Louis D

Then invest in a coma corrector. The most expensive option is the Tele Vue Paracorr T2 and the cheapest is the GSO/Revelation CC. The ES HR Variable CC falls in between, but requires the most in-focus of the three.

You also have to consider how far your nose bridge protrudes relative to your eye sockets and how wide it is. Someone with a very flat face would be much less restricted in eyepiece choice than someone with deeply set eyes and a prominent nose bridge, like myself.

The better question to ask is "Is amateur astronomy being lost to ever increasing light pollution?" For example, in recent years, outdoor LED lighting has made matters worse by spreading stray light across the visible spectrum making light pollution filtration all but impossible.

So, 1.6mm off on the low side for the converted Tele Vue specified value of 40.6mm for the 13mm NT6. The TV spec'ed 43.2mm value for the 19mm Pan and 16mm NT5 is off by 1.1mm on the low side for the former and 1mm off on the high side for the latter. Even if TV had some rounding going on, I would have expected the 13mm NT6 and 16mm NT5 to have the same listed width. My faith in Tele Vue spec accuracy has been shattered. 😱

Here are a couple of references describing color filter use cases.

I have the Zhumell OIII which cost me $10 from Hayneedle back in 2014. This 2009 review on CN shows why it's barely usable. Its passband is shifted 10nm to the right of where it should be. I can verify it makes little difference other than dimming nebula along with the background. Contrast barely increases compared to a 1990s Lumicon OIII I own. The review does praise the Zhumell UHC which I wish I had picked up for cheap back then instead of the OIII. It seems to hit the mark where the OIII missed.

If you really want to try some color filters for cheap, order this set from China. They're a bit cheaper here. I recently received mine and they seem decent enough, although I've yet to try them out under the stars to verify if they are optically flat and don't introduce reflections. They arrive individually plastic sleeve wrapped inside the displayed box, which is inside another clear plastic sleeve. Mine came padded with thin closed cell foam around the entire case that I cut to size to pad the bottom/sides of the case and the underside of the lid to keep the filters from rattling about. They don't have front side threads, so you can't stack any other filters onto them. They are also a bit constricted on clear aperture, so not a good choice for widest true field 1.25" eyepieces. The filter cells are a nice hefty metal, though. I bought them mostly for the magenta filter which is very hard to find elsewhere. I verified that it does a good job of passing red and blue while suppressing green by taking an image of a sunlit translucent surface through it and checking the RGB channels for intensities. I plan to try it on Mars at the next opposition. The green is also a nice light shade that blocks basically all red light according to my tests. It does let some blue through, so it's not chromatically pure green. I paired it with a #12 Yellow filter with front threads to block that blue light and verified it can produce a nearly pure green color in that configuration. The red is fairly light as well, and yet has no orange cast at all to it. I'll have to try it on Mars. The yellow is a bit pale like a #8 Yellow, but might help cut stray violet light on a fast achromatic refractor. Since I already had a #12 Yellow filter, it worked out fine to get this one. The orange is a bit too dark for my tastes. It works, but I'm not sure what objects it would be useful for. The blue is a bit too dark as well for me. It's probably fine, but I prefer a light blue filter for Jupiter. Less is more in that use case. Edit: I just noticed you're in the US. Unfortunately, the seller I bought from is sold out of this set. Another seller has it here for a bit more than I paid. I noticed these sets and these sets with slightly different colors are now available at a slightly higher price, and I don't know if the colors are in the same hues and shades as my set, but they appear to have more clear aperture and might have front threads. The case sure looks slick.

The 16mm NT5 is listed as the same diameter as the 19mm Pan, 1.7 inches. That's 2.5mm wider than the 13mm NT6.

I don't know about your side of the pond, but Agena Astro sells several sizes which are well thought of on CN over on this side of the pond.

The wider the field, the harder it is to take it all in at once using binoviewers because you can't look off axis without losing one or both eyepiece views. You are forced to rely on peripheral vision more and more the wider you go. I find 60 to 70 degrees to be plenty wide when binoviewing for these reasons. That, and apparent fields of view appear at least 5 degrees wider in binoviewer usage for some psychological reason. I've recently found that the SVBONY 68° Ultra Wide Angle 20mm work great in binoviewer usage as I detailed in this post. Of course, if you're not using a Barlow lens element to reach focus in a fast scope, they're not going to look as good to the edge. However, since I'm operating at 3x with my Barlow nosepiece (a Meade 140 2x), these eyepieces are fantastic for an astigmatic eyeglass wearer like myself. For very high powers, I use a pair of Celestron Regal 8-24mm spotting scope zoom eyepieces with the 3x nosepiece. They were also sold under the Olivon label with their spotting scopes. It's just too much of a pain swapping two eyepieces to change high powers in a binoviewer, so I compromise with zoom eyepieces. However, at the slow f-ratio when operating at 3x, the zooms look fantastic as well.

I'm not sure what you mean by "large in mm", but according to the Tele Vue Eyepiece Specifications page, the 13mm NT6 is 1.6 inches in diameter and the 19mm Panoptic is 1.7 inches in diameter. I'll leave it to you to convert to millimeters.

Off topic, but why didn't you phrase it as 3rd of March and 10th of October to be consistent, or were you just baiting us Americans? Until computers became ubiquitous, American wrote the date (on checks and such) as Mar 3, YYYY or Oct 10, YYYY. Thus, there was no confusion in the pre-computer days because no one substituted the numeric equivalent for the month. Americans only reverse the spoken month and day for a very few holidays like the 4th of July and Cinco de Mayo. Logically, for computers to properly sort dates, the only order I use on file names is YYYYMMDD. Otherwise, using left to right sorting with DDMMYYYY as in Europe, all dates sort first, then months, then years. That is not a particularly useful way to sort hand dated documents.

I have my counterbalance weight protruding out away from the tube to offset the weight of heavy 2" eyepieces at higher altitudes on my alt-az mount when using my refractors. It's also mounted about the same distance forward as the eyepiece is backward relative to the altitude axis. Let us know how your arrangement works out for you.

Filters simply cut out some wavelengths of light to make others more prominent. For nebula, a good quality OIII filter can make otherwise invisible nebula like the Veil pop into visibility by blocking all light except around the wavelengths where the nebula emits light. A UHC filter is good for more types of nebula, but doesn't increase contrast as much because it has a wider passband allowing in more light pollution and sky glow. For both of the above, stick with Astronomik or Lumicon brands for best results. I've tried cheap OIII filters, and they are basically blue-green filters that don't even pass the proper wavelengths to be useful. The cheap UHC filters are reportedly better than the cheap OIII filters, but I've never tried one. A Moon & Skyglow (M&SG) filter uses Neodymium doped glass to cut out certain middle wavelengths of light to accentuate the blue and red ends of the spectrum producing a slightly purple hue. They tend to be a jack of all trades and can help somewhat with light pollution and as a decent Jupiter/Mars planetary filter. Don't waste your money on the expensive brands. Every spectrographic analysis of cheap brands I've seen shows they are all almost exactly the same. It's one case where you don't have spend a lot to get decent performance. Variable polarizing filters can be handy on the moon and during solar observing with the proper solar filtration (full aperture or Herschel wedge) to attenuate the light to a level making detail detection easier. Various yellow filters can be handy to cut unfocused violet light on achromatic refractors when observing bright objects, improving sharpness by leaving only the wavelengths which are properly focused. Combined with a light green filter, unfocused red light at the other end of the spectrum can also be attenuated on very bright objects like Venus. Of course, the object ends up being very green. Various color filters can help bring out specific planetary details, but are generally not thought of as particularly useful or necessary.

These folks on your side of the pond have some caps. Agena Astro sells them on our side of the pond. They also sell some eye guards/cups in case you need them as well.

I looked at the Altair wedge and thought it was pretty slick, but I ended up going with the 1.25" Hercules wedge since I never use 2" eyepieces to view the sun. I also couldn't justify the extra $300 at the time for the Altair for as little solar observing as I do. I also looked at the Lacerta wedge, but decided that didn't I want to crouch behind my telescope and look up most of the time since the sun peaks at around 83 degrees above the horizon during the summer here. I was surprised how polarized the light from a 90 degree wedge is with the Hercules wedge. I assumed that you were doing solar observing if you were using a variable polarizer. I suppose you could use it for full moon lunar observing as well, but I just use binoviewers in that case. I rarely swap eyepieces once I find the magnification I want to solar observe at. At that point, I don't feel too bad about the inflexibility of my system. I did put a 2" polarizer in my 2" to 1.25" adapter's M48 filter threads and a 1.25" polarizer on an eyepiece for variable solar dimming on my Dob when using a Baader solar filter. Since I only have 20mm of in-focus available on it with the CC in place, the Meade solution is a non-starter. Let us know how well the Meade solution works for you.

Indeed, minus the 6.5mm and 12mm focal lengths. However, minus VAT, they equate to 104 USD each which is a bit on the high side. That would be over $600 for a complete set if they were all available. Just a few years ago, they were only $400 for a complete set including custom case (before tax).

Wouldn't it be vastly cheaper and simpler to just thread a single polarizer on the eyepiece and a single polarizer on the front of the diagonal? Then, just rotate the eyepiece in the holder to vary the darkening effect? This would require no additional in-focus as an additional benefit. I do something similar with my Herschel wedge. I set the variable polarizer to the maximum brightness I want for the session by trial and error inserting and removing it a few times, rotating the two component filters wrt each other. Once set, I leave the eyepiece in the wedge and rotate the eyepiece to further vary the brightness based on what I'm observing on the sun, taking advantage of the partial polarization of the light from the wedge's prism interacting with at least one of the variable polarizer's filters. This Gosky variable polarizer can be separated into two filters and costs only $16 shipped from China.

If those Meade's were the original 5 element smoothies for a decent price, I'd grab them because they'd be an easy resale if you didn't like them. The Meade HD-60s are discontinued and only available used. I wrote up the following thread comparing them to the Starguiders.

Marked Taiwan with the recessed 1.25" adapter, it's GSO.

Vintage long Barlows simply won't come to focus in many refractors because they don't have enough focuser in-travel if used after the diagonal. This isn't an issue with Newtonians. When used before the diagonal, they will produce more magnification than what they're marked for because the optical path length is longer. Focus should be achievable in this mode, though. Shorty Barlows will work well in either, but cheap ones tend to degrade the image somewhat. Shorty Barlows also tend to increase magnification faster with longer path length because they have a shorter focal length (there's an inverse relationship between them). If you have a GSO/Revelation 2" ED 2x Barlow, the nosepiece is M48 threaded and can be screwed onto the nosepiece of a 2" diagonal like a filter. In that mode, the optical path length will be somewhat longer than when used after the diagonal with the original tube and eyepiece holder, but not a lot longer. As such, you might get 3x at most, so it might be a good option for slightly more magnification. I'll have to try it sometime with mine to see what the resultant magnification and focuser travel requirements are.

Perhaps with short eye relief 4mm eyepieces this is the case; however, long eye relief eyepieces like Pentax XW, TV Delos, and Baader Morpheus don't have these issues at any focal length.

Welcome Chris. I grew up across the Mississippi River in Iowa. I actually toured Bradley University in Peoria when I was considering which college to attend nearly 40 years ago. It seemed like a nice college and Peoria seemed like a nice town. Of course, all I can think of is the phrase "Will it play in Peoria?". I don't know if the majority on here would know that phrase being UK based in large part. Don't be shy about asking astronomy questions.

They look like tree sap spots to me. Do you observe near any trees? Either way, they're completely innocuous. Cleaning them off won't improve the view through the objective at all. If you do feel an OCD need to clean them off, and alcohol based cleaners like BWF don't cut it, Roland Christian of AP telescopes has recommended in the past using a bit of saliva on the end of a clean fingertip. The enzymes in the saliva will dissolve the tree sap and your fingerprints act like a harmless scrub pad. After that, clean as normal. I've never had issues with dew spots because dew is basically distilled water. If it is carrying dissolved air pollution, that's a different matter. Luckily, we don't have much air pollution in the part of Texas I live in, so no issues with dew leaving a residue.

I've been messing around with some cheap Chinese color filters I picked up off of ebay for cheap (the 6 filter set), and combining their light green (similar to a #56) with a GSO #12 deep yellow should block all of the blue (the yellow does this) and red light (the green does this) while transmitting 76% of the green and much of the yellow and some of the orange wavelengths. The Meade green interference filter passes about 94% of the green and most yellow while blocking most orange and red wavelengths and allowing a bit of blue. Adding the #12 yellow should block the last of the blue, but it might be superfluous for achromat refractor usage. I could not distinguish any significant difference in hue while holding the #56+#12 combo to one eye and the Meade green to the other eye. I'll have to try out the two filter variations on bright targets at night in the ST80 sometime as a verification step. BTW, that cheap filter set comes with an excellent magenta filter that equally passes about 78% of the blue and red wavelengths while passing only 44% of the green. I'll be trying it out as a Mars filter at the next opposition. It's way cheaper than the Brandon Magenta filter.