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ES 120deg 9mm vs Ethos... Opinions desired?


Liquid360

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I've just purchased a new FSQ-106EDX. I'll be doing some visual observing. Having previously owned a large SCT I've never dealt with high end EPs. I've already bought a used TV Ethos SX 3.7mm and I'd like to buy just one more. The ES 120º 9mm is on sale and was wondering if I should just stick with Ethos line. If you think Ethos, which would you choose considering the SX 3.7 I've already bought. I have zero experience here so opinions greatly appreciated.

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I have the 21mm, 13mm, 8mm and 6mm Ethos and all are extremely useful in my refractors which are similar in spec to yours. I used to have the ES 20mm / 100 degree and that was excellent too. I've never used or even seen the ES 120 9mm but I've read a few reports on it. For me the Ethos range is really excellent and I don't find myself pining for an extra 20 degrees so I think I'm going to pass on the ES 9mm 120 as I can't see it beating the Ethos in anything other than field of view and it's purcahse price in the UK makes the Ethos look quite low cost !

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same as John,i had both Ethos and ES in 100 degrees and both where optically excellent.Obviously if that uber wide 120 degrees fascinates you,by all means go for it,but i found 100 degrees already more than i need,never mind the extra 20.At the end,all my 100 degrees are gone or will be gone and are replaced with humble 84 or 82 degree eye pieces as thats the sweet spot for me for wide angles.

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A couple of issues when I used the 9mm 120 degree:

--the concave eye lens reflects any and all ambient peripheral light straight into your eye.  I could only use the eyepiece with my hands cupped around the side of the eyepiece or with a black hood over my head, even with the rubber eyecup flipped up.

--when looking off axis toward the front of the scope, you are almost looking the same direction the scope is pointing.  In my peripheral vision, the background was....the sky!

That means the eyepiece needs a top-of-the-tube light baffle that blocks the sky if you look at the edge of the field in that direction.

--with its twelve elements, it is a little darker than other eyepieces in and around its focal length.  It is well corrected, though.

A totally unique experience, and destined to become, eventually, a collector's item.  Works best, IMO, in a large dob (15"+).

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Interesting points raised there Don, not that I am going to be running out to buy one but they don't tell you stuff like that on the ExSc site or the box it comes in I would imagine. I also guess at the price the 15 inch Dob comes with it.

I am more than happy with my spread of Ethos's though I would like to add the 4.7mm, which I am sure I will.

Alan.

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I have not used anything over a 82 degree eyepiece and I honestly find that more than enough, you will see I have just one at that which is my widefield viewing eyepiece. All my remaining eyepieces are 70 - 72 degrees.

I am not sure if this is correct but I read somewhere that 65 degrees is the optimum for comfort viewing before you start  having to move you head to get the full FOV.  Based on my own experiences it sounds about right but maybe someone can tell me otherwise  :rolleyes:

Steve

Found one on ebay from Agena Astro but thats america so £600 posted http://www.ebay.co.uk/itm/Explore-Scientific-2-120-deg-Series-Argon-Purged-Waterproof-Eyepiece-9mm-/111160953517

You could buy 2 delos eyepieces for that price, have you considered that ?

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I find I can see the whole field of my Ethos eyepieces without too much difficulty although I'd agree that the central 70 degrees is viewed more critically. I now have a 10mm Delos and it's superb but I'm not going to be rushing to replace my Ethos eyepieces with Delos equivilents - the "wow" factor coupled with wonderfull optical quality of the Ethos is still a magnet for me.

Give one a try some time Steve before deciding against them. The ES 100's create a similar experience at lower cost :wink:

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Give one a try some time Steve before deciding against them. The ES 100's create a similar experience at lower cost  :wink:

I will do John, not sure if Shane has one to try next time we meet up. 

Like you I am very happy with my own EP collection and love my Delos so even if I liked the Ethos it is unlikely I would change unless a 21mm came along at a very good price  :evil:

Regarding FOV I found this article in cloudy nights. (I copied out the relevant sentence to save people reading it all) but I have read it in some retailers or manufacturers blurb somewhere referring I am sure to 65 degrees http://www.cloudynights.com/page/articles/cat/articles/how-to/eyepiece-review-pitfalls-r361 The human eye has about a 50-degree FOV. Anything greater than this will be perceived as a wide view. Give 65-degree FOV eyepieces a chance before jumping into the 70-degree plus eyepieces.

Steve

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Anything above 68 degrees feels wide field to me, but I prefer 100 degree eyepieces. I can take in the entire field of the Ethos, but I am sure I would be unable to do so with 120 degree eyepieces. I would have to probably sort of look sideways to take it in.

Steve, that Ethos 21mm is a wicked eyepiece. Your wallet may regret getting one, but your eyeballs will love it!  :grin:

Copying from Wikipedia (yes, not the most reliable source):

The approximate field of view of an individual human eye is 95° away from the nose, 75° downward, 60° toward the nose, and 60° upward, allowing humans to have an almost 180-degree forward-facing horizontal field of view. With eyeball rotation of about 90° (head rotation excluded, peripheral vision included), horizontal field of view is as high as 270°. About 12–15° temporal and 1.5° below the horizontal is the optic nerve or blind spotwhich is roughly 7.5° high and 5.5° wide.

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