Through computer-optimized design, a careful selection of optical glasses, and enhanced multi-layer deposition coatings, the Explore Scientific 68° Series eyepieces produce long eye-relief and ensure high image-correction, a flat field, and high contrast across the entire image field. An excellent choice for those who make extended visual studies of detail with subtle variations of brightness, and for those who must wear glasses while observing.
With the introduction of the 68° Series, Explore Scientific has made two important improvements in eyepiece manufacture - the first being 15 layer Enhanced Multi-layer Deposition (EMD) coatings on all glass-to-air surfaces to gain maximum contrast, and waterproofing the eyepiece with the use of Argon gas purging instead of standard Nitrogen gas. Although Nitrogen is a fine choice that will last for many years, Argon is a larger molecule that maintains its protective properties over a wider range of temperatures, and is even more resistant to diffusion thereby further extending the protective waterproof environment of the eyepiece body.
Each eyepiece is meticulously assembled into precision machined metal lens barrels that maintain the perfect alignment of the optical train for years of rugged use in the field. To keep internal reflections to a minimum, all internal surfaces of the eyepiece barrel are flat black, as well as the edges of the lenses themselves to minimize the scattering of light within the lenses themselves.
Explore Scientific's eyepieces are backed with their exclusive Explore STAR Transferrable Extended Life of the Product Warranty. Limited Warranty is one year, which converts to the Explore STAR Transferrable Extended Life of the Product Warranty when product is registered within 60 days of purchase. We think that you will find Explore Scientific eyepieces rank among the finest obtainable and represent an outstanding value.
Sep 5, 2014
Accurate,Easy to Use,Quality Lenses,Strong ConstructionCons: Comments:
My favourite EP in the f/5 dob. Sharp up to 3/4 of the way to the edge in that telescope. Shows some coma beyond that point, but that will be due to the mirror. Outstanding views of extended objects. Southern Nebs, preferably with an OIII, have yielded some of the best views I've ever had through my own, or anyone's scope, using this eyepiece. Pleasantly sharp field stop, big eye lens, very comfortable to use.
This review was provided courtesy of AgenaAstro.com
- Skill Level
- Time with Product
Jul 27, 2013
- User Notes:
- Review by Scanning4Comets of Canada.
Good eyepiece, but not in a fast scopePros:
Quality Lenses,Strong Construction,LightweightCons:
Not For A Fast ScopeComments:
I ordered this eyepiece in May of 2013. I tried it in my yard for quite a few hours after my 10" F/4.7 reflector had cooled for almost 2 hours. Eye placement is very good without any issues at all. I then tested for edge sharpness without a Paracorr. Coma started half of the way out and got progressivley worse as I took the bright star Arcturus and panned out towards the field stop. This is not the eyepiece at fault, it is my short focal length mirror which causes the coma.
However, some eyepieces show hardly any coma from the mirror at all, which I have used before. In my audio report of this eyepiece, which I am listening to now, I noticed that this eyepiece needed close to 1/2" of out focus compared to my other eyepieces, so I used two empty 2" filter cells screwed to the bottom of the 2" barrel to give the it more length. A 14mm Baader fine tuning ring would work perfectly for that purpose.
All in all, this was a really well constructed eyepiece with excellent coatings, perfect eye relief and it played well with filters too. It just doesn't play well with a fast reflector, but if you own a paracorr, I would imagine it would clean up the coma very well.
One other thing I did try, was using it in a Meade 2" Tele-extender and the edges cleaned up perfectly and there was no vignetting at all.
This review was provided courtesy of AgenaAstro.comMar 22, 2013
Outstanding wide field eyepiecePros:
Easy to Use,Strong Construction,Quality LensesCons: Comments:
The 28mm ES68 is the best longer FL widefield eyepiece I've used. It handles a fast system extremely well remaining sharp until the last 10% of the field or better with only slight falloff of sharpness in the outer 10% in my f/5.7 petzval refractor. It also barlows extremely well. One of the things I love about this eyepiece is the nice even illumination of the field as the sky background remains a uniform darkness from center to edge. Pincushion is detectable but very mild in this eyepiece - much less than the level of pincushion in a 27mm Panoptic for comparison. The coatings on this eyepiece are excellent as it has a very high transmission. It is my favorite deep sky eyepiece as it provides bright views of emission and planetary nebula, sharp rendering of stars in clusters and starfields, and galaxies stand out due to the uniform black sky background. I've also been extremely pleased at just how outstanding it is for lunar observations as well. In comparison to the performance of a 27mm Panoptic I would only rate the Panoptic higher in sharpness at the last 5-10% of the field. I would rate the 28mm ES68 higher in transmission, for much milder pincushion, and for color neutrality.
This review was provided courtesy of AgenaAstro.comSort by
Apparent Field of View 68° Barrel Size 2" (50.8mm) Bolt Case Included Yes - Free Agena Eyepiece Container Bolt Case Size Agena 65x80mm Coatings EMD (Enhanced Multilayer Deposition) Coatings Design 6 Elements; Combination of: Dense Crown, Light Crown, Dense Flint, and Lanthanum Optical Glasses End Caps 2 Eye Relief by Design 21.6mm Filter Threads Standard 2" Filter Thread (M48 x 0.75) Focal Length 28mm Lens Elements 6 Lens Groups 4 Parfocal Yes Rubber Eye Guard Rubber Folding Type Blackened Lens Edges Yes Additional Information Body: Anodized Black Aluminum; Laser-Etched Description and Serial Number; Rubber Grip: Internally O-Ring Sealed and Argon Purged
Barrel: Stainless-Steel, Double Taper, Accepts Standard Filters
Manufacturer Explore Scientific Eyepiece Focal Length 20.1mm - 30mm Eyepiece Field of View 61 - 70 degrees Eyepiece Series Explore Scientific 68° Barrel Type Tapered barrel