vlaiv

0.48 to 0.65 of what units? 0.48" to 0.64" (in arc seconds) is exceptional thing and requires belt modded and tuned HEQ5 mount. 0.48 to 0.65 of pixels (default unit if you don't tell it convert to arc seconds) - well that can be poor, average, good, exceptional - depends on guide camera pixel size and guide scope focal length. Any reason to use drizzle? Drizzle is algorithm developed for cases where you have undersampling and you want to try to recover missing resolution. In 99% of cases with amateur setups, one won't be having undersamping and I don't think that anyone is going to do research grade data reduction that requires restoration of missing resolution. On the other hand, when done properly, drizzle algorithm reduces your SNR, and why would you like to do that when the name of the game is get the best SNR you can. Reason why your stars look fatter than they should is because you drizzled - you increased pixel scale without effective resolution gain (you were not under sampled to begin with). When viewed 1:1 this is what your image looks like: Let's suppose you did x2 drizzle, that means that your image should look like this: Ok, now we are talking about nice looking stars rather than having them big and round. Starnet++ is neural network platform and as such - it is not 100% effective. It only "knows" how to deal with data that has been "taught" to deal with. If your image is too much different that data set that has been used to teach starnet - it will fail. People having newtonian scopes have issues because starnet++ does not know how to deal with diffraction spikes, for example. One of reasons why Starnet++ might be failing is drizzle. Try to do regular integration without drizzle and see if that improves things with starnet++

I'm not seeing much of chromatic aberration in the image above to be honest. If you are referring to the flaring of the bright stars - that is something that happens with refractors and can be due to either atmospheric scatter or in refractors to polish of the lenses. It happens on much more expensive scopes, so nothing to worry about. Like said - you might have a bit of issues with focusing or maybe seeing was particularly poor on that night. Maybe your guiding was not spot on, what ever the reason - stars are not quite pin point. If you suspect that you might have some residual color - try using Astronomik L3 or at least L2 as IR/UV cut filter. Just realized - image is titled drizzle_integration. I don't think that you need to use Drizzle - that might be reason for stars not being pin point.

You are using newtonian telescope and newtonian style telescopes have secondary mirror and what is more important in this particular case - secondary mirror spider support. Most of them have either 3 or 4 vanes but sometimes, and I believe that heritage 130 is such - it has single secondary mirror stalk. These cause diffraction spikes on bright stars and that is fact of life. Depending on a type of spider - you can get 2 spikes, 6 spikes, 4 spikes, etc ... Explaining why that happens is rather complex topic, but here is what you should know - spikes happen perpendicularly to each vane you have on your support - hence if you have single stalk you'll have two spikes or rather single line across the bright star. Now that we know how these spikes form - what can we do about them when observing double stars? Well, key is in sentence above - perpendicular to spike itself. Want to change spike direction so you can see companion star clearly? Change direction of secondary support - rotate your telescope a bit and spike will also rotate.

That is always a sensible option - get both, do comparison, keep the one you like the best and sell the other.

As John above said - you should be able to see Cassini division in your scope. I certainly saw it from my balcony few days ago with 100mm scope - a day before above images to the left were taken. You just need practice to spot those things now. As you gain experience - first thing that you will notice is that not each night is the same in terms of quality of the views. This is key for planetary - you need to recognize a good night with steady atmosphere. Good way to tell is to just look at the stars with naked eye - many stars twinkling - probably not a good night for planetary observing - few stars twinkling - probably a good night for planetary. No stars twinkling? Either grab your scope and go if you can see them, or stay inside because it's cloudy Moon is now very bright because it is almost full moon - larger area of it is illuminated and it really shines. Don't try to observe deep sky objects now because the moon causes bright sky and contrast is lost. Moon itself is best observed when it is not full first / last quarter and few days prior and after that are best. In order to know what to expect with Andromeda galaxy / M31, here is field of view of your telescope with 25mm eyepiece: You won't be able to put all of it into your eyepiece - and you'll probably only see central bulge. Look for M32 and M110 as markers - two gray blobs. If you get GSO 32mm eyepiece, view will be a bit better like this: You can use this website to check what sort of field of view you can expect from a telescope + eyepiece combination: https://astronomy.tools/calculators/field_of_view/

I'm not sure that anyone can answer that question if they did not have a chance to use both scopes side by side. I can give you theoretical answer to that question, but it's probably not going to be very helpful. In the end, performance will be very close between two scopes without a clear winner. Theory says that two things are important for "perfect" scope and planetary performance - or rather let's say potential planetary performance as atmosphere plays the most significant part and that is not instrument related. 1. Aperture size - larger aperture gives more resolution - more details can be seen on the planet 2. Central obstruction - larger central obstruction reduces contrast - planet looks more "dull" and this also impacts faintest features - as image gets "washed out" these small faint features get lost 90/900 has smaller aperture but has no central obstruction, while 130/900 is the other way around - has larger aperture and but has central obstruction - even spider support is very thick. On top of that, 90/900 is achromatic refractor and it shows false color - chromatic aberration (although it has little of it being slow at F/10) and that impacts the view, while 130/900 has spherical mirror - although this has been debated: In the end, there is sample to sample variation in both scopes and some will be better / some will be worse. What I can do is show you that aperture with these small scopes does not make as much of a difference as one might think. Here are images of Jupiter taken with 100mm scope and 130mm scope - in this case 130/900 Newtonian as I had that for my first scope: vs and vs Don't look at the size of respective planets - that depends on focal length, camera and barlow lens used - look at the level of detail. Not much difference is there? Btw, images show better detail than ever possible visually - explanation is too technical, but it comes down to processing of the image - something that eye can't do but software does in processing of the image.

Ah ok, yes Altair 102ed has FPL-51 glass and is not corrected for color perfectly. Unlike Altair 102ED-R which is newer model with FPL-53 glass and better color correction. With this scope, you'll most definitively need to refocus between filter changes and when shooting luminance - maybe it would be best if you get Astronomik L3 as that one removes violet and deep red parts of spectrum to suppress star bloating in such scopes.

What scope was this? If using refractor, you should really refocus on filter change. There is exaggerated focus vs wavelength curve: Look at dashed red line. Green is at 550nm, blue is at around 450nm while red is at 650nm - they all have different focus positions. Another thing to be careful with is what RGB filters you are using. Sometimes filters can have UV or IR leak at far ends of spectrum and that can cause star bloat. In that case - use UV/IR cut filter together with particular color filter. Btw, you can process above image in the following way: make it LRGB image and use Ha as luminance - because it is both sharp and captures most of the nebulosity. Human eye is much less sensitive to noise and blur in color than it is in luminance.

I used to have ST102 - and yes, that scope would complement Mak127 much better than ED80 for visual. Only things that I object with that scope are: 1. Chromatic aberration (not really that important for DSO - but sometimes it can bother you on very bright star clusters like M45 or if there is bright hot star in FOV). 2. Focuser is not very good 3. Fixed dewshield For that reason and given that you consider larger budget, I'm inclined to recommend this scope instead: https://www.altairastro.com/starwave-ascent-102ed-f7-refractor-telescope-geared-focuser-468-p.asp This scope still has a bit of chromatic aberration - but at a far smaller levels than ST102. It won't have that much field curvature and will be slightly easier on eyepieces at F/7 but will offer wide fields of view - enough to fit whole M31 into FOV for example. Other two points will also be sorted with that particular scope - it has very nice micro focuser and retractable dew shield.

I don't use filters much - even with the Moon. People say that Baader Contrast booster filter is good one - similar Neodymium moon & skyglow - as it emphasizes contrast. I know that it reduces chromatic aberration in achromat scopes, but so does plain old wratten #8 yellow filter. Only difference begin color cast - as yellow filter casts a yellow tint on the view while other two mentioned filters have rather neutral color cast. Here is very nice page on planetary performance of certain filters: https://agenaastro.com/articles/guides/visual-and-imaging-filters/choosing-a-color-planetary-filter.html Look at above list for planetary use and other than that - I would recommend you to get UHC filter for emission type nebulae. Are you quite sure you have Amici type prism and not a regular diagonal mirror? Diagonal mirrors are fairly simple to use - just put them in focuser and put eyepiece in the other end - regardless of type of prism/diagonal you have. It enables much more ergonomic observation than straight thru observation. You can have diagonal with 90 degrees - usually used for astronomical observations and one with 45 degrees - that is more for daytime use - spotting scope type of use. They are either mirrors or prisms. Mirrors reverse left/right / up/down - as mirrors do. Similarly regular prisms swap things (I think), but Amici prism is special as it presents "proper" image - upright and regular left/right. It is therefore much more useful for daytime observation as in astronomy there is no really up/down and left/right in outer space (it just depends on how observer is orientated / positioned). One drawback of Amici type prism is that it is hard to make quality one and astronomical quality ones are very expensive. Regular ones tend to put a "line" in the view and scatter light - this is because of the way prism is made. Here is what optical path in amici prism looks like: Roof line is the thing that creates that line scatter of light ...

You mean small refractor? I used to own SW 102 F/5 wide field refractor. I now own SW 102mm F/10 refractor - a small step up from your 90/900 in terms of aperture. I also have 80mm F/6 APO refractor which I primarily use for imaging rather than observing. I also had 60mm F/4 - but that was more guider/finder scope than anything else, although I did see some Messier objects with that small scope - but more for fun than any serious observing. Btw, I didn't say anything on your question on what you can see with 90/900. You can see a lot. You can see planets - all of them, but detail on each will be different. You'll be able to see phases of Venus and Mercury (although Mercury is rather tricky to see due to proximity of the Sun - I still have not observed Mercury), some albedo features on Mars - look for Mars in coming months, especially beginning of October - it will be placed good and quite large: 50 degrees of altitude and 22-23 arc seconds in diameter - very nice observing opportunity. Jupiter - you should be able to see main belts and zones and of course great red spot. Saturn - zones and ring system. Uranus and Neptune will be just dots - but you'll be able to recognize color of each. Moon is a delight in almost any scope - observe moon when not fully illuminated - you want some shadow on the moon as that helps with seeing features / terrain. For deep sky objects - you want dark skies. You should be able to see most of Messier objects and some more. I managed to see quite a few of M objects with 100mm of aperture from red zone light pollution of Novi Sad, so you should be able to do the same with 90mm if your sky is darker. Both planetary and deep sky observing requires skill that you need to learn and master. Planetary observation requires relaxed observing position and patience at the eyepiece - waiting for that moment when atmosphere calms down enough and finest detail reveals itself. With DSO observing - you need to get dark adapted and there are few other tricks that you'll learn along the way (tapping telescope as motion helps when trying to spot something on the edge of observability and such tricks). Just to point out - all deep sky objects will be just gray blobs and not much more. You should be able to spot structure in brighter ones with time - particularly star clusters and bright planetary nebulae. Almost forgot - you can observe Sun - with appropriate filter only!!!!. Never point telescope at the Sun unless you have suitable protective filters in place as it can blind you in an instant, cause burns or start a fire. This is also important for finder scopes - best to keep them covered or removed from telescope when observing Sun. Baader solar filter film is rather cheap and you can make your own filter with it (or just purchase ready made). http://www.teleskop.rs/teleskop/filteri/baader-astrosolar-solarni-filter Currently solar activity is rather low but we are past minimum and sun spots should be starting to appear. You'll also be able to see many features on the Sun - like granulation, faculae, ...

For that sort of money, best option is this: http://www.teleskop.rs/teleskop/na-dobson-montazi/2001200-dobson-skywatcher Only downside is that it is bulky telescope, quite large and heavy. You can disassemble it into two parts - Tube and base. Tube fits even small cars - in the back seat as it is a bit longer than 1m, and base should fit the car booth without issues. I transported mine to Fruska Gora like that in a small car. In two parts it can be carried by a single person. Tube is about 11Kg heavy, while the base is 15Kg heavy and somewhat awkward to carry around although it has handles. Btw, check this out, although there seem to be interested parties so might have been sold by now: https://forum.astronomija.org.rs/index.php?topic=7323.0

I use flat exposures in milliseconds and never had issues with my ASI1600 - it is cool model - one released before pro (I guess it was version 2 overall).

My first recommendation would be to take some time and learn how to observe / see with the kit that you already have. This is important for two reasons. First point being - indeed one learns to see, as time goes by you will see more and more. Second point is that you need to see how interested in this hobby you'll be in a long run. Based on that, you can make decision to either invest more money or just use what you have for casual observing now and then. Just changing your eyepiece set and diagonal for something a bit better will quickly reach the price of your scope. Good thing is that eyepieces and other bits stay with you even if you change the telescope (unless you choose to upgrade them also at some point) - so it is long term investment, and that is of course reasonable only if you are committed to this hobby. Having said above, here is what I would recommend in terms of eyepieces and upgrades. This is something that you don't need to think much about - get 32mm GSO Plossl. My only concern is that your current diagonal, if indeed Amici prism and not simple diagonal mirror will have issues with vignetting this eyepiece. This eyepiece will give you widest possible field in 1.25" format at a good price and with very decent performance. It is eyepiece worth having for wide fields and as finder eyepiece. Easiest way to get one would be from here: http://www.teleskop.rs/teleskop/okulari/gso-ploessl-okulari (don't be tempted by 40mm one - no much point in going for 40mm as it will have narrower field of view and in principle show you same amount of the sky as 32mm) Second recommendation would be to change diagonal mirror for something better - both optically and mechanically: https://www.teleskop-express.de/shop/product_info.php/info/p1771_TS-Optics-1-25--TS-Optics-1-25--Star-Diagonal-with-ring-clamb---99----1-12-Lambda.html would be a good choice. I use it with my Maksutov 102 and is indeed very solid diagonal mirror. In the end, eyepieces that I would recommend to get are these: https://www.firstlightoptics.com/bst-starguider-eyepieces.html for general eyepieces and this one in particular for high power views: https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-62-series-ler-eyepieces.html 5.5mm one.

Cone error is rather easy to check, it takes just a 10-15 minutes. Take a star that is about to cross Meridian and go to it - take exposure. Wait for it to cross Meridian, do another goto, scope should change side of pier - take another exposure. Compare star position in two exposures - difference in position is due to cone error.

In Bortle 9 skies you probably won't need to go even that long with your exposure. I think just a couple of seconds per exposure will be needed - this of course means almost any decent mount will do - as long as it can carry your scope / camera combination.

Hi and welcome to SGL. First of all, both stock barlow lens and 10mm eyepiece that come with that scope are not very good/sharp. Second thing is that such combination is probably providing you with too much magnification for your scope. In theory, you should be fine with x180 but in practice only very sharp optics can do than and air / atmosphere needs to be steady. There is a lot of things that you can do to improve your views of the planets like: 1. Place your telescope on the grass surface and not concrete / pavement. Let it acclimatize to ambient temperature - leave it sitting for about hour or so. 2. Make sure you are not viewing over any houses or roads in summer. Concrete buildings and pavement absorb heat during the day and create thermals over night. It is like looking things over camp fire - everything shakes and image is blurry. 3. Be patient when observing planets - try to find best focus and wait for moment of good seeing when things become better. 4. Try to view with only 10mm and no barlow - less optical glass of dubious quality and less magnification. Things will be smaller but sharper and will have more contrast. With more experience you will learn to distinguish between good and poor atmospheric conditions and you will know when is good time to observe planets.

Two things come to mind here: 1. thermals - did C5 get a chance to cool properly on both nights and was second night thermally unstable (like getting cold quickly so scope could not keep up)? In any case this can cause issues for Cat vs refractor on second night 2. Type of seeing effects / aperture size. Effects of seeing change with aperture size. There is something called coherence length and coherence time. This is related to seeing cell size and especially to relationship between cell size and telescope aperture. Small apertures usually "fit" inside seeing cells most of the time and as result main seeing aberration is tilt - image shimmers rather than blurs. Larger apertures usually don't fit inside single seeing cell and this changes dominant aberration - it is no longer tilt and image starts to blur rather than only shimmer. Blurring is responsible for detail loss much more than shimmer. For this reason it is said that smaller apertures better tolerate poor seeing.

Two things come to mind: Vertical line is usually associated with Amici prism either 45 or 90 degrees. What sort of prism do you have in that scope? Can you view image in daylight - like spotting scope and is that image properly oriented? If so - prism could be par of a problem here as such prisms are usually low in quality (astronomical grade Amici prisms cost a lot of money). Second - it seems that focuser mechanism is not good / mirror is slipping. In no way there should be sudden change in focus - it should be gradual with normal working focuser. This could also mean that mirror is not fixed properly and that it also changes position - which would cause changes in collimation depending on where you point the scope.

Oh, I did not notice that - would have thought they have it in stock, but probably issues with supply at the moment.

My approach is to remove background and then stitch images while data is still linear. Once you have stitched larger versions - then proceed as usual.

I would rather go for 38mm version as it provides about the largest FOV one can get from 2" eyepiece. Here is comparison: I have ES82 6.7mm and 11mm. Both are excellent eyepieces and only drawback is that eye relief is tighter than stated - or rather feels tighter. 82 degrees eyepiece really requires one to get close to be able to see it all to the field stop so eye lens of eyepiece is recessed slightly and that makes it feel like tighter eye relief eyepiece. In any case, to me 11mm feels just a bit sharper than 6.7mm, but that could easily be down to seeing and optics used. When I compare 6.7mm to 6mm BCO on any given night - they render same level of detail and sharpness to my eye (well difference being magnification and FOV only really). I'm planning on adding 8.8mm so I guess that 14mm version can't be bad either (however I'm not 100% sure on that - I have not tried it). From a quick search on people's opinions on this EP - most consider it very sharp and often say it's their most used EP - I guess than it has to be as good as others in the line.

Since you expressed interest in 82 degrees FOV, how about ES82 11mm I can't speak highly enough about my sample - probably the sharpest eyepiece I ever used. Looking at your EP collection - I think you are missing ultra wide field one? Not in terms of apparent field thru the eyepiece, but rather maximum possible field of view for ED100 telescope - something that you can use now in summer to sweep milky way and observe large objects like M31 for example? Given your budget and what I said above, I guess this would be my recommendation: https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-82-degree-series-eyepieces.html 11mm version for £129 + https://www.firstlightoptics.com/ovl-eyepieces/panaview-2-eyepieces.html 38mm version at £86 bringing total to slightly over budget £215 + delivery.

I could not play that video but I have strong suspicion I know what is going on. Something like this: (if you can't see the animation above - open this link in new tab: http://serve.trimacka.net/astro/Forum/2015-11-21/post_01/RA_vs_DEC.gif ) Linear drift is related to polar alignment - better polar alignment - slower drift. Zig/Zag movement is related to something called Periodic Error of the mount. Drive train of the mount is not perfect and circular components are not quite circles (but rather egg shaped - on a small scale). That is due to manufacturing tolerances and all - you simply can't make perfect circle. Two way to deal with periodic error (PE) - first is periodic error correction (PEC) and second of course is guiding. PEC can fix things to varying degree - sometimes providing larger benefits and sometimes only minor - depends on what the error is like. If it is "in sync", or rather all oscillatory errors are harmonics of main worm period - PEC can go a long way. On the other hand if PE consists of unrelated frequencies so baseline frequency is not related to worm period - there could be almost no improvement at all. In reality it is somewhere between the two and more often closer to first case - after all gears are made to power worm and it is likely that their period will be harmonic of worm period - so PEC is something worth doing. From what I can see, this mount has PEC capability so consult your manual on how to enable it and do the training. Guiding is self explanatory - and I would advise you to look into it. Maybe off axis guider would be good match for that scope.

It tells you mostly that your OTA is not parallel with your RA axis. This can happen regardless of polar alignment and most notably it is called cone error. You seem to have a bit of that (scope is pointing upwards / downwards of where it is supposed to point when in home position). Again not related to polar alignment - that is related to orientation of your camera. Rotate camera in focuser and you will change direction of star motion when you slew in RA or in DEC direction.