Louis D

I've avoided the 21mm Pentax XL early on and 20mm Pentax XW later on due to field curvature.  I also retired my 14mm Pentax XL in favor of the 14mm Morpheus as my eyes aged and field curvature become problematic.

Try highly defocusing a bright star or planet next time to examine the image for wobbling and bubbling due to atmospheric distortion.

I've done a similar pairing with my 72ED on one side of my DSV-2B mount and the 127 Mak on the other:

5 hours ago, LondonNeil said:

skymax 127. From a bit I've read there seems no real gain going to a 2" visual back

I've found it immensely helpful in getting targets centered.  The field of view does vignette somewhat as seen below, but the extra true field opened up is quite useful.

As you can see, it opens up roughly 80% more linear true field of view.  Light falloff is around 35% center to edge which is surprisingly hard to detect visually.

The longer path through the 2" diagonal does necessitate moving the mirror quite a bit to reach focus, increasing the focal length by at least 200mm.  Thus, if you're never going to use 2" eyepieces, you'd be unnecessarily decreasing your true field of view with each and every eyepiece by making them work at a higher power.

I would add the 22mm Omegon Redline to Don's list.

The discontinued Celestron Axiom LX 31mm, Meade 5000 UWA 30mm, and original mushroom top ES-82 30mm are all more eyeglasses friendly than the optically identical modern ES-82 30mm.  However, you have to hunt the classifieds and various online marketplaces to find used or new old-stock versions of them.

The Long-Perng made 80 degree series have gotten good reviews in the 14mm and 20mm focal lengths in Orion LHD, SL 80º LER / UWA, and other liveries.  To get long eye relief though, you have to completely remove the eye cup as Don says above.  You might be able to find an alternate eye cup to slip-fit in place of it.

The Founder Marvel Ultra Wide version is also available from FLO for £20 cheaper if you can live with its green instead of red color.

If you're not hung up on 80º and could live with 70º, the 22mm Omegon Redline and its rebranded bretheren is very well corrected, eye glasses friendly with the eye cup removed, and not too heavy.  I have the discontinued Astro-Tech AF70 version.  I retired it only after acquiring a 22mm NT4, but am quite content to use it when I only have my B-Team case available.  The Baader Hyperion M43 screw-on eye cup fits it nicely as an eyeglasses friendly eye cup.  The original eye cup is far too thick and stiff to fold down.  This eyepiece used to be only $99 10 years ago, but it appears to have doubled in price since then.  Unfortunately, it's not such a bargain anymore.

If it labels itself as an eyepiece, they does that not make it an eyepiece forum discussion target?

I would think eye astigmatism would still be an issue even when looking at the tiny screen.  I also doubt it is as sensitive and quick responding as the more modern night vision gear, or else the DoD would be switching away from them to an imaging chip approach.

I have both the quartz and regular version of the 2" GSO-made dielectric diagonal.  I can't tell the difference visually between them.

Just avoid the 1.25" diagonals with the curvy eyepiece receiver.  They have a rather large lip at the bottom that causes vignetting with widest true field of view 1.25" eyepieces:

Here's another good thread about various diagonals and clear aperture:

Nicely done.  We had low clouds with gaps and high thin clouds pervasively here in our part of Texas.  It was even worse to the south where they were totally socked in with low clouds.  The low clouds did open up on occasion to reveal both the partial phases and totality.  I got a good look with my scopes at a friend's house within a few miles of the center line.  It indeed looked just about like your images, so well done I say.  I couldn't grab even one image during totality with my telephoto lens because the clouds closed up for the last two minutes of totality.  We also missed the diamond ring effect at the end of totality.  Still, it was fun experiencing it with family and friends.

For the 2017 eclipse, it was just the wife and I in Nebraska with a bunch of strangers.  We had excellent weather for that one, but it was just the two of us.  Now, we're thinking of taking our bucket list trip to Australia and New Zealand in 2028 during their total solar eclipse.  I figure with it going through the Outback, there should be really clear skies.  We might even bring some of our kids and their families along if they're interested.  They're all world travelers.

The only way I would ever become an imager would be to setup a permanent remote observatory at a dark sky location (perhaps a vacation home) that I would get working well onsite and then switch to preprogrammed imaging sessions, weather allowing.

21 hours ago, Don Pensack said:

The 24mm APM Ultra Flat Field is labeled 24mm, but actually measures 24.7mm, so the magnification formula will be way off.

I measured 24.1mm FL in the center and 20.5mm FL at the edge for my 24mm APM UFF.  I measured the FS at 27.5mm, the AFOV at 63°, eAFOV at 65°, and the usable eye relief at 17mm.

Check the classifieds and pick up a used 2" diagonal to see if you use it much, or can come to focus with it.  Here in the US, I've picked up 3 lightly used GSO-made 2" dielectric diagonals over the years for about $80 each off of US astro classifieds.  If you're not picky, you can pick up more traditional 2" diagonals for less.  I'm sure the UK classifieds have similar deals.

You would greatly miss the 30mm UFF if all you have is a 1.25" diagonal.

I used a cheap, low power finder eyepiece for years to locate objects while scanning.  The edge aberrations always frustrated me because I'd think I'd see a planetary nebula I was hunting at the edge only to discover it was simply a bloated star once moved to the center.  Save yourself that irritation and get the 30mm UFF.

I wonder if you could try an alcohol or acetone soak to see if it could coax the water out or clean up the stain.  The acetone might dissolve the cement, though.  Regardless, the cement clearly doesn't cover the entire surface of the two joined lenses.

There's the Hubble Optics UP12 which weighs 32 pounds.  It's a bit of a work in progress if you read the forums, but it can be made to work.

There's also the Obsession 15" f/4 UC which has a 26 pound mirror box and comes with wheelbarrow handles to allow for moving it about fully assembled.  The weight at the handles is 8 pounds.  Their scopes cost more, but tend to not need any fussing to start using them.

I'm sure there's more lightweight Dob options out there, but those two pop to mind for me.

Check the classifieds.  Large Dobs don't tend to hold their value very well in the US, so used models can be bargains.  It might be the same in the UK.

Reminds me a lot of Manfrotto photo gear.  For some reason, they use castings than can crack apart under stress.  They would be much stronger if they were machined from solid billets of metal.

6 hours ago, Stephen196360 said:

Hiya guys

Thanks for the info 

However I'm a little in the dark about offset terms etc

Could someone give a technical drawing etc on the construction or explain exactly what I need

Kind regards steve 

Here's an article about making an off-axis aperture mask.  It should give you the general idea of what is going on.  You would just cover the mask opening with solar film for solar observing, and securely mount the mask to the tube opening.

I would recommend making an off-axis aperture mask out of stiff foam board with the circular opening between spider vanes and covered with solar film.  That way, you'll have an unobstructed view, so there won't be any secondary shadow to fight while solar observing at larger exit pupils due to your scope's long focal length and fast f-ratio.  With the off axis aperture mask, you'd end up with a  roughly 135mm f/12.2 unobstructed solar scope.  Yes, it will be a huge 5.3 inch APO.

I see you already have a truss shroud which is extremely important during solar observing.

It can be a slippery slope if not treated properly.  This poor chap named Mike Clements in Utah is reportedly suffering from the worst case of Bacillus Aperturtitis ever documented:

https://archive.sltrib.com/story.php?ref=/sltrib/news/57034821-78/telescope-clements-mirror-inch.html.csp#gallery-carousel-446996

https://jaysastronomyobservingblog.blogspot.com/2013/02/mike-clements-70-inch-reflector.html

Let us all pray he has a full recovery some day.

36 minutes ago, Mr Spock said:

Ties won't work on my 12".

Why not?  Is it just the roughly 3 foot circumference?  I've daisy chained a dozen or more zip ties end to end to go around very large items successfully.

On 29/03/2024 at 08:16, Ricochet said:

I bought a white one, the only concern is how a large white hood looks to anyone else

It could get you in a heap of trouble in some parts of the US.  I'll take a pass and use a white towel if need be.  It's also handy for wiping off the sweat while solar observing near noon here in Texas.  I run a box fan at full tilt across my body to try to keep a bit cooler while solar observing from mid-April through mid-October.  Heat stroke is a very real possibility, so I also drink plenty of fluids while outside.

Was he using a fresh microfiber cloth being careful to roll it upward while wiping to lift grunge away without dragging it across the surface?

6 hours ago, Jim Smith said:

I gave in and bought a Seestar S50.  Now I can see spiral structure easily! The attached image is 7 minutes stacked in camera but spiral arms are visible even on one 10 second exposure.

Out of curiosity, I edited and upsampled your image in Photoshop Elements and Noiseware to see what it would look like, and I was surprised at how good it came out below:

Those little Seestar S50 camera-scopes sure are nice. 

Or, rather going for a bigger scope, invest in an image intensifying system.  They're also really handy for observing diffuse nebula in real-time.  The only problem is you generally have to adapt non-astro systems to astro use, which can result in a lot of trial and error.