 This video is sponsored by Rainbow Black, a new novel by Maggie Thrasch. These are all refractor telescopes with about five inches of aperture. And let me break that sentence down. A refractor means that the telescope focuses the light coming in using glass lenses. And aperture, you can think of that as how big is the telescope. What aperture technically means is the diameter of the primary lens here in the front of the telescope. And the reason that people are interested in telescopes with larger apertures is the bigger the telescope, the bigger the light bucket, allowing us to see smaller and fainter details in those deep sky objects out in the night sky. In simple terms, you can think of a telescope as an extension of your eye. So the bigger that you make your eye, the more that you can see in the dark. And with visual astronomy, that matters a whole lot. It's often people's top priorities to get a big light bucket, a big aperture, which is why reflectors are very popular because it's much cheaper and easier to produce a big mirror than it is to produce a big glass lens. With photography, there are a lot of factors, though, that can even outweigh aperture when it comes to getting very high quality photos. You know, for one thing, the mount is incredibly important when doing photography, astrophotography. So while this review is going to focus on the optical tubes, the telescopes that you put on the mount, you definitely can't skimp on the tracking mount if you plan to use a telescope this big for astrophotography. And there are other accessories like an auto guiding system that make the mount even more accurate that I did use when I was testing these telescopes for this review. So why am I reviewing these three five-inch refractors? I've previously done these kinds of shootouts at two and a half inches, three inches, and four inches with refractors, and with each shootout, I'm trying to do multiple things at once. One thing that I'm always interested in is a kind of value-to-performance ratio. So I try to pick telescopes at very different price points. So value and price is one thing, but I'm always trying to learn something new. So to test common theories that you hear about buying telescopes, and in this video I'm interested in two things. First, both the SV Bony and the Skywatcher are APOs, meaning that they are triplets that use extra low dispersion glass, and both actually list the type of ED glass they use. The SV Bony uses FPL51, and the Skywatcher Esprit uses FPL53, which is a higher quality. So I'm very interested in knowing, you know, with these glass types, what the difference is when it comes to false color fringing around bright stars, because that's usually what we're looking at in evaluating ED glass. Skywatcher says that it's virtually eliminated, while SV Bony says chromatic aberrations are significantly reduced. But, you know, it'll be interesting to see what those statements actually mean in a real head-to-head. And if that wasn't enough, I'm also interested in a theory. The theory is that the acromatic refractor may be just as good as the more expensive apochromatic refractors if you use narrowband filters. So for the inexpensive telescope, I bought this one. This is the AR127 from Explore Scientific. It is an acromat, meaning that it's a doublet with two glass elements, and neither glass element is ED glass. This telescope is well regarded, I know, for solar imaging with a day star quark, where you're only, you know, focusing a tiny wavelength of light right in the H-Alpha emission line. But I'm going to be trying it with 5 nanometer astrodon narrowband filters. So much wider band passes than a solar filter, but still pretty narrow compared to what we do with broadband. So we're going to see if this theory holds up. I've tested each telescope with both a one-shot color camera and a mono camera with narrowband filters. Both these cameras are full frame with the demanding IMX455 sensor, thanks to ZWO, who has lent me these two cameras so I can do this kind of high resolution testing on my channel. Let's now jump into the physical characteristics of these telescopes, starting with the Explore Scientific. And starting at the front here, this telescope has a fixed dew shield, so you cannot retract this. It's all one piece, which makes it a little bit longer to store. It is a glossy white. And then working our way down, it has a Vixen style dovetail. Only two holes in it, where you can attach the rings, because the rings have to be at this distance apart to support the top handle. So it's all just sort of one big fixed unit in a way. You could take this Vixen dovetail off and put on a longer plate, but you would still need the mounting holes to be in these two spots if you wanted to use the top handle, of course. But all of this mounting gear seems pretty well done. I will say that for some reason they put on this shiny metal plate, screwed on this shiny metal plate on one side of the Vixen dovetail. And I'm not sure what its purpose is, because on a lot of my mounts, all it did was prevented me from actually being able to slide the dovetail into the saddle, because I feel like it made the Vixen dovetail a non-standard width. While if I took that off, it's the standard Vixen dovetail width. So I'm not sure why they did that exactly, maybe to for some systems where it's not a clamp style like this. It's a screw right on the plate. It's to prevent maybe marring of the plate. That's my guess for why they did that. Okay and then working our way back here they've screwed the finder shoe right onto the optical tube, which I don't know. I think it's pretty nice because it puts this higher so I can actually use a guide scope here. But there's also a channel up here in the top handle if you want to do attach a guide scope up there. But this is elevated enough and the fact that it's on the tube means you can use a guide scope successfully right there as well. Okay and then moving our way back here to the focuser. This is dual speed. It's a two inch focuser. I think it's a crayford style. Pretty cheap seeming, you know, not not a substantial. But it does have the markings for distance. If you take off this compression ring there's 48 millimeter threads back there and it does have both a tensioning and a locking knob on the bottom. I'm not sure if it's possible to automate this focuser or if you would want to, but you probably could take the whole focuser off and replace it with a third party focuser pretty easily. To explore scientific with cap off but rings and dovetail installed weighs 13 pounds 14 ounces or 6.3 kilograms. Okay here's the SV bony. It has a retractable dew shield and there are little screw holes here for retaining screws to keep this up but they were missing in the review copy I was sent. This review copy has been with many other reviewers so I think they just got lost at some point but there are three screw holes here for little retaining screws on the dew shield. It is a matte white with a little bit of shine to it. Okay and next up we have the rings and dovetail. It is a vixen dovetail pretty standard one with a few holes different options for where to put the rings. Both the rings and the dovetail have a lot of cutouts. I think this is you know to keep the weight down and it is a very light scope for how long it is. The rings have like a very thin tape-like thing to protect the scope from metal on metal and then this knob right here towards the back of the scope is for rotating the entire focuser. So the entire focuser rotates like that and then you can tighten it up like this. I typically prefer the manual rotator to be back here on the tube rather than up here rotating the entire focuser because sometimes this can put things at awkward angles but you could also make the argument that it allows you to put the focusing knobs at any angle you want which could be beneficial. Okay it has two spots for Cinta shoes. The copy I was given came with one Cinta style finder shoe. If you had a guide scope with some height to it it might be able to clear the rings. I can tell you that the William Optics Unigide don't work with this placement of the finder shoe so I ended up putting my guide scope on top of the rings here which do have tapped holes for attaching you know a guide scope directly or putting on a top plate and then putting your guide scope on the top plate. The focuser is a rack and pinion style. It's not the smoothest I've ever used. It's a little bit noisy. It does have a lock here on the bottom. It's two speeds and it does have markings for how far you have it racked out which is nice for repeating focus and the field flatener which is included in some bundles screws on right on to the end of the tube here. So you take off the visual back and screw on the field flatener and it comes with this adapter to end in m48 threads and then from there you have 55 millimeter back focus to your camera sensor. The SV Bony with cap off but rings plate and flatener installed weighs 14 pounds 11 ounces or 6.6 kilograms. The SV Bony that I was sent didn't include the case that they're now bundling it with but I can see online that it's a soft sided case and this is the bundle that I would recommend. I'd recommend getting the telescope with a case and with the field flatener if you want to use it for photography. If you're not planning to use it for photography for some other use then you could get the OTA only and save a couple hundred dollars but bundle one includes both the field flatener and the case. Okay starting at the front here we can see it's printed right on there. This is the Skywatcher Esprit 120 ED Super Apo Triplet. The dew shield is retractable that far and it's held on by two screws here and I will say that it does have a lot of play. You can see it's moving quite a bit back and forth but at least on this copy so far if I put both of those down lock both of the you know locking screws down then there's no play. It only has that play when these are loose so I'm not sure how big of a deal that would be or if it pose any issues over time. Okay going down the telescope here it has these really nice substantial thick rings that are felt lined to protect the telescope finish and a good green Skywatcher Green Laws Mandy plate here so if you have other Skywatcher things like this EQ6R mount it works really well with the the whole color scheme. Okay and now we're looking at the top of the rings I just wanted to show you that there are five tapped holes on the top of each ring for attaching a top plate or other accessories on top here. Okay and then continuing down the scope this is called a captain's wheel and it's one of two methods of rotation with this telescope. If you loosen this up it rotates the entire focuser and it's not my favorite but it it it does tighten quite well. I think I have it so tight right now I can't even get it undone but I'm sure if I really tried or I got a better angle on it I could and so because this rotates the entire focuser it can put the focusing knobs at sort of odd angles but you also have the option if you want of putting the focusing knobs on top which some people do like doing that for whatever reason you know maybe having to do with adding an electronic focuser and how you want the bracket positioned and things like that. Okay and then continuing down here after the captain's wheel we have the focuser this is a 3.4 inch rack-impinion focuser dual speed of course. It does have a you know the rack-impinions on the bottom here that you're not seeing but then it also has this additional steel rail here on the top I guess just to make sure there's no rotational play in the focuser and this is actually fairly rare I don't see this in too many telescopes so I I think it's a cool addition because I don't you know it prevents the focuser tube from having much play there and then of course it has the markings here so you can get repeatable focus so for instance if you found okay if I hit focus at around five centimeters then you can you can rack it out to that again the next night and I know that you're very close to being in focus. Okay and then back here we have the second method of rotation this is two rings that you and again it's but getting a good angle there we go that you loosen up and then that allows you to rotate the whole camera differently than how the focuser is rotated and then when you're happy with that rotation then you lock it down with this top ring here. It's not my favorite I I think I'd rather have just a little you know locking nuts like as on many focusers just because I think these glossy metal pieces are really hard to grasp especially when it's cold but maybe they do a better job of really locking down rotation I'm not sure my complaint though is just that it's hard to do especially in the cold with like you know you can't do it with gloves you have to take your gloves off and then if it's if it's a winter night and I was testing these in February so it was a winter night it was it was pretty difficult to grasp those when those are cold pieces of metal. Okay and then behind that I just have here attached the included 1x flatener you take off the visual back and add this on uh there's also a optional reducer available from Skywatcher and also one from Starzona they the Apex reducer which reduces even more the Skywatcher one reduces I think 0.77x and the the Apex from Starzona is a 0.6 with cap off but rings plate and flatener installed the spree 120 weighs 22 pounds nine ounces or 10.2 kilograms the spree 120 includes this really nice premium roadie style hard sided case with wheels for rolling it and you can you can have it in this orientation or also put it up vertically like that especially when you're rolling it that's how you would do it it has handles on three sides a substantial handle there and then two other handles on the short sides and then on the inside it comes custom cut with all these cutouts for the different accessories that are included including a right angle corrected finder diagonal for visual and all the different adapters you'll need to use it with the field flatener and things like that and then this is a really cool thing with the spree cases it has these racquet balls built in to protect the telescope and before I jump into looking at all the images taken with these telescopes let me tell you a bit about this video's sponsor the novel Rainbow Black when I want to de-stress I love to get lost in a good novel just to get wrapped up in an engaging story is my favorite kind of entertainment and if you're the same way I have a great book here to recommend Rainbow Black is by author Maggie Thrash who is actually a good friend of the channel and you've seen her in previous videos that I've made she helped me make this one that went on to be my most popular video ever and Maggie's new book is out this week it's getting great reviews and it's quite the epic it takes place over a period of 16 years in the life of a young woman whose parents are falsely accused of satanic ritual abuse and a lot of the book is a legal drama it's seen through the eyes of the protagonist a child as she grows up in and out of courtrooms I think this is a fresh take on the legal thriller and it feels a lot more real than a lot of thrillers I've read because the main character is so fleshed out and raw it's my favorite book that Maggie has written and also I'm biased but my favorite book I've read in years so if that sounds intriguing to you you can get Rainbow Black now it's available on Kindle in paperback and as an audiobook okay we're now going to look at images that I took with each telescope these imaging tests were done over two nights one for one night for the one shot color tests and one night for the mono narrow band tests and you can read all the tech details here you could pause the video and just read through the you can pause the video and just read through these if you want because I'm not going to read all of these out but just to sum it up the one shot color tests were done with the moon not visible behind the treeline at least and I did three-minute subs with no calibration guiding was good it was in an observatory the object was high in the sky so as many variables I'm trying to sort of you know take out of the picture as possible so we can really get a fairly fair test between the telescopes and then the mono test very similar except I was using the 6200mm camera and neuroband filters from astrodon but the guiding was good again and this time I did five-minute subs per filter five each for the HA and 03 so that's it we're going to now look at the images and I'm going to start here with single one-shot color subframes and again these are not calibrated so here is the explore scientific ar 127 and as we would expect from an acromat we have a lot of visible violet fringing on all of the bright stars here's the sv bony 122 with the reducer so the reducer definitely has some vignetting that you can see that there's a brighter part of the field here in center and then here is the sky watcher esprit 120 and it looks pretty perfect this tiny little bit of vignetting in the corners I suspect is from the 48 millimeter threaded adapters I was using not from the scope itself okay and then now we can just quickly look at the center and corners for each scope so the explore scientific I was not using a field flagner because it doesn't come with one and there's there isn't one suggested on their website so you can see the corners are fairly elongated and that's just from not using a field flagner but here in the center we can see it's a lot sharper but we do have that violet fringing that is common with an acromat and then here is the sv bony and it looks a lot more even and flattened out because I was using a flattener reducer and then here is the sky watcher and you can see the sky watcher we don't have the darkening of the corners and the stars look pretty much the same across the entire full frame field well if we look closely at the stars on the sv bony when you look at the bright stars on the edge of the field they get a little bit funky you can see that that halo has some bites out of it and then over here you can see it's a little bit distorted with some split chromatic aberration while if we look at the same on the sky watcher spree they just look perfect no matter where we look even in the extreme corners these look near perfect maybe a little bit of chromatic aberration in the extreme corners but not much distortion to speak of they look perfectly round which suggests it's a nice flat field okay and then now I have the stacks and stacks will you know just any problem optically will just show up even stronger so the the violet fringing shows up even more in the stack than it did in the single frame the vignetting from the reducer shows up even more of course if i had calibrated these with flats that wouldn't show up like that but i'm just wanting to show sort of without calibration what to expect i was also trying to do these tests very quickly so that's another reason i didn't take flats okay next let's look at the center of each stack and this i picked this center because it's you know where the tadpoles are so we can sort of look at the level of detail in the tadpoles but also of course be looking again at the star performance and you can see that the explore scientific the it's it's not just the violet halos the stars are also a lot softer than they are here with the sv bony or the sky watcher spree at first glance here this is just with the screen stretch applied the sv bony and the sky watcher spree look very very similar while the explore scientific of course is sort of the odd man out here let's try to see if we can sort of amp up the differences here between the sv bony and the sky watcher and the way to do that is sort of an extreme saturation test so if we apply just a lot of saturation to each of those crops um that's what happens to the explore scientific i'm just going to close that because i'm not super interested in that one but what i want us to look at here is the difference between the sv bony and the sky watcher spree because remember this is one of the things i was interested in with different types of ed glass this is the fpl 51 on the sv bony and the fpl 53 on the sky watcher can we see a difference in how well it controls chromatic aberration in the center of the field with this extreme saturation test and yes we definitely can so i thought this was a really good test just to sort of prove a point here okay i just i've just zoomed in just a little bit more just so you can really see it in the video if we look at the stars on the sky watcher here there's a little bit of splitting and some people have pointed out that that kind of split might actually be from the atmosphere even high up you can still get some kind of atmospheric dispersion that can cause a split when you do these saturation tests but what is really clear is if you look at all of these bright blue stars over here in the sv bony we are getting violet fringing on those and on the sky watcher they're just looking perfect even this with this super amount of saturation and then if we look at this bright yellow star right down here in in the sv bony it is getting sort of a split color while here it just is not it's just looking it's looking really nice same sort of deal up here with this bright blue star up here we're going we're getting violet fringe on one side of the star and this one it's maybe a little bit green but that just might be noise and i think it's looking just a lot better so this i hopefully makes makes clear what are you really paying for with fpl 53 versus the fpl 51 it's it's a if you're really you know demanding on on color and with bright sources like stars it's going to make a difference now if you look at the nebula you can see the nebula looks basically identical in both shots okay and then that was one thing that i wanted to test the other thing that i wanted to test was how does an acromat like the explore scientific hold up with mono and narrowband filters because a lot of people say if you use it that way it's it's it's pretty amazing how good it is and i actually found this to be true i was shocked at how good this was here is the h a uh five subs stacked and then let's compare that to the sv bony and the sky watcher spree okay and i these are much closer than the one shot color examples and just for people interested here's the oh three for each the oh three on the sky watcher is definitely the best of the batch partly just because the vignetting was definitely accentuated without flats while this has just such great field illumination that it turned out really well but also i'm just seeing much better contrast with the sky watcher compared to the other two with the oh three filter which is interesting because with the h a they seem a lot closer right in terms of contrast i mean i'd still say this sky watcher has the best contrast but the sv bony is pretty close and then the explore scientific actually you know did pretty well considering that's an acromat okay and then this bears out if you actually combine them and do bi-color imaging with the h a no three this is much closer the the we're much closer together between the the cheapest telescope and the most expensive telescope with narrow band then we were with one shot color right or color imaging in general it would be the same case if i did rdb and and mono because that that violet haloing is is something that is uncorrected in the blue spectrum so even if you're to use a blue filter that that extreme violet haloing on acromats is still going to be there while with narrow band because you're just sampling that that very thin five nanometers of light with oh three and h a it makes far less of a difference that it has that extended blue response you can see the stars are about as sharp and controlled in each of these now we are seeing a little bit difference in contrast i think probably because the coatings on the sky watcher are probably the best of the batch here and the coatings on the explore scientific are probably the worst that's my guess for the differences we're seeing in contrast especially with the the more defined oh three on the sky watcher but another successful test proven that with an acromat and narrow band it really punches above its weight but with broad band is where you're really going to have to want to pay for the more premium scope especially if you like that look where you're you're saturating your stars and when i say that look where you're saturating your stars i don't mean you're going to go to this extreme but um this is just an example just to really show the difference but even if you're just sort of saturating them above this which is barely saturated at all you're going to start seeing those aberrations on the sv bony while the marketing was correct on the esprit 120 it it's it's virtually eliminated that chromatic aberration on the stars okay so hopefully that was all useful i really enjoyed this test i i found that by having these sort of goals of what i was trying to find out it helped me sort of focus on analyzing the results and it was a lot of fun i did take all of the data and combined it all together just to make a final picture it's just for fun so this is my final picture of the tadpoles and the surrounding area and i like this picture it's i think it's under 10 hours of data but it's it it came out pretty well due to my dark skies and i i didn't use the broadband data from the explorer scientific because if i had combined this in it would have been distracting so i i just used the broadband data from the sv bony and the sky watcher esprit and then i used the narrow band data from all three telescopes and the processing on this one i just did a starless on the narrow band and then blended that with the broadband to get the natural star color you're now seeing everyone who supports this youtube channel over on patreon.com slash nebula photos it's an excellent community of amateur astrophotographers at all different experience levels but everyone who is on my patreon i have found have been people that want to learn and people that are willing to share their own expertise and there's a few ways we do that one is there is an active discord which is like a members only area uh on on my message board and you can get involved there in a monthly imaging challenge but there's also just all kinds of different discussions happening all the time over there and another way that you can uh get involved and give share your own expertise is i do a monthly zoom call with the whole community and then once in a while we do in-person events and specialized zoom calls as well and i really can't thank my patreon members enough because i'm now doing nebula photos full time thanks to all of you and it's what allows me to make these in-depth reviews like the one you just saw to have the time to actually sort through all of this data and analyze it takes a lot of time so if you enjoy this youtube channel i think you're going to get a lot of benefit out of joining my patreon community and it starts at just one dollar a month and for that you get direct messaging support with me that zoom call that i mentioned the patreon side of the discord which includes the monthly imaging challenge and a whole lot more there's some exclusive videos over on patreon so if you're interested head over to patreon.com slash nebula photos till next time this has been nico carver clear skies