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Usually people with newtonians having light leak

There is really little difference between the two - I mean cropping current setup and using longer focal length telescope. Difference is in ability to actually achieve certain resolution - which depends on guide performance, seeing and aperture size (in non trivial way). First thing you should do is to measure what you've been able to achieve in terms of resolution / star FWHM with your current setup. My guess is that you'll find your stars to be in 3.5" to 4" FWHM range. In order to say properly sample at something like 1.5"/px - you'll need about 2.4" - 2.5" FWHM stars. This requires decent seeing and at least 6" of aperture if not more.

Printing this very moment: Print in place hinged cable clip for cable management of AZGti imaging setup (USB and power cable)

It is if you keep pixel size the same, As you increase aperture - focal length also increases, and if you keep pixel size the same - sampling rate increases - which negates effects of aperture increase. EdgeHD with 0.7 reducer and x3 bin will have 203^2 * 1.68^2 = 116308 which is x5.96 baseline If you can accept 1500x1200 px image and narrow FOV ...

@Lee_P What is it that you are hoping to achieve? 400mm FL with 72 giving you somewhere about 2"/px is very good combination for nebulae. If that is your interest - I don't really see what you intend to improve upon. There is certain relationship between quantities that you need to consider: - Size of FOV - Sampling rate - Image pixel count. You don't really have too much wiggle room as far as sampling rate goes. You are already at 2"/px - and realistically - you can go down to 1.4" - 1.5". You can certainly sample at higher resolution - like 1"/px or below that - but there is really no point in doing so as aperture sizes, seeing and mount performance won't allow you to go lower. This puts some constraints at above dependence - you can't shoot large detailed FOV if you have certain amount of pixels at your disposal. Longer focal lengths will reduce FOV and at some point you will have to start to bin your pixels in order to maintain sampling rate (and ultimately speed - defined as total imaging time to reach certain SNR). That will in turn result in image with less total pixels. For example - you can happily image with 8" aperture on HEQ5 class mount if it is in form of compact scope - like EdgeHD 8" or 8" RC Both of these scopes will have very large focal lengths - but you can still image at around 1.5"/px with them. EdgeHD will have 2000mm of FL which you can reduce using their reducer to something like 1400mm - RC has 1600mm. Bin your pixels x3 and you have effective focal length of about 500mm (which is increase over your current 400m). Cost is reduction in FOV and your images will have something like 1500x1200 px if you don't do mosaics (btw doing mosaics negates aperture advantage as you need to spend time on each panel - no free lunch). In any case - question is - what you hope to change compared to your current setup?

Thermometer probably sitting in direct sunlight for those 58C

Never really got around doing anything about it really.

Difference is minor. Decide on other factors. If you have good offer for OSC model - go for it. I use guide camera as planetary camera as well and I prefer OSC in that role so I guide with OSC. Never had any issues because of that although I guide with OAG at 1600mm FL.

Hi and welcome to SGL. Maybe you are looking from further away then you should be? There is something called eye relief for each eyepiece - distance that you should place your eyeball with respect to top most lens of eyepiece. If you position your eye further away - you won't be seeing whole field of view offered by eyepiece. Are you seeing field stop? That is edge of the FOV - dark part where there is no sky or object to be seen? It should be in the field of view when you position your eye properly. By the way, eye relief for celestron x-cel 25mm is about 16mm - so you need to put your eye fairly close (but not as close as some other eyepieces - 16mm is quite decent eye relief).

You can do image of M51 with ST80, but there are several things that you must take care of in order to succeed: 1. do your best to make focuser usable. It is weak link as it will sag and in general perform purely 2. Use aperture mask to tame chromatic aberration. Aim for F/10 or so to minimize it. Possibly use Wratten #8 filter in this role as well. This will create yellow cast on the image so be sure you know how to color correct in processing for that 3. Because you stopped your scope down - use longer exposures and more of them

Hi and welcome to SGL. I don't use PixInsight, but rather use open source software called ImageJ. For above procedure you only need two commands: - image / stacks / z-project (with min as projection method) - analyze / measure (these are menu items). I'm sure PixInsight also allows for above to be done easily, just look up how to check image statistics (average, median, min, max, standard deviation and such - and use min), and since it can stack - I'm sure it can use minimum as stacking method.

Might be balancing issue. Altitude is well balanced since scope itself balances it, but azimuth is not. Adding counterweight shaft and CW could do the trick - but would probably defeat portability side of things. This mount is on my "want" list.

Hi and welcome to SGL. Yes, you had your setup pointed to the right location - and yes - it is there in the image! Maybe not as clear as you've hoped it would be - but it is there: Here is a bit wider screen shot for reference:

This one as well (or other more expensive variants with different / larger focusers or FPL55 glass or whatever): https://www.teleskop-express.de/shop/product_info.php/info/p6679_TS-Optics-PHOTOLINE-130-mm-f-7-FPL53-Triplet-APO-Refractor.html but it is approaching max payload of the mount (add accessories and you'll be pushing 14Kg easily).

https://www.teleskop-express.de/shop/product_info.php/info/p3041_TS-Optics-PHOTOLINE-115-mm-f-7-Triplet-Apo---2-5--RAP-focuser.html

Hi and welcome to SGL. You should probably look at this model from SkyWatcher as good general purpose visual scope (no imaging): http://skywatcher.com/product/dob-8-traditional/ Scopes that you've been looking are newtonian scopes mounted on Equatorial type mount. This type of mount can track the sky rather easily (single axis rotation) - either by hand or with simple electric motor, or you can get full fledged goto mount (that will find objects for you as well as track the sky). Drawback is setup time and fact that newtonian scope is not well suited for use on EQ type mounts for visual. This is because eyepiece gets into rather awkward positions and you need to rotate tube (in its rings) to make it accessible. Dobsonian type mount is far easier for simple use. It is manually pushed scope to find objects and track (although you can also get goto version of that as well) with very comfortable seating position. Eyepiece almost does not change position (you do need to "move around" the scope as you rotate it on its base - but that just means moving chair before you sit at eye piece again). Maybe look at some YouTube videos / reviews of these scopes to get the idea of how big they are and what is involved in using them.

My bet is on this one. There is calculator that can tell you approximate distance between dust particle and sensor depending on F/ratio of scope, pixel size and diameter of shadow. Do search net for one of those to help you diagnose possible location of dust particle. As far as calibrating it out - it should calibrate out if you use proper calibration. Any "shortcut" can cause under / over correction (like using bias instead of proper darks or skipping some calibration files). Looking at image that you posed - Blue filter seems to have over correction on vignetting as well that is visible (there seems to be circle in background of different intensity?). What is your calibration workflow? Nope. In order to get proper color in stars - you really need to do full color calibration. To the first approximation - you can scale R, G and B channels based on photometric measurement of a star of known temperature, but in reality you want to use color correction matrix rather than simple weights. If you don't want to mess with all of that (and it is a bit more technical) - look into Siril for example, or given that you have PI - there is also "photometric" calibration tool. These are of questionable quality, but many people use them and will therefore produce "expected" looking image (although often not really correct).

Here is example of collimation issue on my RC8 with 4/3 sensor (ASI1600): Top left corner: Top right: Bottom left: Center of the field: After collimation (although for this one seeing was poor so stars are soft): Corner: Center: When you get good collimation - stars tend to be round all over. Mind you - this is ~22mm diagonal, not ~28mm

RC type scope will not have coma, but they will have astigmatism. Elliptical shaped stars are sign of astigmatism. Looking at the image above, I would say that you need to do proper collimation of your scope. Round defocused star in center of the field is not enough for good collimation as there could be issue with the primary. There also could be some sensor tilt as well, but leave that for later if you still have issues after collimation. Here is a good guide and explanation on collimating RC8 - https://deepspaceplace.com/gso8rccollimate.php I personally don't like Bahtinov mask for checking defocus in corners and rather rely on FWHM values instead (I also use FWHM for focusing rather than B mask). Not much of a difference to worry about. Plate solving depends on pixel size as well, and pixel size is often rounded up. For example - ASI071 is said to have 23.6mm width, 4.78um pixel size and 4944px in width. 23600 / 4944 = 4.77364... So either pixel is not 4.78 or width is not exactly 23.6mm or both values are just a bit different than quoted and there might be row of pixels that is not used or something. In any case 1635mm is close enough to design FL of 1625mm so don't worry about that. Yep, look at explanation on above link to understand how tilt of primary (and focal plane) can lead to different star shapes across the field. ASI071 is APS-C sized sensor and that is approaching size of corrected field for RC8. You might never get pin point stars in far corners of the sensor unless you use flattener. Corrected circle is quoted (by TS in Germany) to be 30mm - or rather as they put it: "Astrophotography with camera sensors up to 30 mm diameter possible without corrector". I'm not really convinced this means pin point stars up to that diameter, but rather acceptable star shapes up to that field size (whatever is acceptable to each of us ). I think it would be best to do proper collimation and then see if your corner stars are good enough or should you crop or consider using flattener.

Here is example of joined prominence images: and associated 16bit tiff: composite_prom.tif Do be careful when using barlow. If you change something to your setup - like distances, image size will change. Two parts of prominence image were of different magnification and that makes stitching even more difficult. Now you can take that image and combine with original image in the way you want.

I think tiff format is fine - it won't display automatically, but sometimes it is better to post data like that as it can be posted in higher bit format. Including jpeg or png version does help people see what is going on right away.

I think that with prominence images you simply don't have enough detail to do the stitching. There is no shared feature between top and bottom images except for over exposed solar disk - and since there are no features on solar disk as it is over exposed - there really is nothing to orient by. There is no way of determining rotation as disc can be rotated by any angle and it will still be - disc. Best thing to do is to compose by hand / manually. Open images in say PS or Gimp, put them in separate layers - set top layer opacity to some small value to be able to see how to align them - and then move one layer until it matches other one. Then crop top layer, set opacity back to 100 and flatten image.

That is just beautiful!

I actually diagnosed elephants foot and other issues with first couple of layers to issues with z axis. I ended up disassembling and putting back together my printer - this time taking care of adjusting all things that can be adjusted - making frame as square as possible, wheel tension on both sides of z axis, leveling of x bar and making sure z axis lead screw is as parallel as possible. It is still not as good as it can be, and I wanted to print z axis motor bracket - but I gave up on that as I only have PLA at the moment and that should be printed in higher temp material like ASA or ABS. I also added CR touch probe and will replace motor / z axis lead screw coupling to flexible one. There is a bit of z axis binding when x axis gantry is all the way down as z axis screw is not fully parallel. This should fix a bit of binding until I get ASA to print z axis motor adjustable bracket. This is easy fix and very cheap one (less than 2e here per flexible coupling) - and it should be performed by anyone having Ender 3 series. It is really strange to use rigid coupling on shaft that can be (and often is) slightly bent to motor shaft. I think I'll be adding at least 2 additional mods to my printer: 1. dual z axis drive (to fix issues with x axis gantry sloping when changing z direction) 2. all metal hot end (to be able to print ASA without issues at 255C).

We do - almost no one is using OSC at x2 pixel size. It really does not matter in this case, I just wanted to point out that RASA8 is in no way capable of producing 1.5"/px image at that actual resolution. That is something we often don't consider - spot diagrams. I've seen some telescopes that come with RMS figures for their spot diagrams and that is probably the best we can do in determining possible resolution of the system (combined with guiding RMS and seeing FWHM).