focus to bring all of the field into focus.  Unsharpness at the edge is mostly due to astigmatism in these images.

Most scopes that I am aware have a field curvature that accentuates the field curvature in the 14mm and 20mm Pentax eyepieces.

The Edge HD would do best with flat field eyepieces as you suggest.  The Morpheus will still look flatter of field than the XL/XW eyepieces, but not as flat as the Delos.