vlaiv

Sure, to stop unwanted electromagnetic interference with their "sensitive bits"

I think it is down to processing. Here is simple processing done in Gimp and ImageJ. Color calibration is on a single star (B-V index of 0.16) and I did not pay much attention to color work flow, but data is good and sharp. Not sure what step in processing above resulted in "mushy" looking image.

Interestingly enough - people seem to choose very similar but incorrect colors even on help page by star tools we get this Teal colors in the left image - no star has teal color.

https://www.startools.org/modules/color

This happens a lot with startools when one uses their "color balance" feature. It produced unnatural cyan, green and yellow colors in the image. @Pitch Black Skies If you are aiming for natural looking galaxy image - it's worth consulting reference image. core is much more orange / yellow glowing and outer arms are really not that blue. It is much more steel / white / light grey kind of blue. Colors of stars are really colors of objects of a certain temperature. You can get pretty good idea of what sort of colors you should be getting in a galaxy if you simply take light of certain temperature - see this as an example and compare to above Hubble/ESA M101 image: That is simply the range of colors that you'll see in a galaxy. This second image is taken as an example of what LED light of different color temperature produces. Or the same scale from wiki: going from 1000K to 12000K temperature.

one set of darks should be in the same conditions you have when shooting lights - with only front of the scope covered by cap. another set of darks should really be taken in different conditions. Sometimes IR can cause light leak, and no matter how much "blankets" you put - IR can get thru (it will go thru plastic as well - metal or aluminum foil stops IR). In order to remove anything scope related, it is best to really do it in house. Put camera cap on, place it on the desk face down or alternatively do this: I personally don't use aluminum foil - but I do place camera "sensor down" on the desk so that desk acts as additional IR block. Turn off lights in the room and shoot darks. Simple as that.

Here is what I would do to diagnose light leak: - take your setup in conditions you would otherwise use to shoot lights and just cover the scope with front end cap and shoot single or small sequence (in fact you should take 3-4) of darks at exposure lengths you are usually using (like one to few minutes). You can do this on a cloudy night so you don't waste any imaging time. - Take your camera off the scope and bring it into a dark room. Put cap on it and place it face down on a wooden table and take same darks as you did on a scope (so same exposure, gain, offset, temperature - all). Post subs for inspection, or do inspection yourself: - different mean ADU value between subs is red flag - any sort of pattern in sub created by subtracting two darks is red flag. Ideally you want their mean ADU value to be the same and when you subtract one from another - result should have ADU of 0 (will be the case if mean ADUs are same) and stretched result needs to be pure noise - no pattern present what so ever. If you find above not to be the case - cause might be light leak. If you do the same with two "scope" subs and two "house" subs - and you find that you don't get the same pattern - it is 99.99% light leak. Dark subs need to be 100% the same except for the random noise - if they are not, it means that there is some sort of external signal in them that is changing with external conditions (like taking subs on scope or in house).

That is already stretched version like one attached above as image, so not really usable for anyone wanting to see quality of the data itself.

@BrendanC Have you tried what I suggested to see if there is light leak in your setup? I just downloaded one of each subs and did simple calibration and pattern is present in calibrated sub - but it does not correspond to any of calibration files - which suggests that it is not calibration related. So here are in order - very stretched dark, that looks like usual dark from ASI1600, calibrated light frame, and single flat frame. To my eyes pattern in lumianance sub after calibration does not "carry" signature of either dark of flat. It sort of has darker interior with dominant dark patch being around M82. Flat does not have such feature. It does - but it is located in other place. Peak intensity is closer to M81, and if flat is under or over correcting - we would be bright or dark spot near M81. Similarly - if we compare patterns in dark - they don't match background in calibrated sub. If you look at result of your stacking - you'll notice something interesting This is image split by color channels. It looks like light leak is changing position as scope tracks across the sky. In fact - Red and Blue (first and last) - look like 180 rotated images which suggests that you did red and blue channel on different sides of meridian and that scope was flipped between these two filters with respect to light source that cause the leak.

Whether LP suppression filter is beneficial - depends on how much light pollution have and what type. It reduces both target signal and LP signal. It helps only if it reduces LP signal more than target signal - and that happens only if LP signal is strong and if it is of a certain type - that is best blocked by LP filter. Since you are at Bortle 5 - I don't think you really need LP filter unless you are certain that most of your LP is from sodium lamps (high and low pressure sodium - yellow type street lighting). Astronomik L3 will also be better at reducing star bloat as it cuts off offending far ends of spectrum (as a contrast - L-Pro lets light up to and past 700nm).

Not going to help much - and you don't really need it. Eyepieces that you already have - 40mm one in particular, will use up complete illuminated field provided by telescope - you can't get wider field because scope does not provide it, so focal reducer won't help. What you will see is smaller central portion of the FOV with strong vignetting - so you'll see same piece of the sky only smaller. If you want to get the maximum out of SkyMax - maybe look into changing back port of the scope for 2" version. It won't add much, but maybe you'll be able to use 30mm or there about field stop eyepieces in 2" format compared to 27mm max of 1.25" format. That is maybe 10% increase in max FOV, and odds are - it will have some vignetting.

Just be careful with that idea of using uncoated glass for solar. Reflection of uncoated glass is about 4% or 0.04 per surface. You'll have two uncoated surfaces (don't forget to use uncoated secondary as well!) - so that is 0.0016 (0.04 x 0.04) This means that uncoated newtonian can reduce sunlight to 1/625 Baader solar film is ND 5.0 - it reduces sunlight by 1/10000 - or 16 times more. It would be good to include ND filter as well in the system (much like Herschel prisms do - they have 4.6% reflectivity and add ND filter to get needed combined neutral density / light reduction). You would need ND 1.2 filter to reach total ND 5.0 levels. Simple moon ND filter is something like ND 0.6 - 0.9, so I would add one of those and variable polarizing filters so actual brightness can be tuned at the eyepiece. Good thing about Herschel wedge is that it polarizes the light - so you need only one polarizing filter at the eyepiece to control level of the light (by turning the eyepiece).

Leave it as is - I don't think you can do anything to improve it. It looks excellent - well balanced composition, very natural blending of foreground with background, really excellent image. One of rare images where you can just look at milky way and "feel" that you are floating around the massive bundle of stars filled with gas and dust. Well done!

As said above ASI224 or ASI385 depending on how large sensor you want. Both have AR coated window so you'll need IR/UV cut filter and you will need F/15 system to be at critical sampling rate so look for x1.5 barlow - or better, barlow element that you can adjust barlow/sensor distance to get exact F/ratio needed.

Do bear in mind that I just gave example there - I'm not saying go for 50s vs 3minutes - unless you calculate so. So what is the difference? Only difference if you image for same total amount of time (like 1h in 60 one minute exposures, or 1h on 30 two minute exposures or again 1h in 12 five minute exposures) - is level of read noise. All other noise sources just add up with integration time - they don't care about number of subs - they just care of total amount of integration time. Read noise is only one that depends on number of subs. For the same imaging time if you use longer subs - you will need less of them - and you will add less read noise. Noises add in particular way - not like signal that you just add together like A+B, but instead add like vectors so for noise it goes like this: square_root(A^2 + B^2) or square root of sum of their squares. This type of addition has important property. If things that you are adding are significantly different in magnitude - result is very close to larger one. Here is an example - if we say have 1 and 10 and we add them regularly - we get 1+10 = 11 There is some difference between 10 and 11 as result Let's now add 1 and 10 the way noise adds - we will have: square_root(10^2 + 1^2) = sqrt(100+1) = sqrt(101) = ~10.05 (or more precisely 10.049875.....) In first case we had 10% increase, but in second case, while adding same two numbers we had increase of only 0.5% Larger the difference between two noise sources - less impact smaller noise source has. Point of choosing particularly long exposure length is to make read noise smaller than any of the other noise sources. In particular, above approach is targeting LP noise - that is why we measure background levels - to see how much LP there is (and consequently what is associated noise). There is a point where we no longer distinguish between noise levels. This is found to be when read noise is between 3 to 5 times smaller than LP noise. Just as an exercise - we can calculate total resulting noise increase in both cases: 1 and 3 for example (that is three times larger): sqrt(9+1) = sqrt(10) = ~3.1623 1 and 5: sqrt(25+1) = sqrt(26) = ~5.1 In first case, increase is 5.4%, while in second case it is 2% I usually like to use x5 rule rather than x3 - just to be safe, although 5.5% increase in noise is imperceivable Here are examples: two different noise patches in the image above - right one has 25% higher noise level than left one. You should be able to tell the difference between the two. same thing, but here one is 5.5% higher noise than the other. You can't really tell the difference (maybe, just maybe). With 2% difference - visually there is definitively no difference. So there you go - that is how we select subs. If you calculate your sub to be short - there is no drawback in going longer as far as image quality goes (you will have less data and that is good for storage, but some algorithms like more data to work with, so get at least 20-30 subs in any case. Also - with longer subs if something goes wrong - you throw away more data)

You won't find ready made Solar Ha filters for binoculars - optics of regular binoculars is incompatible with Solar Ha filters. Maybe you could DIY solar Ha binoculars - much like people DIY larger binoculars out of refractors. Maybe take two 70-80mm scopes and two quarks and then join them to make binoculars. Or purchase two lunt 40mm and join them to form binoculars. You'll probably have issues to focus both eyes for image to converge, and you'll have to operate tuning mechanism for each eye separately. Another thing that you might do to get DIY binoculars is to take 35-40mm front mounted etalon and attach it to each objective of your binocular. Then you would need a way to add blocking filter before eyepieces of binoculars. Most blocking filters are mounted in diagonals and it is hard to find suitable blocking filter to be mounted on binoculars. Maybe easiest solution would be to take regular solar ha scope and add binoviewers?

As far as I know - yes, Sharpcap has the feature (not sure what it is called) - that can be used to determine necessary exposure length. If you want to do it yourself - procedure is rather simple: - take one of your raw subs and calibrate it properly. - convert ADU values to electron values - you can read e/ADU value from fits header or from data published by manufacturer of the camera. This is simple multiplication of pixel values with constant. - select patch of sky without any target / nebulosity and as empty as possible (odd faint star here or there should not be a problem). Measure median value in that patch of the sky. If patch is completely void of objects you can also use mean value, but median is better as it will remove impact of few stars if there are any. - take 25 and multiply with squared value of read noise at given gain settings and divide with above value - this will give you factor needed to multiply current exposure length to get proper one. Example: You have sub that you debayered since camera in question is 2600mc, that you exposed for 3 minutes at gain of 100. e/ADU value for this gain is ~0.25, so you multiply pixel values with 0.25 to get electron count (use green channel). Now you measure background value and you find that it is 200e, you also see that there is 1.5e of read noise at gain 100 from ZWO graphs. Exposure length multiplier will be 25 * 1.5^2 / 200 = 56.25 / 200 = 0.2815 You exposed for 3 minutes or 180s when in fact it was enough to expose for 180 * 0.2815 = 50.625s or ~50s (if you get number greater than 1 - that will mean longer exposure than you used, if you get smaller than 1 that will mean shorter exposure than you used).

Maybe alternative would be to get Baader twist / click lock thing for their focuser? That is supposed to keep things well clamped and centered on optical axis? https://www.firstlightoptics.com/adapters/baader-2-s58-clicklock-clamp-for-diamond-steeltrack.html

No, I would try distancing ring first as it is far easier and cheaper solution. I wrote above as it occurred to me that I have similar setup on one of my scopes and that you can use combination of adapters to the same effect. I have 2.5" focuser and on one of scopes I have x0.67 reducer (RC8" scope and CCD47 reducer). CCD47 has M48 thread and 2.5" focuser has M63 thread. It is far better if I sink reducer in focuser tube then to simply screw it on with adapter as focal reducers move focus position forward. In order to make it all work, I'm using this adapter: https://www.teleskop-express.de/shop/product_info.php/info/p9781_TS-Optics-360--Rotation---Thread-Adapter---M63-to-M68--M54-and-2-.html https://www.teleskop-express.de/shop/product_info.php/info/p5144_TS-Optics-Adapter-from-M68-and-M63-to-M48---Riccardi-Connection-Adapter.html First is actually rotator and second is the adapter. It has larger M68/M63 thread that is used to attach it to focuser and it has M48 on both sides I use this telescope facing M48 to screw in reducer. That gave me idea - in order to sink your corrector in focuser and still have threaded connection - you need something that will have M48 and T2 female threads facing telescope side and M48 o T2 thread facing camera side. There is simple way to do that and it looks a bit like this: This is 1.25" filter adapter for T2 thread and it is used like this: You screw it into T2 thread and then you screw filter into it. I linked above M48 / T2 version that you would need. I'm going to give you just diagram of that part being used: You can screw things together and it will hold - in the same way this holds: Nut in above image is tube with female M48 thread and two nuts that push against each other is M48 Steeltrack adapter and M48 / T2 adapter - once you screw them together - they will act as one unit. You then have T2 thread facing telescope side (you'll need T2 extension to bring it out of assembly - and you have female M48 facing the camera. In any case - this just shows that with proper combination of adapters - you can both sink your corrector inside focuser and have threaded connection - but it is somewhat complex and expensive as you need to purchase 4-5 separate bits and cost adds up. Go with distancing ring as a lip that will lean against focuser to keep everything straight and if you really want threaded solution - well, above is one version of it. Ideally - you would want baader steeltrack adapter that has T2 thread facing the scope and camera side - but I don't think they make such thing.

There might be another solution - threaded one. Baader steel track has threaded connection, if I'm not mistaken Probably M58, but I'll check. Actually - it is S58 (what ever that means), but there is this adapter: https://www.teleskop-express.de/shop/product_info.php/info/p8220_Baader-M48-Adapter-for-2--Diamond-Steeltrack.html Now you need M48 female thread that is a bit longer and you need T2/M48 conversion ring https://www.teleskop-express.de/shop/product_info.php/info/p13710_TS-Optics-Adaptor-with-female-T2-thread-and-male-M48x0-75-filterthread.html You also need long M48 female thread extender. https://www.teleskop-express.de/shop/product_info.php/info/p4515_TS-Optics-Adapter---continuous-M48-female-thread--as-with-2--filters-.html and simple T2 extension Here is diagram of how it would all fit:

Well, this is about it: There is color there - but it is mostly very dull and inaccurate as you did not use UV/IR cut filter.

That explains it. IR/UV filter is a must. With fast ED doublet - it is forth looking into Astronomik L3 filter to restrict spectrum even further. That is normal for raw data as sensitivity in the green part of the spectrum is strongest. You need to do color calibration to get proper colors. I'll post my attempt of processing a bit later when I get the time to do it.

There seems to be something wrong with your scope. Either that or there is large difference in the quality of stacked subs. look at these stars - they seem to have core to one side and coma like halo on the other. If all subs are like that - it is a sign that optics of the telescope is misaligned or something. Stars should be point like. Now it can happen that some of the subs used to stack the image have nice tight stars and others are simply out of focus and then stacking made combination of the two - but I doubt it by the looks of the stars in the image. If you post single sub - we can see which one is it.

I switched to threaded connection in my setups to avoid that, but here is what I would try if you can't manage threaded connection: Get one of those distancing rings for T2, metal one, not plastic (it needs to be rigid) and put it between corrector and extension. This will create sort of stop / edge so when you are inserting corrector - it will only go inside up to this distancing ring as it is larger than focuser opening. Something like this: Then, when inserting corrector - turn scope so it's pointing up and slide it up the focuser tube until it reaches this distancer and then hold it flush against focuser tube. This ring is supposed to prevent tilt as it is perpendicular to optical axis. While holding assembly against focuser - tighten focuser compression ring. Do this without camera attached so that you have less weight. After everything is firmly secured in focuser - screw on camera at the end of extension tube. You will probably need to mark things to get proper orientation (just insert with camera attached first and mark way corrector is oriented so you orient it the same when camera is not screwed on - when you screw on camera later it will be at wanted orientation). Hope this helps.

Not sure, as I don't have SCT experience. I do know that with moving mirror focusing - position of focus plane plays a part because it alters separation between primary and secondary mirror. Not sure how it affects correction (it does introduce small amount of spherical aberration) as it changes focal length of the system somewhat. Given that you have regular focuser fitted at the back - that might not be an issue. You probably need not worry about it at the moment. Focus on getting proper distance for now.