Louis D

I realize that. It's also why a lot of products with microelectronics in them are delayed. There's also a shortage of workers around the world slowing things down. A lot of folks took early retirement, older workers don't want to risk getting C19 and so aren't working or are working other jobs, and still others became self-employed during lockdown. China is experiencing an energy crisis as well that is affecting factory production. Texas had Snowmageddon last February that impacted petroleum refining and chemical manufacturing. This then impacted other manufacturers like foam producers which impacted mattress and seating manufacturers. The ripple effect is still sorting itself out a year later. It's been a perfect storm of events leading to the current supply chain crisis.

Didn't you say you added a 2" Clicklock to your Mak in another thread recently? Do you have a 2" diagonal and any 2" eyepieces for it yet? Here's my setup with a 2" visual back and large 2" eyepieces. The first photo has a decloaked Meade 40mm 4000 SWA in the diagonal while the second photo has a 35mm Baader Scopos Extreme in the focuser. The 40mm Pentax XW would probably do well in it, but I haven't tried that combo at night since getting the XW a over a year ago. I did take a snapshot with my cellphone camera through the combination as shown the third photo. It's lighter than either the Baader or Meade.

I find fine focusing with the foam wrapped focus shaft on the 127 Mak easier than fine focusing with my single speed Crayford focuser on my Dob. It's very smooth with next to no backlash or mirror flop. The Crayford is a bit notchy due to the high preloading on it for heavy loads. Thus, it takes a bit of grip on the knob to get it to move. I love the fact that none of the visual back's load is transferred to the focusing mechanism. It's all born by the rear cell which does not move during focusing. No matter how much load is on the Mak's visual back, focus feel remains exactly the same. It's such a refreshing change, especially from the fracs' focusers which can struggle at high altitudes under heavy loads. The Dob's focuser load doesn't change much with altitude by comparison. However, once I've got a Barlow, PBI, CC, and 17mm ES-92 in there, it starts to feel a bit boggy.

Starting out, I'd go for one of the cheaper zooms plus a 32mm Plossl for widest field views. At f/12, all would perform excellently across the field. 7mm to 8mm is about as high as you can go on a 127 Mak due to small exit pupil issues anyway, so it's a good fit for the Mak. Technically, you could go all the way up to an 84mm eyepiece for a 7mm exit pupil, but such a 1.25" eyepiece doesn't exist; and if it did, it would be like viewing through a straw since it would have about a 20° apparent FOV.

I just carry my 8" Dob outdoors in one go snugged up against my body using carrying handles on either side of the rocker box. Next, I remove the Telrad from its storage box and attach it to the tube. I then remove the scope's end caps and check collimation (usually still spot on), and I'm good to go in under 2 minutes. Of course, it needs to cool down, so I do this 30 minutes to an hour ahead of time. For the Mak or frac, I have to get the tripod out, spread the legs, level it, get the scope out of a case, attach it to the mount head on the tripod, remove end caps, retrieve diagonal from OTA case, remove caps, insert it into the scope, retrieve and attach a Rigel QuikFinder, lock the axis clutches, carry the top heavy tripod/mount/OTA combo out the backdoor, and set it down to let the OTA cool. This takes no less than 5 minutes. Honestly, I much prefer the Dob; but I do use the others just to mix things up a bit. The Dob has much less assembly required and just sits at the back of the coat closet upright and out of sight. The collapsed tripod/mount combo is tucked in toward the front corner of the coat closet since it is much slimmer. The Mak and frac cases rest on the floor at the back of the closet in a stack. The Mak/frac/tripod/mount combined take up less space than the Dob, but each has a much smaller aperture, so is it really a fair comparison? I do like the DSCs on my Dob, but they're a pain to align because I have been reduced over the years to a narrow sliver of southern sky due to tree maturation in my backyard. I generally can't see two bright stars at the same time, so I guesstimate on Polaris, align on a bright star, and then refine the alignment on easy to find objects like a planet or bright DSOs. I've found SkEye on the smaller scopes to be really helpful since it needs no alignment and gets me within a few degrees every time. It would be neat if the developer added plate solving using the camera and a 45 degree mirror like Celestron's StarSense. Of course, I've learned to make do without tracking over the years. I did make a crude, homemade EQ platform early on, but it was just one more heavy piece to carry out each time to observe, so it became scrap. Perhaps an integrated aluminum one would be acceptable to me now. Amateur astronomy is a journey, and preferences can change over time.

About a decade ago, someone local here was selling a complete Meade LX200 10" with field tripod for $400 on Craigslist, and no one would bite. Maybe in today's used market environment you could get a decent price for it. Big SCTs, like big Dobs, don't have good resale value compared to APOs and smaller scopes.

Do you like goto because you have difficulties finding objects or because it tracks or both? You could always put DSCs on a Dob to find objects and the Dob on an EQ platform (with the DSCs in tracking mode) to get both with a large aperture.

I'm hearing that semiconductor manufacturing probably won't sort itself out until well into 2023. I figure that most other industries are in a similar condition. I'm glad we bought a new car in July 2020 despite the raging pandemic while inventory was still good.

And even the new ones can be converted back to the old Mak thread size by simply unscrewing the included SCT adapter ring. The 127 Mak I bought for my daughter came this way.

What exactly do you use for a controller since it isn't shown? I'm presuming a home-brew box with buttons or a switch and batteries?

Since the rubber grip on the focuser shaft of my used 127 Mak split and immediately fell off of it anyway (this was not disclosed by the seller, grrrr), I wrapped it in racquet grip tape and then shoved a cut down bicycle foam grip over that. Both were sourced from ebay for $1 each. With so much foam between my finger and the shaft, I don't get much shake during focusing. There is still a gap next to the 2" visual back as seen in the photos below. I also keep Sorbothane pads under each tripod foot to cut settling time from 3 seconds to 1/2 second.

The Barlow will likely cleanup the edges of the 16mm Nirvana. The Barlow will likely require refocusing unless you get a telecentric magnifier like a TV Powermate. There may also be vignetting, but you won't know until you try them together. A telecentric magnifier will not vignette. A 2x Barlow may not really be 2x, and certainly won't be for all eyepieces. Even those that are bang-on 2x when the eyepiece focal plane is right at the reference plane (eyepiece shoulder) will be some other power if the eyepiece focal plane is above or below the reference plane. Thus, it's not a foregone conclusion that you will get exactly an 8mm equivalent with the combination. Swapping in a Barlow and refocusing is a pain in the dark. I prefer to leave the Barlow in all night if I am using one and work at elevated powers across all eyepieces. A 40mm Plossl in a 1.25" barrel yields a fairly narrow apparent field of view with very long eye relief but nets you a slightly larger exit pupil in the process.

Does the image alignment vary as the diopter adjustment is spun on either eyepiece holder relative to the other? My Arcturus BV is only usable with both adjusters screwed all the way down. I'm not the familiar with the WO 20mm eyepieces, but if they have undercuts, there's a strong possibility that they will tilt during tightening of the holder collet. Upon looking at the WO BV, it appears to have a single thumbscrew that pushes against a compression ring rather than using a proper collet to maintain centering. This could be pushing the eyepiece to the side, and if the thumbscrews on both holders are not in the same radial position, they could be pushing the eyepieces off center in different directions.

When I was regularly using my 15" Dob, I would quite often use 350x thanks to our often steady Texas skies. At an exit pupil of 1mm, it was quite usable. For your 12", that would equate to 300x. Thus, I would say 300x for sure. 430x? Probably not very commonly considering the 0.7mm exit pupil which is right at what I consider the usable lower limit for exit pupil size. If your skies are steady, though, it should be doable. I have a 3.5mm Pentax XW that I rarely use in my f/6 scopes to produce a similar exit pupil. Such an eyepiece would probably be my last eyepiece purchase while building a set because it gets used the least, at least by me. I only have it because I snagged mine for $212 off of Amazon a few years back during a flash sale. I couldn't resist. 😁 Unless it's something you're passionate about, you'll probably regret splashing the cash on such a specialty eyepiece. I rarely find that I can see any more detail at a 0.6/0.7mm exit pupil than at a 1mm exit pupil. I'd splash for a binoviewer if you want to tease out detail at high powers. I always find two eyes are better than one for such purposes.

There's no central obstruction when using a parabolic mirror off axis via a circular mask. Here's a discussion of the concept on CN. Here's a technical description of the optics. There are still aberrations as discussed in the latter treatise. Here's how to get a 14.5" unobstructed telescope using a 36" primary mirror: DGM Optics used to make and sell the OA-4.0 Off Axis Newtonian, among other sizes, using off axis circular cores from larger mirrors, IIRC.

What about with an off axis aperture mask between the secondary spider vanes?

But on the flipside, it's long focal ratio makes getting to large exit pupils for narrowband nebula filter usage difficult. If you want a 6mm exit pupil at f/12, you need a 6*12=72mm eyepiece! Good luck finding a 2", let alone 1.25", example of one. Surplus Shed, Russell Optics and Siebert Optics (in 2.5" to 4.3" barrels) all sell some home-brew examples on this side of the pond, but that's about it to my knowledge.

It's not just seeing. The exit pupil becomes so small at very high powers that floaters in your eye's vitreous humor start to noticeably block the tiny pencil beam of light before it gets to your retina, just like clouds in the sky. I flick my eye to the side to get a few fractions of a second better view before they drift back to the center and block the view again.

I would put in some downward-firing solar powered LED landscaping lights along whatever is supposed to be lit up by the floodlight. They are much less blinding due to their low intensity and remain on all night. My neighbor has some, and they're pretty innocuous for astronomy.

I believe Long Perng.

Exactly. I don't know why they don't offer a visual version with a shorter main tube to accommodate a diagonal. They could use a longer focuser drawtube to support straight through usage as well.

I almost pointed that out as one serious advantage of zooms at high power in my post above. It's one of the main reasons I often use a pair of 8-24mm zooms in my BV. Operating at 3x with the Meade 140 Barlow nosepiece, I'm getting a 2.7-8mm zoom range without changing eyepieces. This is very useful for high power BV observing. It's also why I like photographing wildlife with a long telephoto zoom on my DSLR. I can acquire the target at low power and then zoom in as needed to properly frame the subject without losing it while swapping lenses since I can't always use a tripod. High resolution sensors are also nice because I can crop in post while still having plenty of resolution for printing or web usage. It's simply not possible for me to swap two eyepieces in a BV on an undriven scope at high power without losing the object, so a pair of zooms it is. Thanks for bringing up zooms in this context.

For me, it's a pain trying to reacquire an object in narrow-field eyepieces at high power using undriven mounts during eyepiece swaps. Even with widefields, I have to position the object at the very edge or just off the edge of field, swap eyepieces, and then quickly find the object again before it drifts out of field. This is made especially difficult if the alt-az mount swings upward slightly while swapping out heavy eyepieces or if the eyepiece snags in the focuser taking the scope upward with it. That aside, I much prefer my 9mm Morpheus to my 9mm Vixen LV despite the views and eye relief being very similar. The view is more immersive, less claustrophobic, and offers better context in the Morpheus.

I have a 60mm finderscope made from the front end of a 60mm pair of binos. The rear end is a machined Delrin adapter for 1.25" diagonals. I think it was made by Russell Optics in the 90s. It's mounted in 50mm finderscope rings toward the back end. I use a Celestron 90 degree erect image prism diagonal focused by slipping it forward and back. It pairs quite nicely with a 127 Mak to bring in the widefield views impossible with the Mak. It's a bit heavy, so it's CG has to be mounted inline with the altitude axis pivot point to prevent the alt-az mount from flopping about at differing altitudes. I use a 24mm APM UFF in it to cope with the ~f/4 speed of the objective. I also modified a 70x300 cheapie telescope from ebay to take a 2" diagonal and eyepieces to really max out the possible widefield. So far, it doesn't work as well as the 60mm bino conversion, so it's a WIP. It needs flocked and the PVC bits need to be centered better. So far, I've got less than $30 in it, so I'm not complaining. It would be different if I didn't have so many spare parts from previous projects laying about.

Based on reviews from that company you despise, watch out for the zipper breaking. China's use of pot metal instead of steel is pervasive and troublesome. One of the screws in my GSO coma corrector sheared off in my fingertips. I can't get the part stuck in the hole out, so I replaced the other screw with a cap head steel screw and now make do tightening only one screw. Also, every alignment screw on my 2000-era ST80's 6x30 finder's two rings sheared off the same way making it useless. A well known Chinese alt-az mount also uses molded pot metal instead of machined steel, leading to the possibility of an entire side simply shearing off under load. It is cost cutting measure such as these that have led to the poor reputation of Chinese made goods, not some shadowy conspiracy trying to besmirch their good name.