 These four telescopes are all small refractors that are popular for astrophotography. The reason I picked these four to review in this video shootout is this one is a doublet, this one is a triplet, this one is a quadruplet, and this one is a quintuplet. And if you're new to all of this, what these words refer to is the number of glass elements inside the telescope tube. You'll often hear people say things like, don't buy a doublet for deep sky astrophotography. But I've rarely seen comparison tests of what the actual differences are under the night sky comparing all these different types. So that's what this video is all about. I've done a bunch of testing with these four telescopes, and if you watch to the end, I think you'll have a good sense of what each telescope is capable of. Hey, my name's Nico, and this channel is all about astrophotography. Since this video is a review, we're going to start with a few disclosures. The Ascar 65PHQ was sent to me by Ascar to test out. After the review, I can either send it back to them or purchase it. The William Optic Xenostar 61 was lent to me by Allstar Telescope, which is an awesome astronomy store in Canada, but they also shipped to the US. And I want to give a huge thank you to Allstar Telescope and definitely encourage you to check out their online store when you're thinking about buying your next telescope. The Sharpstar 61 and the Meade 70 APO, these were both bought personally, but with generous financial support of my Patreon members. And this video also has a sponsor, which is brilliant.org. And I'll say a little bit more about them midway through. So let's start with a little history starting with Galileo. Telescopes existed before Galileo, but Galileo was the first one to popularize taking a telescope and looking up at the night sky. And Galileo's telescope was a rudimentary refractor. It was a singlet, a single objective lens, which focused the light onto an eyepiece. And while his telescope was good enough to see a lot of firsts, he was the first to see the moons of Jupiter and things like that, the view would be pretty bad by today's standards because it was full of what we now call chromatic aberration, because a single lens isn't capable of focusing all the colors of the rainbow at once. So then Isaac Newton comes along and solves this problem in a very interesting way. Instead of using glass elements in his telescope, he uses mirrors, ground to particular shapes. And this works quite well. And many astrophotographers are still using his design, a Newtonian reflector to this day. But that wasn't the end for refractors. We go another hundred years into the 1750s and we have the first successful doublet refractor called an achromat. And this used a crown and flint design to greatly reduce chromatic aberrations. Sometime later, we get the apochromatic telescope which used even more glass elements three this time or a triplet, and that reduced these chromatic aberrations even more. So for visual use, we can stop there. A high quality triplet with an eyepiece, you're gonna get the best views possible. But there's an issue with doublets and triplets for photography, which is they're only well corrected in the center of the field of view. And so this is fine for visual observing because our eyepuple is pretty small and it's circular. But if you think of a camera sensor, it's usually much larger and rectangular. So unless you're gonna use a very small camera sensor, like one the size of your eye, you'll wanna add a field flattener to the telescope, which adds another two to three glass elements to your doublet or your triplet. And what a field flattener does as the name suggests is it flattens the image so that the stars will be round all the way to the corners of an image, even when taken with a larger sensor, like a DSLR, even full frame on some telescopes. Now with a quadruplet or a quintuplet, what they usually do is they put that field-flattening elements right into the tube and they make it part of the design so you get a flat field right out of the box with a camera. And that's why these are sometimes called astrographs because you don't need to add a field flattener, but they're also not quite as good for visual use. So it makes it a little simpler because with a field flattener, you do have to worry about back focus. While with an astrograph, you might still need some spacers to reach focus, but you don't have to be precise about it. As long as you can reach focus with these telescopes, you have the best correction. Well, with a field flattener, you have to get the correct back focus or you don't get that full correction, the full flattening effect. Now, when it comes to price, usually an astrograph is going to be more expensive than a doublet or a triplet, even when you include the price of the field flattener, which again, for photography, you're always going to want. But let's quickly look at the prices of these four scopes with the field flatteners included. And you can see in this case, the triplet actually comes in slightly under the price of the doublet and the mead quadruplet is a full $340 more than the Ascar quintuplet. So we can't just assume pricing will go up when we add more glass. It's really a lot more complicated than that and beyond just the optics inside the telescope tube. People will pay a premium for certain brands of telescopes because of many factors, including quality control, reputation, the actual mechanical parts, like the focuser. And that's actually what we're going to look at next, the actual physical characteristics of these telescopes, like their focusers and rotators, their build quality, and any included accessories like rings and guide scope attachments and things like that. Okay, we're starting here with the William Optics Zenith Star 61-2. This again was sent to me by All-Star Telescope along with this field flattener, the flat 61A, which is a adjustable but dedicated field flattener for this telescope. And William Optics has a great reputation. That's why you see them everywhere. They make a lot of refractors and they are priced competitively, but they are maybe a little bit on the mid-tier premium. And I think it's a well-deserved reputation because they always do an excellent job with the build quality and mechanics on their telescopes. And they are innovative. For instance, all of their newer telescopes have this built-in Bodinov mask right into the cap for the telescope. It comes with this just metal piece that screws off and then there's a clear Bodinov mask built right into there into the cap. So that is really nice. And I did use this successfully when focusing this telescope. For the other telescopes, I had to supply my own Bodinov mask. In terms of the dew shield, I wish it had a lock. That's my only complaint about it. Otherwise it works well. It's plenty long enough. The reason I like a lock on the dew shield is if the way I do flats is I put a flat panel up here and without a lock, this just collapses down. It doesn't come with your typical guide scopes into a shoe attached here. Instead it comes with this top piece which is the same as the Redcat top piece right on the ring here. And I actually prefer this, putting the guide scope in line with the telescope rather than offset. So this is really nice. This is great. I wish all telescopes had the focuser tension and lock up here rather than down at the bottom where it's much harder to get at. And this one is also nice and big. So it's very easy to loosen up focus and then lock down focus with that nice big knob up there. On this side of the focus travel you can see millimeter markings which is great for, you know, repeatable focus and getting you to the sort of the right point right away before the night even starts. This whole piece back here is the field flattener and it comes with this nice camera rotator. So you have to rotate the whole camera back here. You just loosen up that silver knob right there and then you can just turn this whole thing with this neural ring right there. It's a little bit tough to move but I actually like that having a little bit of tension because it means that it's not going to slip. Then when you've found your correct rotation you just lock it back down with that knob right there. This is an adjustable flattener which means it has about, I don't know, 20 millimeters of adjustment and some people don't like this adjustable field flattener. I think once you get used to it it's pretty nice but one thing I really like about the field flattener design is the way that to attach a two inch filter is you just screw it here into the back of the field flattener and then just screw this piece back on which is super easy and will make changing out those two inch filters really easy if you need to. And then of course on the back of the field flattener we have the normal 48 millimeter threads that you can attach a T-ring or a dedicated astro camera to. Just remember that from the back of these threads that's where you need the 55 millimeter spacing to make the field flattener work. Next up we have the Sharpstar 61 EDPH2 and then I bought it configured with the 0.8X reducer flattener which is this piece back here and I think is another three elements of glass. This is a very small telescope one of the smallest I've ever used probably and it came with a dovetail that I found way too short. Really the biggest flaw mechanically I found with this is the dovetail that it came with was comically short it didn't even fit into this saddle in terms of locking it down with both knobs it was that short. I put on a slightly longer Prima Luce lab red dovetail plate down here which makes it at least usable. The do shield is also pretty short it doesn't have much travel and it does not have a lock. The cap is just your standard metal fits right on. Feels like a nice snug fit. It has both a top handle and a Sinta style shoe for your guide scope right there all on this heavy duty ring. Up here this unlike the William Optics this is not a focusing tension the focusing tension is down here at the bottom. What this is is it allows the whole focuser to rotate which is useful right because a lot of times I want to be able to change rotation and so that is nice to have. Now the curious thing is this piece back here also rotates if you loosen these three screws. But what I would suggest is don't do that because the only way then to tighten up this rotation would be to tighten up these three screws which is very inconvenient. This rotation is a lot easier because it comes with a thumb screw. The only thing you have to be careful about is if you have the focuser knobs at a weird angle they might run into something. So just be careful there. The focuser travel does have millimeter markings up here at the top and they're very clearly marked. Now in terms of adding a two inch filter this I think is one of the worst offenders. I could not figure out how to do it easily. It goes in here but this is quite deep before you get to the threads for the flatener element. Now this little threaded piece does screw out. So I guess you can screw it out, add the filter then drop the whole thing back in and screw it back in with these, I don't know. I just did not understand how to easily add a two inch filter. I was able to do it just by dropping the two inch filter in and really getting my fingers in there but I sort of messed up the matte finish inside there by doing it that way. So not my favorite in terms of that. The actual flatener, reducer flatener is actually up here in the focuser. So this is just an empty piece that screws on to the back. And again I've already talked about why I don't like this rotator with the three screws that you have to use a screwdriver on to loosen. I would just suggest tightening those up. I don't think they should have included this at all. We in the whole focuser mechanism rotates already. On the back we have our standard 48 millimeter threads for attaching your camera. Okay, next up we have the Mead 70 millimeter Hapo. This is a quadruplet design. It's the most expensive of the batch. I bought this used from JC Astro Photo on Instagram because it seems to be discontinued but it was a very popular telescope while it was available so you probably can still find it used. In terms of the mechanics it seems to work quite well. Like other telescopes it has the focuser tension here at the bottom but it has a nice two speed focuser. It does have the millimeter markings right on the focus travel there. And then it has a rotator. I'll loosen that up here. And the rotator has a thumb screw that you can loosen and then this whole back piece rotates and then you just lock down the thumb screw and it does seem to work quite well. Now this whole rotation mechanism if you take off all of the little set screws and the thumb screw this whole piece can come off and that's where you add a two inch filter. So not the easiest solution to change out filters because you would actually need a screwdriver and keep track of these screws because they have to come all the way out for this piece to come off to put in the two inch filter. Once you actually get it off it's pretty easy to put in that filter then put the whole thing back on. The dew shield is not locking but it seems to go out plenty far and is plenty long. In terms of what's included it is pretty minimalist just rings and a plate. And then on the top of the rings there are quarter inch, 20 screw holes. So this is where I would add a guiding setup but it also has screw holes up here for ascent to shoe. So that's it on this one. Oh and I guess I should also say it has a nice matte finish that's sometimes hard to see in videos but the first two telescopes that I showed have more of that sort of shiny finish and the mead is like super ultra matte white with the next blue accents. Oh and one more thing I should mention is it has these little tilt tip screws. So if you were noticing some kind of tilt issue it has these tilt tip screws facing back this way which I think would work quite well for addressing tilt if you saw any. So that's a nice addition as well. Okay then finally we have the Asgar 65PHQ, the PHQ line. If you've watched my channel before I've reviewed other ones in it but it's their premium astrographs that are a little bit on the slower side so you get better star performance but they're not as fast as like their FRA series. And so this is a 65 millimeter telescope but at F 6.4. So that puts you at 416 millimeter focal length. Now that's very similar to a very popular telescope that used to be available from Astro Tech called the AT65Q which had very similar specs but has been discontinued for a while. In terms of the mechanics here we have the Dew Shield that extends quite a ways. It's a little bit tougher to bring out than some of the other ones but I like that and then it also has the lock which is very much appreciated which the other ones didn't have. It has your standard metal cap and then it has some nice rings here with a small top handle. I can just barely fit my hand in under that handle but I do have large hands. It has your normal Cinta style shoe for a guide scope. So if you did wanna put your guide scope up here I'd probably take this top handle off and put on a plate up there. It has a nice focus travel with millimeter markings but also rotation markings. It's the only one of these four scopes that has the rotation markings which I find really useful when I'm trying to repeat rotation across multiple nights or working on mosaics and things like that. I did find the manual rotator which has a lock right there. Very tough to move which I didn't like because it was, I like a little bit of tension but this one is like super tough to move even when this is all the way loosened. And my issue with that is with a light setup like this it might throw off your polar alignment if you're really yanking on this to change rotation. So I just had to very carefully apply tension and just move the rotator really slowly and then that seemed to work fine. Like the others in the PHQ series it has sort of gradations so you can use different kinds of spacers if you want but I only tried it with the normal 48 millimeter spacer here at the end. And you can't just attach an astro camera right to this. You will need some additional spacers after this final spacer to reach focus. So just keep that in mind even though this is not a particular back focus you'll need some spacers back here to reach focus. It comes with a very long Vixen Dovetail which I very much appreciate because you can for me you can never really have a long enough Vixen Dovetail. I like to often put a guider on the front or put my pole master on the front and having that length is very important for those kinds of things. Just like the William Optics this scope is very well designed in terms of adding a two inch filter. You just take off this final piece in the adapter stack and a two inch filter fits in right there and then you just screw this piece back in. So very easy, much easier than the Sharp Star or the Mead in terms of adding a two inch filter or changing a two inch filter. In my videos I like to focus on the information that you can only get by really trying out the gear but when I wanna understand the fundamentals behind light optics and the physics involved I go to Brilliant. Brilliant.org is a hands on way to learn science and math interactively in just a few minutes each day. There are thousands of lessons with new ones added each month so you're never going to run out. The lessons that I think will really enhance your understanding of telescope optics are in the course scientific thinking that I'm showing now and have been really enjoying. So to try everything Brilliant has to offer completely free for a full 30 days visit Brilliant.org slash Nebula Photos or click on the link in the description. The first 200 will get 20% off Brilliant's annual premium subscription after the free trial. Okay, now we're gonna go through the actual image comparisons. Of course this is a very important part of any test of telescopes and I will warn you that these are pretty subtle differences we're gonna be looking at. I did shoot with both a color camera, a one shot color camera, the ASI 2600MC and then I also shot with a mono camera, the ASI 2600MM. These are both APSC sized sensors but they have pretty small pixels, 3.76 micron pixels so it should reveal any sort of deficiencies in a telescope. But I have a lot to go through here so I'm going to breeze through some of it just to give you an idea. I mean here's a color image, here's a mono image. So we're gonna look at all of these different images but I'm gonna go through some of it faster than other parts because I'm gonna spend more time on what I think are the most interesting differences to see but I'll put up all of this data somehow online so you can take a look at it all if you're interested in really pixel peeping. Here's the tech details for this shoot. What I try to do when I'm comparing telescopes is pick an object that's fairly high in the sky and shoot it on one night and not just get single exposures because a lot of times you can't really see things until you stack at least a few exposures, get a little bit of integration but I try to get through the telescopes as quickly as possible so that we're not getting different sky conditions. So I did all of this in about two hours with the object high in the sky, the jellyfish nebula and I took five by five minutes for each picture. So 25 minutes total. This was all on the same mount, the AM5 with the same guiding system. I did monitor the guide graphs and make sure that we weren't seeing any big changes in guiding. Hopefully everything got sort of equalled out in terms of that. So let's first look at what each telescope produced in just a single five minute raw frame. These are not calibrated. I actually didn't use any calibration frames just because I didn't have time to shoot flats in between the different telescopes because I was trying to do this quickly but with a crop sensor, you can see there's not much of a vignetting. It's pretty flat actually already. So this is the doublet. This is the William Optics Zenith Star 61. Here's the triplet. And you can see that with that reducer on, this is a wider field of view. We're getting this cluster up here. Here is the quadruplet. And this to me looks very similar to the doublet, not only in just the field of view but also in the results that we got, which sort of makes sense. Cause the doublet with a field flatener sort of becomes like a quadruplet in a way. And then here's the quintuplet. This is the ascar, a little bit tighter crop cause this is a F 6.4. So that puts us at 416 millimeter focal length. Okay, you can see though, no major problems with any of these raw frames, no vignetting, nothing like that. And now here is the same thing but stacked five frames stacked. So the nebula comes out a little bit more and you can see again, they all look pretty good. Okay, so next up, this is made with the script aberration inspector under image analysis. And what this does is it takes a crop from the center and the corners and the far edges of the picture just to show you sort of what the star field looks like. And with this William Optics doublet, I think this looks really good. I don't see any problems really with aberrations. The stars look nice and round out to the corners. No visible chromatic aberration. With the sharp star 61, you're seeing more stars in each square and that's to be expected because we're getting a wider field of view here. This is at 360 millimeter focal length and this is at 288, but it doesn't look quite as good. The stars have a few more sort of like aberrations in the corners, like a little bit more chromatic aberration and elongation compared to the doublet. William, then that we have the Meade 70 and again, I don't think this looks quite as good as the William Optics Z61 in terms of corner performance. But you could say that in the center, it's maybe a little bit sharper and maybe a little bit sharper all around but we're just getting a little bit less sharp in the corners because of those aberrations. And you know, some of those aberrations might be tilt but I don't know. I think I'm seeing some sort of elongation of the stars in all four corners. Okay, and then here is the Ascar 65 and this one to me looks the most technically perfect. Now, sometimes I find that technical perfection can get a little bit boring actually because you lose some star color. I feel that when you get the stars get this small and perfectly tight, you don't really see the star color quite as well but it does look technically perfect to me so I'm not gonna complain there. Okay, and then here I did a crop in on the jellyfish with this bright star propus which is often a problem in extra images. You can get all kinds of weird things going on but all of these telescopes rendered it just fine. I was using an IR cut filter by Astronomik and you know, these all look perfectly acceptable. I think that you can see the Ascar with its slower focal ratio produces slightly tighter stars. The sharp star, you know, with its reducer, you're going to get stars that are a little bit more bloated but you also get a brighter image. And then the jellyfish, I mean, the William Optics doublet and the Meade quadruplet. To me, these images look very, very similar. They're at about the same focal length and I'm not seeing a huge amount of difference there. Okay, so one reason I wanted to shoot mono in addition to one-shot color, which is all I usually do in these tests, is because of this thing that you hear about if you're shooting mono and you can focus a particular color, especially with a narrowband filter, a doublet is gonna work as well as any other scope. And I've never really found that to be the case. I can still always tell differences even with narrowband between telescopes. And so I wanted to just test that theory again with these telescopes to see if it's true that you can really tell no differences once you move to a mono camera. So I shot with three nanometer HA and O3 from Antlia. And like I usually do, I shot the HA when the moon was full and the O3 when the moon was not risen yet. So no moon. I shot 10 by five minutes with both filters for each telescope. So 50 minutes HA, 50 minutes O3. And again, I didn't do any calibration here just to save time so that I could get through this as fast as possible. Oh, and the HA and O3 were taken on different nights. But again, I tested all four telescopes on each night with each filter and then just did the combination. All right, so let's quickly look through here. So here's the HA on the doublet. Looks quite good. Here's the HA on the sharp star. Here's the HA on the mead quadruplet. And there's the HA on the ascar. And one thing that I think is interesting here that you might be able to see is that we're already, with the narrow band, you can really see, I think the differences in focal ratio. Like this ascar in this HA looks a lot more undeveloped and noisy compared to the sharp star where I'm seeing in just 50 minutes of data, some really faint structures come out. While in this ascar one, which were in an F6.4, it's gonna need a lot more time to get to this level. But of course, by changing the focal ratio, you're also changing your field of view here. And so there's no free launch. If you want more details, you're usually gonna have to accept a slower speed unless you are getting into really large telescopes. Okay, here's the O3. And again, look at the difference here between F6 and F4.5. I'm seeing a lot more O3 structure in the faster telescope. And the Antlia O3 does have these small halos on bright stars. So you can see that happens on all the different telescope brands. None of them are immune to that because that's actually something that's going on with the filter, not the telescopes. Okay, and then here is the results of combining the HA and the O3, where I put the HA in the red channel, the O3 in the green and the blue channel. And just like with the one-shot color, I tried to process these as similarly as possible. And you can see, even though the ascar is the slowest, when you're more zoomed in on the target, it does, I think, make a cool impact where you're feeling more of the frame with the nebula. So it might not matter too much that this one is actually much further along in terms of signal-to-noise ratio. Because when you're feeling more of the frame with the nebula, I think it makes a really big impression. But again, that just goes down to target selection. So don't play too much attention to that. Okay, but when we zoom in here, you really can, I think, see, hopefully this comes across on YouTube, that the William optics and the ascar, which are the two slowest scopes, are showing a lot more noise than the mead and the sharp star, which are faster scopes. The mead is at F5 and the sharp star is at F4.5. So, and that would just carry through. I mean, the more time you put into the target, you're still gonna be able to see those differences with photographic speed. The other thing I think is interesting here is, normally I don't really like narrowband stars that much because they always look sort of ugly, but among these four, the ascar stars actually look pretty good for HOO stars. Well, these other ones are more what I expect from narrowband stars, right? I'm sort of like, the color is pretty disappointing. It's a lot of just sort of blue and white and not much variation in between. Now, they did all get somewhat the color of propus as this sort of dark orange reddish star. I would say that in terms of the propus performance here, the doublet and the triplet are suffering a little bit compared to the quidruplet and the quintuplet and the ascar probably did the best job there. So, what do we take away from all of this? Well, one thing that I found really interesting was, I didn't find that the differences in one shot color were greater than the differences in narrowband. Actually, I found the differences in narrowband and mono to be greater than one shot color. So the opposite of sort of the common wisdom. The other thing which is probably obvious to everyone is that not a huge amount of difference between these four scopes, you know? When you add a nice camera and mountain guiding and all this stuff, the truth is that all of these scopes which range from $600 to $1300 are gonna give you pretty good results. There's minor differences. The ascar has slightly tighter stars in exchange for being a slower scope. The sharp star gives you a wider field of view than the other three. So if you're looking for something in particular, you might choose one scope over another. You know, you might also go on the brand's reputation or something like that. But in terms of just raw imaging performance, I think all these scopes are really gonna get the job done. 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 all people who want to learn and are very willing to share their expertise. We have over 900 members now. There's an active discord you can get involved in and I 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 videos like the one you just watched that takes several months to organize and to pull off. So thank you so much to all of my current Patreon members. And if you enjoy this channel, I think you'll get a lot of benefit out of joining my Patreon community. It starts at just $1 a month and you get direct messaging support with me, a monthly Zoom chat with the whole community, a monthly imaging challenge where we pick different, you know, challenge every month and a whole lot more. So if you're interested, head over to Patreon.com slash Nebula Photos. Till next time, this has been Nico Carver. Clear skies.