michael.h.f.wilkinson

That is lovely! Well worth the long processing time, I would say

Hi Rick, welcome to SGL. My first proper scope was a home built 6" F/8 Newtonian. Great scopes that can show a wealth of planetary detail and are very nice DSO scopes as well. The XT6 has the same spec optics, and should be a great visual instrument

Clear skies at last, so I thought I would go for an easy target in M31. I thought I would have a test of the Sigma 120-300 mm F/2.8 Sports lens I have, with the Canon 550D for easy of attachment. I got a fairly bright star lined up quite easily, focused in live view, and then did a first test shot. After some head scratching and swearing, checking the mount for issues, it finally dawned on me that I had left the lens as it was used for sports photography, so image stabilization and AF where still switched on. After setting both switches off, I did some test shots at full aperture, but these were not that encouraging in the corners, so I went for F/4. I got some 120 subs at 60s ISO1600, and stacked the results in APP (with flats, darks and dark flats) The upper left corner is still not good. Bit of a pity, as the lens is very fast. Maybe a smaller sensor like the ASI183MM or ASI294MM will fare better

Haven't compared to Star Xterminator, only to Starnet++ (which I find dreadfully slow). Ours should be able to go up to 30 Mpixel per second on a quad-core machine

Very interesting. I have students helping develop a new tool (non-AI but using morphological connected filters) to do something very similar. Would be interesting to see the differences side by side (speed wise, there is no contest, ours beats Starnet++ by a mile)

Really superb image of a rarely imaged subject

I prefer star-hopping in RA and DEC with my EQ mount, which doesn't require much set-up time for visual. Even for planetary imaging (or solar, when I don't have a hope of seeing Polaris) a rough polar align is usually sufficient.

I find 250 frames often leads to noisy results, I find, especially working at F/30 and a quite narrow 0.3 Å bandwidth. I might get a new filter that matches my newer, more sensitive cameras better. A better grade filter may also have higher transmission

Am experimenting with that. Will post the results later

Little mosaic of just 4 panes using the 8" Tri-Band SCT with Baader TZ-3 tele-centric lens, Solar Spectrum 0.3 Å H-alpha filter, and ASI174 camera. Seeing got increasingly choppy, and I might have missed exact focus. I stacked 2000 frames out of 10,000, 5 ms exposure time. Must work harder at getting good focus. This was mainly a test of my new laptop, equipped with an Intel Core i9, 32 GB RAM, a 2 TB SSD, and nVidia RTX 3070 with 8 GB. This happily captured the data at 100 FPS, so that's good. stacking in AS!3 was really a lot quicker than before. The 16" 2560x1600 display is also a joy to use.

Got this shot with the Tri-Band SCT, ASI183MM, Lunt Herschel wedge, and Baader G filter 2000 framesout of 10000 stacked Seeing was not good, but still happy with the result

I am very pleased with my APM 80 mm F/6 triplet, which complements my 8" SCT nicely on wide-field views (about 5.3 degrees at 15.5x with the Nagler 31T5 "Panzerfaust"). I did have imaging in mind when I bought it, and the price at that time was great (699 euro), but a fast 80 mm to 100 mm ED doublet or triplet is an outstanding wide-field visual instrument, and excellent travel scope. For the latter purpose, I would go for 80 mm, given the weight.

I find APP well worth its modest price. Very intuitive

Excellent image, really like the processing

Nice results! No luck here these last weeks, alas

Nice shot! I use star calibration in Astro Pixel Processor to get the star colours correct

Last week I was in the jury of an astronomy PhD defense in Ghent, and got a tour of the old observatory. They have a beautiful Steinheil 9" F/11 refractor on a Cooke and Sons mount in a lovely wooden dome. Apparently, they still have open evenings every week, weather allowing. It was pouring with rain, so no luck.

I got a second-hand Lunt LS35 years back and was immediately hooked. This was during a period of rather higher solar activity, but the views, even through a 35mm instrument were great. I even started imaging with it. Things got progressively better as I moved to a 60, and then 80 mm instrument Click for full resolution version

I have the APM 80mm F/6 triplet which is an earlier version with the same optics. I am very happy with it as a wide-field visual scope, it is also a very nice imaging scope and travel companion. I mainly use it for DSO and solar imaging. Views of moon and planets at higher magnification are great, although I much prefer my C8 for those. Here are some images taken with the scope, and of the scope.

Solar spectrum filter, I presume. What bandwidth?

Stunning, especially for a single sub

Mine has an m4 metric screw (interchangeable with the one from my EQ3-2). I bought mine in 1995, in Celestron black livery, there might be differences between different models

Taking lots of flats or bias frames does not as a rule take much time, so I typically create 50 each, reducing the noise levels by a factor of about 7. That is adequate, I find. Less would probably work. Darks take quite a bit longer to acquire, due to the long exposure times. However, with fixed-point cooling, I can take darks whenever I like, so I just let the camera take 50 of them as well. Previously I used 30, and that also works well.

I am certainly going to remove some spacers. I think I forgot to include the filters in the computation of the back-focus distance. I will first shave off 0.5 mm, and see what happens.

Got the 8" Tri-Band SCT out yesterday, to have a go at the larger ARs. Seeing was very variable, but I managed to get a few decent shots. White light: H-alpha: When the seeing is good, this scope really gets a load of detail, with fluctuating seeing like I had yesterday, I had to chuck out many panes of the H-alpha mosaic made with the ASI174MM at F/30. The WL is actually a crop of the much wider view provided by the ASI183MM at F/10