Sky-Watcher 180mm f/15 Maksutov-Cassegrain Telescope (OTA Only)

BH #SK180MMMCOTA • MFR #S11540
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Sky-Watcher 180mm f/15 Maksutov-Cassegrain Telescope (OTA Only)
Key Features
  • 180mm Aperture Maksutov-Cassegrain OTA
  • 2700mm Focal Length, f/15 Focal Ratio
  • Limited-Diffraction Optical System
  • Antireflection Fully Multicoated Glass
With the largest aperture in the series, the Sky-Watcher 180mm f/15 Maksutov-Cassegrain Telescope is a powerful astronomical tool that remains manageable and portable. The Maksutov design exchanges the conventional front corrector plate of a Schmidt with a convex meniscus lens, resulting in a smaller secondary mirror that limits obstruction and increases contrast, while eliminating the need for periodic collimation. This modified optical path results in a slower focal ratio and narrower field of view versus a similar Schmidt, but the optical benefits, when coupled with the larger aperture and fully multicoated optics, make this an ideal scope for making detailed solar, lunar, and planetary observations, while being able to resolve deep-sky objects like stars, clusters, galaxies, and nebulae.
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Sky-Watcher S11540 Overview

With the largest aperture in the series, the Sky-Watcher 180mm f/15 Maksutov-Cassegrain Telescope is a powerful astronomical tool that remains manageable and portable. The Maksutov design exchanges the conventional front corrector plate of a Schmidt with a convex meniscus lens, resulting in a smaller secondary mirror that limits obstruction and increases contrast, while eliminating the need for periodic collimation. This modified optical path results in a slower focal ratio and narrower field of view versus a similar Schmidt, but the optical benefits, when coupled with the larger aperture and fully multicoated optics, make this an ideal scope for making detailed solar, lunar, and planetary observations, while being able to resolve deep-sky objects like stars, clusters, galaxies, and nebulae.

The scope is outfitted with a large 2" visual back. To get users started, Sky-Watcher includes a 28mm long eye relief eyepiece that produces 96x magnification and a 90° star diagonal for viewing with the optical tube assembly (OTA) pointed at or near the celestial zenith. The OTA is offered here without a mount or tripod for users who have a reliable support system or want to use it as part of a dual-OTA setup for star parties or observation/imaging rigs. It is outfitted with a Vixen-style dovetail plate for use with compatible mounts. This OTA's compact form factor belies its observation power and resolution and is ideally suited as a grab-and-go option for quick observation sessions or heading out to remote locations.

Optical Performance
  • 180mm aperture
  • f/15 focal ratio
  • 2700mm focal length
  • Front convex meniscus lens corrects spherical and chromatic aberrations as well as comas (off-axis aberrations) across the entire field of view
  • Smaller secondary mirror versus Schmidt-Cassegrains reduces obstructions and increases contrast
  • Fully multicoated optics maximize light transmission to improve brightness, color rendition, sharpness, and contrast
  • Resolution: 0.64 arcsec
  • Internal primary mirror focus
  • 2" diameter visual back accepts larger eyepieces and accessories
Mounting
  • Requires mount and tripod for proper use
  • Vixen-style dovetail plate
  • Weight: 19 pounds including OTA, dovetail plate, finder, diagonal, and eyepiece
Included Accessories
Eyepiece:

  • 2" barrel diameter
  • Accepts most 2" astronomical filters
  • 28mm eyepiece yields 96x power
  • Comfortable long eye relief

Diagonal:

  • 2" snout and eyepiece holder
  • 90° angle places head in a comfortable viewing position
  • Star configuration corrects image horizontally for terrestrial use

Finderscope:

  • Relatively low 8x magnification provides a wide field of view for easier alignment and faster star-hopping navigation
  • 50mm aperture helps resolve dimmer objects that dot finders cannot
UPC: 050234115407

Sky-Watcher S11540 Specs

Key Specs
Aperture
180 mm / 7.1"
Focal Length
2700 mm
Focal Ratio
f/15
Eyepiece
Yes, Removeable: 2" Diameter with 90° Star Diagonal
Optical Design
Maksutov Cassegrain
Aperture
180 mm / 7.1"
Focal Length
2700 mm
Focal Ratio
f/15
Eyepiece
Yes, Removeable: 2" Diameter with 90° Star Diagonal
Finderscope
Yes (8 x 50)
Mounting
Vixen Style, Dovetail
General
Weight
19 lb / 8.6 kg
Packaging Info
Package Weight
22.8 lb
Box Dimensions (LxWxH)
30 x 13 x 11"

Sky-Watcher S11540 Reviews

Best online astronomy company

By Mary
Rated 5 out of 5
Date: 2025-10-16

B&H sells many things, but for astronomy I find them to be the best overall. It starts with their prices- I purchased the 180 Mak for $250 less than any other store. It shipped immediately and their online and phone Customer Service was so prompt as to be almost immediate. Granted, the CS team does not have the technical knowledge astronomy retailers have, but they were otherwise very helpful..

Scope & B&H Excellent, SkyWatcher NOT

By Jeff
Rated 1 out of 5
Date: 2024-06-19

Firstly, before getting into the details, I need to make clear that B&H not only provided the best price, but outstanding customer service. This has been the case for me everytime I've purchased from them, and it's why I'll continue to do so. As far as the Sky-Watcher 180mm Mak is concerned, it is an excellent visual planetary, lunar, double-star scope. I've replaced the visual back with an ES diagonal, Baader click-lock, and upgraded to an Starlight microfocuser. The only thing I don't really like about it is the short vixen style rail. I feel it should be bolted to the scopes heavier ends and run the full length of the OTA. Now for the bad. This rests solely on Sky-Watcher themselves, specifically tech support. I had to purchase two of these 180 Maks. The first one came with the primary mirror covered over with a bluish, smoky haze. I didn't notice it at first, in fact I had the scope for 3 weeks, before I could even use it. But in daytime seeing, and then with a flashlight, the haze became easily apparent. I immediately contacted SW for support. I emailed pictures and the description of the issue. And their (Alex) response was brief, it shouldn't look like that return to retailer. No courtesy, no apologies, no sympathy, no explanation. I thought they would want to correct the problem in good faith, understand as a customer I just spent well over $1000 and would want to show their concern for a poorly delivered product, nope, return it. I couldn't believe how short and uncaring he seemed. And I made it clear I'm a current SW 10 Flextube Synscan dob owner/customer. So nervously I contacted B&H, who, as I mentioned earlier, was fantastic. Courteous, considerate, professional. Because of limited stock, made arrangements to get me a new one quickly. I wish I could remember the guys name, he was excellent. The second Mak arrived and I immediately checked it. And, as was one of my concerns, it was hazed over too! (This haze was apparently from outgassing from paint or lubricants used inside the scope, and the scope being sealed before it could dry or cure.) Now, I contact Sky-Watcher again, expressing this is the second one. And SW (Alex) response? Send it back to the retailer. I guess I was to just keep laying out $1000's until I got one that wasn't messed up! Obviously, there's a bad batch of these. Now I'm furious, this is the size/type of scope I wanted, and SW is short and inconsiderate. Their responses are literally one sentence, and basically return it and buy another. I'm calling, emailing, bugging the heck out of them. Finally, the tech support guy sends me an RMA, tells me he didn't think they opened up these Maks but after looking into it, they do, send it in and they'll repair it. Now, after the hassle, do I trust the repair, will it be recollimated? Do these guys really know what they're doing? Theoretically, it should come back to me better than new, right? Well the repair guys send a form email, but they don't respond to questions. So, the whole time I'm concerned, I've been back and forth shipping multiple scopes off, paid out double waiting on a return, worried the return won't be accepted...ya know, valid concerns. A complete headache and hassle. In the end, it arrives in the same box it has been sent back and forth from one side of the country to the other, and the box is just smashed on every corner and in between. Fearing the worst, I checked it out and the scope was cleaned, it was perfectly collimated, and works beautifully. They did leave some lint specs on the meniscus, but overall, I feel the issue was corrected. However, SW left a very bad impression, that I can't get over. Pretty close to the worst interaction I’ve ever had with company for such a precise and delicate product or at this price point.

See any errors on this page?

question

what is the actual size of the central obstruction INCLUDING the baffle?
Asked by: itzchak m.
With secondary baffle, the obstruction is about 30% by diameter.
Answered by: Peter
Date published: 2025-01-13

What are some good goto mounts / tripods for this ...

What are some good goto mounts / tripods for this telescope?
Asked by: Jeff
That Celestron 93607 is not nearly sturdy enough for this telescope. The rated capacity is only half the weight of the scope.
Answered by: David
Date published: 2022-12-31

question

Do you sell a focal reducer that would be suitable for this telescope, the 7 inch Maksutov f/15, or do you know of one?
Asked by: William K.
The Celestron f/6.3 Reducer/Corrector will be compatible with this scope. Website link: http://bhpho.to/1JT4a4N
Answered by: Alex S.
Date published: 2025-07-15
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