Louis D

22 minutes ago, heliumstar said:

Thanks for posts everyone. I own or owned XW, SLV, Morpheus and liked them all. Time to try Delite?

My prescription for astigmatism is Cyl Right -1.25, Cyl Left -1.5 and Axis Right 170, Axis Left 5. Realistically do I need glasses when observing> I don't use eyepieces with less than 2.5mm exit pupil at the moment as I am mostly after double stars and planets and observe deep space with camera.

According to Tele Vue, astigmatism in your case is likely to be noticeable in exit pupils above 1.5mm:

Thus, you might want correction between 1.5mm and 2.5mm.  I assume you meant "more than 2.5mm exit pupil" above since most double star and planet observation is done at small exit pupils.

I have 2 diopters of astigmatism in my observing eye, and I can see it at 1mm, and somewhat below that as well, though it is subtle.  If you use a driven mount and only observe small objects like double stars and planets on axis, you can probably get away with shorter relief eyepieces and just back off from the eyepiece while wearing eyeglasses.  Compare the views with and without glasses to determine for yourself your astigmatism tolerance threshold.

The Vixen SLV range have long eye relief and a reasonable form factor, though only a 50 degree field of view.

The Meade 5000 HD-60 also have long enough eye relief to use with eyeglasses and are slightly smaller than the XW and Morpheus.

Make sure to get a pair of single vision, distance only eyeglasses for astro work if you have presbyopia as well as astigmatism since you want the entire field of view at the same focus distance.  Since it is next to impossible to get glass lenses, the next best is low index plastic to avoid the off axis chromatic aberration of high index lenses.

42 minutes ago, Dash1st said:

 I have got to show that video to my wife, as it puts everything in to much better perspective.....it will also end up making her want me to spend more money on something much bigger. 😵

That video is pretty damning of some objects that view fine in smaller scopes like the Pleiades and Orion nebula.  Sure, color is non-existent, but I can see nebulosity in both and fine details in Orion from my suburban backyard.  Add an OIII filter, and Orion really jumps out at you.  Globular clusters need aperture to be resolved, and then they are spectacular.  Galaxies really do need dark skies.  The video is dead-on accurate there.  The video skipped smaller open clusters which are beautiful to look at in most scopes.  Planets are probably the most disappointing for newbies.  They are small and details are minimal.  However, Saturn's rings and Jupiter's main belts are usually visible in even small scopes and the Galilean moons are fun to watch as they dance around Jupiter.  The moon is spectacular in just about any instrument.

Just get something and get out there and observe. 😁

20 hours ago, Anthony1979 said:

Its so i can store them safe in a cupboard without them getting damaged or dusty

As long as you keep dust caps on both ends of your OTA (and a plug in the focuser for Newts), you should be good for preventing dust intrusion.  I've seen folks using shower caps for this purpose if their scope didn't come with end caps.  Dust on the outside is of no importance, and shouldn't be much of an issue anyway in a closet/cupboard.

As far as damage prevention, bubble wrap is surprising good for this purpose.  I've had an ST80 in a gym bag wrapped in bubble wrap near the bottom of the closet for 20+ years, and it has nary a single ding or dent and the focuser works fine.  I was a bit concerned at first in the 90s, but time has proven my worries to be unfounded.  When I put my daughter's camping telescope kit together, I bought a 22" long duffel/gym bag and wrapped her 127 Mak in bubble wrap before putting it in the main compartment.  I then wrapped the finder scope in bubble wrap and put it in a side pocket.  Other pockets hold various accessories.  It's worked out pretty well for her.  She loves the fact I picked out a purple bag (her favorite color) as well.

4 hours ago, mikeDnight said:

I'm pretty certain you'll get lateral colour with any wide angle eyepiece.  It's just the nature of the beast. There's noticeable LC with my 17.5mm Morpheus but I don't notice anything around stars, just the moon; but its not a lunar eyepiece. My narrower field pseudo Masuyama's are free of false colour. Horses for courses I suppose.

There varying degrees of edge LC with wide angle eyepieces.  I find it noticeable and intrusive with my 30mm ES-82, but almost non-existent in my 30mm APM UFF.  It's quite noticeable in my 13mm and 17mm AT AF70 eyepieces, but almost non-existent in my 12mm and 17mm ES-92 eyepieces.  As far as Morpheus eyepieces, it's quite noticeable, along with field curvature and astigmatism, in my 14mm's outer 15%, but all are pretty much non-existent in my 9mm.  I have no experience with the 4.5mm.

Why?  Are you planning to travel via airlines with them as checked baggage?  The cost of true flight quality aluminum cases would be more than your telescopes.  The cheap ones from China only have metal at the edges.  The textured shiny parts in between are actually textured plastic and are easily punctured.

I would look for large plastic totes, sealing or non-sealing, your choice, if you have a need to stack heavy weight on your scopes in storage at home.  If nothing is going to be compressing them, simply wrap them in bubble wrap and put them in a large duffle bag or tripod/light-stand/gig case and stand them on end in a closet.

The Vixen SLVs are being closed out by FLO for a good price.  They view very similarly to the Pentax XL/XW, just much narrower.

I would just find a sturdy duffel bag of sufficient size to hold the OTA and accessories, plus bubble wrap around everything.  I did that for my daughter's 127 Mak so she can take it camping and not look expensive in the open back of an SUV like a flight case would.

For the tripod and mount, I got her a Gator bag.  They are very sturdy.  You might want to bubble wrap the mount, but I wouldn't bother with the legs.

5 hours ago, RobH2020 said:

Hi all, 

I'm just getting started with compiling a collection of accessories to enhance my viewing. I want to add to the collection slowly, so i get a chance to learn from each new thing and use that experience to better inform the next purchase. 

With that in mind, i was wondering if I'd be better served getting filters earlier or later in the process?

By filters I'm sure i don't really know what I'm talking about but i see on FLO a narrowband UHC filter (unbranded) and a celestron "CLS" filter - City Light Something, or essentially a light pollution filter. Both around forty quid, which is my budget. Both sound useful for me, I'm in a red zone (urban/ suburban). I'm interested in seeing more nebula - improving the Orion nebula, i saw someone said a filter helped them see the veil nebula with similar equipment to me in similar conditions. 

So... any thoughts or advice? : ) 

i have an f/8 skywatcher dobsonian 6", with the stock 10 and 25mm eyepieces, and an 18mm BST StarGuider coming for my birthday... as well as an astro essentials moon filter and an astro essentials 2x barlow.

thanks!

Rob

You might also invest in a full aperture solar filter to expand your observing opportunities into the daytime.  I've been using a home-made cell for Baader Solar Film for 20+ years.

3 hours ago, JOC said:

LOL

Mind you I was thinking more in terms of someone actually owning 101 different EPs!!

There are quite a few folks who have many eyepieces.  Jim Barnett and Tamiji Homma on CN both report having hundreds of eyepieces, though each has thinned the herd over time.  I'm sure there's some folks on SGL that have hundreds as well.  I have just over 60 myself.

3 hours ago, John said:

William Optics did actually have a 9mm 101 degree eyepiece:

That extra 1 degree makes all the difference !

Sort of like in Spinal Tap: "These go to eleven."

Is the date set correctly?  For solar system objects, an alignment is not enough to find them.  Ask it to find Sirius, the bright star to the left of Orion as you face south.  If it finds it, your alignment is probably good.

20 minutes ago, Piero said:

 

By 'tipped' do you mean off-axis towards the primary mirror?

 

1. A primary mirror axial misalignment will cause coma on axis (coma due to misalignment).

2. A focuser axial misalignment will cause the stars to focus at different points across the focal plane.

3. A secondary mirror (severe) misalignment will cause unequal field illumination.

 

It's rather obvious that only the first one degrades on-axis, therefore 2 and 3 reveal nothing on a star testing as this is conducted on-axis.

 

Of the 3, the last one is the less critical for visual astronomy. 

Without coma corrector, the first one is the most critical. With coma corrector, also the second becomes rather critical. All of them become more critical in faster newtonians. 

There is nothing to fear in this process. If wrong, it can be fixed and rather easily.

Correct, the secondary is slightly off-axis toward the primary.  Think of a laser beam striking the center ring itself rather than the hole.  Now, the primary is tipped to send the laser beam back to the center of the laser's output.  So now, you've got some primary mirror axial misalignment induced by the secondary mirror misalignment, correct?  Would a collimation cap be immune to the effects of the tipped secondary when aligning the primary causing the primary to be aligned correctly irrespective of the secondary tip or would it result in the same situation as with the laser?

6 hours ago, Piero said:

Even so, this test doesn't tell you anything about secondary and focuser alignments.

I've often wondered, if the secondary is tipped relative to the true optical axis, but the primary is compensatingly tipped so the center dot looks centered in a collimation cap reflection, what affect does this have on the image?  Does Suiter discuss this condition?  I ask because I'm never quite sure if the secondary is pointing exactly at the center of the primary each night even since I check it infrequently, only performing a quick primary check each night.

I would start by seeing if any of your pre-existing eyepieces will reach focus on that tree.  If not, with the focuser racked all the way out, loosen the eyepiece (I'd start with your lowest powered one) and start lifting it up and out of the focuser, always looking in it to see if the tree comes into focus.  If it does, note the distance between the shoulder of the eyepiece and top of the focuser tube.  You'll need to get an extension tube at least that long to reach that close of a focus.  I'd probably get one another inch longer so you don't have to have the focuser racked all the way out and to allow you to focus even closer in the future with the focuser racked all the way out.

1 hour ago, paul schofield said:

Thank you all for that info. I've added the vixens to my short list too, thanks John. I do still own the Baader genuine ortho, but to tell the truth I never use it as I find it a real challenge like looking through a straw, albeit with a great image once found. 

By all accounts, the Vixen SLVs below 9mm actually have a 45 degree field like their predecessors the NLV and LV did.  Thus, they're going to appear straw-like to you as well, but with much better eye relief.

The 6.5mm Meade 5000 HD-60 is very well corrected at f/6, has a 65 degree apparent field of view as I measured it via projection, and is comfortable with or without eyeglasses thanks to having both a flip up-down eye cup and a twist-up eye cup.

You'll need about 100mm of in-focus/back-focus to reach focus without using an OCA/GPC.  The Williams unit comes with a 1.6x one that might be decent.  The 1.85x and 3.0x ones that came with my Arcturus binoviewer were awful.  They introduced linear coma as if they had tilted optics.  I use the nosepiece from a Meade 140 2x binoviewer to reach focus at about 3.0x instead in my Dob.

9 hours ago, jetstream said:

Down the road a 2" APM 20mm HDC or the TS equivalent tsxwa 20mm is a super low power eyepiece.

They would work as very well corrected 70 degree eyepieces with eyeglasses, I suppose.  I would still error toward the 22mm TS-Optics Expanse since usable eye relief would be the same at 70 degrees (with the eyecup removed via unscrewing) and the price and size are much smaller.  Yes, the correction at the edge at 70 degrees won't quite be there compared to the XWA.

First, what's your total budget?

Second, which of the BSTs do you tend to use most often?

Third, can your son use all of the BSTs successfully with glasses?

Fourth, how do the BSTs perform in the f/7 scope?  I assume the edge issues are when used in the f/4.7 scope, correct?  The 5mm and 8mm work find at f/6 and above across the field for me.  The 12mm through 25mm have some edge issues at f/6, but starting around 50% out rather than 33% out.

By all reports, the Baader Hyperions do poorly below f/7, so they would be an improvement only in field of view.

The ES-82s do better, but have short eye relief.

I'd probably steer you toward the Baader Morpheus line.  Not as expensive as the Televue Delos or Pentax XW, but very close in performance and with a wider field of view and just as much eye relief.  I have the 9mm and it is terrific at f/6.  I also have the 14mm, and it is just a bit worse at the edge.  The 6.5mm is supposed to as good as the 9mm.  The 17.5mm, 12.5mm, and 4.5mm are slightly behind the 9mm and 6.5mm, but ahead of the 14mm from what I've read.

At 22mm, the Omegon Redline (Celestron Ultima LX, Olivon 70, AstroTech AF70, Arcturus Ebony, Telescope Service Expanse ED, Astromania SWA, etc.) is very good out to 95% of its 70 degree field at f/6 and with good eye relief.  I'd guess it's a bit worse corrected at f/4.7, though.  Keep in mind, it's a 2"-only eyepiece.

The discontinued 22mm Vixen LVW is supposed to be very good in faster scopes and have decent eye relief, but is difficult to locate used.  It is 65 degrees and a 1.25" eyepiece.

It looks similar to a CLS-CCD filter.  Perhaps it's a light pollution filter?

It could be that the Zeiss solution is intended to dissolve really tough grunge such as tree sap, but doesn't actually wipe cleanly away and requires a follow-up with another cleanser.

7 hours ago, Apollo_95 said:

My understanding of Barlows is that they double or treble the magnification of the EP & make the images bigger but not necessarily any sharper. Is this correct?

For low contrast objects like Jupiter, they'll actually appear less sharp once a certain point of no return is passed in terms of magnification.  A zoom eyepiece is useful to determine exactly what that Goldilocks magnification is.

For high contrast objects like star clusters, there's very little breakdown of image sharpness with increasing magnification.  In fact, some globular clusters could be partially resolved in your scope with enough magnification.

1 hour ago, rwilkey said:

Generally speaking, the more you crank up the magnification, the more the object becomes fainter and less sharp.  Yes, the object is larger, but you loose detail.  The Moon and Saturn can take a lot of magnification though (250x).  Jupiter not so much, about 150x. 

In my experience, it's more dependent on exit pupil, seeing conditions, and fineness of optical figure than absolute values.  With my well cooled 15" Dob and steady Texas skies, I was able to view Jupiter just fine at well more than 200x in the past to see festoons and barges within the belts.  With a 130p and typical UK skies, I would expect 100x to be about the useful max on Jupiter.  An 8" Dob should be capable of 125x to 150x on Jupiter.

17 hours ago, daslolo said:

Animated diagrams! So nice!

It looks like a result of the eyepiece design, is there a thing I can do besides a longer eyecup to get feedback?  I am getting severe kidney beaning with very wide AFOV eyepice (Meade 607018, 100 Degree, MWA 21MM, 2-Inch).

 

Definitely SAEP.  I had heard the MWAs were susceptible to it, and this pretty much confirms it.

As long as your eye's iris is fully dilated, you probably won't notice it.  However, this rules out using it in the daytime, for solar observing, lunar observing, at twilight, in a heavily light polluted area, or shortly after leaving a lighted area for a dark observing area.  I also recommend staying back a bit and not trying to take in the full view to the field stop.  I find the 12mm and 17mm Nagler T4s have some SAEP and have learned to deal with them in this manner.  That, and I replaced them with 12mm and 17mm ES-92s which completely lack SAEP. 😄

38 minutes ago, Adam1234 said:

Hi all, so following on from my previous post on help with collimation, I have taken advice and bought a collimation cap which is much easier to use, and I can actually see the mirror clips (which I couldn't with Cheshire).

Below is a picture of my efforts using the collimation cap, please let me know if this looks good...

 

Thanks Adam

You're barely off on primary collimation.  I generally can't perceive any difference between being in that state and tweaking the center dot to the exact center of the O-sticker with an f/6 scope, so I'd call it good enough for most observing.