Standard eyepieces provide sharp, pinpoint star images at the center of the field but as you look out toward the edges, stars often begin to get blurred and out of focus. Eliminating this distortion usually calls for expensive optical designs with additional lens elements to eliminate the field curvature. But these new BST eyepieces use a 5 or 6 element design that offers a flat field over the entire field of view at an attractive price.
Featuring large eye lenses, wide fields of view (from 53°-65°), and generous eye relief (from 9.6mm-24.4mm), these eyepieces are a pleasure to use. Fully multicoated lenses maximize light transmission and edge blackening of all lens elements ensures excellent contrast. Other features include safety recess grooves on the 1.25" barrels, standard 1.25" filter threads, and twist-up eyecups.
May 23, 2017
BST 1.25" Flat Field Eyepiece - 16 mmPros: Cons: Comments:
At 70+ years of age my eyes are not what they once were, one has cataracts and the other has a new plastic lens. Therefore, I do not want to spend money on optical quality that I will never see. I use mostly 1.25" eyepieces as I hate changing out the 2" bushing in the dark when switching from a 2'' to a 1.25'' eyepieces. The BST 16mm fits my needs very well and with a 60 degree field of view works well with planets and open clusters. The thick rubber eye cup is one feature that I like as I have had several of the thin rubber cups disintegrate with age. The eyepiece is used with my 114mm f5.3 refractor and my 127mm f10 cass it works well in both. The eyepiece has some softness at the edges but the "sweet spot" is very large and gives great views even in the f5.3 refractor. I do a lot of work with students and they have a tendency to put their fingers in the middle of the eyepiece and say what's this? My older BST eyepieces have undergone multiple cleanings and the coatings are still perfect. I consider the coatings on these eyepiece to be of outstanding quality for the price point.
Pros: Light weight, generous field of view, excellent
Con: Lacks a built-in automatic finger print cleaning thingy.
This review was provided courtesy of AgenaAstro.comMay 10, 2017
16mm flat field eyepiecePros: Cons: Comments:
Good price for the quality, shipped immediately and very well packed and presented. I have purchased from Agena before and have always been satisfied, and this time is no exception. The only minor disappointment is that the diameter of the rubber grip seems to be about 1 mm smaller than advertised. Normally this would make no difference whatsoever, but I wanted to fit this eyepiece in an adapter for photography and the size was important for the fit.
This review was provided courtesy of AgenaAstro.comJun 24, 2012
An excellent valuePros:
Lightweight,Quality Lenses,Easy to Use,Strong ConstructionCons: Comments:
I've been looking for a 16mm eyepiece that has enough eye relief to allow me to wear my eyeglasses while observing. The 16mm BST Flat field offered by Agena Astro fits this need. It has ~17mm of eye relief and I can easily see the entire 60 deg AFOV with glasses on. The construction of this eyepiece is excellent. Optically it provides nice sharp central field views with very good contrast. This eyepiece does struggle to handle a fast system as edge performance is not very good. However, when I use the 16mm Flat Field with a 2.5x Powermate the edge performance improves dramatically. The eyepiece has no problems with blackouts or kidney beaning - very comfortable to use. I give this eyepiece a 4 star rating instead of a 5 star rating only because of edge performance in a fast system. In all other respects I see no reason not to give it a 5.
This review was provided courtesy of AgenaAstro.comSort by
Apparent Field of View 60° Barrel Size 1.25" (31.7mm) Bolt Case Included Yes - Free Agena Eyepiece Container Bolt Case Size Agena 52x80mm Coatings Fully Multi-Coated Height (with Eye Guard) 2.24" (57.0mm) Max Width 1.59" (40.5mm) End Caps 2 Eye Lens Diameter 0.83" (21.2mm) Eye Relief by Design 19mm Field Stop Diameter 16.5mm / 0.65" Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6) Focal Length 16mm Lens Elements 6 Lens Groups 4 Rubber Eye Guard Yes Blackened Lens Edges Yes Manufacturer BST Eyepiece Focal Length 15.1mm - 20mm Eyepiece Field of View 51 - 60 degrees Eyepiece Series BST Flat Field Barrel Type With safety undercut Eyepiece Weight 3.50oz (99.22g)