Louis D

I used the 27mm Panoptic for years at that focal length until replacing it recently with the 30mm APM UFF. The Panoptic is a bit sharper on axis, but has worse eye relief, more field curvature, and more edge astigmatism than the UFF. At 40mm, I use my Meade 5000 SWA that I picked up for $125 when Ningbo Sunny bought Meade and cancelled their remaining SWA and UWA orders with JOC (Explore Scientific). That's how the crop of Explore Scientific Maxvision eyepieces came to be. Once decloaked, it's been my favorite lowest power eyepiece. It's close enough to the 41mm Panoptic that I've never felt the need to buy one.

I've often wondered why Synta continues to offer this archaic style focuser in their Dobs when GSO and others offer more modern 2" focusers with 1.25" adapter inserts (and dual speed to boot). GSO Dob focuser:

Yep, tube weights go up rapidly in refractors. You could look into fiberglass tubes to keep down the weight somewhat. The length also goes up rapidly because longer focal ratios have to be used at larger apertures to keep false color at acceptable levels. False color gets worse at larger apertures given a constant focal ratio and constant optical formula. Mirrors don't have this issue, thus all the squat, giant f/3-ish Dobs with aggressive coma correction. Here's a chart showing the relationship between refractor aperture and focal ratio and the level of correction for a given optical formula. ED and APO variations are similar, but the colors start out more left shifted. You can keep weight down by going with an alt-az mount to avoid counter weights if you're just doing visual work.

How are you liking their new film? I used it in their eclipse glasses in 2017, and everyone at the observing site agreed they were way sharper than the cheap, mylar glasses, but that's a pretty low bar to judge it against. I've been using the Baader Solar Film for 20 years to good effect on my scopes, but I always wondered if I could do better.

They cost a fortune compared to consumer grade tools, but commercial grade hardened steel driver bits and sockets pay for themselves over the long run. For example, after chewing through countless cheap Philips head bits while screwing together a deck, I paid $6 20 years ago for a single hardened steel Philips head bit. It's still going strong today after thousands more screws.

I use 2" diagonals in my 72mm and 90mm refractors because I have many 2" eyepieces that I love to use in them. Balance could be an issue, but I just use a long dovetail that projects back toward the focuser to achieve balance. Most 1.25" diagonals I've had experience with have been fairly flimsy or have unnecessary stops in them to limit clear aperture. My GSO 2" diagonals experience none of these issues. I even use a 2" diagonal on my 127mm Mak despite the small rear baffle because it vastly opens up the views without noticeable vignetting. Bright stars do produce funky oval distortions from a reflection somewhere. Two inch eyepieces that I use on a regular basis in my refractors (and Dob): 40mm Meade 5000 SWA 35mm Baader Scopos 30mm ES-82 30mm APM UFF 22mm Nagler T4 17mm ES-92 12mm ES-92 In the past, I've also use the following 2 inch eyepieces in my scopes: 42mm Rini Erfle 40mm Meade 5000 Plossl 38mm Rini MPL 35mm OVL Aero ED 30mm 80 Degree Widescan III clone 29mm Rini MPL 27mm Panoptic 22mm AT AF70 17mm Nagler T4 12mm Nagler T4 in 2" mode I love panning about rich star fields at lower powers discovering star clusters that are not at all obvious at higher powers. It's sort of like going out for a drive on an empty road and just enjoying the scenery instead of heading for a destination. It's just relaxing to have no particular observing plan which allows me to unwind after a stressful day.

More questions for you: Do you have a 2" diagonal for the refractor? What are you using for low power in the Starmaster Dob? I have a large range of low power eyepieces that I've tried and used over the years, and I guess it depends on your preferences for eye relief, edge correction, apparent field of view, and true field of view which one I would recommend to you.

Sounds good. Way to keep the economy moving along as well. 😉 Let us know your impressions of it once you get settled in with it.

I've used my Arcturus binoviewers with my 127 Mak natively, and I didn't notice any vignetting. I've read that the focal length does increase somewhat, along with spherical aberration, but for casual viewing, I never noticed anything. If I put my 3x (effective) barlow nosepiece on it, I'd be at 4500mm, so that would be a total non-starter. As far as losing aperture, 127mm Maks have a measured 118mm of clear aperture due to the undersized meniscus corrector, so you're already down on aperture before you start moving the mirror, so don't fret it and just enjoy the views.

It's not the apparent field of view that matters, it's the field stop that matters. The max field stop supported on these binoviewers is around 22mm, give or take a millimeter. I'm not sure what the field stop diameter is on the 16mm Nirvana, but it's 22mm for the TV 16mm NT5, so you should be okay. This assumes you can fit your nose between the eyepieces. I use a pair of 23mm Svbony/Vite 62 degree aspherics from ebay in my binoviewer most of the time. They're pretty good at f/12 in my 127 Mak. Keep in mind that you generally won't be able to look off axis without losing the view in at least one of the eyepieces, so on-axis sharpness out to about 50 degrees is the main thing to look for. Also, look at the weight and width of the eyepieces. I find 60 degree eyepieces look more like 65 to 70 degree eyepieces in a binoviewer.

Here's my fairly compact setup. You could substitute your spotting scope for the AT72ED, a larger aperture SCT for the 127 Mak if that suits you, and the dual alt-az mount of your choice for DSV-2B. The only tricky part might be sliding into position to observe between the two rear legs of the tripod. Once you're seated on a small observing stool, though, you're good to go.

Nor will it be able to frame large, bright objects like the Pleiades, Hyades, or Collinder 70 that are good targets even in light polluted skies, though I have found that cheap 15x70 binoculars do a good job of showing them. As far as cool down time, my 127 Mak is a bit slower to cool down than my 90mm triplet.

Go back and sample some individual frames to see if the highlights were blown out in them. If so, you need to either resort to HDR techniques or bring your exposure level down somewhat. Since this is essentially terrestrial photography, expose for the highlights because you can always reclaim detail out of the shadows in post processing if you're capturing at greater than 8 bits per channel. If the highlights are not blown out in the subframes, then it's the stacking process responsible for increasing the combined exposure in those areas.

Heck, let's blow a big chunk of his budget on the Celestron NexStar Evolution 8 EdgeHD with StarSense. I was impressed with the planetary views through it and how easily it was controlled from a tablet at a star party a couple of years back. It was recently purchased by a newbie with deep pockets, and he was very satisfied with it's views and ease of use. He was using Tele Vue Delos and Ethos eyepieces with it.

Did you receive the 35mm Aero ED? If so, how are you liking it in your scope?

I like the Meade CCD Dichroic Color Filter Set I picked up new for $30 a few years back better than the dyed type filters. Transmission seems much higher and colors much purer and more intense. It's just a shame they aren't offered in more colors at this price. Regardless, the effect on planetary viewing is still subtle at best. Bandpass plot for them:

A 90mm triplet with FPL-53 might be another option. I've really been enjoying my TS-Optics version on a DSV-2B alt-az mount. It's optical quality terrestrially would easily rival high end 90mm spotting scopes. It's more compact than most 100mm scopes, so car transport is certainly an option. With the removable tube sections, it is natively binoviewer compatible without having to use any extra optics to reach focus. A Newtonian might be difficult to use from a narrow balcony because you have to look into the side of the front of the tube. I'm not sure a 150mm refractor would fit very well on your balcony, either, since the tube is about a meter long. I'm assuming your balcony is only a meter deep and 3 meters wide. As far as what you can see with each size, it's mostly a difference in resolution and brightness at a given magnification. I wouldn't worry about getting the perfect scope to start with. Get something reasonably sized and get observing.

Why are all the highlights blown out? They look like video frame captures as a result. Otherwise very nice images.

I can't imagine dealing with the meridian flip visually with a manual EQ mount. At least fork mounts don't have this issue.

I link to stuff on CN all the time and haven't had my hand slapped by a moderator yet. I always try to give attribution, so there's no confusion about what is being linked. To make it easier to click through on links, pick some words in your posting to make into an active link, highlight them, click on the diagonal chain symbol fifth from the left in the composer window tool bar which will bring up a pop-up window. Paste your link into the URL field and click the "Insert into post" button.

If you're looking for the 1.25" and 2" barrel covers: FLO 365 Astronomy Teleskop Service And a top cover for many smaller 1.25" eyepieces.

I was trying to view something nearly overhead in my Dob a few months back and was quickly reminded of Dobson's Hole. The motions were really confusing trying to rotate and tilt to keep it in view. I can really appreciate the ball mount for this type of viewing.

True, you could use an equatorial platform instead to move that 13.1 inch Coulter he used to take DSO astrophotos.

For about the same money in the US, I would get used Televue Nagler T4s in the longer focal lengths if wide AFOV and longer eye relief are your two main deciding factors. They are known quantities with good resale value. If you're willing to give up 2 degrees of AFOV, the Baader Morpheus are a better choice given their larger eye lenses and longer eye relief. I have measured my 9mm and 14mm Morpheus to have 78 degree rather than 76 degree AFOVs.

I assume better polish or different coatings led to less scatter. I've read that Brandons continue to use a single layer coating to minimize narrow angle scatter.