102mm Aluminum Tube Achromatic Refractor

This is a magnificent telescope. Price-Value you get a lot of telescope for your money. I have a Mak127 and was looking for a refractor which I could used to get wide views. The Mak is great for planets, the Moon and DSO, but the field of view is really narrow. A 32mm Plossl give me 1.08 degrees of sky, and as you go higher in magnification I'm usually under one degree with any eye piece. The ES102 on the other hand provides 2.51 degrees with the same 32mm eye piece and a whopping 4.12 degrees (16x magnification) with a new 42mm (65 AFOV) 2" eye piece I just got. That is basically the same magnification and almost field of view I get when looking thru my Celestron 15x70 binoculars. This is basically a telescope that will show you lots of sky in crispy and sharp wide views. The price is amazing when considering that just the dual speed focuser and the 2" inches diagonal together will cost you this much. My only 'grip' is with the view finder. Don't get me wrong, it is a good view finder. However, I already have an illuminated 9x50 viewfinder from Orion that not only does not flip the image in any way, but makes finding objects easier due to its 90 degrees right angle eye piece. I definitely recommend to upgrade if you can. You can get an adapter from ScopeStuff online store that will let you attach any viewfinder with a vixen mount. Even a red dot is probably a better option, and even better if you are a beginner. I used a 'Y' adapter to add both, a 9x50 illuminated view finder and a red dot (see picture). But back to the ES102. It is well constructed, its main front lens is pristine, the focuser with two speeds makes focusing really easy and the dove-tail allows a good hold. The telescope also comes well packed and protected in a double cardboard box. At higher magnifications you'll get to see some minimal false color, but that is really not a big issue for me. If I want to see planets or the Moon I use the Mak127 instead. However, on the first day testing the ES102 I looked at Saturn using a Hyperion Baader 13" with a 2x Barlow and it looked beautiful. The magnification was basically 102x and I could see the rings. The view was sharp and clear and I could not see any false color somehow. This telescope can technically provides magnifications from 14x to 166x. I do recommend getting a nice SRA case for it, which is what I did (see pictures). It will protects your scope and you will be able to show off your ES telescope in style. What a great telescope. Kudos to Explorer Scientific for making this affordable and beautiful scope.

First let me say that the scope in and of itself is great and I am impressed with the optical quality. I have been in amateur astronomy for over 20 years and know my scopes. The buyer of this scope will not be disappointed as long as they are aware of the comparisons/contrasts between getting a reflector vs. a refractor or SCT. I first pointed the scope at Jupiter using only a 24mm eyepiece and even at at level of magnification with no filters I was able to pinpoint fine quality cloud patterns that my 6" reflector--even when collimated properly--couldn't detect. Next, I turned the scope to the Orion Nebula (M42) and the Pleiades open cluster (M45)(using a 32mm eyepiece) and the pinpoints of light were fine and sharper than a starfield in a Star Trek movie. M42 looked great--nice contrast! The fine adjustment worked perfectly for focusing along with the standard coarse adjustment.The only reason I didn't give this 5/5 stars is because of quality control. Explore Scientific guarantees in their website that their scopes are given rigorous QC tests, but this scope must have slipped through. The screws holding the finder scope were twisted off the "track" so that the screw's ridges were stripped out from being off. I had to use a power drill to unscrew the screws and set them properly. Other than that I would definitely buy this scope again and recommend it to a fellow observer.Be aware though, this is not quite in my opinion an beginner's scope. It does NOT come with a manual (at least mine didn't) or eyepieces. It is assumed you know how to already operate and mount a scope on an existing tripod, and have a set of eyepieces.Overall, for me, it is a great scope!

Nice 5 inch Achromat refractor. For the money vs size, it can't be beat. Explore Scientific got it right here.Do be aware being an achromat it will show false color fringing on bright objects/planets. Know this going in.On deep space objects (DSO's are nebulae and the like) it does a very credible job, excellent for it's size class.If you have another telescope for planets, then by all means this is a great value for hunting DSO's.

Comes Out Of Collimation. :(

A screw next to the front lens came loose, rolling around in the dew shield area...I did not see any scratches however. Too bad the dew shield does not slide back to shorten the very long assembly. Got an Orion padded bag, about 40" long to store and carry the telescope. Lots of purple fringing on bright objects, trying a low pass yellow filter, not that much help and that cuts down the amount of light coming through. The finder scope cross hairs snapped inside about a month after purchase and Explore Scientific does not answer their customer support inquiries when I asked for a replacement. The finder should have a diagonal as well, because if looking higher than 45 degrees in the sky, it is very difficult to position yourself to use the finder.

Image loses sharpness/focus as you move from center to edges. Note blurry palm tree in upper right corner of photo.

A remarkable value: a great two-speed focuser, an excellent two-inch diagonal, a solid finderscope, and mounting rings all attached to an optically excellent achromatic refractor that yields crisp views with minimal chromatic aberration (despite its relatively fast focal ratio). Highly recommended.