Louis D

I can easily resolve M13 and M22 in my 8" Dob at 200x or higher, but not in my 72mm or 90mm fracs. They just run out of resolving power it seems.

Now maybe y'all will understand why private American sellers won't ship out of the US. There's too high of a probability of items being stuck in customs for an interminable length of time and the buyer requests a refund. That, and some countries have a high probability of fraudsters buying items, and then defrauding the seller in multiple ways without any seller protections.

I would assume so since most foam sheets for smaller cases don't exceed 2" in thickness. To get more thickness, more sheets of foam are stacked together.

Nice find. I didn't come across those in my searches.

As much as I suspected. I've been in no hurry to switch from ebay and Amazon for Chinese sourced items. Both will support the buyer in every case of fraud.

I use my 2" GSO ED 2x Barlow with the TV Panoptic Barlow Interface more than any of my 1.25" Barlows because I enjoy being able to use my large array of 2"-only eyepieces at double the power. As I said above, I just stick the combo in the focuser and leave it for an entire viewing session just to change things up.

Aligning a massively off secondary with a laser is the only thing they excel at. You just have to be careful not to lase your own eye(s) when looking down the front of the tube to get the beam centered on the primary because the return beam can be no where close to the secondary. I wave my hand over the front to figure out where the return beam is before looking down the tube. Done right with the secondary collimation screws quite loose, it's very intuitive to figure out which way the mirror needs to move to getting it pointing straight at the primary's center. You then just carefully tighten up everything and move on to collimating the primary.

At least here in the US, the only recent arrests have generally been of rednecks stupid enough to lase a police helicopter. Hello, they have night vision cameras on them that can easily pinpoint your location.

I have green laser sights permanently mounted to each of my scopes or alt-az mounts or permanently attached to a Synta/Vixen finder foot. They have built in alignment screws and come with a momentary switch on a coiled cord as well as a push button toggle switch. They also come with either a 1 inch diameter barrel mount or a Picatinny rail mount. For permanent mounting, I affix a short Picatinny rail to the scope (think Dobsonian). Here's the sight I've been using. They're pretty cheap from ebay China if you're willing to wait a few weeks. You'll also need to order the proper rechargeable lithium ion batteries and charger. I prefer the longer battery version (18650) of these sights because the battery lasts longer on cold nights than the shorter 16340 version. The longer version only became available in the last couple of years. The sight is longer, but I think it's worth it. Just buy a regular green laser pointer separately for outreach. You don't want to be faffing about trying to realign the laser sight each time you dismount/remount it. They hold alignment really well once set.

The 12mm will yield 63x, the 8mm 94x, and the 5mm 150x. Ideally, I'd like to see 75x and 125x which would be 10mm and 6mm for day to day usage. Splitting the difference, the 8mm at 94x seems like a good bet for a first eyepiece. If you find yourself wanting a bit lower power most of the time, get the 12mm. If you think a bit more power is needed, the 5mm would be logical. Personally, I'd lean toward the 8mm and 12mm combo under UK skies despite my initial 5mm/12mm recommendation. FLO has a 10% discount if you buy two at once, and they sponsor this site.

Almost assuredly M43x0.75 and M42x1 since it's meant to reverse mount lenses onto a Universal lens mount (M42x1) rather than a T2 (M42x0.75) mount. The 43mm thread is almost certainly 0.75 pitch which is the standard for filters. That means the thread pitches are backward relative the Baader adapter (M43x1 and M42x0.75) despite the diameters being the same.

Most 2.5x Barlows measure closer to 2.1x to 2.2x from what I've read. Regardless, the 6.5mm should provide decent high power views. I would probably recommend getting a 5mm BST Starguider instead for even higher power (150x) along with a 12mm BST Starguider for a decent mid range eyepiece (63x) to replace the so-so 10mm kit eyepiece. To get to a very wide field of view, you could get a 35mm Aero ED 2" eyepiece sometime in the future. Yes, the exit pupil will be 7mm, and it will struggle at bit a f/5, but the wide true field of view for locating and centering objects makes it totally worthwhile. I've got multiple Barlows and rarely use them. They're clumsy to add and remove. When I do use one, I tend to put it in the focuser and leave it, doubling the power of every eyepiece, for a given observing session.

I can totally understand why fast Dobs have become so popular based the above cartoon. That's a Webster 28" f/2.7. Can you imagine putting that on an EQ mount, especially if it was f/8 like '50s era Newts?

Which lens in the diagram was flipped? It looks like only the negative lens in the lower barrel could be flipped and still get the whole thing to screw together.

I literally couldn't find any other M43x1 adapters or step rings anywhere on the internet.

I always thought that this site was fairly accurate, but if you say there are no correct internet discussions of collimation, I'll believe you.

Most Newtonians have such a large radius of curvature (equal to their focal length) that the field is very nearly flat for most eyepieces. Refractors, especially short focal length ones, present a very curved field having a radius of curvature of about 1/3 the focal length. Thus, the latter are far more demanding on eyepieces and the observer's accommodation.

What's also a revelation is to hold your hand in front of the scope in the winter after pulling a glove off. The out of focus image shows the heat waves radiating off your hand.

Then pick up a second hand Manfrotto 3068. They have a 40 pound capacity and have variable leg angles along with a geared center column. I use mine with a DSV-2B mounting a 90mm triplet APO on one side and a 127 Mak on the other with no issues.

Most of those don't allow for plunge cuts, though. I like the heated steak knife idea. One could probably find a set for cheap at a thrift store to experiment with. I'd probably learn the technique on discarded foam first, though.

Ever tried to look higher than 45 degrees in the sky with a 45 degree diagonal? You either need to raise the telescope above eye level, crouch down low, or sit on the ground or close to it.

It amazes me there's no commercially made suitcase Dobs. I think there are some bespoke makers in Europe, but at a very high price. US bespoke Dob makers focus on large, high end stuff where profit margins are large. It seems like Synta could make something compact and affordable, but they tend to focus on high volume, mass market Dobs.

Most amateur visual scopes have planes curving away from the eyepiece at the edges.

Try removing the original visual back and just hold the T2 visual back up against the back of the bare tube to see if it will reach infinity focus with your eyepiece requiring the most in-focus. Slowly pull the T2 VB away to see how much space you have for an adapter and can still reach focus. This experiment won't cost anything.

I've found 60x on my ST80 is about the highest useful magnification due to my scope's spherical aberration and false color. I can push my 72ED to over 100x by comparison thanks to the better color correction and lens figure. Moving up from a fast achromat to at least to an FPL-51 doublet makes a huge difference in the purity of the views. Moving up from that to an FPL-53 doublet or triplet is more of an incremental step in comparison. Those old school AZ3 alt-az mounts are pretty horrible, but still better than the $15 photo tripod that came packaged with my ST80 20 years ago. It is absolutely dreadful. I now use it as a light stand for portraiture photography, and even then it's hard to set a fixed lighting angle.