Louis D

2 hours ago, RobertI said:

There was much less astigmatism in the Morpheus and virtually no colour at the edge.

Interesting.  I would have thought the 17.5mm Morpheus was astigmatism free at f/7.  My 14mm shows a bit at f/6, but the 9mm appears astigmatism free to the edge, just like my 10mm Delos.

Are you sure you weren't seeing defocused stars due to the field curvature of your refractor?  Make sure to refocus for the edge to see if it sharpens the stars out there into pinpoints.  If they switch between radial and tangential lines on either side of best focus at the edge instead of oblate circles, that truly is astigmatism.

46 minutes ago, Mr Spock said:

This is a four year old thread and 25585 is no longer a member 

1 hour ago, TheLookingGlass said:

Just wondering , where is your review of this eyepiece?

He's active over on CN using the same ID if you're really that interested in contacting him.  John Huntley is exclusively active over there now as well.

As for me, I enjoy the more civil discourse here on SGL; although I'll admit I've sometimes done my part to push the boundaries. 😁

I generally keep a 35mm to 50mm extension tube on hand for helping with close focusing.  I've found it really helps with Maks in particular.  You'd think they can close focus with the whole moving mirror thing, but they can't.

I recall the person had the bulb upright in a stand you'd normally screw into the ceiling, and had the cover snugged to the tripod legs with ties of some sort to keep it from touching the bulb under the center of the tripod.

I've also heard of using an aquarium heater to avoiding melting issues.

3 hours ago, grjsk said:

How big must the swing be before it becomes a problem?

Well, I definitely recall seeing it when I took it out of my air conditioned house at about 76° F into the 98° F evening, so about 22° F or about a 12° C difference.  Bright stars were spikes.  At first I thought it was pinched optics until it warmed up after about 30 minutes.  Stars were nice pinpoints after that.

I've not dealt with rapidly dropping temps while observing here.  The seeing is usually terrible under those conditions, so I don't bother.

17 hours ago, grjsk said:

Looking forward to read your notes on the new scope. I have a 72mm doublet myself, and I am contemplating a slight upgrade. The obvious choice would be a 80mm f7 (fpl53), but a 90mm triplet has also crossed my mind. A 90mm ED would be a perfect option (if it performs): bigger than the 80 doublet, but lighter and cheaper than the triplet.

I had been looking for a 120/125mm FPL-53 doublet when a TS-Optics 90mm FPL-53 triplet showed up used for a decent price.  I realized it would be much more manageable in size, so I went for it and have been very happy with my decision.  The only downside is that it can take 30 minutes to equilibrate if its more the a few degrees cooler or warmer outside than in my house where I store it.

That sounds like a Synta made scope with that 3 screw attachment method.  If you measure the circumference and divide by π (~3.14), you should get the outer tube diameter.  The inner diameter will be a few millimeters less.  At that point, you can start to search for a Synta focuser adapter (or Synta native focuser) in the correct size.

On 19/10/2022 at 16:29, Matt S said:

Now if I can get my hands on a bigger Mak, that’d definitely improve the view

Or a big Dob with a premium mirror.

I just bungee cord my assembled Dob upright to one side of my Astro van (inside, of course 😄) and pack around it.

I've also heard of folks keeping a low wattage incandescent bulb under the cover of the scope, at the bottom, to drive out condensation.  You still might have spiders or other bugs making a home in it, though.

3 hours ago, Barry-W-Fenner said:

Morning,

As I understand it, Quite a few on here use a pair of  17.5mm Morphs for bino viewing. Hopefully someone can confirm back on the viewing experience.

 

17 hours ago, F15Rules said:

Are Astro Tech just a reseller, or a marketing arm of a company like Long Perng?

Astro-Tech is Astronomics's (in Norman, OK, USA and CN's sponsor) house brand, just like StelllaLyra/StellaMira are FLO's house brands.  The actual manufacturers tend to be GSO, Long Perng, Sharpstar, KUO, etc.

Synta seems to be coalescing their business around their house brand Sky-Watcher and their purchased brand Celestron rather than continue selling through Western house brands.  JOC is doing the same with their Explore Scientific and Bresser brands.  You'll still see some of their stuff under other brands, but it is becoming rarer each year.

I don't know what Sunny Ningbo is doing brand-wise since they lost custody of the Meade brand to Orion USA.

Just needed to apply a bit of Doctor Who's transdimensional engineering to make the inside bigger than the outside, that's all. 😉

2 hours ago, allworlds said:

I own and can suggest the Skywatcher Heritage 76.

They are so amazingly bad, they show up in thrift shops around here for $20 or less all the time.  They're hard to put on a target, and due to the spherical primary, only the central 50% of the field is usable.

This has been quite the interesting thread. 😉

I see some boxes marked FRAGILE (Fra-gee-lay).  They must be Italian. 😉

Here's a thread on CN from two years ago on this very subject.

2 hours ago, F15Rules said:

Note also that the Morpheus are all at least 76deg fov, a couple are a bit more

The older focal lengths all seem to be about 78 degrees, but most reports peg the newer 17.5mm at 74 degrees.  Since I already have a 17mm ES-92, 17mm NT4, and 17mm AT AF70, I just don't feel a compelling need to add a 17.5mm Morpheus to see if that number is true and if it bests those.  Perhaps someone on here with one could perform a flashlight/torch test on it to determine the AFOV.

Go out and do some ATM reading on mirrors, I just did myself.  Each glass type has its pros and cons.  I'm not sure there's a one best answer to which glass type is best for commercial grade mirrors.  For high end mirrors, fused silica (quartz) is probably the way to go.

If you just want to show her the moon's craters, Jupiter's main bands and Galilean moons, Saturn's rings, Venus's phases, the Orion nebula, and showcase open clusters, just about any budget scope will work in my experience.  It comes down to the quality of the view, the ease of finding objects, and the ease of tracking once found.  Moving up the price scale improves each bullet point.

I figure my 127 Mak is operating at about 1800mm instead of 1500mm with the additional path length causing the mirror to be moved so much.  Thus, the 20mm eyepieces would be operating at about 16.7mm.  With two eyes, the combined image appears larger than with a single eye, so you may be experiencing this phenomenon.

Since Pyrex changed from using borosilicate glass (looks colorless edge-on) to tempered soda lime glass (ordinary glass that looks green edge-on) with the 1998 divestiture of Corning's consumer division to World Kitchen LLC, I'm not sure it makes any difference.  Borosilicate glass is known for thermal shock stability, not necessarily gradual thermal stability.  Borosilicate glass's coefficient of thermal expansion is 6 times that of fused silica (quartz) glass, so it is more of a marketing ploy than anything else.  Besides, they can now use soda lime glass and call it Pyrex, so you don't really know what they're actually using.

By the way, if you are shopping for vintage Pyrex and want to make sure it is borosilicate glass, look for it to be colorless edge-on and for the brand to be PYREX all in upper case.  The newer soda lime glass versions are green edge-on and say pyrex all in lower case.

Yes, not everyone's bank is the same.  I put $500 toward my daughter's first telescope 3 years ago at Christmas, and all of it was used equipment to stretch the budget.  She was 24 at the time, and it was a bit of a late college graduation present as well, but still a gift to my daughter nonetheless.

The age of your daughter will also play into the recommendation.  Even though my daughter was 24 and a working electrical engineer experienced in electronic hardware, she was still overwhelmed and taking notes from my walk-through of how to use it properly.

Did the 127 Mak come with a 1.25" or 2" visual back?  The current US version has a 2" visual back.

You're going to want to attach the dovetail foot to a longer dovetail bar to achieve balance.

The R&P focuser should be a nice upgrade from my AT72ED.  Its focuser slips under heavier loads at high altitude pointings despite increasing the tension on the focuser set screw.