Louis D

4.2% difference isn't all that unusual in wide fields. The 35mm Panoptic has about 7% distortion, and it is highly regarded.

If it still provides decent views, consider yourself lucky and move on. At $149, repairs are not economical if you can't perform them yourself.

Roadtrip indeed. My wife and I just got back last month from a 1400 mile each way road trip to Michigan to visit her family. That way, we got have our own car at the destination (rentals are hard to come by right now), had the opportunity to visit with other friends and family and attractions along the way, and avoided the maddening mayhem of American airports right now. It doesn't hurt that we paid about $2.89/gallon for gas along the way, which is way cheaper than in Europe.

I compiled a list of over 500 of the places I've visited on trips around the US to give y'all some idea of how much there is to see within our contiguous borders. I haven't even traveled the Pacific Northwest yet! US_Destinations.pdf

Now we just have to wait for the US guvmint to reopen the US to Canadians. The Canadian government has already done this for vaccinated Americans.

Now you're just making me jealous of your equipment and viewing conditions. You could probably refer to your viewing conditions as ultra premium. Part of the reason I want a retirement/vacation home in the Sacramento mountains of New Mexico.

But sadly, not ultra-premium like the Masuyama line. 🤣

Just watch out for kidney beaning (SAEP) in the 6mm and 9mm eyepieces within the Svbony set. Some folks are more sensitive to it than others. Otherwise, they're well thought of at f/10 and even f/6.

Like ultra pasteurized milk as compared to pasteurized milk? At least that's quantifiable.

From what I was able to find online, your scope has a 24% central obstruction by diameter, so it's a good compromise between being oversized and undersized. There will be some light falloff if you were to try astrophotography, but since it's considered a visual only scope, that's irrelevant. Some folks prefer visual only scopes with no larger than a 20% CO to maximize contrast at the expense of full illumination.

You want to keep the CG of the whole rig well within the footprint of the tripod feet. I keep my tripod legs well spread apart under my DSV-2B mount to ensure this happens. That's why I'm not a big fan of tripods legs that don't have variable leg spreaders.

Agreed on triplets. I have a 90mm FPL-53 triplet, and it takes about 30 minutes to reach equilibrium, which is quite annoying for a grab and go scope. @StarWomble Since neither triplet you're looking at has FPL-53/55 or FCD-100 glass, you might as well get a FPL-53/55 or FCD-100 doublet. The CA will be about the same, but it will be lighter and quicker to equilibriate. The Altair Wave Series 125 EDF, TS-Optics Doublet SD-APO 125mm, etc. have been well received and have an FPL-53 doublet in your price range.

It sure looks like a GSO made Dob. These have been branded as Zhumell at first and later as Apertura, along with Orion's recent SkyLine, here in the US, Revelation in UK, and Delta Optical in Poland. Anyone know of other brandings? I'm always concerned about the altitude bearings based on the number of them up for sale on CN classifieds. Either they mounted the tube with rings to a EQ mount or they mounted their own bearings (probably larger) and made a new Dob base to match. I'd love to see GSO offer a JOC style Dob altitude bearing as on the ES and Bresser Dobs.

I quit using these covers over my grill years ago. They would always disintegrate within a year outside in the Texas sun. It turns out grills don't really benefit from a cover anyway.

Try putting a heavy duty garbage bag over the rig and under the tough cover as additional leak insurance. Shop for contractor clean-up bags or 55 gallon drum liners in the 3 to 7 mil thickness for extra security. They're insanely tough, but probably not UV resistant, so the need for another cover.

The center one generally is for adjusting height along the optical axis and rotation of the holder along that same axis. There's generally no reason to change either from the factory setting. The three on the back of holder need to be loosened in a counter-clockwise manner before the holder can be tipped at all. There's nothing spring loaded in there. All three are snugged up tight against the holder. Before mucking about with them, first check to see if the secondary is already centered and square to the focuser with a sight tube. It should be circular and centered in the tube. After that, verify that the secondary is pointing straight at the primary. I generally use a laser collimator for this. If the beam hits the center of the primary mirror center mark, you're done. Last, check that the primary is aligned with the optical axis. I generally use an Aline for this. Once the secondary shadow is perfectly centered within the primary mirror center mark (easiest if it's a ring mark), you're done.

Seriously, though, some of that may be due to lack of eye relief or having a difficult to hold exit pupil, either of which can make it tiresome to use for extended periods of time. If you've got the bucks, try a 17mm ES-92 sometime instead. It has 17mm of usable eye relief and an easy to hold exit pupil. The view is just all there, all at once. You don't have push in hard or tip your head to see the edges. Just look straight ahead while hovering above the eyepiece, and it appears to be full of stars well out into your peripheral vision.

Not surprising since their website has the following spec right near the top of the page: All items have a working temperature of -15°C to +80°C. It regularly got down to -25°C where I grew up, so that would mean keeping this style storage box inside during the winter.

Do you also prefer standing well back from a window when looking outside? 😉😁

I wonder if they're from the same line reviewed on CN in 2006. That's a great price. The best I could find for them was $186 on ebay.

Are you dissing my travel solution? 😉😆

The original CN thread on eyepiece graphs. Here's the original chart that started that thread which Tom then modified: Explanation sounds correct except for this bit. The amount of light integrated across the two fields of view (32mm and 40mm) should be the same since each has the same field stop (and likely field lens) size. The 40mm simply compresses that light into a smaller apparent field of view yielding a larger exit pupil which can be useful with aggressive nebula filters such as an OIII filter. You can get low cost 2" to 1.25" adapters which you can leave permanently attached to your 1.25" eyepieces to avoid having to deal with an adapter on the fly. You can even replace the thumbscrew with a grub/set screw to make it more flush fitting in the focuser and your eyepiece case. If you do this, you don't need to limit yourself to 2" eyepieces. Here's an image from CN showing exactly this with Tele Vue eyepieces (along the bottom edge of the image).

Either one would work for your preferences. The SW 8" 200P, though, is much bulkier to move around and store. It does come with a 2" focuser which will allow for nice, wide field views. Overall, the 200P will outperform the 150P, but it really comes down to your preferences for storage and carrying it outside or transporting it to your observing site.

2" eyepieces enable a wider true field of view, not necessarily a wider apparent field view. It's all dependent on the size of the field stop inside the eyepiece that determines the true field of view. A wider apparent field of view at a certain magnification requires a wider field stop. At a certain point, that wider field stop may not fit inside a 1.25" barrel. That is when the eyepiece design must be moved to a 2" barrel. At some point, even a 2" barrel isn't big enough and a 3" barrel is needed. Of course, this requires a bigger focuser and secondary mirror which decreases contrast in Newtonian designs. 3" eyepieces are fine in refractors, but you need a 3" diagonal. Here's a diagram Tom Dey on CN put together to illustrate the field stop limitation of each barrel size. 0.965" was the standard for entry level scopes 50 years ago instead of 1.25". The takeaway is that 50 degree AFOV eyepieces are limited by field stop at 32mm in a 1.25" barrel, 68 degree eyepieces stop at 24mm, 82 degree eyepieces stop at 16mm to 18mm, and 100 degree stop at 13mm. In a 2" barrel, they stop at 56mm, 41mm, 31mm, and 21mm to 25mm, respectively.

So, rather than upgrade your 1.25" eyepieces to BST Starguiders or similar for high power usage, you bought a 2" 2.5x Barlow despite having no 2" eyepieces, correct? You do know the main reason to buy 2" eyepieces is to get wider fields of view than is possible with 1.25" eyepieces, right? Putting them into a 2.5x Barlow completely negates that advantage because it puts you back in the realm of what is possible with 1.25" eyepieces. For instance, let's say you buy a 40mm Pentax XW to get to a widest possible field of view. Good, I highly recommend doing something similar. It will allow you to take in much wider swaths of the sky than is possible in a 1.25" 32mm Plossl. Now, you put the 40mm Pentax in your new 2.5x Barlow, and you end up with a 16mm, 70 degree eyepiece that is massive in length, girth, and weight, not to mention cost. Why not just buy a 16mm Explore Scientific 68° Series or OVL Nirvana-ES UWA-82º Ultrawide eyepiece in a 1.25" fitting? It would be so much lighter and more compact. Unless you need the long eye relief due to strong astigmatism in your observing eye (which you did not mention), I can't think of a good reason. Most people just buy 1.25 2x Barlows because they're cheaper, lighter, and more compact than 2" Barlows. That, and they tend only Barlow their 1.25" eyepieces to get to very high powers. What was your reasoning for buying a 2" Barlow?