Louis D

Here's a quick comparison I did last night with the KUO 152 achromat (top row images) against the GSO 150 f/5 Newt (bottom row image). The upper left image is unfiltered while the upper right image is filtered with a Baader Semi-APO filter. The single Newtonian image is completely unfiltered. I adjusted the refractor gamma to bring them into alignment exposure-wise with the Newtonian since they were a bit overexposed. Please disregard the blown out highlights in the upper row as they are simply artifacts of my poor ability to handhold the phone, align it properly, and adjust exposure for afocal projection. All images were taken with my 12.5mm APM Hi-FW eyepiece using afocal projection with my Galaxy S7 phone's camera. The upper images work out to 72x while the lower image works out to 60x. I thought it more important to use the same eyepiece than try to match magnifications. The violet fringing in the upper left was actually stronger to the eye than what the image shows. I don't think phone cameras are very sensitive to far violet light. The Semi-APO image fairly closely resembles reality except for the yellow fringe. It appeared to be a faint violet fringe to the eye. I think it's due to the different sensitivities of the eye versus the camera to various wavelengths of light. The lower left image is accurate except for the brown color cast. That was due to having issues matching exit and entry pupils handheld. The absolute lack of color fringing is accurate. The Newtonian image to the eye was sharp and etched. The achromat images to the eye were slightly fuzzy edged even filtered. The violet cast was mostly distracting on high contrast features. Unfortunately, those are the very things most worth looking at on the moon. I will say that the Semi-APO filter tamed the extreme violet fringing enough without adding much color cast that I found the image pleasant to view. I'll try again tonight if I get the chance to see if I can improve on the results. No guarantees.

I tried out my 40mm Lacerta ED in my 150 f/5 Newt last night on the moon. While I could detect a slight secondary shadow dimple on the face of the moon, I had to go looking for it. I wouldn't consider it intrusive at all.

Got ya beat. I still use PSE 2.0 from 2001 for my photo editing. It came on a CD with a scanner purchase with the activation code printed on the CD sleeve. I have it installed on multiple machines around the house. It does what I need and doesn't depend on online activation. Even after 20+ years, I keep learning new ways use its features. I do keep an old 2006 XP computer with a PCI to SCSI card for my Minolta slide scanner and a Firewire port for my old MiniDV/HDV cameras. I've already converted all of my tapes, but my son's girlfriend just came into possession of her childhood tapes, so I'll be converting those for her with that old machine. Sometimes being a pack-rat pays off.

If you tension the cheapened GSO LB focuser enough, it will easily lift heavy loads, just with a bit of stiffness in the action. I've used it with the GSO CC and a 2 pound eyepiece (40mm Meade 5000 SWA) without issues. I have the original V1 version of the focuser on my KUO 152 achromat. It's a beast. I've not noticed any tendency of it to slip and it is buttery smooth. It's practically over-engineered. I have no idea what their current V3 focuser is like, though. While the V1 focuser has plenty of focuser travel, I'm not sure it would accommodate a BV's needs. Even on my f/5 GSO Newt, the secondary is fairly large to avoid vignetting because it is intended for imaging. I've used it with my 40mm SWA mentioned above, and I haven't noticed secondary shadow being an issue. I can't speak to the f/4, though. It is one of the reasons I went with the 6" f/5. I had also read balance is a concern with the 8" f/4 due to difficulty getting the rings and associated dovetail bar in the correct position due to the focuser's location on the stubby tube.

I thought the StellaLyra 12" f/5 Dobsonian comes with the standard GSO 2" Crayford Focuser for Reflectors: While the GSO OTA Newts come with a cheapened version of the GSO 2" Linear Bearing Crayford Focuser for Reflectors: Notice that the pre-tensioning set/grub screws were removed from the GSO LB focuser that is available for purchase separately: This leads to the problem I mentioned. Notice that your focuser has at least one pretensioning set/grub screw, so it avoids this issue. You're right, the standard GSO focuser works fine while the GSO LB packaged with their OTA Newts has the issue I mentioned.

Swap in the 6" f/5 and it's the same setup I have. You have to be careful with that dual speed focuser to not reduce tension too far. If you do, the draw tube drops to the bottom of the focuser. It's a known issue with it because it has no separate pre-loading tensioner. I rides fine on my DSV-2B mount while the 152 achro is clearly overloading it.

On dim DSOs or bright objects? I'd say on dim objects, it's fine up to 100x. For example, I recall the Trapezium looking good at that sort of power. On bright objects, it needs green filtering to achieve sharpness at any power. By way of comparison, the 6" f/5 Newt looks good at any power and brightness of object. If secondary spider diffraction spikes are showing in the Newt, violet and red are showing in the achromat, so there's always a trade off between these two on brighter objects. However, the Newt is sharp while the achromat is a blurry mess needing green filtration.

I totally agree. Even a 6" or 8" f/4 or f/5 Newt with CC yields fantastic wide field views. You just want to avoid going so large in exit pupil that secondary shadow becomes an issue. I find my 6" f/5 GSO Newt a joy to use on an alt-az mount. It's light, holds collimation well, and has sharp, color free images.

Got the image. 😁

Of course, you bring up the interesting conundrum of corporate support in even 20 years. Who's to say that Celestron will keep that particular webpage running even that long to kick out your codes to you. It's also likely the app will no longer work on those future phones due to lack of support, so you'll need to keep your last working phone with Starsense loaded limping along on a long dead dead battery continuously plugged in to a charger. This isn't that far-fetched. I'm still using Sky Commander DSCs I bought way back in 1998, 25 years ago. They're not fancy, but they still work great, and they support realign on object that Starsense does not to refine the alignment.

I ask because I'm used to uninstalling a license from an older machine and reinstalling it on a newer machine as with Photoshop. Apparently, that's not how Starsense works.

We treat summer like most other folks treat winter. We tend to hole up in air conditioned buildings and race between them in air conditioned cars during summer like most folks do with heated buildings and cars in the winter. From mid-October through mid-April, we generally have wonderfully mild weather and spend most of it outdoors similar to how other folks spend spring to fall outdoors. I often observe in shorts and a T-shirt during that time in the early evening. At most, I throw on a windbreaker and long pants to mitigate the evening chill on colder nights. The US as a whole has 90% of homes air conditioned and practically all businesses have A/C. Here in Texas, it's pretty close to 100% for both. As others have said, it doesn't help when you're observing outdoors. It's sort of similar to how a heated house in winter doesn't help to keep you from freezing while observing outdoors in colder climates.

Quick Chinese/Taiwanese astro manufacturers FAQ: Sky-Watcher is Synta, from mainland China. It is the largest astro products manufacturer for true entry level equipment (not that stuff sold on ebay or in big box stores at Christmas). However, it tends to have a lot of rough edges mechanically. Optically, they're generally fine. Their scopes target the most cost conscience consumers. Bresser in Europe and Explore-Scientific in the US is JOC from mainland China. They tend to have better mechanics than Synta, but they cost more. They target the mid to higher ends of the market as folks want better equipment. Optics are quite good. GSO is from Taiwan and is sold under that name and many house brands. They tend to be about equivalent to JOC on quality and market positioning. It's not clear if they have any mainland China suppliers. Long Perng is from Taiwan and almost always sells under house brands. Their eyepieces and scopes (mostly refractors) tend to be of very good quality. It's not clear if they have any mainland China suppliers. KUO is from mainland China and almost always sells under house brands. Their eyepieces and scopes (mostly refractors) tend to be of very good quality. I'm sure I missed one or more, but those are the major players I see again and again.

A bit off-topic, but what's up with Tak focusers? I've never heard of AP, TEC, or, for that matter, most Chinese/Taiwanese made APO refractors having so many problems reaching focus with a range of eyepieces and diagonals. Is it due to a lack of focuser draw tube travel range? Is it because they were only intended for 1.25" diagonals? I have heard of issues reaching focus with binoviewers in many refractors, but that's excusable since they require 100mm of additional in-focus travel. My 90mm TS APO has two removable OTA sections to adjust its overall length for imaging vs. monoviewing vs. binoviewing.

You just did. Now your brain should lock-up trying to reconcile this.

Among the two you listed, I'd go for the Bresser because of the slightly larger aperture and slightly better mount. However, both are achromats, so don't expect terrific planetary views as compared to an APO refractor at a much higher price or a 5" or larger parabolic Newtonian at a similar price. It would help if we knew what country you're located in with regards to purchasing advice.

Quick question. As you upgrade your phone over time, can you migrate your Starsense unlock code from phone to phone to phone an unlimited number of times?

Well, due to heat, an older hiker died in Death Valley National Park, a couple of hikers died in Valley of Fire State Park (Nevada), and a hiker died in Grand Canyon NP. So far, no reports of astronomers dying due to the heat.

It reminds me of a breech-loading cannon from this angle: Maybe StarBlaster for name? 😁

The problem is, you can never have enough eyepieces. That's why Eyepieceaholics Anonymous (EA) was founded.

At low to medium powers on dimmer stars and DSOs, both the 6" achro and 6" fast Newt show similar views. The Newt doesn't show diffraction spikes on dimmer objects, so that advantage of the refractor is lost. The unfocused light in the frac is hard to detect, so that advantage of the Newt is lost. I like having the eyepiece up nice and high on the Newt. I refuse to extend the legs on my tripod due to the inherent shakiness in so doing, so the refractor's eyepiece ends up a foot or two off the ground which is really uncomfortable. On DSOs in particular, I see no advantage to the frac over the Newt when you figure in cost, weight, and cool down time (the frac has more glass to cool).

Roughly what power was that image taken at? I can try to capture an image of the moon with the 152 achromat at a similar power sometime for comparison.

From this telescopeoptics.net eyepiece spot diagram collection, it's pretty clear that Abbe Orthos fail to keep the image rays within the airy disk at f/5 (first spot diagram column) off axis, and do much better at f/10 or especially f/15: Thus, it makes sense to slow down the incoming light cone from f/5 to f/12.5 with a 2.5x Powermate.

Those shots in your achromat look way better than what I'm seeing through my 152 achromat. The purple wash and orange/red highlights really cut down on the contrast in my scope. There's only a hint of purple wash in the darkest shadows in your scope by way of comparison.

I haven't looked through a 150 ED, but I have compared my 80mm f/5 achro to my 72 ED, and the views are not comparable at all. The unfocused violet and red ends of the spectrum (spherochromatism) along with spherical aberration ruin the overall sharpness of the ST80 compared to the 72ED at all but the lowest powers. I haven't had a chance to check for SA on my 152 achro yet. My point is, don't draw conclusions for how an achromat at a particular aperture might perform based on a similarly sized ED scope.