Louis D

No, it's just slightly less humid. You have to go at least another 200 miles inland before it starts getting arid. It's still pretty humid out there, though.

I keep my astro gear stored indoors in my climate controlled house and have had no degradation to any surfaces including mirrors after 20+ years. Some stuff stored in my shed gets a layer of mildew and/or rust build up over time, so I would never put anything valuable in there beyond a lawnmower. I'm in Texas about 200 miles from the Gulf coast. Dew points in the summer tend to be in the mid-70s (about 24 C). If you can keep good air circulation through your shed, you might be okay, though.

You responded to a "member" who posted exactly that one post in 2018 and never visited again.

Assuming a fixed aperture. If aperture is allowed to grow in proportion to focal length (constant f-ratio), you get the same amount of light but at a higher magnification. That's the draw of big, fast Dobs. You get increased image scale at the same image brightness. That, and increased resolution, so it's a win-win proposition all around.

There's nothing to fix. There's no up or down in space. You just get used to it in short order. Adding a rectifier with internal roof prisms will degrade the image quality. If you really want to view objects right side up, stand on the opposite side of the scope and lean over it looking into the eyepiece upside down. The two will cancel out and the image will appear right side up to your brain.

I think my only vintage Meade eyepiece is the 14mm 4000 UWA smoothie. It's pretty well corrected for a nearly 40 year old design. However, stray light control is abysmal. It's definitely not a lunar or solar observing eyepiece. I picked it up for under $100 due to cosmetic flaws. I just wanted to see if it was really "all that". I also have some more modern Meade gear. Two sets of Meade RGB interference filters (one set picked up on clearance for $20 or $30 and another set packaged with a used filter wheel deal) and the 40mm 5000 SWA. The filters have so much higher transmittance than dyed filters that it's remarkable. The 40mm is really a JOC/ES 40mm 68 degree SWA that I picked up during the great Meade fire sale around 2013 for $125 new. I compared it directly against my new 40mm Pentax XW-R, and found that the Meade was slightly sharper at the edge and flatter of field. However, the Pentax is a bit sharper in the center and has little to no SAEP issues. It's also so much lighter. I haven't yet decided which to be on the A-team going forward. I would like to pick up a Meade 56mm 4000 Plossl smoothie some day. Bill Paolini liked it better than the Tele Vue 55mm Plossl in his comparison piece 12 years ago. That, and it is super cool looking to me with its classic lines. It might be useful in my 127 Mak for exit pupil reasons as well.

Which two are you referring to? It could be simple matter that the FPL-53 version is old stock bought at a lower price in the past while the FPL-55 version is new stock bought at higher, pandemic pricing.

At first I thought you had exchanged them for Meade 4000 Plossl smoothies, which being 5 element, Kowa made, are still sought after today.

As a computer engineer who has been designing computer chips for everything from mainframes and super computers to GPUs and smartphones over the last 35 years, I've come to realize that the vast, vast majority of the world relies on the expertise of a very tiny number of engineers and scientists to create and maintain modern technology. To the unwashed masses, today's technology is basically indistinguishable from magic. What's really scary is that vanishingly few engineers and scientists venture into the political realm, meaning that those in governmental positions are of limited technological understanding and set technology policies by which everyone else must live based on this limited understanding.

FPL-55 is a newer, supposedly easier to work with glass than FPL-53 while maintaining a nearly identical Abbe number, 94.66 (FPL-55) vs 94.93 (FPL-53). Both are way ahead of FPL-51 (81.54). Either FPL-53 or FPL-55 will probably work equally well.

Do you have any issues with vignetting of some 2" eyepieces in your PCII? I've read some reports that certain eyepieces don't play well with it.

I've sometimes seen thin wire loosely connecting the flotation triangles on large Dobs and had wondered what it was there for. They're usually not strung particularly tightly, and now I know why. It's just there to prevent gross rotation of individual triangles.

Of course, there's the famous Mars as big as the Moon to the naked eye during opposition email that stemmed from someone shortening this factual statement "At a modest 75-power magnification Mars will look as large as the full moon to the naked eye" to simply "Mars will look as large as the full moon to the naked eye" to make it fit the narrative style. The original quote was apparently too wordy.

When used in 1.25" mode, they're mostly parfocal with Pentax XL/XW, AstroTech AF70, ES eyepieces, and many others that focus at or very close to the shoulder of the eyepiece. Using the 2" mode would require racking the focuser outward to compensate and would also result in poorer coma correction with the GSO CC.

You could make a dolly/trolley/buggy/cart for it with jacks at the corners. You'd wheel it into position, and then drop the jacks to raise it off the wheels. To move it, simply raise the jacks and wheel it to another location and drop the jacks again. The jacks can even be used to help level the base on uneven terrain. Something along the lines of this, but with a Dob platform:

Well, for that price it's worth trying out. I think I paid about $25 for my 25mm spacer ring, so about a buck a millimeter. Adapter rings and spacer rings are probably the most overpriced astro gear there is. You can always pull an eyepiece up out of the eyepiece holder and retighten it to see if the additional spacing improves coma correction with a too short spacer ring. You can't push an eyepiece further into the holder with too long of a spacer ring, so there is that advantage to the 20mm ring.

I use a TSFLAT2 with both my AT72ED and TS-Optics 90mm FPL-53 triplet to flatten their fields for visual use. There is no change in their focal lengths. I've seen images showing it works well for astrophotography as well.

Saturn is low even from Texas. I was able to easily make out the Cassini division and a band on the night of July 30th when it was crossing the meridian in the middle of the night. This was with an 8" Dob with an Arcturus binoviewer and 3x Barlow to reach focus with 15x microscope eyepieces. Using two eyes helped immensely to pick out fine details. I used the same setup at the Mars opposition to pick out fine details on it as well. It wasn't as effective on Jupiter, though. I was only able to pick out bands and a few dark barges on it. The contrast was just too low for festoons or white ovals. I tried some filters, but nothing helped much.

I will agree to disagree with Don on the spacer length again. I use a 25mm spacer to good effect with my range of eyepieces. Most focus within 5mm of their shoulder and I get 95%+ of the coma corrected out without messing with the spacing on most of my eyepieces. As I stated above, my 12mm NT4 is the only one needing parfocalization because it focuses 20mm from its 2" shoulder. That's just too far off to work well with the GSO CC. The uncorrected coma is intrusive without parfocalization.

Looks really similar to my 1998 vintage 2" Orion Deluxe 2x Barlow. It wouldn't surprise me if Vixen was sourcing these for Orion during that period. It's an excellent Barlow, just huge. There should be a single light baffle about midway down the tube interior. Check the optics end. Does it look like this?:

Just a wee bit more expensive. Hopefully it's been working out for you.

The 3.2mm should be good for resolving globular clusters as well. It's the only Paradigm (Starguider BST) I don't have, so I can't verify how good or bad it performs. The 5mm performs quite well, though. Not as good as my vintage 5.2mm Pentax XL, but still quite good.

I forgot to mention that with the 25mm spacer ring in the GSO CC, I need 11mm of additional in focus which is quite manageable. Also, immediately replace the shoddy screws with steel M4 cap head screws. One of mine simply sheared off while tightening it on an eyepiece and I haven't been able to remove its remnants from the holder yet. It used to be available as the Revelation CC in the UK/Europe, but I'm not seeing it listed any longer. As @Sargares says above, it is available as Omegon in Europe and might be in stock. Ping them about availability. You could also try a wanted ad on (I think) Astro Buy Sell or even here on SGL classifieds. In the US: Agena Astro in the US carries it as GSO, but is out of stock. Astronomics of Cloudy Nights fame carries it as Astro-Tech, but is also out of stock. High Point Scientific has it as Apertura, but is out also out of stock. OPT has it as TPO (the version I have, IIRC), but is out of stock. There's also the Explore Scientific HR CC that requires 35mm of in focus and has an adjustable eyepiece holder. It's also out of stock and quite a bit more expensive.

There won't be much difference in performance between these and the aforementioned Svbony set at f/10. Their 70 degree line is an introductory, budget wide angle line under the Bresser brand. Opticstar is the JOC factory direct branding.

My questions about this: How much back focus is required for it? I'm seeing ~55mm of spacing to the image plane, but that doesn't address in-focus. If a lot of in focus is required, how do you insert it deeply into a 2" focuser with all those knurled rings hanging out? How do you insert 2" eyepieces into a 1.25" holder? Most CCs come with 2" eyepiece holders. How much spherical aberration is introduced at high power? Will you need to remove it to get the best image in the center at high powers? How much does it flatten a curved Newtonian field? It doesn't mention this at all. Most folks in the past simply attached the MPCC to the 2" filter threads of low power 2" eyepieces with the appropriate amount of M48 spacer rings. They didn't not use it as a general purpose CC. The MPCC won't change the focal length of your scope, but I also see nothing about it doing any field flattening, only coma correcting. I ended up getting the GSO coma corrector and added a 25mm M48 spacer ring between the holder and the optics section. I parfocalized my 12mm Nagler T4 to work with it. The rest of my eyepieces come to focus close enough to the eyepiece shoulder so as to not need parfocalization to get good coma correction. The GSO mildly field flattens as well, which is a welcome benefit. It does add some SA, so I remove it at high powers.