Louis D

Not seeing it. I just pull the 1.25" diagonal and 2" to 1.25" adapter and binoviewer with associated OCS/GPC bits for reaching focus out of the focuser and replace it with a 2" diagonal and eyepiece to switch between modes. On my Dob, I just pull the binoviewer and OCS/GPC bits out of the focuser and put an eyepiece in its place. On my Mak without OCS/GPC focus help, it takes forever to move the mirror enough to reach focus with just a diagonal and eyepiece after pulling out the binoviewer. Thus, I don't switch modes on it during an observing session. I don't see how the quick changer would help unless it has an extension tube incorporated in it to match the backfocus of the binoviewer. Am I missing something here?

It depends on the magnification used. At low powers, you're not likely to see any difference except perhaps on the brightest objects. Where you will see it is at high powers where there will be a slight violet violet fringe around bright objects with FPL-51 that is much more subdued with FPL-53, especially in triplet form. However, even the most APO refractor still has some fringing compared to a Newtonian at high powers. If you've always used pure reflectors as I have, it's a bit of a surprise that the term APO doesn't equate to absolutely false color free, especially on either side of best focus as you find that best focus. I would equate APO to very well tamed false color. In a reflector, a white star is always white no matter which side of focus you're on by comparison.

I find 8x binos to be right at the limit for me to hand hold. I need to be sitting with my elbows braced for 10x and above to get decent views. If you're going to be standing, I would go with 8x42 bins. Sitting, 10x50s will work.

Yep, I did the same thing several years ago, except in reverse. First, the 17mm ES-92 replaced my 17mm Nagler T4. The next year, the 12mm ES-92 replaced my 12mm NT4. Now if only ES would make a ~22mm version to replace my 22mm NT4. 😉 I don't think I'll hold my breath on that one happening any time soon, though. I bought the 26mm Meade MWA to see if it could fit the bill, but it actually worked out to be closer to a 25mm Morpheus. 🙄 It's actually grown on me in that role once I'd adjusted my expectations for it. If you like the 12mm ES-92, you'll love the 17mm version. It's actually a bit better corrected at the edge, and a bit easier to hold the view in.

Have you tried contacting Tele Vue in NY by phone? I've read they can supply replacement caps, so they might also do eyeguards.

My old 14mm Pentax XL has worse field curvature than the 14mm Morpheus, and a narrower field to boot. However, it is pin sharp and astigmatism free to the field stop once refocused. The wider field and lesser field curvature of the Morpheus ousted my venerable XL from the spot it had held in my A-team case for 15+ years. I decided I could live with the edge astigmatism since it was in a part of the field that doesn't even exist in the XL. In all other ways, the two eyepieces were basically equivalent.

This is a great topic along the lines of the famous Meade 4000 Plossl threads. How to distinguish early Japanese made from later Chinese made Celestron FRs.

Working as designed. Never mind that the design (or implementation) is flawed.

Not astro related, but it reminds me of my wife's workplace where the batteries in a UPS caught fire, destroying an entire server room. She and a coworker actually fought down the flames using fire extinguishers brought to them from all around the building. They managed to save the office building by keeping it out of the drop ceiling (the fire department arrived 15 minutes after the fire was out), but my wife was hacking up black soot for days. The room was nearly an entire loss except for some backup tapes that somehow survived in their tape drives. As a result of this fire, we will not use battery based UPSs inside our house. There are flywheel based ones, but they are only made in enterprise class sizes ($100,000+ units).

If you're buying used, avoid the Meade FR unless you really know what to look for. In the past, there was time when their FRs had optical issues. The Celestron is a solid bet in the used market. I've never read of any issues with them. The Antares will be similar to the Celestron from what I've read. The Starizona corrector is the one to get if you're very picky about image quality.

No, the central 50 degrees of the Morpheus will show the same amount of sky as the Plossl at the same magnification. 12.5mm focal length determines the image size. You'll just get to see what was beyond the field stop in the Plossl for better context. It should work fine on planets, especially for those of us without a tracking mount. It gives more dwell time between nudges.

The Askar is made by Sharpstar. I have one of their 90mm APO FPL-53 triplets under the TS Optics brand. Hopefully, your FRA600 works out better for you than the Esprit did. I can say that I have spiky stars in my Sharpstar triplet until it acclimates, but I'm just a visual observer.

I have the 14mm and 9mm Morpheus. The 9mm is world class sharp. It's very close to my 10mm Delos. The 14mm is very nice in the central 85%. The outer 15% tends to fall off in sharpness slightly due to astigmatism and field curvature. I wouldn't get a 12.5mm Morpheus if I already had a 14mm Morpheus. My 12mm ES-92 views entirely differently and is 2-inch only. If that new APM wonder-zoom pans out, I may get it next. It would cover my most used focal lengths.

If you think the 12.5mm Morpheus is big, you'd better stay well away from the 12mm ES-92 shown below on the far left. Your Morpheus is similar in size to the 12mm Nagler T4 or 13mm AstroTech AF70 below:

Probably a 1/4-20 nut/bolt which is the same as camera tripod threads. It's an incredibly common size over here.

Thousand Oaks makes a polymer based solar filter which is also perfectly safe to use as well.

I don't do imaging, but rotating the focuser on my fracs on my alt-az mounts can lead to the focuser knobs being in really awkward positions. I do have a built-in camera rotator on my 90mm Sharpstar made TS-Optics APO focuser that is handier to use than loosening the diagonal screws or rotating the focuser to bring the eyepiece to the side. I suppose if you have a motorized focuser on your frac, then the orientation of the focuser is irrelevant as long as the motor clears the mount. Perhaps if you manually focus once and then take hours of data, then focuser awkwardness could be lived with.

I was thinking in terms of a 4mm orthoscopic eyepiece that the quoted post might have been referring to. In that case, the metal barrel thermal mass far outweighs the thermal mass of the tiny amount of glass. Perhaps that poster has large transference of heat from the metal barrel into the glass leading to the image boiling they saw. I was just theorizing to try to explain what they are seeing. I don't use tiny, high power eyepieces due to their limited eye relief; so I have no direct experience to draw upon with regards to that person's experience. My high power Pentax XL and XW eyepieces sit outside with the scope cooling in their case, so there's no equilibrium issue with them. I could try leaving the 3.5mm XW inside sometime on a cold night to see if there is any effect on the image. However, we're rapidly moving toward spring here, so the nights will be warming up dramatically over the next month, limiting any time to try such experiments this season.

Tele Vue designs their eyepiece in-house in the USA which leads to increased R&D costs to recapture. They also manufacture them in dedicated factories in Japan and Taiwan to avoid design copying by Chinese firms. TV designs their eyepieces to work well down to at least f/4. They also tend to have higher levels of polish and better stray light control internal to the eyepiece, leading to less ghosting and light flooding with bright objects. I believe they also test every eyepiece in-house before shipping them to retailers as a quality control check. All of this attention to detail increases the cost of their eyepieces relative to Chinese made eyepieces. Nikon, Pentax, and the late Docter/Noblex also had similar design, manufacturing, and marketing methodologies with prices to match.

Reaching thermal equilibrium should take just a few minutes given the small element sizes. The metal barrel may pose more of a cool down issue. Perhaps at high power this boiling might be briefly observed. At low powers, I've never noticed any boiling effect when doing this with large eyepieces I grab from cases left in the house for later comparison. For instance, I was swapping my 40mm Meade 5000 SWA with my 40mm Pentax XW-R, and could see no initial boiling effects this winter despite grabbing the Pentax from off the dinette table by the back door since it doesn't have a permanent eyepiece case home yet. The temperature drop was about 30 degrees F. After 45 minutes of swapping on different targets, the difference in views between the two eyepiece remained unchanged despite both reaching thermal equilibrium by then. I've repeated this observing pattern dozens of times in the past 20+ years when comparing eyepieces against other eyepieces left in the house in auxiliary cases, and I've never seen boiling attributable to low to mid power eyepieces not being thermally acclimated. I'm incredibly picky about image sharpness, and I just haven't seen this effect. I was surprised to see spiky stars in my 90mm triplet APO for 30 minutes or more after bringing it out into the cold. Everyone always talks about how refractors don't require cool down time. Well, I found out otherwise.

My first astronomy observing book was Binocular Astronomy by Crossen and Tirion, 1st edition. I still think it's a decent read, and the start charts in the back are excellent.

There's a Kaiser 100mm Push-On Lens Cap at B&H Photo in NYC, so there should be something similar in the UK.

Not really. The thermal inertial of the glass in eyepieces is very low compared to objective lenses and mirrors. They are also very small pieces of glass in comparison, so temperature differentials within them even out in very little time. As others have said, keeping them warm enough to prevent dewing is a good idea. I wear eyeglasses at the eyepiece, so they act as a moisture barrier between my eye and the eye lens. As a result, I rarely have dewing issues.

To expound upon @vlaiv's response to your question, the exact section of the website is 12. TELESCOPE EYEPIECE. The diagrams are in sections 12.3 and 12.4.

Sorry, but I think @vlaiv covered it pretty well.