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This is what Jupiter usually looks like in my 8" dob at x200 power when the seeing is decent: (viewed from about half a meter at 96ppi device).

I can't be completely sure but that looks like EQ3 class mount. I think you need something with more payload capacity to carry 8" CC No. Adding more weight will help balance the scope - but it won't improve mount stability. Views will be shaky and overall experience not so good. You really want something in EQ5 or higher class for scope that is alone something like 8.5Kg and with accessories can easily get up to 10kg. Probably yes, but I'd like to advise you to check few things again before you decide on purchase (just to avoid being dissatisfied by new scope). 1. Did you check collimation on your old scope? 2. Did you let it cool before observing planets? 3. Did you optimize your observing session - did things like - avoid viewing over large bodies of water, houses or anything that absorbs heat during the day 4. Do you know how to spot poor seeing and recognize good seeing? 5. Did you optimize exit pupil / use right eyepieces for the job? There are a lot of things that go into having a good planetary session. If everything is done properly, then yes, larger and better scope will give you better views, but not all the time as much depends on conditions. You really need to manage your expectations. It is very easy to find very large and detailed images of Jupiter, Saturn, Mars online these days, but that is not what you'll be able to see thru the telescope. Jupiter will be about the size of pea held in hand in front of you. Not larger than that. You can make it somewhat larger - but it will be blurrier and that is not necessarily what you want. In ideal conditions - difference between 127mm and 200mm scopes on planetary will be less than twice, but most of the time - both scopes will be limited by atmosphere and will show roughly the same view. If you understand all of the above - then yes, 8" CC will give you very good planetary views and be very good platform for planetary imaging with appropriate gear (dedicated planetary camera, tracking mount, laptop, etc ...).

8" CC is very good instrument for planetary and for imaging. Do bear in mind that for best images you need to use special technique that requires dedicated camera - planetary type camera and special processing. It is so called "Lucky" type planetary imaging. Mounting such instrument on EQ class mount is a bonus for observing as it will track the target and you won't need to nudge the scope every so often. Just keep in mind that you'll need larger mount than for Mak127 as this scope is heavier. Low cost alternative that will give you very good planetary views would be 8" F/6 dob mounted newtonian. Drawback is that it is manual tracking and you can't really do photography on it.

There is a reason why there is such a price difference, and these are two very different instruments. It really depends what you plan on doing with your scope. 200P is general purpose visual instrument. That is its strong side. It can do different types of astrophotography - but there are better models of the same scope that are meant for that - like 200PDS (dual speed focuser and optimized secondary size). 8" CC is very specific instrument - it is suited to planetary and lunar visual, but much more for photographic applications. It comes with decent dual speed focuser and has massive focal length of 2.4m. It has quite large corrected field - up to APS-C size so you don't need any sort of corrector - which is good for certain applications like IR part of spectrum that works best with purely mirrored systems (no refraction in glass). What will you be using the scope for?

ImageJ will let you stack with minimum. Just form a stack from your subs (which is just a "pile" or "collection" of images - in ImageJ lingo that is stack whether you stack it or not - you can simply do it by "File / import / image sequence") and select: Image / Stack / Z Project and select minimum method: If you shoot bias - which means minimum exposure time, temperature should not make much of a difference - but in principle - it is temperature dependent. As temperature causes dark current buildup and dark current will also raise signal level - it can skew results. It will be gain dependent as well - that is why I mentioned that you should set your parameters the same way as when imaging - gain, temperature, etc ... and only vary offset to determine which value to use.

I'd say that you should focus on focus - try to get it spot on. I'm not sure if DIY dew heater is a good idea (unless you know what you are doing). Too much heat will mess up your optics and focus again. With changing temperature - scope length changes (heat expansion / contraction) - and that shift focus position very slightly - but enough to throw focus off. Best conditions are stable conditions - if you can get dew heater to give stable temperature (no warm - but maybe 1-2C above ambient) - that would be ok. Dew won't usually mess too much with sharpness. It will produce scatter around bright stars but sharpness will be ok. It will lower SNR though because it block light.

Well, this APOD shows exactly the same structure of Ha: https://apod.nasa.gov/apod/ap180108.html I was completely unaware of these structures around M31 (they are of course within our galaxy and not really around M31). @peter shah Excellent capture!

I found this on Ha around M31 These are VTSS fields And07 and And09 that show some Ha structure around M31 but I can't really positively match shapes to the shapes in the image above. However, this data is rather low quality. source: http://www1.phys.vt.edu/~halpha/

Hi. Huh, I'm not sure I'm seeing any sort of nebulosity in above image. What sort of gear did you use to take above image? My guess is really fast small aperture newtonian? Say 130p F/5 or even 100mm F/4.4? You have significant coma, your stars are very out of focus and there is substantial vignetting. Colors are just consequence of boosting saturation very much and not having calibrated data.

This makes me wonder - people report IFN around M31, but here it appears to be Ha in nature. I wonder what it really is?

Probably most important thing to check is if camera supports RAW format. Action cameras are really geared towards creating HD video of action at high FPS - which means that primary format will be compressed video. One of the reasons web cams are not adopted more in AP role is precisely that - they are designed to work over USB 2.0 connection which has low transfer rate and web cams use lossy compression for video. Lossy compression is good for daytime photography but looses information - and that information is very important in low light scenarios when we stack the data to get good SNR.

I think that is just UK part of www.telescope.com - Orion owned telescope web shop. Orion telescopes is US based and has similar scopes to SkyWatcher and other brands. I think it is more popular in US due to being based there. If you look US youtube reviews - you'll more often see Orion ShortTube 80mm F/5 being discussed while in Europe it is more often SkyWatcher ST80, but both are really the same scope. For example, this scope: https://www.telescope.com/catalog/product.jsp?productId=132684&src=row3col1-prodimage is the same scope found with different branding like: https://www.altairastro.com/altair-starwave-115-f7-ed-triplet-refractor-9198-p.asp 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 used to be sold by StellarVue as well - look up their SV115T, and so on ... In that sense - it is recommended as it is mostly the same stuff you can also purchase from others, it is just the question of price and customer support. I have no experience with that as I've never ordered from them.

It is good time to start with such scope. Jupiter and Saturn will put on a show in few weeks (although they are low - they are close to opposition now) - and summer sky is full of interesting things to observe. Moon is best observed when not fully illuminated. For start aim around first and last quarter and observe along the terminator (line separating bright and dark side).

To me, simplest way would be to put offset to 0 and then do single bias sub. Load that sub into any tool that will inspect things for you and get min value and histogram. With low offset - you should get clipping to the left of histogram - a bit looking like this: bell curve will get clipped on left side. If this happens - you should look at min value and that is minimum pixel value that your camera outputs. In 99% cases it will be 0. As for tool - I use ImageJ. It is free/open source tool for scientific image analysis. It opens FITS files - and can plot histogram, do analysis of image and so on. We add offset precisely to avoid this sort of clipping to the left. If read value is 0 - you have no idea if actual pixel value was less than zero or zero and that is bad. For this reason we want bell shaped curve to be above zero in 99.99% of cases. If you shoot couple dozen of bias subs (or even say 8 of them) and look for minimum pixel value among all subs and all pixels - you are just decreasing probability that any pixel will be at or below floor (read noise has gaussian distribution and there is always chance some pixel will have lower value - point is decreasing that chance to acceptable minimum).

Here is methodology that I would suggest: - Set other parameters as per your preference (gain, temperature, whatever) - and start with some offset. - determine what is minimum value your camera outputs (probably 0 but it can sometimes happen that floor is not 0) - take set of bias subs. Maybe couple dozen of them - stack using minimum method - inspect resulting stack for minimum pixel value - if it is equal to floor value of your camera (again, probably 0 value) - increase offset and go to step 3, if minimum pixel ADU is larger than floor - you are done.

Do you have any chance to see one in person? Either XT10 or XT8? Telescopes are, interestingly enough, almost always larger in person than on images. There are two things to consider when deciding between XT10 and XT8 scopes. First would be added weight and bulk and second would be coma and need for more expensive eyepieces. First one should be self explanatory (19Kg vs 25Kg), and I'll briefly address the second one. XT8 is F/6 scope where F/6 is ratio of focal length and aperture size 203mm / 1200mm = 1/6 often written as F/6 or just F6. XT10 is F/4.7 scope because 254mm / 1200mm = F/4.7. Smaller F number is referred to as faster optics means that light hits focal plane at shallower angles. This is important when choosing eyepiece type. Most eyepieces work well with slow scopes (slow being F/8 and larger like F/10 or F/12). As speed of optics increases and field of view of eyepiece increases - edge of the field aberrations also increase. On fast optics (meaning F/5 or below) only very expensive eyepieces show clear image to the edge of the field. Other start to be blurry some distance to the edge. Another aspect is important and that is exit pupil of eyepiece. Faster scopes give wider exit pupil than slower scopes. At some point, if exit pupil is wider than what your eye pupil can expand - you'll loose light. In this particular case, as both scopes are newtonian scopes, there is also coma to worry about. Coma is aberration inherent in parabolic newtonian mirror - faster the scope, more coma it will show. That is off axis aberration that makes stars look like little tear drops at edge of the field. This is what coma looks like in photo (stars look like little comets - hence the name for aberration): So to recap - XT8 is slower scope, easier on the eyepieces, while XT10 is faster scope (in fact, rather fast scope) that will require more expensive eyepieces to have pin point stars up to the edge and possibly a coma corrector device to clean up coma in widest views. From this part of your question, I'm getting the feel that budget is not overly big concern for you - as you are mentioning Ethos eyepieces, in that case - you'll probably be able to afford eyepieces that work well in faster scopes, so that is not as much of a concern. Adding coma corrector is probably not out of the budget either. Only thing to be aware with coma corrector - is that it somewhat complicates observing and adds more glass to optical path. Some people don't like that as more glass means more chance for view to get distorted and dimmed (although with modern technology - that would be minimal). What I would like to bring to your attention is that choice of eyepieces is very personal thing. Some people prefer large fields of view (like 82° or 100°) some don't. I personally don't like very large AFOVs. I have 82° eyepieces (Explore Scientific range) and although I love the eyepieces for sharpness - I don't really like that large AFOV. Best size for me is around 70° (68° to be precise as that is AFOV that I've used). 62° is also fine and I would not mind using only 62° for the rest of my life - I would not feel like I'm missing out something. There is also ergonomics of the eyepiece, eye relief - if you are wearing glasses or not. Simple diopter glasses can be removed for observing, but if you have astigmatism and wear cylinder - then you need to observe with glasses - and that means long eye relief eyepieces. Bottom line - don't rush into getting the most expensive eyepiece as it might not be the best eyepiece for you. In fact - you are yet to learn what you value in eyepieces. Get some observing experience first and then star building your preferences from there. 10" F/4.7 will not give you wider field of view in comparison to 8" F/6 - both have the same focal length so they will give same magnification and hence field of view with same eyepiece. With same eyepiece, only differences between the two scopes will be: 1. Everything will be brighter in 10" scope - both targets but also background sky (larger exit pupil) 2. Edge of the field will look better in 8" if you don't get the best eyepieces and use coma corrector. Coma applies only to very low magnifications and large true fields of view 3. 10" will have potential to show you a bit more. A bit more of planetary detail, a bit deeper on deep sky a bit more resolved star clusters and so on. This is only potential and difference is subtle. Views will much more depend on other factors. 8" in darker skies will simply outclass 10" in light pollution. Even 4" will show more in dark skies than 8" or 10" in town. Here I'm talking about deep sky objects. 8" properly cooled and managed will show better detail on planets than 10" if not properly cooled and managed. 10" has larger mirror - larger piece of glass and cools more slowly. 10" is a bit more sensitive to collimation because it is faster - properly collimated scope will show much more detail than scope out of collimation and so on. Only if you pay attention to all these details, then yes, 10" will be better, but not by much - difference will be more visible on deep sky objects as planetary detail is much more restricted by atmosphere then by aperture size at this level of aperture size. Thing that will best enhance the viewing - is the viewing itself. Getting under the stars and learning things - experience, will bring most rewarding enhancement. Observing is a skill - more you observe, better you become at observing. Your brain / eye system learns this skill and really starts to show you more stuff - you learn to see fainter stuff, you learn to discern detail. You also learn how to manage your environment (getting dark adapted, using peripheral vision, waiting for deeper darkness, waiting for things to cool and atmosphere to settle and so on) and recognize good and bad conditions for particular type of observing. You don't have to spend much and get "the best" equipment to have the most fun. Just learning about the sky and understanding what you are seeing and learning a bit about these celestial objects is rewarding thing that brings most of the fun.

Nova and supernova are two different things. Supernova is exploded star, while nova is transient phenomena that does not destroy the star. It is usually pair of stars orbiting close enough so that smaller (usually dwarf) star stars pulling material from larger neighbor. This material is then heated by rapid rotation and at some point runaway fusion event is triggered - on that material, but not on either of two stars. This process emits bright light that brightens whole star couple of magnitudes. As this is regular nova - I expect that it gives off same amount of Ha radiation as any star with similar temperature - meaning not significant amount. Very nice image by the way.

Yes, aperture controls resolution when the scope is diffraction limited. That is always true if we don't include effects of atmosphere - like when we do planetary imaging at critical sampling rate. Most scopes are diffraction limited on axis - even cheap Chinese mass produced telescopes. However, some astrographs are not diffraction limited. Why is that? Because they are astrographs and it is much more important that they have large corrected field then diffraction limited field and because they will be used in long exposure where seeing can mask effects of diffraction limit on scope. If you are going for wide field of view image that you sample at say 3"/px, is it important for your telescope to have spot diagram that fits inside 1.28" (airy disk diameter of 8" scope), or can you have one that maybe fits inside 2.5" circle. Both will be smaller than single pixel. Such wide field scope needs not be diffraction limited.

This depends on a) What you mean by more detail b) if you assume detail in terms of resolution - then it will depend on respective star FWHM. Telescope with smaller FWHM will produce sharper / more detailed image. If by detail you assume "depth" of image or achieved SNR - then HyperStar will win for given imaging time - it will be faster system as it has more aperture on same resolution If they both sample at the same sampling rate / resolution - then yes, there will be no difference in terms of crops - you can crop the same region and it will have the same size in pixels

It is sort of like that with small difference - optical blur adds up. If you take two otherwise identical scopes - one diffraction limited and other having say bad spherical aberration that makes it not be diffraction limited (spherical greater than 1/4th wave) - and place those on the same mount and under same skies (say side by side setup) - one that is diffraction limited will produce tighter stars - smaller FWHM.

We can't simply equate these two as Dawes limit is an approximation (empirical). What we can do is use well established formulae. 5in telescope has 127mm of aperture and for that optimum sampling rate for planetary case is 0.41"/px. We have very exact solution to this and it is based on: https://en.wikipedia.org/wiki/Spatial_cutoff_frequency combined with Nyquist criteria for sampling of band limited signal. However, this is case where there is no atmospheric influence. For long exposure images - it much more depends on sky conditions, mount tracking and other factors. There is simple formula in that case as well and that is FWHM / 1.6. If your system produces FWHM of 3.9" (like above hyperstar) then you need to sample it at 2.4375"/px. Going in opposite direction - if you sample at 0.9"/px - you better have 1.44" FWHM stars in your image. In my experience - that is not likely in regular seeing that by itself is 1.4" or more (without added optics and mount performance).

First advice would be to purchase telescope from a well known supplier of astronomical gear. Avoid amazon and department stores and such (unless you are very confident in what you are purchasing). Second important point - stocks are quite low at the moment as all C-19 thing has upset worldwide trade and transportation. It is very likely that you'll need to wait a few weeks for your telescope. Orion XT8, Skywatcher 200p dob, Bresser 8" dob - are in essence very similar instruments (all good quality). They have same capability and only difference is in accessories / eyepieces and mechanics of dob mount (all are quite ok). https://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-200p-dobsonian.html https://www.firstlightoptics.com/bresser-telescopes/bresser-messier-8-dobsonian-telescope.html https://uk.telescope.com/Telescopes/Dobsonian-Telescopes/Classic-Dobsonians/Orion-SkyQuest-XT8-Classic-Dobsonian-Telescope/pc/1306/c/1316/sc/1352/p/109907.uts?refineByCategoryId=1352 Yes, I have one in my basement - SkyWatcher 200p version, and it is often used (not as often as I'd like but that will hopefully change soon). 8" dob is really life time visual instrument. Many people never feel the need to upgrade to something bigger. Just do keep in mind what sort of instrument you are using and what are its strong suits. It is great visual instrument that will show you plenty of stuff - planets, moon, deep sky objects. It is however on undriven mount so you'll have to find objects yourself and track them (not issue for low power views where drift time is in minutes - not ideal for high power views - when you have say 10-15 seconds to observe planet before you have to nudge the scope to recenter it). This can be changed later by adding equatorial platform that will track the sky for limited amount of time (say half an hour or hour before it needs to be reset): https://www.teleskop-express.de/shop/product_info.php/info/p10148_TS-Optics-EQ-Dobsonian-Telescop2-Drive----Platform-for-50--N-S.html It is best used seated - so get good height adjustable chair, and it is heavy and bulky. If you are ok with all of that - then it is perfect beginner and advanced observing scope. AzGti is very nice little mount that can be easily converted to Eq version for wide field astrophotography. That is very good and affordable way to get into astrophotography - but it can only hold lightest / smallest telescopes. I have one of those as well: Here it is converted to EQ mode (very DIY) and ready to snap some images of heavens. It really depends on your budget. I think that AzGti is something that people doing astrophotography should have for wide field applications - but that might not be everyone's interest. It might not be in everyone's budget either - there are cheaper solutions like DIY barn door tracker and similar. Do keep in mind that: - it is of limited use as regular mount - it will hold only small telescopes like 100mm Maksutov or maybe 70-80mm light weight ED/APO refractor, but can work in both Az and EQ mode - it is suited for wide field / low resolution work as AP mount - it needs a bit of DIY to make it work in EQ mode (need to get wedge, counter weight bar and counter weight and flash special firmware - instructions can be found online) - it is mass produced item and some people had issues like roughness in tracking or noise or stiff axis - but that can also be fixed (although warranty is void when opening the mount)

Here is interesting reference: taken from here: https://www.cloudynights.com/articles/cat/articles/the-amazing-hyperstar-a-guide-to-optimize-perf-r3013 We have 3.9" FWHM stars on 14" telescope - ideal pixel size being 7.8µm (2.43"/px).

Noise by itself is not really that important - it is signal to noise ratio that is important. ISO is just multiplier and as such does not impact SNR at all (it does a bit but in different ways). If you multiply ratio of two numbers with same coefficient - well, that ratio does not change 5:1 is the same as 5*2.23 : 1*2.23 (you can simply cancel out 2.23 from ratio). What ISO does for astrophotography is two fold: 1. It affects full well capacity and your ability to record bright stuff like star cores properly. This does not mean you should use low ISO because of this - as there is another better way to deal with that - you just take a few short exposures that you use to replace over exposed parts in long exposure image (just scale data properly before blending). 2. It affects read noise - high ISO means lower read noise. Again - read noise is not something that should overly concern you if you know how to handle it. It is only important as long as it is largest source of noise - but with DSLRs in light polluted areas - it very quickly becomes unimportant. In any case - read noise should be determining factor for your exposure length - you expose until you swamp read noise with other noise source (like thermal or LP noise - both of which grow with time while read noise constant per exposure). All this means that ISO is really not that important - go with some nice middle value and if you want higher ISO - you can expose for shorter and if you want lower ISO - expose for longer so that read noise is swamped by LP noise for example. Simple as that

Have no idea what Tosh means :D, but I have two observations: 1. Hyper star is not diffraction limited system - far from it, it has very large spot diagram - I think that 1.46"/px for hyper star is over sampling. 2. I'm not sure if 5" refractor is able to achieve 1"/px in regular conditions. In the end, I'd like to add that I agree with you on 5" vs 11" hyper star - just try to make planetary image with 11" hyper star and you'll see how easily it can be out resolved by 5" refractor.