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Ceph and Cass

ES 25 100?


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Morning all.

Having recently tried out some 100 degree eyepieces for the first time I am hooked! I was using ES eyepieces and thankfully they were more than good enough or my needs, so I can (for now) avoid the Ethos route!

I am now looking at some options for low power wide field eyepieces in my 12" f4.92 dob. I have been considering the ES 20 100 in combination with the ES 30 82 (to get the max FoV from the 30*82 and higher mag and lower exit pupli from the 20*100 - people seem to feel there is a big enough difference to justify both). However, might splitting the difference and going for the ES 25 100 be a viable alternative? The costs are roughly the same.

So what would you rather have? The stats in my scope would be:

ES 25 100: x60mag, Exit pupil 5.08, FoV 1.57

OR

ES 30 82: x50mag, Exit pupil 6.1, FoV 1.64

ES 20 100: x75mag, Exit pupil 4.07, FoV 1.33

All that said, I have not actually seen any reviews of the 25*100 - has anyone had any experience with it?

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I seem to have ended up with the latter option, the Nagler 31mm 82 degrees and the ES 20mm 100 degrees. My 12" dob is F/5.3

The ES 25mm 100 was not on the market when I was making my choices though so it will be interesting to see if anyone has one and whether they feel it's a better option than the two eyepiece route :smiley:

I guess the key thing is whether the 25mm / 100 can perform really well in an F/4.9 newtonian. Al Nagler said he would not make an Ethos longer than 21mm because of performance compromises that they did not want to accept but ES may have found a way to do it.

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I know there is someone on site with a 25mm but I haven't seen any reports from him on it, other than a brief PM that he sent me. Which seemed to suggest it was very good. I am sitting on the fence on this as anything Al Nagler says should be listerned to, I think there is a greater chance the compromises he was talking about have been compromised. That said I am sure it will perform in many scopes very well indeed, however I do not know about scopes down to F4, says he as if he had one.

Alan.

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Thanks guys. I think that is in line with my thinking as well. In the absence of any reviews I will go for the 20*100 and 30*82 for now - it has the advantage of giving me a little more flexibility. It also means I can get one of them much sooner than if I went for the 25*100, which would need quite a bit of saving up for!

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Iam absolutely sure the 20mm and the 30mm will perform superbly for you. I am a sort of person that would want the 25mm just because it was there. If the 30mm is as good as the Meade 30mm, bear in mind they were from the same factory, you are in for a treat. Word of advice, don't drop it on your foot, i think it weighs more than the Televue. When I sold my Meade it weighed in at 1.305KG, there is a fair chance the Ex Sc will be much the same.

Alan.

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I'm always a little bit skeptical about anything a manufacturer states as incontrovertible truth, even Unc Al, because it's just his opinion, albeit a pretty hefty one!

After all, Nikon and Pentax don't seem to have spent much time worrying about what Tele Vue think and lest we forget, one mans unacceptable edge of field aberrations are offset by another mans abhorance of inaccurate colour cast. TV don't get everything perfect and as they're far from the most expensive out there, they're unlikely to.

If I were starting my EP collection again now, I would probably have bought the ES100 25mm instead of the ES82 30 & 18mm. With nearly the same FOV as the 30mm, but a darker background, it's persuasive. I also find I tend to jump from the 30mm, straight past the 18mm to the 14mm, as it tends to suit the subjects I like better. With a 25mm in the case, for me at least, the 18mm would be almost entirely redundant.

I'm also not sure that it's a dead cert the 25mm will be notably worse at the edges, as speculation might have it. To be honest, the ES82 30mm is jolly good in this area, but in my 12" Dob, you're a long way from revealing this, unless you add a coma corrector into the mix. The 25mm FL will be slightly less sensitive to coma, so even if it did introduce a touch more astigmatism, would it be any worse over all?

It needs someone who's had both, to give a definitive answer. :)

Russell

Edited by russ.will
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I don't think Al Nagler said it could not be done. All he was saying was it would involve design compromises that he / Tele Vue did not want to make to the Ethos design.

If someone else can do it and it works well enough to sell then good for them :smiley:

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Exactly and lest we forget, we all have our own idea of personally acceptable compromise to overlay on top of what each manufacturer chooses as theirs. I just get a little uneasy when I see such statements passed on by a third party, as it's no substitute for actually having made the comparison.

I guess it's my natural inclination, coming from the hi-fi world, where right and wrong are subjectively even more blurred and objective opinion is far thinner on the ground than it is in this hobby. I think that's why I find this hobby a comparative relief. At least this world has agreed on the best way of objectively measuring absolute performance. Oh! Hang on..... :grin:

Russell

Edited by russ.will
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Exactly and lest we forget, we all have our own idea of personally acceptable compromise to overlay on top of what each manufacturer chooses as theirs. I just get a little uneasy when I see such statements passed on by a third party, as it's no substitute for actually having made the comparison....

Sorry if I made you feel uneasy Russell (assuming myself to be the third party) :embarrassed:

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I don't undestand some people, reading this all the way down you get the idea that he don't like it very much, then gives it a B+ and almost an A, both of which when I was at school put you in the highest grades of the class.

Alan

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I don't undestand some people, reading this all the way down you get the idea that he don't like it very much, then gives it a B+ and almost an A, both of which when I was at school put you in the highest grades of the class.

Alan

just what i was thinking too, god knows what he writes about a bad ep, hehe
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I have the 30/82 and 25/100 but due to the weather have only been able to use the 25 a couple of times in the C11. It's just pinpoint stars right across the field to my inexperienced eyes, and I did not notice other aberrations - not to say they didn't exist, just that I was looking at the view! Unfortunately I can't double check at the moment as I'm in the middle of moving. Also bear in mind that I use a C11 Edge HD which is corrected for field curvature and coma, so your mileage may vary...

It is 1.2kg as described, but the 30/82 is 1kg anyhow, so if you can balance one you can probably balance the other. I should add that I've been very happy with the 30 though, and only considered the 25 when I was offered it at a good price, and then encouraged by the one and only Mr Potts :D The 20mm ES or 21mm Ethos are too close to the 17mm Ethos for me and my long focal length scopes, so the 25 was more appealing. I should probably sell the 30/82 now :eek:

Addendum: doesn't sound like a bad EP to me, but I guess he's just critical? I'd expect most people (like me) wouldn't notice most of those compromises/flaws unless they were pointed out during a session :D:eek:

Edited by Dunkster
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Dunk,

You didn't exactly need a lot of encouragement, did you. I was only thinking of you the other day I wondered how you were?

I am almost as bad as you, I got talked into getting a 21mm E by Damo and I haven't even used it yet. With me though the weather isn't a problem and I am not moving, too much new stuff. Good luck with the move and I hope you will still be on site.

Alan.

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Wow that's some aircraft you were on. I looked at your post to check where you were and it said Berkshire, 2 hours later your in Australia, some plane. Hope all went well and your getting to grips with the strange sky. I know when I was down there last it all looked very strange, even though I knew the shape of Scorpious when it's overhead almost it sort of catches you out.

Alan.

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Well I certainly did not see the twist at the end of that review coming - its actually quite funny! Thanks for the link John. It sounds like it is performing pretty well Dunkster - thanks for the feedback.

Reading Russell's comments on skipping from the 30 past the 20 to 14, I wonder if I might end up doing the same thing. My interests are either very large (open clusters, larger, brighter DSOs, starfields) or very small (doubles, globs, planetary nebula), but not so much galaxy hunting (I have neither the sky nor the patiance at the moment ;-) So the max FoV is a must, either the 25 or the 30, but I could end up skipping right from there to the 14 and lower. That would point strongly to the 25 (same FoV as the 30 but darker background and an exit pupil I can grow old with).

Given all that:

- Is there a type of target that the 20*100 (or an Ethos 21) is just *perfect* for?

- Would a mid/low power set of 9, 14, 25 (all 100 degree) seem sensible for what I am interested in or would I be missing a trick somewhere?

Of course, given enough time I will probably end up with them all in the end anyway, but its good to pretent I am being sensible for now at least ;-)

Paul.

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Sorry if I made you feel uneasy Russell (assuming myself to be the third party) :embarrassed:

Good lord John, absolutely you were not - You, because you've had the time to experience a great range of EPs, notably stick to commenting on comparisons you've actually made and I note - You're careful NOT to extrapolate results to other EPs just because they're from the same line up. Even my limited experience has shown that is a path fraught with pitfalls.

No, what I'm saying is that the web being what it is, such 'facts' can gain credence through numbers, when the numbers who've actually had that experience can be vastly smaller. Equally, the fact that someone can structure a review and get it published, can also cement a legend, but equally create an unfounded myth. These facts/myths can then start to get parroted as fact, simply because they were in a review and/or enough people repeated it.

I may also dare suggest (and this is based on dealing with a LOT of high end hobby product from America) that TV are skilled in their marketing, as US companies tend to be. Al's statement about not producing stuff he's not happy with, is a case in point. The reputation of the company lends this statement weight at face value and it is true, that everything they produce hits that mark. However, it could also be read as them not having figured out how to do the products that they don't offer. Heresy! No, they're an awesome company of well deserved repute, but they're not omnipotent! Mind you, the views I've had through a workmates TVs, also show that they ain't far off, for a price. It makes you wonder what they could do if they cut loose and charged Nikon prices and indeed, given their manifest abilities, why they don't?

Mind you, the Nikon reputation seems to be cemented into imortality by the rarity of the independent information available. One assumes they occupy another level, but most of what you read about them dismisses them as a realistic proposition due to their price. I find that ironic, considering that nearly everybody who writes that sort of opinion has invested the sort of money in there EPs that would seem totally unbelievable (unjustifiable?) to the lay man. Hell, I use all of my camera lenses about 10x more than my Astro EPs, but guess which I've got more money tied up in? Now I look at it that way, I really should sit myself down and have a good talk with myself! :grin:

That link you posted above was a fascinating read BTW. I read it and having got to the conclusion, had to read it again to be sure I hadn't got confused along the way. I'm not sure whether he really liked the ES100 25mm and simply dwelled on the faults inherent in the 100deg breed, or hated it outright, the conclusion being added as a sop to stop it looking like a hatchet job. One thing's for certain, you'd want to read a few more opinions on the EP before you felt you could lean on that review to make a choice!

Russell

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Of course, given enough time I will probably end up with them all in the end anyway, but its good to pretent I am being sensible for now at least ;-)
Never a truer word spoken!

Your viewing preferences seem broadly in line with my own and I often think that if I were starting again, with what I've learned about my own preferences since (eh?) that I'd probably have pooled the cash into the 9, 14 & 25mm, plus a ES Focal Extender/TV Powermate. Of course, this speculation is idle on my part as the 25mm (or the 20mm) wasn't available when I started on my path.

Then again, some of the views I've had through my Meade clone Maxvison SWAs have also caused me to wonder if chasing UWA views, is expensive for it's own sake? I'll have to wait for darker nights to return, but I had a couple of nights to compare my ES82 18mm (basically a Meade 5000 18mm UWA) against the Maxvison 24mm (basically a Meade 5000 SWA) and it left me wondering if trying to push the field stop out of your field of view is actually worth the expense. Okay, the 18mm offered a darker background, but the 24mm is easier to look through for extended periods and it's not like a 68deg FOV is anything like Ortho claustrophobic in use. It's a nice, physically relaxed view. The thing is, short focal length SWA prices can fill your case with more EPs to circumvent worrying about focal length jumps and the money saved can dump a better scope on your mount, or a better mirror in that same scope.

Even if you look at Televue, a 17mm Delos alone is £100 cheaper than a 17mm Nagler, which in turn is a staggering £280 cheaper than an 17mm Ethos. Multiply that difference across 3-4 (or 5) EPs and your 5" achro suddenly becomes a 5" Triplet Apo, or your 12" Newt becomes a 16" Newt, or buys you 1/8 wave 12" mirrors. Purely based on user reports, the SWA Delos is regularly compared to a wide field Ortho for sharpness edge to edge(and Orthos are blindingly sharp) and the extra aperture/better objective lenses/mirrors in the scope will render far more extra detail, reveal more faint fuzzies/more structure in currently visible fuzzies and support higher magnifications t'boot.

You gotta love hindsight!

Russell

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Well I certainly did not see the twist at the end of that review coming - its actually quite funny! Thanks for the link John. It sounds like it is performing pretty well Dunkster - thanks for the feedback.

Reading Russell's comments on skipping from the 30 past the 20 to 14, I wonder if I might end up doing the same thing. My interests are either very large (open clusters, larger, brighter DSOs, starfields) or very small (doubles, globs, planetary nebula), but not so much galaxy hunting (I have neither the sky nor the patiance at the moment ;-) So the max FoV is a must, either the 25 or the 30, but I could end up skipping right from there to the 14 and lower. That would point strongly to the 25 (same FoV as the 30 but darker background and an exit pupil I can grow old with).

Given all that:

- Is there a type of target that the 20*100 (or an Ethos 21) is just *perfect* for?

- Would a mid/low power set of 9, 14, 25 (all 100 degree) seem sensible for what I am interested in or would I be missing a trick somewhere?

Of course, given enough time I will probably end up with them all in the end anyway, but its good to pretent I am being sensible for now at least ;-)

Paul.

I'd say the 9, 14 and 25 would give you a really nice spread of FOV, my guesses are that gives you 60x, 107x and 167x, roughly 1.6, 0.9 and 0.6 degrees FOV. 25 for wide, 9 for busting globs, etc. Not sure about what the 14 is useful for :confused: other than a nice view :D

With the 25/100 you're sacrificing a small (5%?) amount of total FOV compared with the 30/82 (the 25 has the smaller field stop according to ES), but other than that it's a question of how you want to experience that view :cool:

If you really wanted to push the boat out, there is a 9mm 120 degree model... very rare beasties, not surprisingly with their price tag :eek:

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