symmetal

There's a good interactive map at https://www.timeanddate.com/eclipse/globe/2024-april-8. I can even see it from home. Looking forward to it getting 1.38% darker, three minutes before sunset. 😁 Hope those in America get a good view. 🙂 Alan

Yes, it certainly makes a difference. Impressive result. Have you tried just adding the Ha as the L channel. It should be less noisy than the SHO derived L, although it doesn't appear to have added noise to your image. The Oiii in your L may have improved the detail in the Blue structures, so maybe you made the right choice. 🙂 Alan

It's worth chacking the solver options in ASTAP aren't set to downsample (bin) the image. Run ASTAP and from the opening screen click on the 'Sigma' setup symbol as shown. On the following screen click on the 'Alignment' tab, and in the 'Solver' section check that 'Downsample' is set to 0. The 'Field of view (height)' is likely set to 'auto' but you can set it to your current FOV if you wish to possibly make solving quicker, though if you are likely to change your cameras or scopes it's worth leaving it in auto. Alan

Here's a chart I made for the ASI1600 which takes all the maths out of it. 🙂 If you expose until the read noise from the sky background is around 5x the read noise then the read noise itself becomes insignificant. At that exposure duration you may as well start another exposure as there is nothing to be gained from exposing for longer. You can easily get your image sky background ADU by hovering the mouse over the background of your image in your capture program or use the image median value, (as long as there is not a lot of nebulocity present). The average (mean) ADU value of your master bias frame is also needed, so that the actual effect of camera offset can be incorporated into the results. If you're using offset 50 then the chart should be fairly close but I've included the Excel file below so you can download it and fill in your actual bias value if you wish to get a more accurate result. The exposure calculator is a quick way to get the optimum exposure from a sample image. Just fill in its sky background ADU and exposure time, the required ADU (like 1965 from the chart) and it will calculate the exposure to achieve that. Different filters will need different exposure times to achieve this optimum background ADU of course. Luminance will be around 1/3 that of RGB, and narrowband will be much longer. The chart has been approved by vlaiv who is a proponent of 5x read noise swamping for optimum exposures. 😃 The 3.16 swamping factor is a holdover from early threads on the CN forum, but as vlaiv pointed out 5x is a better figure. ASI1600, Sky Background ADU v2.xlsx Alan

Not sure if it's suitable but Accu.co.uk do a range of threaded inserts and the M10 one in the link, and shown below, has an outside diameter of 14mm with a pitch of 1.5mm which is M14 fine pitch. M14 coarse pitch is 2.0mm. It's self tapping so should clean up your damaged threads and it's stainless steel. The M10 inside thread should clear the shaft on the worm by the looks of it. They aren't cheap though at £8.40 for a single item. Alan

Another great set of images, though I tend to prefer the mono images 🙂. Alan

Excellent image with plenty of detail. 😊 Not oversharpened either as there's a very nice clean edge to the Moon. Alan

Noise is random so one sample has no correlation to the previous or next sample, unlike the signal which will add samples together linearly. If we had a noise free signal arriving that registered say 10 units arriving per second on the sensor we would register 10, 20, 30, 40, 50 units on the sensor over 5 seconds. As there is noise present the actual values arriving wouldn't be 10, 10, 10, 10, 10 but something like 9.9, 10.2, 9.8, 10.0 10.1 On those five samples the noise is -0.1, 0.2, -0.2, 0.0, 0.1 units. In reality the noise will be a random +ve or -ve value away from the expected 10 units, with the magnitude of the variation dependent on the poisson distribution curve so there will be many more small noise variations compared to large noise variations. You can consider these noise samples as vectors pointing either in either a +ve or -ve direction, with the length of the vector being how far away it is from the noise free value of 10. Over many samples it's likely that the next noise sample will tend to have a value averageing about 0 so it's vector direction likely ends up near 90 degrees to the previous sample which was possibly slightly +ve or slightly -ve. Over many samples these noise vectors can be considered to be at 90 degrees to each other so the final noise value is the vector addition of these vectors, which is the hypotenuse of the triangle formed by the two noise vectors. Pythagoras says the length of the hypotenuse (of a right-angled triangle) is the square root of the sum of the squares of the other two sides. Hence my initial formula adding the four noise vectors together using Pythagoras. 🙂 I'm sure that was as clear as mud. 😁 That's my best understanding as to why noise vectors are considered to be at 90 degrees to each other, but I'm sure @vlaiv will be able to give you a better answer if I'm wrong.😉 Alan

I would wait until you see what results you get with your Canon lens with your current camera as far as corner star shapes are concerned before buying a full frame sensor. It wasn't until I bought the RASA 11 that I could take full frame images with the 6200MM with good overall star shapes. My Canon 'L' 100-400 zoom gave poor star shapes over the whole frame unless I stopped it down to f8 when it was tolerable. A prime lens should be significantly better than a zoom of course, so hope yours performs well. I tend to software bin my 6200 images after stacking, as the full size images can be a bit slow to process, especially if doing a mosaic. 2x2 software binning gives 2x the noise and 4x the signal, so a 2:1 improvement in S/N. Noise adds by using the square root, so with a read noise of say 2e, the 2x2 binned read noise is sqrt( 4 * (2^2)) = 4e. 🙂 Alan

It looks like yours was the first Canon lens to have the the focus motor incorporated inside the lens pipnina, and also use the USM principle of operation. From Canon's website: "In the early days of autofocus photography (Canon's first SLR with AF was the T80 in 1985), the AF drive motor was frequently located in the camera body or attached to the lens and drove the lens mechanically. In 1987, with the introduction of the EF lens mount and its fully electronic connectors, Canon was able to miniaturise the autofocus motor to fit inside the lens itself. This raised the possibility that each AF motor could be optimised for the lens it was fitted into, thereby providing faster autofocus. However, there was still a need to create a high-powered AF motor for fast aperture lenses with larger focusing groups, which could work efficiently and deliver fast, smooth and quiet autofocusing. The result was the EF 300mm f/2.8L USM lens, with a ring-type Ultra Sonic Motor (USM) that was both fast and near silent. In 1990, new manufacturing techniques made it possible to reduce the cost of manufacture, and ring-type USM motors found their way into Canon lenses at a consumer price level." Alan

Hope the one you're buying from Russia works out for you @pipnina. In your first post you said the lens was non IS and non USM, though it does say Ultrasonic on the label implying it's USM focusing. Did you get it cheap because the USM isn't working? How will yours focus if that's the case? As they are quite inexpensive I've bought a set of these EF extenders to make it easy to get to the lens connections and have a go at interfacing with an arduino. I programmed my current arduino based autofocusers to use the Moonlite autofocus driver, to avoid having to write a separate Ascom driver, so it should be fairly easy to adapt it to create EF protocols I would think. 🙂 An official Canon extender is £170 for one, but these are £38 for all three so no great loss if I ruin one of them. It'll mean drilling a hole in the side of one of them to solder wires to the rear of one set of contacts. Alan

Sorry to hear this pipnina. Hacking the lenses is possible though it likely needs a microcontroller like an arduino to emulate the commands from the camera. Getting the wires to connect to the lens contacts is the tricky bit. This blog entry shows how one person did it along with a quick video showing it working. It;s referring to EF-S lenses but I'm sure EF lenses would use the same protocol. 🙂 https://howiem.org/wordpress/2016/07/07/motion-control-canon-ef-lens-hacking/ Canon EF-S lens protocol I may have a go with an old lens, just for curiosity's sake. Alan

This site is useful for listing what targets are visible and when https://telescopius.com/ Alan

Under the search heading of 'Telescopes' there aren't many choices but the closest is probably I believe n.e.s. means 'not elsewhere specified'. Alan

"Sy, you're making a crisis out of a drama."