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."

I'm more concerned with why your battery is called Steve. 🤔 Alan

It's odd that Switchcraft do 2.0 and 2.1mm versions as they are so similar, and 2.1mm is a much more common size for DC connectors. However, if you click on the 'Datasheet' link on the 2.1mm connector you linked above it says the centre pin is 2.0mm just like the datasheet for the 2.0mm connector you posted earlier. The centre pin is split and spread slightly to provide a good contact when the plug is inserted so I think a 2.1mm or 2.0mm plug would connect fine in either situation. The L722A part in the connector name of the three versions you linked to has a 2.0mm centre pin, so one saying it's 2.1mm implies a 2.1mm plug works fine in a 2.0mm socket, due to the 2.0mm pin being spread apart. In that case you may as well get the first one you linked to as that is intended for wire connections, while the other two are intended for PC board mounting. Clicking on the datasheet for the connector you choose shows which pins you want to connect your red and black wires to, red to centre pin and black to sleeve, leaving the sleeve shunt unconnected. I think that the xL722x series of connectors are Switchcrafts version of the common 2.1mm connector, with a threaded sleeve, and their xL712x series are their version of the common 2.5mm connector, with a threaded sleeve. 🙂 Alan

They are both in fact panel mount, the difference is that the PCL722A is to fit directly on a PCB (through hole) while the L722A is intended to connect to wires so the L722A would be the better choice in your case. Don't worry about them having three pins on the connectors. It looks like your original photo just has the third pin cut off anyway. It's common to use these connectors in battery powered equipment with the option of external power. The battery -ve goes to the third pin and with no external power plug inserted it's connected to the black -ve power wire. When you plug the power plug in it breaks this connection so and the battery is disconnected, and the power supplied externally. As there is no internal battery in your situation you can ignore the third pin. Alan

That's a file from Microsoft's Visual C runtime library. You can download them from here. https://learn.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist?view=msvc-170 You'll need the X64 versions if you have Windows 64 bit or X86 for Windows 32 bit. The first link for 2015 to 2022 should be what you need, with older versions further down. Alan

Normally flares do 'point' to the star causing it but overlaying in Stellarium, nothing stands out as a cause. It's not very 'flare' shaped either which doesn't help. 🤔 It's normally stars out of frame close to the edge of the scopes FOV which cause flares rather than stars in the frame. Alan

I just found out that a new header keyword of ROWORDER was added to the FITS specification about 4 years ago to help resolve this issue, but unless software is rewritten to look for this keyword it will of course be ignored. Here's a couple of topics about it. https://pixinsight.com/forum/index.php?threads/support-for-fits-tag-roworder.14906/ https://www.indilib.org/forum/ccds-dslrs/7695-introducing-a-new-roworder-keyword-in-fits-headers.html Alan

Some astro image processing software flip the images vertically while others don't. It's to do with how rigidly they conform to the fits standard. Fits was initially designed to store graphical type scientific data where the origin (0,0) is at the bottom left. Pixel image data has the origin at the top left. There is nothing in the fits file header, afaik, that states which orientation the data should be presented so it's up to whoever's processing the fits files to decide. Programs dealing with only astro images should decide that 0,0 is top left, while others stick to the original fits convention that 0,0 is bottom left. Alan

Good to see the film was easily removeable MM. If you got the camera at a good price compared to a new one, it may be worth considering keeping it, and giving it a proper clean with the sterile cleaning sticks and fluid. Up to you of course. 😊 Alan

The rotator is located before the field flattener lens elements, so the FF spacing requirement is unchanged. If you had the FF adjustable spacing set to 12.9mm before changing the rotator it will still be 12.9mm after changing the rotator no matter what thickness the rotator is. The only change necessary is that as the StellaLyra is 12.2mm longer, you will need to rack the focuser in by 12.2mm to regain focus. 🙂 I have a Flat 61A in my spares box without a rotator on the front, (not sure when I got it or why), and it has an M54 x 0.75 male thread on the front, so the StellaLyra rotator should fit fine, assuming you can rack the focuser in by 12.2mm from its current focused position to accommodate it. Alan

Assuming you're using the ZenithStar 73 scope in your signature MM, and not binning, putting the large and small circular dust spots into the Astronomy Tools Dust Calculator puts the small dust circles 1.1mm in front of the sensor and the large dust circles at 10.1mm from the sensor. The smear pattern circle structure are a similar size to the small dust spot circles. 10.1mm seems a reasonable distance for the sensor protect window at the front of the camera, while the sensor itself could quite easily be 1.1mm from the front of the sensor cover glass so I'd put my bets on you having to clean the sensor itself (or the front of its cover glass to be more precise) rather than the camera sensor protect window. 😉 That'll mean opening up the camera, though that's fairly easy. You could change the four desiccant tablets at the same time if you wished. Your mono camera of course won't have the colour filter that's shown (Bayer matrix) I've used one of these sensor cleaners on my ASI071, as I ended up with dust on it after opening the camera to change the desiccant tablets, and the cleaner worked very well. You may need to use a couple of the cleaning wands on yours to make sure as your marks are more extensive.. Edit I was assuming that was a full size image you initially posted of the flat, but it's dimensions are 50% that of full size so it's either binned 2x2 or resampled to 50% before positing, or it's a crop of the original full size image. If it's binned then the Astronomy Tools dust distances calculated need to be doubled which doesn't make much sense so I'm hoping it's a full size crop. 🙂 If the Astronomy Tools calculator wants the radius of the dust spots entered and not their diameter, (it doesn't say), then it being resampled 50% means the original distances I calculated are correct. 😁 Alan