The Telescope Built Like a Camera Lens: WO GT81 WIFD Review

so every telescope has got two ends there's the business end on the front and the party end and the back and in recent years we've only really seen Innovation to the optics for the front end of a telescope and there hasn't been much Innovation on the back end where the camera and the focuser go this end of the telescope arguably is equally as important as the front end is and it's going to affect a lot of your user experience and how good your images are so let me make a brief comparison to you all here is a small little telescope and in order to focus a telescope you have to adjust a focuser on the back now this focuser is going to slide the camera in and out and put it into the focal plane but if you're using a modern camera lens like this 135 millimeter lens then you can focus this all day and the length of it is not going to change everything's going to stay nice and mechanically stable and we don't really need to worry about how much weight we hang off the back because it's all going to be rigid and the moving elements are within the mechanism of the optic itself now you can probably see where I'm going with this in astrophotography the way you have the camera mount to the back with the focuser is actually incredibly important now especially when you're using big cameras like today's full-frame cameras with Filter wheels and oags the weight you add to the back of the telescope starts to add up really quickly and when you stack that onto a draw tube and start to pull it out from the telescope that weight is going to impact your photos because it's going to apply a moment arm on that draw tube which is going to cause some tip tilt in your system not only this the further back you pull the camera out of the Optics the worse the vignetting of the system is going to be so the big question is why don't we use telescopes like we do camera lenses now in truth there have been some attempts by companies to make telescopes like camera lenses before so specifically the Vixen vsd and the William Optics Redcat telescopes which are great telescopes but they are challenging to use because it's difficult to make them auto focus telescopes this is because with the helical design it's difficult to attach a motor you have to use a belt system and it can be quite difficult to get it set up for autofocus so the real question is has anyone made a telescope with a crayford style focuser that still has the internal focusing element like modern camera lenses do and the answer is yes as of now what I got here is the William Optics gt81 wifd and this does just that it operates just like a modern camera lens would where the back of the camera is rigid it's stable in the back of the telescope which bridges in the stable but the actual Optical element is with inside the OTA and it moves by itself so now you don't ever have to worry about the weight on the back of the telescope because this stays rigid and this comes with some other benefits that we're going to get into for the rest of this review of the William Optics gt81 wifd so whenever I review a telescope and I've only reviewed one other telescope there's a couple key factors I like to hit I like to talk about the Optics I like to talk about the mechanics the thermal stability and I think there was one other as well as the uh the user experience which is very very important so let me talk about the telescope and the first thing we're going to do is we're going to cover the uh the mechanics of it because the mechanics are kind of the main selling point the most interesting part of the telescope mechanically it's very interesting of course it's a it's a new patented design it basically works like a modern camera lens does so internally there is a mechanism that moves the lenses on the inside to actually move the focal plane onto the Imaging chip so obviously the main advantage of that is there's no more Focus or tilt and you have less vignetting because you're closer up to the optical path now I don't have a very heavy camera to test this with but if you're just looking at this this thing has m93 threads on it so I'm pretty sure I could stand on the end of this draw tube and still be able to shoot through it I mean this thing is pretty pretty beefy the back end also has a really lovely um Rotator mechanism I'll give you a nice sexy close-up shot of it but it's just very smooth and it's got a lot of good markings for your pointing angle which is really really cool now what else we got here so the actual focuser itself is is very interesting too again it is internally moving but it's just like a standard you know a course adjust and then the fine adjust threads on the other side here which is uh you know pretty standard the one thing I that I find is kind of interesting with the focuser is that they've got it's hard to see there's a focus or locking knob like on the bottom of the focuser and I'm kind of confused about what the point of that is because you don't really need it per se I mean the thing is with a standard refractor focuser where you're moving a draw tube on the back the locking mechanism is really important to make sure that your camera doesn't go flying down from the weight of the gravity if you're playing it at Zenith but in this case like I could have the telescope straight up and down and I could shake as much as I want but it's not really going to move the internal focusing element so this actual Focus locking knob is kind of pointless and the other problem is you can't reach it at all because it's like buried under the dovetail plate I could flip it upside down but uh yeah it's kind of interesting how it is you would need to run the telescope upside down if you wanted to uh actually use that Focus or locking knob which if this was a standard refractor would be a complaint but it's not because you literally don't have to use the focus or locking knot because there is no load on the focuser apart from the lens itself so that's pretty cool I like the rings that it came with it's got nice Rings it's got a nice handle slash scope plate on the top which is pretty handy so yeah the the carrying handle is pretty nice the lens due Shield is pretty standard um it comes with a thumb screw I didn't put it on I mean it's just kind of you know it's pretty uh snug without the tightening screw so I don't even know if I'm gonna bother putting the tightening screw on but I mean mechanically it's a great telescope it's uh it's very nice to use and I never got to put an auto focuser on it because I don't own one but it is supposedly a zwo eaf compatible some of the eafs struggle under load I know the eaf I've used the zwo eaf on some Takahashi Scopes and they really struggle with those under load it's nice that it won't be under load in the situation of this telescope so thermally it seemed to perform pretty fine when I use it for deep Sky I used it out in Death Valley National Park and it was pretty cool so there were some pretty big temperature swings and I didn't bother refocusing at all because I only have manual focus no Auto focuser and it seemed to hold up pretty well over the course of the Imaging run which is great if we're also talking thermals the the telescope also does have a thermometer on one of the knobs I've never actually used a thermometer on a telescope before manually but I mean I guess it could be handy to figure out how cold it is outside next let's just talk about the Optics really quick so this is an 81 millimeter F 5.9 refractor it's a triplet it's you know just your pretty standard tried and true bread and butter 80 millimeter refractor there's no nothing crazy here it's it's going to be what you expect so good Optics nothing to complain about on the optical front the package I got when I used the telescope came with the 0.8 X adjustable reducer which performed pretty well I will have to say it's really really nice to adjust this thing is the adjustable reducer and when I put it on at first my first time using it I looked at the corners and I was like oh my God the corners are terrible what's happening and I just quickly made a couple adjustments by unthreading the reducer and within like five minutes I had my reducer completely adjusted and it looked great so that's not a very common experience I've had before with doing backspacing is being able to adjust it on the fly so I really really really appreciated that part of the experience optically now the rest of the Optics I use it with my full frame Canon 6D when I was shooting with it and the corners were fine there was no chromatic aberration and there was no internal reflection so I shot one image around roof Yuki and it performed it performed well so optically this telescope is really nice it's a classic wo gt81 optically so you'll see many many great images online on Astro bin with scopes with the identical Optics to this one and you know you're going to be getting something good with this the other thing I received in the pack along with this telescope since I got the astrophotography bundle was this uh 30 millimeter guide scope the little uni guide which sits at the top of the handles here and it was nice I was using this as a as a travel rig because I brought it out to me during a workshop so this ended up being a nice simple solution to use with my uh my harmonic Mount and it worked really well for getting photos so the last thing I touch on usually is the user experience of the telescope and this is kind of what this telescope is completely optimized for the focusing was really great obviously you don't have to deal with Focus or tag I don't have to deal with the focuser coming loose on the clutches there's no issues on that front at all the other nice thing about it given the the mechanical elements inside the telescope is that it balances pretty much over the middle of the telescope there's no uh super back heavy classical refractor problems going on here something you might see with like some of the smaller 61 millimeter telescopes is that the telescope is so front heavy or back heavy once you put the camera on not the case with this it balances pretty much over the middle again the the adjustable reducer slash field flattener was probably the coolest part of the user experience itself it's not like you're totally screwed if you don't have the right adapters and you just have terrible Corners no that that problem doesn't exist and you can totally adjust it on the Fly which is really cool and not only the um the reducer but the other thing on the back the Define camera angle rotation adjustment was really really good I like all the fine markings that it has on it it's just very smooth you know it has a premium feel to it which I like all right so now that I've talked about just some of the general characteristics of the telescope let me tell you about the photo I shot with it and how I how I got the actual image so I took this telescope out with me to my Death Valley workshop with Derek Culver and Ian Lauer and on the final night we got some pretty nice weather it was pretty iffy though it actually started raining after we set up so I had to tear everything down set everything back up after it stopped raining and I was able to get to Imaging after that now I shot roofyuki with this telescope I also shot Thor's helmet but I haven't edited that yet maybe I'll edit it for this video but I shot rofyuki and Thor's helmet on my agm-27 with the Canon 60 and I was Auto guiding using the uni guide on the back like I said before very easy to get to work with the uh the harmonic Mount and then I spent the whole night until sunrise shooting row of Yuki and I ended up getting this photo of roe with only a couple hours of exposure time which was really cool and I'll also show the photo of Thor's helmet if I actually edit it it's pretty uh it's a pretty small Target and I was just kind of looking around for something so this telescope was able to produce some good images for me I also shot the moon with it the other night but yeah it's it's a great telescope it has a unique design that's pretty Centric on the user experience the main point that I see in this telescope versus getting another one is the fact that you don't have to pay for an expensive focuser this is something that I do on pretty much any other refractor I get let's say I got like an Orion 80 millimeter refractor or if I got a Skywatch or triplet the first thing I would do with any such refractor is rip the focuser off and replace it with a different one and I even do this on every Takahashi I've used I've tried using takahashi's with their stock focusers and they're just not good you're paying for like this expensive multi-thousand dollar instrument but the focuser is never up to the standard of actually doing full frame Imaging with the telescope which is a lot so you end up having to pay anywhere from 900 to 2 Grand maybe even four grand on an aftermarket focuser that can actually deal with a full-frame camera on the back for deep Sky Imaging now this isn't the case with such an instrument I mean this this telescope can handle full frame and you're not going to be spending another one to four thousand dollars on a focus or on the back just to get it to work like you would on Takahashi instead you could use something as simple as you know maybe a little Prima luche eaf or a little zwo eaf spend maybe like 200 to 300 to make it auto focus and you don't have to worry about replacing the stock focuser so that's the that's the role I see this telescope filling is it's a refractor that actually has a good stock focuser which is pretty rare that's the cool part about this telescope but yeah overall I would say you can't go wrong with getting a telescope like this especially if you don't want to deal with paying a bunch of money for a focuser that actually works and if you're planning on doing full frame Imaging with a big 6200 mm or a qhy 600 then this is a refractor that's actually going to be able to handle it with a filter wheel all the filters in an oag there's not going to be any concerns with actually using a big camera like that on this I would like to think Aegina Astro for sending me the telescope for this video you can find this telescope on their website they didn't pay me to make a review for the telescope they just sent it out I do have affiliate links for it so I will get a small commission for taking it out and shooting the photos and putting in the work so if you're interested in picking up the telescope head over to Regina and uh that's where you'll find it anyways I hope you found this review useful helpful informative any kind of way and I'll catch you guys in the next video

Channel: Bray Falls

Views: 16,881

Keywords: astrophotography, WO GT81 WIFD, WO GT81, william optrics, internal focuser, telescope, telescope review, astronomy, astrobackyard, nebulaphotos, zwo, asiair, hem27, pixinsight

Id: s-IW0dPb8W8

Length: 15min 23sec (923 seconds)

Published: Tue Apr 18 2023