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14mm 100 Degree Explore Scientific Eyepiece

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#1 mloffland

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Posted 15 December 2009 - 11:44 AM

14mm 100 degree Explore Scientific Eyepiece

#2 Mike B

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Posted 15 December 2009 - 12:19 PM

Mark-

Thanks for the write-up on the ES14-100... i really enjoyed reading thru you & your friends' experience using this EP- particularly in a large Dob, and alongside the TV13E!

One thing that was noted by everyone was the eye-relief of the ES 14mm is noticeably longer than that of the Televue 13mm Ethos; this made the ES 14mm a more comfortable eyepiece to use.

Now, this intrigues me. I've viewed thru the TV13-E, while wearing eyeglasses (as i typically need to do :p), and cannot see the entire FoV no matter how tightly i "push-in". I figure, since i'm only getting 80-90 degrees of it, why not just stick with my current TV12T4 & 17T4 Naglers?

The ES specs note the ER, iirc, as one-half mm *shorter* than the Ethos... but you guys all felt it actually had MORE? I'm assuming the "more-ER" aspect was with the eyeguard folded down. Did anyone actually try viewing while wearing eyeglasses? What value would you estimate is more accurate for the ES14's ER?

Thanks again! I guess maybe i need to get re-excited about this EP... like i need another hole in my wallet!!
:lol: mike b

#3 BillP

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Posted 15 December 2009 - 01:48 PM

Mark - Great write up on the ES14 and puts thing in context to the Ethos quite nicely. Also very nice to see some multiple people voting on preferred views.

Mike - Eye relief is measured from the center of the lens. So depending on how far the lens is inset, and then if there is any concave curve to the top eye lens, it's pretty easy to have a shorter ER eyepiece feel better than a longer ER eyepiece as it all depends on how far the manufacturer insets them and how strong of a curve the eye lens may have. Would be interesting to hear how far above the outside surface of the top EP housing the ER is as this is a more practical measure for users.

#4 David Knisely

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Posted 15 December 2009 - 03:32 PM

As was pointed out in the earlier CN Reports review of the 14mm E.S., the eyepiece weighs in at 1.875 lbs (1 lb 14 oz), not quite 2 lbs as this review says, although the difference is minor (it is still one heavy eyepiece). It is heavier than the 13mm Ethos, but lighter than the 31mm Nagler. I had to keep the screws on my star diagonal tight with this one, but no more so than when I use my old Meade 14mm Ultrawide. This review states:

The next thing I looked for was any fringe color or hint of it, there was none, and again everyone concurred. Jim mentioned that the power line which was running horizontally thru the FOV appeared to be curved, I pointed out that the power line did sag a bit on its own, but Jim thought that it appear more curved than it should. So, to test if the ES 14mm was causing this I nudged the scope a little bit to put two power lines in the FOV, one of the power lines running thru the top half of the FOV and one running thru the bottom half. If there was any field curvature (like a fish-eye lens would produce) the power lines should show different amounts of curve, there was no difference visually evident in the two power lines, both had the same sag, and Jim concurred.


On chromatic aberration, the eyepiece is pretty well corrected for it across the field, although with careful study, a very small amount of lateral color can be detected right at the field stop on objects like bright stars or the moon. It is minimal and quite acceptable. As for "field curvature", what is being described is not field curvature, but barrel distortion. Field curvature would show up as stars at the edge of the field being out of focus while those at the center would be in-focus (or vice-versa). There is a modest amount of barrel distortion for linear objects that run fairly near the field stop, but it is not as large as with some eyepieces I have reviewed and certainly is not a show-stopper when it comes to an eyepiece choice. The 14mm ES is a good eyepiece, even if it is somewhat of a "beast". Clear skies to you.

#5 Mike B

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Posted 15 December 2009 - 03:54 PM

Hi Bill-

Interesting... i know that differing manuf's methods of representing this aspect can create non-intuitive field results. That is, actually enjoying more (or less :bawling:) ER than one expects.

This isn't the first report i've heard (seen?) claiming more generous ER for this EP, compared to the E13. Maybe i'll be fortunate enough to see one for myself, in-the-flesh, to make my own appraisal!

Steady air, there-
:grin: mike b

#6 David Knisely

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Posted 15 December 2009 - 06:38 PM

Hi Bill-

Interesting... i know that differing manuf's methods of representing this aspect can create non-intuitive field results. That is, actually enjoying more (or less :bawling:) ER than one expects.

This isn't the first report i've heard (seen?) claiming more generous ER for this EP, compared to the E13. Maybe i'll be fortunate enough to see one for myself, in-the-flesh, to make my own appraisal!

Steady air, there-
:grin: mike b


I measured the 14mm 100 Degree E.S. eye relief at about 14.5mm, so it is fairly close to that of the 13mm Ethos. Clear skies to you.


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