 This is an inexpensive lens from TT Artisan, this is a medium-priced refractor telescope from William Optics, and this is an ultra-premium lens from Canon. All of these can be used for Deep Sky Astrophotography, but what's really the difference? That's what we're going to find out tonight. I'll be pointing all three of these at the flaming star nebula in the constellation Araiga in a single night shootout and sharing all my thoughts with you on what I find. Hey, my name's Nico Carver, and I'm a Deep Sky Astrophotographer. This video was the result of a question that I often get, which is, why get a small refractor telescope for astrophotography when there are so many telephoto lens choices in the same focal length range of around 200 to 500 millimeters? And it's a good question, and with this video, I'm going to try to answer that as best I can using these real-world examples here. So to give a bit of a spoiler, it's not just about the final image or image quality. There are a lot of practical reasons in terms of focusing, compatibility with other astro gear like mounts, and other astro accessories like filters that make the small refractor desirable if you're really getting serious about astrophotography, especially Deep Sky Astrophotography. But camera lenses have their place too, and they offer a lot of versatility if you're not all in on astro. And they come in all kinds of different price points. So I thought it would be interesting for this video with the two lenses to compare a lens on the low end of price, the TT Artisan 500 f6.3, with a lens on the high end, which is this Canon 100 to 300 RF 2.8. Before I jump into the review, let me share a couple quick disclosures. This TT Artisan 500 f6.3 was sent to me by TT Artisan for review. Same thing with the William Optics Spacecat 61. William Optics sent this to me for review. The Canon 100 to 300 f2.8 RF lens I rented from lensrentals.com, and that was done with proceeds from my Patreon campaign. And then finally, the Skywatcher GTI mount that I used for testing these is on loan from Skywatcher USA. So thank you to all these companies for the opportunity to review their products here on the channel. I really appreciate it and allows me to make cool videos like this. So the first thing I want to talk about is what goes into an astrophotography kit that's going to work with optics like these. 300 millimeters focal length, you know, in the case of these two, and 500 millimeter focal length in the case of the TT Artisan, is a long enough focal length in all of these cases that for deep skywork, meaning taking pictures of nebulae galaxies, you're going to want a tracking mount. You don't want to do this untracked. And you're probably also actually going to want an auto guiding system with lower focal lengths like 135 millimeter. You could just use the tracking mount or maybe even go untracked. But for 300 millimeter and up, I would suggest the tracking mount and an auto guider. And what is auto guiding? It's this thing right here. It's this tiny little telescope, a separate telescope from your main one, and also a separate camera that goes with the tiny telescope. And what this does is it makes the tracking mount more accurate by looking at the stars and doing a fast refresh. Like every second it's taking a new picture. And if those stars move out of place, it sends a small correction to the tracking mount. So the auto guider and the tracking mount work together to allow you to take long exposures several minutes long without star trailing. You get those pinpoint stars and that's what's really needed in astrophotography to reveal these dim objects in deep space like the flaming star nebula that we're going to be looking at tonight. Telescopes and telescope mounts like this Skywatcher Star Adventure GTI or these ZW harmonic drive mounts use different dovetails than is standard with regular photography. What I mean by dovetail, it's like the mounting plate, like an Arca Swiss plate in regular photography. The version of that in astrophotography would be a Los Mandi plate, which is a wider plate, or a Vixen plate like I'm using here. And these Vixen plates are dovetail plates are called that because they were popularized by a Japanese telescope manufacturer called Vixen. Still around makes mounts and telescopes, but mostly for the Japanese market. So step one, to even get the lenses onto the tracking mount is we need to buy a universal Vixen dovetail plate and some specialty machine screws called quarter inch cap head hex screws in the right length to attach the lens foot here to the dovetail. And we have to do all of this just to get it attached to the mount, but we still haven't figured out how to mount the guide scope. So my solution to mounting the guide scope with a camera lens is I get an extra long Vixen dovetail. The dovetail has to again be long enough that I can under sling the guide scope and camera in front of the mount like this. So again, with a refractor, all of this stuff is already thought out for you. I should say an imaging refractor like this space cat 61, I can just take this out of the package, put a few pieces together, attach the whole thing to my mount, and it's all ready to go. With any camera lens, you're going to have to do a fair amount of ordering other parts and rigging them all up in order to use the lens as a deep sky astro lens. Now, once you get past that hurdle with a lens, let's say you want to use a filter like a duo narrow band filter. Those are very popular today because they block a lot of light pollution and they let through a mission nebulae. With the refractor, you can just screw off one piece here on the back, install the 48 millimeter threaded filter in the spot designed for it, screw the piece back on, and then the filter is held securely inside the telescope. Really neat. With the camera lens, you're going to have to hope that your particular camera has some kind of clip and filter that you want to use designed for it. So if you're a Sony or Nikon shooter, you may find there's very little available for your particular camera with the refractor. Again, any kind of astronomical filter is open to you. Okay, the next big thing is focusing. And with the Spacecat Refractor, this is a really nice focusing system. It's an internal focus system that William Optics has patented, but then it has the traditional telescope focusing knob and the 10 to 1 reduction knob for fine focus control. The Spacecat also comes with a really cool clear Bodnov mask built right into the lens cap. This is an excellent tool for nailing focus manually by using a diffraction pattern that this mask creates with bright stars. And if you want to automate your focus with an electronic third-party focuser, with a lens, you need to find a belt and a sort of probably a 3D printed part that will work for that. And it may not really be worth it because once you add a belt, you can't rotate the lens easily. Well, with the refractor, it's very easy to add a third-party electronic focuser. And then rotation for framing purposes is never an issue here because it's here in the back behind the focuser. And this manual rotator is great. It even has the markings, so you can know exactly how far you're rotating. So I've gone through many of the advantages of the telescope for astrophotography purposes, but what about the advantages of the lenses? These ones, the TT Artisan and the William Optics, are very hard to change focus quickly for fast-moving subjects. So a big part of what you're paying for with the Canon is excellent optics, like top of the line optics, but optics that can also auto-focus very fast and reliably across a zoom range. And this brings us to another point, which is focal length. The Spacecat 61 telescope has a fixed focal length of 300 millimeters at f4.9. And that's it. There are no other options. It's just that. But it does that incredibly well. That's what it's designed to do. The TT Artisan is a fixed focal length 2 of 500 millimeter focal length at f6.3 as the maximum aperture, but you can stop down that aperture with an internal iris to a minimum aperture of f32. That kind of very small aperture is not needed for astrophotography, but it does give it more versatility for daytime shooting compared to the refractor, which has no internal iris. The Canon has a zoom range of 100 to 300 millimeters, and it can do a maximum aperture of f2.8 across that whole range and a minimum aperture of f22. So for regular daytime shooting, that kind of versatility is what you're really paying for, to be able to shoot at various focal lengths in any kind of lighting condition, bright sun, nighttime, dusk, whenever it doesn't matter. And with image stabilization in the lens means it's ready for anything. This is a Swiss Army knife of lenses in terms of the situations you could put it in. The TT Artisan is less versatile. You'd probably only use it on a tripod because there's no image stabilization. It only has manual focus, but you can stop it down. So if it's a bright day, you need to stop it down. You can. The refractor is the least versatile for daytime, but that's of course intentional because every design choice with this telescope was made with astrophotography in mind. It's not even designed for visual astronomy. This is an astrophotography telescope, an astrograph they sometimes call it. And I should also mention the Spacecat definitely has my favorite branding of the bunch, at least the most fun branding. I mean, look at the front lens cap there. And it even came with a Spacecat toy with a moving tail that my kittens were really entertained by. The last thing to talk about here is the actual glass inside these instruments. The quality and configuration of the glass inside is important for controlling imperfections that will pop up in your image. And a big one to pay attention to, a big imperfection that's important for astrophotography is chromatic aberration. Because when chromatic aberration is well controlled due to high quality glass, the stars are going to be all their true color with no color fringing around the bright stars. When chromatic aberration isn't as well controlled, the stars will have magenta violet or even multicolored fringing around them. And that can be very distracting to the final, you know, impression of the image if there's a lot of really bright violet halos. The TT Artisan uses eight glass elements and two extra low dispersion glass elements. We don't know what type those are. They don't state. The William Optics uses four glass elements in a Petzful configuration, and at least one is extra low dispersion of the FPL 53 synthetic fluorite variety. And FPL 53 is considered one of the best, if not the best and most expensive when it comes to ED glass. The Canon uses 23 glass elements for a claim to be ultra low dispersion, although they don't specify the glass type. One element is a fluorite crystal lens, and they're using actual fluorite. That's going to be the most difficult to manufacture the most expensive and the rarest way to control chromatic aberration. And I believe Canon is the only big company who actually makes fluorite lenses. So even if you get one in a high-end telescope like a Takahashi, that fluorite lens element was probably sourced from Canon. I'm interested in all this stuff, like glass types and all that, but I'm by no means an expert in it. For me, the proof is in the pudding. And that's why with these shootout reviews, I always get out under the stars and take pictures with each setup, trying to keep the all other factors as similar as possible, like same mount, same camera, to really give you an idea of what to expect from these different optics. So let's jump on to the computer and review all the images taken. Okay, here are the tech details for this shootout. I won't read through these. You can pause the video and take a look if interested, but basically all the gear is the same. I shoot these all in the same night with the object tying the sky, trying to equalize things as much as possible. I also changed the total exposure time for the stacks based on the focal ratio. So I can try to sort of equalize the signal to noise ratio in the stacks. We're going to first look at some single exposures with just an auto stretch, nothing done to them. And really what I'm trying to show here is the field coverage. And so you can see with actually all three of these, the field coverage is excellent. And that's something I've actually noticed with full frame lenses is usually there's not too much vignetting with a telephoto lens. And that's true of the TT artisan here and the Canon here. So we're not seeing much shadowing of the corners, which is good. Now with telescopes, it's actually rarer to not have some vignetting in the corners, but the space cat 61 did a really nice job here with field elimination and I don't really see any vignetting. Okay, next we're going to look at the corners and the center of each one, just from a single exposure. So here's the Canon. You can see that it's quite sharp in the center. And then we have some distortion in the corners. It looks like this side is a little bit worse than this side. I think that means there's some kind of tilt going on, perhaps, probably with how the camera is connecting to the lens. I'm not really, that's usually where the issue is. It's a little bit better here with the space cat. If you look at the worst corner on the Canon, it's right, it's this one right here, and it looks pretty out of focus, pretty blurry. While we're getting a little bit better correction or actually quite a bit better with the space cat. Again, probably the worst corner is up here. So maybe that suggests that my Canon RA has a little bit of a sensor tilt issue. But if we look at the other corners and the sides here, they're just a lot cleaner, a little, a lot, you know, quite a bit less distorted here with the space cat compared to the Canon zoom lens. Now the TT Artisan actually surprised me because while, yes, we can see the classic chromatic aberration violet halos, which I expected with a $300 lens, in terms of distortion, it's really not that bad. I mean, this is pretty impressive for a $300 lens. Now you're seeing fewer stars, but I want to explain that that's not because it's less sensitive. That's because we are more zoomed in with this lens where we're changing the sampling of the stars. Because this is at 500 millimeters and this one is at three, these two are at 300 millimeters. But I think it's still okay to compare things at different focal lengths as long as you're aware of what you're looking at. Now let's move on to the stacks. I tried to keep the processing very minimal and similar with each of these stacks. Here's the Canon. I got the rotation quite a bit better with the space cat because the rotation is so much easier when you have that little rotation in the back than it is when the lens is, you had the only way to rotate is with the ring and it's a little annoying, so I didn't try too hard. Since I was doing all this testing fairly quickly, of course. Okay, and then here's the TT Artisan. And you can see again, yeah, it's more zoomed in than these two. These are both at 300 millimeter. This one is at 500 millimeter. And you can see with these, there's a little bit of a color difference. I'd say that the Canon feels a little bluer. The space cat feels very neutral to me and the TT Artisan looks a little bit yellow or greener. And so I'm thinking this is just down to the glass types. All of this kind of stuff, though, can be normalized, you know, changed with color correction, especially if you have a program like Cyril or Pix Insight, you can use a photometric color calibration. I didn't do that here because I think the differences are sort of interesting to see. And then this is the last comparison. And this one I find very interesting because they are so similar. In terms of detail and what I'm seeing here among these three, it's like really close with the Flaming Star Nebula. Now remember, this one, the TT Artisan is at 500 millimeters. Well, these ones are at 300 millimeters. So it's not as sharp as these two lenses because we're looking at something that's much more zoomed in. And these ones are basically matching it, but at a lower focal length. However, though, for a lot of deep sky objects, who cares, right? You're wanting that zoom anyways. So it's like, why not go for the cheaper lens? Well, why not? There are reasons, of course. Many of them I've already addressed in sort of the advantages with the telescope. If you're in a light polluted area and you want to use a filter, boom, right away, you're running into an issue with the lenses while with the telescope, it already has that place to put in the filter. There's all kinds, and then the place for the guide scope, place to connect to the mount, there's all kinds of reasons why the telescope for practicality beats this $300 lens. But in terms of optical performance, there's not a huge difference here. Now, if you are a pixel peeper, and what I mean by that is someone who really likes to go in and look at the stars up close. Of course, with a lens that's $300, you're going to see some of this violet fringing on the stars. And the longer the integration, actually, the more time you put into it, the worse that gets. So that's sort of an annoyance. And once you get really experienced with astrophotography, these violet halos really might start to bug you. But if you're a beginner, I don't see any reason why you might not start with something like the TT Artisan before upgrading maybe later on to something like this refractor, which is going to, again, not maybe blow you away with how much better the image is. But when you really look at those details, like the stars here, like if I look at this star right here, even zoomed out, I can see this has a really nice natural blue halo in this image. And in this one, it's sort of muted. I don't really see much color. And the Canon, I should say, I haven't been talking about as much, but it did very well too. And it should for a $10,000 lens. But I guess the Canon, I just am including here in case I have any watchers who are already into like sports and wildlife and have something like this, and they're like, well, could I use that for astrophotography? And of course the answer is a resounding yes. It's a very impressive lens for astrophotography as well as those other things. So to sum up, I would say the Canon is your all-rounder. If you have this lens, you can use it for astrophotography, but you can also use it for any kinds of other things. The Spacecat is going to be the one you want if you're a dedicated astrophotographer for all the practical reasons, but also because it actually will give you the best results if you really care about things like the star profiles in the corners of a full-frame sensor, which if you're doing something like mosaics or something, that can actually be pretty important. And then the TT Artisan here is the Value Champ, of course. It's giving excellent results considering how inexpensive the lens is. Okay. And then the last thing I want to show you here is, as I was putting this video together and talking to William Optics, they let me know that they want to offer a special discount code for viewers of this channel. So if you're interested in getting a Spacecat 61 after seeing this review of it, you can head over to williamoptics.com, order it, and use the code Nebula Photos at checkout for $50 off that telescope. And so again, that's Nebula Photos at checkout. And I'll have links for all three of these products in the description. So thank you very much for watching. Hope you learned something here. And until next time, Clear Skies!