Product Description
While the longer focal length 30mm Explore Scientific provides an even wider field of view with an f/4.5 scope, the 30mm also has a very large 6.7mm exit pupil that is larger than many observers' eyes can dilate. That effectively wastes some of a Dob's light gathering capacity, as some of the full light cone falls on the observer's iris, rather than entering his or her eye.
In addition to its wide field, the 24mm Explore Scientific has an extra benefit for you. It is O-ring sealed and argon-purged to be 100% waterproof. This prevents internal fogging in the eyepiece; keeps the interior dust-and fungus-free; and makes it easier to clean, as there is no risk of excess cleaning solution getting trapped between the lenses.
The latest computer design programs have been used to optimize its performance. Its six element/four group design uses low dispersion and high refractive index lenses and full multicoatings for high contrast, high resolution, and flat field images across its very wide 82° field of view. The lens edges have been blackened to improve contrast.
A 12" f/4.5 Dobsonian reflector will have a full 1.43° field at 57x with this eyepiece, able to encompass all of the Pleiades in one field. Even an 8" f/10 catadioptric will have a 0.98° field almost two lunar diameters across, for thrilling views of the larger nebulas, like Orion. You can use the calculator in the "formula" tab above to see just how wide the field will be with your particular telescope.
With 17mm of eye relief, this Explore Scientific eyepiece provides virtually unvignetted views for eyeglass wearers, although the 82° field of view is so wide that even non-eyeglass wearers can't see the whole field at once. All observers have to move their eye from side to side to take in the immense view, so vignetting in the conventional sense is not a problem.
The eyepiece has a soft fold-down rubber eyecup and comes with dust covers for both ends of the eyepiece.
This individually serial numbered Explore Scientific eyepiece is backed by a limited one year warranty, which will be extended to an Explore Scientific transferable lifetime limited warranty when its warranty card is registered with Explore Scientific within 60 days of purchase. Here's a link to full details on this unique transferable lifetime warranty.
Tech Details
| Barrel Size | 2" |
|---|---|
| Eye Relief | 17mm |
| Field of view | 82 |
| Focal Length | 24mm |
| Number of optical elements | 6 |
| Weight | 1.6 lbs. |
| Warranty | 1 year, extendable to lifetime |
Reviews
The ES82 24mm 2" is a very good ocular, and does quite well in sharpness and contrast, color is good and edge of field performance is good with the fast refractor.
Eye relief is tight, but I do not wear spectacles while observing so the ER is good enough. Though, even jamming my eyeball into the eye lens of the 24, I still could not see the edge of the image circle; gotta move the head around for that.
I will not knock this ocular for it's weight, because it's a 2" ocular with a lot of glass in it to allow for it's quality 82* AFoV. It's size works well with what it offers, no-bones there.
This ocular is a keeper, and it will retire it's smaller brother, the ES68 24mm 1.25" from duty and to seek a new home.
CS
The Other Jason (Posted on 8/26/2019)
(Posted on 1/4/2019)
I did have a QC issue - an O-ring on the telescope side was bulging out, meaning it wouldn't be able to hold that Argon seal. However, Explore Scientific held up their warranty and RMA'd the eyepiece. (Posted on 12/28/2018)