Sky-Watcher Evostar 100ED 100mm f/9 ED doublet apochromatic refractor


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This 100mm Sky-Watcher Evostar 100ED doublet apochromatic refractor is a premium scope with high contrast/high resolution performance and premium accessories at a very attractive price . . .
Our Product #: S11120
Sky-Watcher Product #: S11120
Recommended Accessories

Product Description

This Sky-Watcher Evostar 100ED apochromatic refractor has:
• 100mm f/9 apochromatic doublet optics using an ED element
• dual-speed 2" Crayford focuser with 10:1 ratio fine focusing
• 2" dielectric star diagonal with 2" and 1.25" eyepiece holders
• two 1.25" Long Eye Relief eyepieces (20mm and 5mm)
• 8 x 50mm right-angle finderscope
• dovetail shoe for installing on a Celestron CG-5 mount or any Vixen-style altazimuth or German equatorial mount
• two-year warranty

The Sky-Watcher Evostar 100ED uses a crown glass element, an ED glass element, and state-of-the-art optical multicoatings in its apochromatic ED doublet optics. Combined with the moderate focal ratio, this results in images with visibly less chromatic aberration than you find in refractors with a similar aperture but faster focal ratio. In addition to the lack of chromatic aberration's annoying halo of unfocused violet light around bright stars and solar system objects, there is no loss in contrast such as you will find in reflector and catadioptric scopes that have a secondary or diagonal mirror hanging in the light path to scatter light..

The 100mm Sky-Watcher doublet optics are even more appealing when you consider that this Sky-Watcher apo is loaded with features other manufacturers charge extra for (or don't even have available) - such as an 8 x 50mm right-angle finderscope, a 2" dielectric star diagonal with 1.25" and 2" compression ring accessory holders, two 1.25" LE (Long Eye Relief) eyepieces (LE20mm and LE5mm); and a foam-lined aluminum-clad carrying case.

The Sky-Watcher PRO 100ED has enough premium high contrast/high resolution optical performance to let you use it on an altazimuth or equatorial mount as the heart of your observing system. Its light weight (only 6.6 pounds) doesn't require a big and expensive mount, so it's easy to afford and easy to take out and set up for observing on a moment's notice. Considering its surprisingly low price for an apochromatic doublet, adding in the extra features you get at no extra cost, and in view of the great optical performance that comes as standard equipment, the 100mm Sky-Watcher PRO 100ED is a terrific buy!

Features of this telescope . . .

Apochromatic ED doublet refractor optics: 100mm (3.94") aperture, 900mm focal length, f/9 focal ratio.  The ED element is precision-polished from high grade ED (Extra-low Dispersion) glass. This ED element produces superior sharpness and color correction by minimizing the chromatic aberration, the "false" color fringing seen around bright objects when light rays pass through standard crown-and-flint doublet objectives. The result is to reduce spurious color halos and fringing to vanishingly low levels.

Fully multicoated optics: Each air-to-glass surface in the Sky-Watcher Evostar 100ED doublet objective lens has MHC (Metallic High-Transmission Coating) antireflection multicoatings on all air-to-glass surfaces for high light transmission, minimal light scatter, and excellent contrast.

Internal light baffles: Contrast-enhancing internal light baffles in the tube and focuser drawtube and a specially darkened tube interior provide dark sky backgrounds and high terrestrial contrast.

Dew shield: The supplied dew shield slows the formation of dew on the lens in cold weather to extend your undisturbed observing time. It also improves the contrast, similar to the effect of the lens shade on a camera lens, when observing during the day or when there is excessive ambient light at night, such as a neighbor's backyard security light. The 6.6 pound optical tube measures 36.22" long, including the dew shield. A slip-on metal dust cap is standard.

Dual speed 2" Crayford focuser: The precision-made no-backlash focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with 10:1 reduction gear microfine focusing. This provides exceptionally precise image control during high magnification visual observing and critical DSLR or CCD imaging. The large focus knobs have ribbed gripping surfaces so they are easy to operate, even while wearing gloves or mittens in cold weather. Lock knobs lets you adjust the tension on the drawtube to accommodate varying eyepiece/photo accessory loads, as well as firmly lock in a photographic focus.

2" dielectric star diagonal: The supplied standard equipment 2" mirror star diagonal of the Evostar 100ED slips into the focuser drawtube's 2" eyepiece/accessory holder. The 2" diagonal has 99% reflectivity dielectric mirror coatings for high light transmission. A supplied 1.25" accessory adapter slips into the 2" diagonal to let you also use 1.25" eyepieces. The 1.25" accessory adapter can also be inserted directly into the 2" accessory holder on the focuser drawtube to let you use a 1.25" image erecting diagonal, or 1.25" photographic accessories.

Supplied eyepieces: Two 1.25" long eye relief eyepieces are supplied as standard equipment - a 20mm (45x) and a 5mm (180x).

Finderscope: The Sky-Watcher Evostar 100ED comes with an 8 x 50mm right-angle finderscope that is fully-multicoated to insure maximum brightness and contrast.

Mounting dovetail: The Sky-Watcher Evostar100ED apo from Celestron has dual hinged split-ring tube rings and a dovetail mounting bar that fits directly into the Vixen-style dovetail slot on the head of many of the most popular medium capacity altazimuth and German equatorial mounts. Such mounts include the Astro-Tech Voyager II altazimuth and the Celestron AVX Advanced Series go-to equatorial, among others.

Shipping/storage case: The scope comes in foam-fitted aluminum-clad shipping/storage case.

Two-year warranty: The Sky-Watcher Evostar 100ED doublet apo is protected by a two-year limited warranty against flaws in materials and workmanship.

Tech Details

Aperture 3.94"
Focal Length 900mm
Focal Ratio f/9
Highest Useful Magnification 225x
Weight 6.6 lbs.
Optical Coatings Metallic High-Transmission Coatings (MHC)
Resolution 1.16 arc seconds
Supplied Eyepiece two 1.25” LE (Long Eye relief) eyepieces (LET20mm and LET5mm)
Telescope Type Refractor
View Finder 8x50
Visual Limiting Magnitude 12.5
Warranty 2 years


Review by:
I've been using this scope with Baader zoom and a 20mm Nagler in addition to the stock 5mm. First let me say that this scope can take power(when the skies allow!),maybe I got a really good one but frankly from what I read about this scope its probably average, so I'm using 360X on mars last night with superb sèeing and in moments of perfect seeing it looked etched as if a Hubble picture. Sublime view and lifetime best. This is the stock 5mm "planetary"58 degree and a GSO 2inch2x ed barlow. Pretty impressive telescope!!! and its so obviously underpriced that it has to be a special dispensation from the astronomy gods for us poor amateurs, so when it goes on sale do yourself a 'good' and get one! Views of the moon with the zoom is a wonderland maybe should say wonder'other'land and again the 5mm was superb. Cruising the Summer starclouds and nebulae with the 20mm, truly a stardream come true! Last point and one that surprised me was that the star colours(canadian eh!)were so intense and saturated,they looked absolutely beautiful! so very much better than in my old c8 that I once used. Please do yourself a favour and BUY the d*#%&d telescope already! (Posted on 10/4/2020)
Review by:
I've been in the hobby for about six years now and this telescope was a recent purchase (about a year ago). I've used a variety of telescopes over the years from refractors to reflectors and even some Maks. For Astrophotography (my primary interest), refractors are hands down the easiest for use. No collimating. Easy to focus. Sharp pictures. I've been using the Skywatcher on my Orion Sirius mount for a year now and it gives wonderfully clear images. The weight is light enough that the mount can easily handle it and I'm managing 5-10 minute subs without any trouble. I did get the Reducer/Flattener for this Telescope too (a good investment if you plan to do imaging with it). If you're looking for a longer focal length refractor, you couldn't go wrong with this one. (Posted on 9/9/2019)
Review by:
Yes, you can spend a lot more money on a 4 inch APO refractor, but, on the average night with normal (i.e. not so great) seeing will your view be twice or three times as good? Having looked through many 4 inchers, including those that cost about $3,000, I think not. So, if you don't win the 2019 Astronomics prize scope, also a 4 inch APO, take a very close look at this Skywatcher. Often on sale for about $800, it is a slam dunk bargain. Gorgeous views of the planets. Close double stars that just pop out and stay put as double without dancing around or squeezing back together. Razor sharp crater edges and rilles on the Moon--and a black sky background on deep sky objects and almost no chromatic aberration. On nights of excellent seeing the difference between the Skywatcher and the expensive scopes is minimal for the average amateur. And what you save can be put into a nice mount. With its light weight and fantastic performance it has easily become my most used scope. Plus, it comes with two eyepieces, a 2"/1 1/4" diagonal, a 90 degree finder and a very acceptable aluminum hard case. Buy it. You will NOT be disappointed. (Posted on 7/29/2019)
Review by:
This is a wonderful telescope. There's very little false color, it's light, and it comes with a lot of useful accessories (a 99% diagonal, a right angle finder, and a good eyepiece). There's no better deal in amateur astronomy.

It does have a couple minor downsides. It's slow and therefore long, which make it harder and heavier to mount than some other 100mm telescopes (don't just look at the weight when mounting a refractor). It does have some false color - though not much - and although the build quality is high, it doesn't compare to that of a Takahashi or TeleVue (though those are much more expensive of course). The aluminum case is very heavy and uses cardboard, so it's not exactly a keeper. The finder, in my experience (I've owned two) is barely useable. So it's great - get one of you can! - but not perfect. (Posted on 7/24/2019)
Review by:
As others have written, this is probably the best bang for the buck (or euro) available right now. It's a very good quality scope, optically and mechanically, at a sweet-spot size that's not too demanding on the mount. Because the mechanicals are good (not otherworldly great) it's not ultra-expensive, either. Great value. (Posted on 7/22/2019)
Review by:
This telescope is an absolutely excellent value. The doublet objective lens is smoothly polished and precisely aligned with the focuser; chromatic aberrration is barely noticeable around the limb of the Moon and the stars are text book Airy discs at high magnification. I' impressed with the supplied accessories. The 2" mirror star diagonal and the 5mm eyepiece are first rate. The 2" Crayford focuser is quite robust for observing with 1.25" eyepieces. It focuses smoothly and has no slop. Form, fit and finish are superb. This telescope deserves to be carried on a premium mount - I use a Losmandy GM8 and the set-up is rock solid for lunar, planetary and double star observing. You'll be hard-pressed to find a better telescope in this class for the money. (Posted on 1/27/2019)
Review by:
This is probably the best deal right now for apo refractors. It has provided me with some very memorable views of the planets and double stars. I especially remember seeing the swan nebula for the first time at a dark site location. It has worked as an amazing outreach telescope; it is exactly what the general public expect in a telescope.

The only upgrade I would look at is with the focuser. I actually liked the OEM focuser, but it takes up alot of in focus. There are some after market focusers that will increase the in focus for binoviewing or using a herschel wedge. All in all, I highly recommend this for anyone. (Posted on 1/14/2019)
Review by:
Well it basically a 4" refractor. When I was growing up as a teen in the 70's you either got a 6" f/8 Newtonian reflector or 4" refractor. I ended up with the Criterion RV-6 Dynascope 6" Newtonian reflector which was a popular scope for serious budding amatuer astronomers back then .. the quality 4" refractors at that time like Unitron's were expensive as refractors these days still are. So it was with excitement not long ago I read some glowing reviews of the Sky-Watcher ED100 Pro f/9 and decided to take the plunge and fullfill my childhood dream of some day owning my own 4" refractor. The price for what you get with this scope is incredible. A very nicely finished tube assembly with great doublet optics, and a very workable 2" focuser. My only gripe would be the 8x50 finder is not quite up to the quality of the scope itself, but that can be upgraded obviously .. and the finder it does come with gets the job done. I personally swapped a Scope Stuff Telrad finder shoe adapter for the 8x50 on mine as Telrads are what I've been using on my other scopes for years. The scope gives crisp views of the planets, moon, and sun with a good solar filter, and very nice views of deepsky objects with good widefield eyepieces like Teleview Naglers .. but actually the included eyepices aren't that bad to my suprise! Its kind of a swiss army knife of a scope that can be used for deepsky astrophotography with the focal reducer Sky-Watcher sells seperately, and for solar system photography its good to go at its stock f/9. This is definately a keeper for me. (Posted on 12/8/2018)
Review by:
First, the scope is excellent! One of the best views of M31 and M32 I have ever seen. The metal tube is of excellent quality and makes the scope durable. The case is decent but does come dented in one corner. The longer focal length proves excellent for visual use and lunar photography. The only complaint is the plastic focuser that was stiff and seemed to be the weakest link of the telescope. This should be metal but does function well enough. No CA, and stars are clear and precise. All in all, a great Apo for the money. (Posted on 12/4/2018)
Review by:
I've had this scope for the past 5 years and it still impresses me with its color correction on the Moon and planets. I constantly use it at 200x and it holds up well. Does a good job too on DSOs but I prefer my 8" reflectors for that type of observing. This is a long scope so you'll need a decent alt/az or eq mount. Like one of the previous reviewers I'm using a Stellarvue M2 alt/az mount and it provides steady views at 200x. Highly recommended and great value for the price! This scope goes on sale a few times a year and can usually be found for around $700. (Posted on 11/16/2018)
Review by:
I push this over 200x on Moon and planets when seeing allows and find no trace of chromatic aberration. The views through this scope are simply pristine. The smaller aperture darkens the background sky adding something to the aesthetic of open clusters. Some may call the case chintzy but I like it as is - it does the job with minimum weight. (Posted on 10/26/2018)
Review by:
Having used Orion's ED80 for years, I was nervous about whether or not my little AVX could handle this OTA. Upon receipt, I was very surprised to find that once I equipped it with visual accessories, it only weighed a scant 11lbs, whereas the ED80 weighed 9lbs 6oz. Go-to's are just as accurate and it settles very quickly. For a 4" F/9, this is LIGHT and balances easily. It's become my favorite, able to handle wide-ish FOV's for sweeping around, but also fantastic for lunar, planetary, and doubles. (Posted on 10/8/2018)
Review by:
This was my greatest telescope so far. This is literally a planet and lunar killer, only withheld from the aperture. The finish on the tube is superb. I seen virtually no color around the moon, Jupiter and Saturn. The stars were as pinpoint as you could get. The focuser upon arriving needed some work, but was never a deal breaker in how great this telescope is. (Posted on 10/6/2018)
Review by:
My first APO refractor. The build quality/mechanics are good (but not exceptional) and the optics are great for visual - nice sharp, pinpoint stars. At f/9, this is a long scope - a heavy tripod helps. I use a steel CGEM tripod with a Stellarvue M2 alt-az mount. In my book, this makes it a bit heavier/bulkier than "grab and go." It does what a 4" of aperture can do. For my interests and given that I already use a heavier tripod with it, I might be tempted to go ahead and move up to 5" and shorter f/ratio to get a bit more light gathering ability in the same length OTA. Overall, hard to beat for the price. (Posted on 10/6/2018)
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Supplied Accessories

  • 100mm f/9 ED doublet apochromatic optics
  • Split hinged tube rings with a Vixen-style dovetail
  • 8 x 50mm right-angle finderscope
  • 2" dual speed Crayford focuser
  • 2" dielectric star diagonal with 2" and 1.25" eyepiece holders
  • 20mm (45x) and a 5mm (180x) long eye relief 1.25" eyepieces
  • Dew shield
  • Dust covers
  • Foam-fitted carrying case.