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Not to mention that ST102 is F/5 achromat that has enormous chromatic aberration - you'll shoot just a blurry mess of color rather than a planet.

Unfortunately, this is DIY thing as far as I know. Actually scratch that, according to this thread: You can apparently order those online, like from here: https://www.fpi-protostar.com/crvmnts.htm If you want to DIY those, you'll need a thin piece of metal that you'll bend into shape (smoothly) - 180 degrees one works good. Things to remember when choosing spider support - you need at least 180 degrees arc - less than that and you'll have only partial diffraction - only in certain directions and not evenly spread. Length of support is related to strength of diffraction - keep the length at minimum. Make sure all "degrees" are covered equally - having for example 270 degrees which will be 180 + 90 degrees - these 90 degrees will bias diffraction to one side. There is a free software that will calculate resulting diffraction from central obstruction (and support) - let me see if I can find that for you. Unfortunately I can't seem to find it, but @sharkmelley used it back in 2013 to explain some phenomena so could possibly provide a link to that? (I found link to software in the mean time): https://www.cloudynights.com/topic/547413-where-to-find-maskulator/ I just thought of a very quick way to remove diffraction spike on Heritage 130p - it is very easy thing to do and in principle it is "external" to scope - no modifications needed, but you will need to make aperture mask. Take cardboard and make mask that you will place over the stalk that holds secondary mirror. Be sure that you have nice clean cut. So it is just a series of circles (can be smaller or bigger) that you tape together to cover the stalk. Just be sure you secure them in place and they don't fall onto your primary mirror. Black cardboard works the best of course. This will remove diffraction spike.

I agree that color perception will be different under difference circumstances and that is why we have standards - like sRGB. Images are supposed to be encoded in sRGB standard when viewed at computer monitor because that will render most closely resembling color as if object was viewed in conditions defined by sRGB standard. These parameters correspond to viewing conditions most people use computer monitor in. Dimly lit room with neutral background (white wall within dimly lit room), etc ... This is irrespective of perception and it is related to spectrum of recorded light. You are partially right that one needs to examine spectral content of the light - but luckily our vision is based on tri chromatic system and we don't need a full spectrum in order to reproduce color. We just need to provide three values in particular color space. For CIE XYZ space, here are matching functions: If you compare that to your camera response, you'll notice that these functions are different. Even if we take CIE RGB space (not to be confused with sRGB space): Still not the same. First step would be to create color transform matrix from camera space to some absolute color space like XYZ. After that we have standardized transforms to common color spaces like sRGB. Depends on what your image represents. Does it represent an image that observer would see at an eyepiece of a telescope somewhere on the earth (thus looking thru earth's atmosphere) or does it represent image that observer would see when looking thru a telescope in orbit - or floating in space some distance away from Jupiter? Both cases can be represented in such way that "observer" sitting in their dimly lit living room and looking at properly calibrated computer screen would see the same color as their respective counterpart. One just needs to apply proper set of transforms for their camera and wanted outcome (in case of telescope on earth - simple camera -> XYZ -> sRGB linear -> sRGB gamma encoded, while in case of observer in outer space camera -> remove atmosphere influence (blue scatter attenuation) -> XYZ -> sRGB linear -> sRGB gamma encoded). Most people do following to their image: raw_camera_values -> null transform to sRGB -> color balance using some some automatic algorithm No proper encoding of gamma in sRGB, treating camera RGB values as if they were sRGB linear values and doing automatic color balance based on algorithm (usual grey world or similar algorithm that just assumes that all RGB components should be equally represented in regular image and that on average world is "grey" - very poor assumption when you have subject like Planet that can have distinct dominating color). Now we have a huge problem - problem of what people are used to. If you do yellowish Jupiter and explain to people that this is what Jupiter looks like thru the eyepiece - they will say that it "does not look good" because it is different than most Jupiter images that they've seen in their life - all being wrong because all of them are done with same wrong processing.

Never fully understood this stance. Color is what it is - take an object and image of that object and look at them and if color is the same - it is proper color rendition, if it is not the same - color is off, simple as that. Fact that we can't take Jupiter and place it next to our image of Jupiter does not change the fact that Jupiter has certain color and we should be able to capture it properly. Take two images of Jupiter and if you process color properly - they should look the same color wise - have same hue, same saturation, etc ... We don't even have issue of lighting here - planets are always illuminated with same light source and we know spectrum of that light source.

Just realized I did not answer the question, but since I don't do double stars much, I can give what I think would be probably best beginner double star instrument taking all things into account (budget also). 6" F/8 newtonian with thin curved spider and 20% secondary obstruction would be my choice.

Not all reflectors have diffraction spikes - even newtonians. Diffraction spikes are feature of straight spider vanes. Curved secondary support when done properly does not produce spikes and many people that don't like spikes for planetary or double star work modify their telescope with curved spider vanes.

Ok, this is going to need a bit of explaining again, but this will by the easiest bit by far so bear with me. Here we are dealing with "digital" phenomena. Both image is digital as being collection of numbers or pixels and display device is digital - again having certain number of display dots or pixels. Both have certain resolution - here term resolution is used to denote number of dots / pixel count or "megapixels". Easiest way to display image on the screen is to assign each pixel of the image (a number value) to corresponding pixel of display device (light intensity corresponding to that number value for each display dot). This is so called 100% zoom level or 1:1. First of these two gives "scaling factor" (we will talk about that in a more detail shortly) while other just says the same with ratio of two numbers 1 divide with 1 gives 1 and that is a whole value or 100%. Problem with this approach is that not everyone has same resolution display nor images all come in same "standard" resolution. Images vary by size (pixel count) and so do display devices. We now have 4K computer screens while old mobile phones have resolutions like 800x600. That is quite discrepancy between them. For that reason we scale image - we don't change it - it remains the same, but we rather change mapping between it and the display screen. Most notably there is "fit to screen" scale mode. It will fit whole image - however large to pixels that are available on screen. Let's say you have 1920 x 1080 computer monitor and you have 5000x4000 image. Image will be displayed at 26.74% of its original size in order to fit this screen. Or in another words it will be displayed at 1080 : 4000 ratio (it will use 1080 pixels available to the screen to display 4000 pixels of image). This means that image is scaled down for display - again image is not changed - it is only displayed differently. Numbers in PI in window title like 2:1 or 1:5 - show current display zoom in the same way. First one 2:1 - means that image is zoomed in x2 since 2 screen pixels are used to display single image pixel. 1:5 means that image is displayed at 20% of original size since one screen pixel is used to display 5 image pixels (it won't display 5 pixels at the same time - software and computer chooses which one of 5 pixels will be shown but to our eye it looks as it should). Now we understand display scaling - 1:1 and fit to screen "modes" of displaying the image. Two of these are very important - 1:1 and Fit to screen. Fit to screen shows whole image at once regardless if image is larger or smaller than screen - it will zoom in/out just right amount to be able to display all of it. It is very useful for viewing image as a hole to see composition in the image and to see relation of target to FOV and such. 1:1 is also very important as it shows image to the "best level of detail" that current display device can show. If you look at your screen with single pixel turned on - you should be able to see it. Computer monitors are made so that you are seeing finest detail in the image when sitting at normal distance away from it. We should make our images the same - we should optimally sample the image and when we display such image in 1:1 mode - it should look good and sharp. You can always recognize if image is over sampled when looking at it at 1:1 zoom level. Are stars small and tight / pinpoint like or are they "balls of light"? Now the final words related to this. Software does not see pixels as little squares or dots of light. Software considers pixels to be values with coordinates. In some sense, software always see image as 1:1 or 100% scale. When you zoom in or zoom out image when looking at it in PI - you are not changing the image itself. That will have no impact on how Starnet++ sees it for example. If you rescale your image in software then you are actually changing it and rescaled image will appear differently to Starnet++. Rescaling changes pixel count of the image, while zooming in and out does not do anything. Drizzle integration rescales your image - makes it have more pixels (x2 or x3 - depending on your settings) and this is why it looks larger - because it is larger, however detail in the image does not change (it is supposed to change - that is why algorithm has been developed in the first place - but even if it does change and resolution is restored - that happens under very specific circumstances - like original image is under sampled and you dithered and all of that). It is the same as if you took your image and upscaled it by factor of x2. Stars now have more pixels across and when we view that image in 1:1 or 100% (As software sees it) - stars look bigger than in original image. Starnet++ has probably been trained on properly sampled images with tight stars and that is why it has problems when stars have many pixels across - it just can't tell star from a nebula feature that has many pixels across (it expects stars to have just few pixels across). Hope all of this makes sense and helps?

I just realized that there is probably more down to earth way to explain things. For example first part relates how different things that blur image add up. Here is intuitive way to understand it (and to try it out) - take any image and do gaussian blur with sigma 1.4 for example. Do another round of gaussian blur with sigma 0.8. Resulting image will be the same as if you did just one round of gaussian blur with sigma of not 2.2 (1.4 + 0.8) but rather of ~1.6 which is sqrt(1.4^2 + 0.8^2). So blurs add in quadrature and three main blur types are seeing blur, guiding blur and aperture blur. In any case, it is a bit complicated stuff, so main point is - you can't really use lower sampling rate than about 1.7"/px when using 80mm of aperture and in most cases you should go for 2"/px - that is if you don't want to over sample. I honestly don't know. I understand drizzle algorithm. I have my doubts if it works at all and how good it works in general case - but that needs further investigation. I have improvement on original algorithm that should work better if original algorithm works in the first place (yes, I know, it's funny to improve on something that you don't think works in the first place). However, I don't understand how drizzle is implemented in pixinsight - so I can't comment on that one. I think that DSS implementation is straight forward, but interestingly enough - original algorithm calls for 2 parameters not one so I don't know how ticking x2 translates to two parameters. Original algorithm asks for - resulting sampling rate and pixel reduction factor. x2 is directly related to resulting sampling rate. It will enlarge image x2 hence it increases sampling rate by factor of x2. However, you don't need to reduce original pixels by factor of x2 - you can reduce it more or less as per original algorithm and I have no idea what selecting x2 (or x3 in DSS) does with this parameter.

They look the same - this means no improvement from drizzle, but they are not the same with respect to starnet++ Left image is zoomed in x2 while right one is zoomed in x4. As far as Starnet++ is concerned - stars are twice as large in left image than in right image.

Ok, I'll be brief and to the point since this is rather technical, but here it goes: - we can approximate resulting star FWHM from aperture size and corresponding Airy disk, seeing error and guiding error. You need to convert everything to "sigma" of corresponding Gaussian approximation. Guiding error is already given as that. Seeing is converted by dividing with ~2.35482 (that is two times square root of two times log of two - a conversion factor between the two FWHM and sigma for Gaussian) and Airy disk is converted to sigma by conversion factor of 0.42 / 2.44 - this is for Airy disk diameter. You take these three and calculate resulting sigma as square root of sum squares. Multiply with 2.35482 to convert back to FWHM - As for sampling rate, it is about Nyquist sampling theorem and star PSF gaussian approximation of certain sigma/FWHM. We can get that with following approximation: Fourier Transform of Gaussian is a Gaussian. We take a frequency of Fourier Transform that has value less than arbitrary threshold - for example 10% and we see what is sampling rate that corresponds to this frequency (twice max frequency). If we do the math, it turns out that FWHM/1.6 is a good approximation as frequencies beyond that are attenuated more than 90% and hence can be neglected.

Excellent! I also have Heq5 that I tuned and belt modded myself and indeed it runs at about 0.5" RMS when sky plays along (had it once at 0.38" RMS!!). Astro tools gives general advice and I don't agree with some of their calculations and recommendations. One of those being sampling rate. Here is example: In no universe will any amateur with scope less than 8" benefit from sampling rate of less than 1"/px, but they say 0.67"/px is fine. For 2-4 FWHM seeing and 80mm scope, even with excellent guiding of 0.5" RMS, star FWHM that you can expect will be 2.71" to 4.4". With those star FWHM, sampling rate should be (FWHM/1.6) in range of 1.7"/px to 2.75"/px and not 0.67"/px-2"/px You are at lower bound of that so there is a chance that you are slightly oversampled rather than undersampled. General rule is that for 80mm scope you want to be at around 2"/px. If you wish, we can go into a bit more detail on sampling resolution and FWHM and all of that so I can explain reasoning behind what I've just written but it is a bit technical,

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.