 Long time viewers of this channel will know that I love fisheye lenses for us to photography. I find the perspective of taking in so much sky in one photo really fun and rewarding. And I did a shootout of fisheye lenses a couple of years ago, and when it came to the Sigma lenses in that shootout, I found the Sigma 8mm circular fisheye was pretty good, but a little slow at f3.5 wide open. And then I found Sigma's other offering at that time, the diagonal fisheye, the 15mm f2.8, was disappointing for Astro. It was a little faster than the circular fisheye, but it had a lot of distortion on the stars, even way stop down to something like f5.6. Well, fast forward to a couple of weeks ago, and Sigma America sent me an email saying, we have this new fisheye lens, could I review it? And I was prepared to actually say no, because I have a lot going on right now with the solar eclipse coming up in under two months. But then I looked at the details in the email and I saw a number one, this is a fisheye lens in their art series, which is reserved for their very best lenses optically. And then number two, this is an f1.4 fisheye. And that's just, you know, unheard of. It's literally the first f1.4 full frame diagonal fisheye lens ever. And in my fisheye shootout video a couple of years ago, to give you some perspective, the fastest full frame fisheye lenses I had available and tried were f2.8, a full two stops slower than this lens. And so when I saw these details, I thought, you know, I got to try this lens. I'll move some things around, make this work. And I also knew from those details that this lens was going to be really expensive. And a few days later, they emailed the price, which is $2,000 US. And I get it, that is really expensive for a specialty lens like a fisheye. But this is no ordinary fisheye. Sigma's really created something here that is one of a kind. Because typically with fisheye lenses, I've always thought of them as, you know, they're fun. You know, you get that kind of wild perspective, but they're not the kind of lens that you would hold to a high standard in terms of technical performance. They're not like sharp lenses. I wouldn't consider them high resolution lenses that you would really be able to resolve a lot of details or nice star profiles from. And they're typically not very fast either. So maybe not the best rest of photography. My favorites from that shootout that I did were actually some of the slowest of the bunch, f3.5 or even f4 wide open in terms of the Canon. So to have a fisheye come out that is well corrected and sharp across the field at f1.4, using a 61 megapixel sensor is just mind-boggling to me. As a lens nerd and a lens collector, I'm very impressed at what they've achieved here. But all that said, in terms of practical considerations, this is still a specialty lens with a high price point. Fisheye is probably not in most photographers' bags because it's not your typical way of seeing the world. It's a little bit weird, right? You get that fisheye distortion that a lot of photographers maybe don't like. But before I go any further with getting more into the details and the imaging tests that I've done with this lens, let me share the disclosure since this is a review. Sigma America sent me the new lens, the 15 millimeter f1.4 DGDN diagonal fisheye, as well as a Sigma FPL camera, and a Sigma 14 millimeter f1.4 DGDN. Sigma 14 was at my request because I was interested in comparing it to the fisheye here. And this was all sent to me 11 days ago, which allowed me to quickly get out and do some tests and put out this review to coincide with the announcement of this new lens today. I'm not paid by Sigma. They have no input into what I say in this video. And after the video is released, I'll be returning all the gear to them. So on with the review, let's talk a little bit about the physical characteristics here of this lens. Like the 14 millimeter f1.4 DGDN that Sigma released eight months ago, this is an incredibly heavy lens, actually another 200 grams heavier than the 14 millimeter. The 14 millimeter is 1170 grams or two and a half pounds. The 15 millimeter fisheye is 1360 grams, which is three pounds. And like that other lens, the 14 millimeter to support all of that weight, it comes with this tripod socket, which is a nice rotatable ring with an Arca Swiss compatible foot for mounting on your tripod. And this ring allows the lens to easily rotate to any orientation, including vertical, horizontal, but anything in between. This lens is in Sigma's DGDN art line. So that means it's for mirrorless cameras and mirrorless full frame cameras. At the moment, just Sony E mount and L mount are available. I'm testing the L mount version of the lens. I'm testing it with Sigma's flagship camera, the FPL with its 61 megapixel sensor. For astro and camera nerds out there, this is the famed Sony IMX455 sensor that is also in the Sony a7R series, the newer ones and several full frame astro cameras like the QHY600, the ZWO ASI 6200. It's a very good sensor for testing optics. It's the same sensor I use for testing telescope optics these days. It has a pixel pitch under four microns. So it's not going to hide any faults, you know, any optical aberrations that are there are going to be apparent. Other than that, this lens is very consistent in terms of features with the 14 millimeter f1.4 that I reviewed a while ago. It has focus by wire, meaning you can't use this on an astronomy camera. It needs electronic focus. The electronic focus can lock with a switch, which is cool. It also has the lip up here to prevent the dew heater band from slipping into the field of view. That's of course very appreciated on a fisheye lens because I do actually remember struggling with that a bit when I did the fisheye lens shoot out. It's very easy to have that dew heater band just come up a little bit too far and then you get it in your shot. Again, like the 14 millimeter Sigma is definitely designing and marketing this lens for astrophotography, which is really cool that they're paying attention to our market, which I'm sure is not a huge market compared to like sports, wildlife, landscape, some of the other domains that Sigma is targeting. I think it's really cool that Sigma is making lenses for astrophotographers. Let's take a look at the images that I've taken with it now and we'll compare them to shots with the 14 millimeter f1.4, which again is a rectilinear ultra wide that I've reviewed previously. For me, the reason I'm interested in comparing it is that was the champ. That's the champion when it comes to technical performance on an ultra wide angle. I think it's going to be interesting to compare this new fisheye lens from Sigma to that one. Okay, let's jump in here. All these images you're going to see in these tests were taken on February 13th from 7 to 8 pm from my backyard observatory. I was considering going somewhere more exotic, but I just wanted to get these tests in while I had the lens because it was a pretty short review period. I put the lenses on my sky watch or mount, which is on a pier in the observatory as mentioned. I was using the Sigma FPL camera at ISO 1600. All of these test images are going to be straight from camera. That means in processing, you would change the contrast and colors and things like that, but these are fairly flat images that haven't been processed much because it's easier to see what we're looking at if you don't process the images. At the very end, I'll show what it would look like if I did a light processing on the picture. The moon was up, but it was pretty low in the sky and out of frame, and it was only 20% illuminated, so it was still a fairly dark sky. I have about a mortal three sky here. What you're seeing here emanating up and to the right a little bit in both pictures is the winter Milky Way. For people not familiar, the winter Milky Way in the Northern Hemisphere is not nearly as prominent as the summer Milky Way, where we see the core, we're looking into the core of the galaxy. In this comparison, which is the full frames from each camera, of course, the first thing you might notice is that they're fairly similar, but there are some key differences that jump out at me right away. One is that the stars look a lot more prominent in the upper half of the photo in the Sigma 14, the rectilinear lens, than they do in the fisheye lens. This will bear out again in the crops, especially looking at the corners, because what's going on here is the rectilinear image has to correct these corners, which actually makes the stars a bit wonkier. It's good for foreground things because it makes the lines more straight and look more natural how we would see them. You can see we have pretty extreme fisheye distortion in straight lines in the lower half of the image here, but in terms of rendering a star field, which you can sort of think of as a dome above us, the fisheye image actually gives you tighter stars across the whole full frame image. Well, with the rectilinear image, because it's having to correct those corners, the stars get a bit bigger and more pronounced in the extreme corners of the image. Now, it's still doing a great job for an ultra wide angle. Don't get me wrong, but I'm just sort of pointing out a key difference here between a fisheye and a rectilinear lens. Another thing you may notice, and I've zoomed in to show this a little bit better, is that I'm centered on beetle juice here, but sort of my goal with this image was to show off this cool asterism called the winter hexagon. And so it's in each image, but if I put some lines to show how those stars connect, the winter hexagon goes from serious at the bottom to cappella at the top, you can see that it does sort of change the shape a little bit of the winter hexagon. It gets a little bit more stretched out in the rectilinear image. And then also, it's a little bit more zoomed in with the rectilinear image, like we're getting a wider field of view here. There's more headroom above the winter hexagon than there is here. Remember that this is a 180 degree field from corner to corner, and this one's 114 degrees. The other thing I found really interesting in looking at these images was if you look at this cluster right here, this is, I believe, malloc 20. It's that big open cluster at the center of Perseus. In this image, it's right here in the frame, and it looks nice and tight. In this image, it gets out here, and look how much it's expanded due to that, how it's correcting the corners. It's pretty amazing, I think. I should have mentioned this earlier, but you can download all of these slides and images, because I know that it's going to be hard in a YouTube video to really appreciate this. I can't emphasize enough how weird this image is to have perfect stars, but have the fisheye effect of how we actually see the night sky as a dome, where it's curved, but then to have perfect stars across the field. It's a really trippy image, and it's really rewards zooming in and just sort of looking at it. It's almost like a survey image, like a mosaic in how perfect the stars are across the field. Okay, now I'm just going to run through my standard comparisons. Whenever I review lenses, I start with vignetting here. Vignetting is how much you have shadowing in the corners due to light fall off, how well it's illuminating the field. Of course, this is a full frame, and usually vignetting improves as you stop down the lens. This is at f1.4, so this is the worst it is going to get. I would say it's perfectly acceptable on both lens, but maybe a little bit more strong in the Sigma 14, but almost the same. It looks like the diagonal fisheye has taken the lead in terms of how flat it is. I can still see a bit of vignetting at the whole top of the frame up here, and on this one it's so minimal it's barely gone. It's almost gone. And then at f2.8, this one looks perfectly flat to me, so I think at f2.8 the fisheye is now just a flat field. I don't see any issue with vignetting there. This one I still see a little bit in the corners at the top. Okay, and then at f4 they both look flat, so I don't really see any vignetting in either image at f4. Okay, here's the center crops at f1.4, and this was interesting to me too just how similar the star fields are in the center between the diagonal fisheye and the rectilinear image. I mean, I guess this all makes sense. This is something I never really thought about, that in the center of a fisheye image and a rectilinear image, if you're talking about almost the same focal length, they're going to look incredibly similar. The stars are going to be spaced about the same, but then it's really just when you get away from center that they change so dramatically. I'd say the Sigma 14 is maybe just slightly tighter, slightly better color. Like, if you look at Betelgeuse here, it looks a little bit more saturated than on the 14 than it does on the fisheye. And then this star here, I can't remember the name of it, it's the other shoulder of Orion. Again, it just looks slightly tighter on the Sigma 14. Okay. And then here at f2, they look remarkably similar, and that's just what I found with the rest of my images. f2.8, f4, these all just look perfectly matched. If you ask me which one is which, I would have no idea. They're so close to each other. Color, sharpness, clarity. I don't really see a huge difference between these lenses at center. Now, it was a completely different story in the corners. As I sort of alluded to when we were looking at the full frames, because the rectilinear image, the Sigma 14 has to correct the corners to get rid of all of the barrel distortion and give you straight lines, the star field is going to be quite a bit wonkier compared to the center. Well, with the fisheye, the corners of this lens look about as good as the center. Now, not quite. I mean, if I zoom in, you can see there is a little bit of distortion there. But that is so minimal compared to this one, right? This is at f1.4. Look at that. We have little, little rabbits if you zoom way in, little bunny ears. While this one, they're just slightly elongated, but zoomed out. This is already at 200% zoom. It just looks like the stars are much bigger and spaced further apart and a little bit blurry with the 14 millimeter and with the 15 millimeter fisheye, they just look perfect. I mean, you really have to zoom in to see that there's anything weird about the corner stars. So that's amazing. I don't know how to really express how interesting this lens is to me. Now, in terms of what you could do with that artistically, I'm not sure yet, but it's technically just a really interesting lens. Okay, and then here's f2. It's basically, you get slightly better correction with both, but really it's the same story. They look about the same. And it just sort of continues, you know, slightly better correction at f2.8, but still a huge difference between the two. And then at f4, I do think that, you know, the Sigma 14 ultra wide angle, it's starting to give you sort of round stars, but they're still quite a bit bigger and spaced further apart. With the Sigma 15, let's zoom in and take a look at them. Yeah, they're nearly perfectly round. Even this is probably zoomed in at like 800% now. And they look just great. Here, if we look at the Sigma 14, we've gotten rid of the little rabbit ears. They're still a little bit elongated. I'd actually say in terms of star profile, star shape, these are not too different. The big difference here is just they look a lot tighter with this one just due to how the fisheye effect is rendering the star field versus the rectilinear lens. Okay, and then last thing I want to show you here in this video is just this is an example of an unprocessed image straight from camera. This I believe I shot at f2.8 about 60 seconds ISO 1600. And then here's how I would do a nice processing on it. Now, my processing might not be exactly to your taste, but just to show you again, here's straight from camera. And here's with processing. And all I really did was I brought out the winter hexagon by making those stars slightly accentuated and brought out some of the dark nebula features in the winter Milky Way and some of the other nebula features. Now, this is a stock camera. It's not modified for H alpha. So it's not going to bring out something like Barnard's loop in a single one minute picture, but we can see the rosette here right in the middle of the winter Milky Way. And we can see the California nebula up here. There's the Pleiades, the Hyades. So to sum up, it's a super interesting lens. If you're really into this look, I could definitely see getting it. I'm considering saving up for one. For me, the whole reason to have the Sigma FP is really for these new mirrorless lenses that I find so exciting. And this one is super exciting. I mean, to have this kind of star field with a with a fisheye lens, who knew that was even possible? So I hope you enjoyed this one, looking at this new lens from Sigma. If you have any questions, leave them in the comments. This has been Nico Carver, Clear Skies.