Explore Scientific EPs - and advice on an all-round EP kit

[stephenb]

Time to add an eyepiece to my collection of... one. I own a single, solitary 27mm TV Panoptic with my 18" 4.5 Dob.

I'm looking at a 14mm Explore Scientific 100 deg eyepiece (can't justify +$700 for a TV Ethos)

Can anyone recommend a retailer/dealer to buy from? I currently have found these two:

http://www.eyepiecesetc.com/EXPLORE_SCIENTIFIC_14MM_100_WATERPR OOF_EYEPIECE_p/2101140.htm

http://www.optcorp.com/explore-scientific-14mm-100-degree-eyepiece.html

Any recommendations? Any Oz dealer for these?

Cheers,

Stephen

[AG Hybrid]

I got mine from Optcorp. But that was when our dollar was at $1.10 US. But, even now its still great value. There's a couple local vendors. VTI Optics and Extravision.

[MortonH]

I've bought a number of items from VTI Optics and their service is very good. The website doesn't currently list the 14mm 100D so send them an email to check availability.

[stephenb]

Thanks Adrian and MortonH for your quick replies.

I'll shoot them an email shortly and see what they can do....

On a broader topic I've been considering expanding my EP kit (from one lonely EP) and creating a kit of 3.

Thanks to some advice from Bintel I am now looking at this range and the magnifications based on an 18-inch f4.5:


27mm TV Panoptic 68° - 76x mag
17mm TV Nagler 82° ($379) - 121x mag
9mm YV Nagler 82° ($499) - 228x mag


Now checking some comparisions to the ES range I come up with:

ES 6-Element 28mm 68° - 73x mag
ES 9-Element 14mm 100° - 146x mag ($339)
ES 9-Element 9mm 100° - 228x mag ($399)

ES is less expensive.... but Imay have to factor in shipping which will close the gap slightly. Thoughts on this hyperthetical, 3-piece, all-round EP kit?

[PeterHA]

Same Here,
I dealt wit James from VTI and he replies to e-mails swiftly and you even can pick item us to safe on postage.

[astro744]

Note the 16mm T5 Nagler is closer to being parfocal with your other two. See http://www.televue.com/engine/TV3b_page.asp?id=214#.U2h3QYGSy5I Column F.

However the 17mm is a 2" version and has a big eye lens and is good for eyeglass wearers whereas the 16mm is not. Both are quality eyepieces though. An alternative would be to replace your 27mm Panoptic with a 26mm T5 Nagler which happens to be close to Parfocal with the 17mm T4 Nagler. The 26/17 is a very nice match and both have 82 degree apparent fields. The 26mm T5 Nagler also has a bigger true field than the 27mm Panoptic and slightly less exit pupil.

Note though the thickness of your 2" to 1.25" adaptor will come into play when swapping eyepieces that are parfocal. I personally like the 26/17 combination.

[Astro_Bot]

Well, my thoughts are that, compared to 100° eyepieces, you will get 95% of the enjoyment from 82° eyepieces and 90% of the enjoyment from 68° eyepieces. Personally, I can't see the edges of an 82° field of view in one go, anyway, so that's wider than I need.

If you have any budget limitations at all (which, apparently you do) then you'll save a lot of money from going with, say:

ES 28mm 68°
ES 18mm 82°
ES 8.8mm 82°

... or even more eyepieces while still saving a little money:

ES 28mm 68°
ES 20mm 68°
ES 16mm 68°
ES 11mm 82°
ES 8.8mm 82°

The ES 82° and 68° eyepieces are also smaller and lighter than 100° eyepieces. ES eyepieces are either Argon or Nitrogen purged to make them moisture-proof.

Food for thought.

[sopticals]

If I were you, I would be inclined to shoehorn a ES30mm 82deg, into you lineup. A great widefield ocular, for a larger aperture dob,(helps someway to overcome the ever shrinking FOV as aperture increases). This ocular is a formidable rival, to the Nagler 31 t5 82deg, at a much lesser cost.

[David Niven]

I would avoid the ES 100D and go for the 82D instead.
The 100D is pricey and the 82D gives more than sufficient fov for all practical purposes.

[sn1987a]

17mm and 10mm Ethos or Naglers with Paracorr, I quite like my 11mm type 1 Nagler too. Televue beats everything else I've tried with my unsophisticated eye :)

[casstony]

The ES 11mm 82 degree is competitive with the T6 Nagler and much cheaper. The ES 6.7 and 30mm are also excellent. I haven't tried the others.
At 17mm (and other focal lengths) you could consider Delos - very comfortable and less likely to fog up with the long eye relief.

While many ES eyepieces are decent replacements for Televue, the 100 degree series is not among them IMO. Ethos has barely enough eye relief for the FOV while the ES equivalents have a recessed eyelens which reduces useable eye relief by 2 or 3mm.

[AG Hybrid]

The ES 14mm 100 + ES Coma corrector makes everyone's argument invalid. (except eye relief and green letters) 100 degree's of flat, pin point perfection and together they are still cheaper then an Ethos 13mm.

Psyk!!!!;)

I jest, I jest you Televue fanies.

No, but really. Just a winning combination.

[stephenb]

THank you all for your replies. I'm trying to digest all this info so give me a few hours to do so... but if it makes any difference I already have a Feathertouch SIPS coma corrector (http://starlightinstruments.com/store/index.php?route=product/product&product_id=49) which I might add, was the best investment I've made in a long time. The first time I looked at 47 Tuc I nearly fell backward off the ladder!

Back to the ES/TV discussion.....

[Camelopardalis]

If you're looking for a high magnification EP for planetary, the 9mm in your list, you could save a few $s and get the Pentax XF in 8.5mm...the smaller apparent FOV is largely irrelevant and it's a nice piece of quality glass for under $200 from VTI. Alternatively, the ES 8.8mm 82D is another balanced EP for a lot less.

IMO the 100 degree experiences are better at lower magnification, although if you're Dob is non- tracking I can understand the inclination...

[Varangian]

The ES 14mm 100 is the best EP I've ever looked through and that includes Naglers, Delos', Pentax XF (never looked through an XW or XL). There are a multitude of CN reviews comparing the 14 mm 100 ES l with the 13 mm Ethos and the only difference noted was $$$. I use my 14 mm in a fast dob and enjoy a flat field with no discernible astigmatism across the entire field. You cannot see all 100 degrees but when you close with the lens and look around in there it really is pretty crazy - especially at a dark site.

VTI do not currently stock the 100s

[David Niven]

The ES 6.7 82D is the best in the series and especially suited for planetary viewing.
Their 24mm 68D is also a good ep for low to medium power viewing.
You can't go wrong with these.

[sn1987a]

Well I've tried all these eyepieces and I keep coming back to the Televue Ethos and Naglers. Other Dob owners I view with have checked them out in their Dobs too and then they go back to their Ethos and Naglers, I'm just sayin'. :shrug:

[Varangian]

Of course they do Naglers are like old pipes you've been sucking on for 30 years - irreplaceable. I think some people also stand by an eyepiece when it costs 3x the amount of one of potentially equal quality. Many respected reviewers on CN suspect the ES 100 and Ethos designs are one and the same and that the ES are a direct rip-off. Certainly most reviews I looked at o/s struggled to split them.

If you've already got an Ethos sure you'll go back to it, no one is saying they are better than Ethos, not me anyway as I've never had the pleasure of an Ethos but if you are trying to decide on ES 100 and Ethos there are a plethora of comparisons that suggest that the ES 100 is up to it's eyeballs in the fight and costs half the price.

[MattT]

For some more thoughts….
Kind of with Astro Bot on this.
Had quite a few of the ES 82's…nice but short on the ER front so sold them.
Had 9 14 and 20 100's... really nice but short on the ER front, which meant I didn't use them after the initial wow factor wore off…so I sold them.
Had and still have the ES 68º really nice. They tick the box on the ER front with the exception of the 16mm, but it's such a beautiful eyepiece it's failings there are forgiven.

After a few years of buying, trying and selling, I stayed with the 68's as they are the easiest to look through... for me.

For the ES line up I'd say get the 34 24 20 and 16 ES 68º add a 1.25" 2x barlow and thats it…covered.
The 16mm is a bit tight on ER, but worth it…. a gem of an eyepiece.

If you really want a 14mm the best is the Denk 14, contrast, flat field…..the only eyepiece I wish I still had, the ES 16mm is quite close, in comparisons I did when I had both, which is why I sold the Denk.

My Newt is an Orion Optics UK 10" f4.8, with an ES coma corrector which gives pinpoint stars to nearly the edge, 98% out.

The problem I had with the 82 and 100's is to see the full field I was having to get close to the glass, give me the 68's any time, way more relaxing.

With a nice scope and focuser and CC, your most of the way there anyway.

Matt

[Don Pensack]

Well, whatever eyepieces you decide on, a good starting point for an 18" f/4.5 (assuming a Paracorr in the focuser) is a set:
30mm/15mm/10mm (+/- 1mm)
or, without a coma corrector (which I wouldn't recommend at f/4.5):
26mm/13mm/9mm
Then, add eyepieces in-between or above as needed, but at least you'd have "the basics".

[stephenb]

Amazing the amount of replies I've receive on this thread, so thank you to you all. I've been attempting to digest all the information and offer a reply.

Firstly I didn't want to turn this into a TV vs ES discussion (Ford/Holden, Apple/PC) :lol: but I know some people are passionate about their products and I appreciate your advice, thanks :thumbsup:

My biggest concern is eye relief and AFOV and if I purchase one or two eyepieces will they be comfortable for me - and if they're not I've just blown my money. I may be fretting too much over this (as I often do).

Having said that, I have rarely used top quality glass and have owned GSO/Bintel EPs for several years, so anything will be a step up in quality (The TV 27mm Pan trounced anything I tried from GSO)


I recently sold my Powermate is is was just too cumbersome and heavy for the finely balanced SDM


So, here is my refined list....


1 - 27mm TV Pan (keeping for the moment)

2 - ES 14mm 82° (1.25") or.... ES 18mm 82° (2")

3 - ES 8.8mm 82°

[stephenb]

Thanks for your reply Don, I've sent you a PM.

[Camelopardalis]

I'd go with the 14 and not the 18, as the 18 would be too close to the FOV of the 27 Panoptic.

Since they're so reasonably priced, you might want to consider chucking the ES 11mm in there for the nights where 8.8 might be too much...the 11 is another cracker for the $ IMO.

This may be the breaker for you though - note that none of ES82/100, Nagler T6 or Ethos are particularly generous with eye relief, you will have to get in there with the rubber cup for the full experience!

[Camelopardalis]

...and if you save all that $, treat yourself to the ES 30mm...it'll widen your view considerably over the 27 Panoptic :D

[MortonH]

The ES 11mm is particularly tight on eye relief. I sold mine for that reason. The 8.8mm has ok eye relief but lately I've been wishing it had a bit more.

Go in between the two and get a Pentax XW or Delos 10mm?

[Astro_Bot]

Actually, the ES 82d 14mm is the only one in the line-up that I wouldn't recommend - due to field curvature apparent in the outer 20% of the field - I used to own one. Pick any other ES eyepiece. ;)

Forget about the relative AFOV (68, 82, 100). IMHO, that's just a personal preference for how you want your view "bordered". All that you can comfortably take in is in the inner 65-70 degrees or so; 68 degrees is enough, and beyond that is window dressing.

Having said that, I have some 82d eyepieces, but that's because I like the view at that focal length - if there'd been a 68 degree eyepiece at that same focal length, with the same performance, I'd probably own it!

BTW, Don's advice is good, if a little short on explanation. Selecting eyepieces is usually best done by picking your lowest and highest practical magnifications (based on a number of factors, including how often you will get to use it/them), selecting corresponding eyepieces at those extremes then in-filling using f/stop intervals (halving the exit pupil area), though mostly you would start with double f/stop intervals (a double f/stop below is equivalent to halving the eyepiece focal length). So, for example:

27mm Pan = exit pupil of 6mm at your focal length (a good figure - largest practical size is 7mm for young eyes and 5mm for old eyes, with 6mm being a good in-between number)

Double f/stop below 6mm is 3mm exit pupil >> 13.5mm focal length.
Double f/stop below 3mm is 1.5mm exit pupil >> 6.75mm focal length.
In-filling at single f/stop intervals also gives 19mm and 9.5mm focal lengths.

So, if the 27mm Panoptic is your starting point, you would have the following set:
27mm, 19mm, 13.5mm, 9.5mm, 6.75mm.

But, don't get too hung up on these numbers - they're only a rough guide. For example, I also have a 40mm eyepiece for wider views (not applicable to you as the exit pupil would be far too large) but didn't want more than 5 widefield eyepieces, so I omitted some focal lengths and picked others in between f/stops to cover the range.

Specifically, my ideal range would be:
40mm, 28mm, 20mm, 14mm, 10mm, 7mm

Restricting myself to commercially available eyepieces and with some focal lengths in between f/stops (in bold):
40mm, 28mm, 18mm, 11mm, 6.7mm.

This arrangement works very well for me. Your mileage may vary. :)

[Varangian]

I do not recommend the ES 82 in the 14mm it is far inferior to the rest of the 82 range. Not only are stars seagulling in the outer 25% but the field here is actually blurry!

[Camelopardalis]

No seagulling or significant field curvature in my scope, so I suggest you check your scope/eyes :D

[Astro_Bot]

Hmmm. If you're the one that can't see a frequently-reported aberration in an eyepiece, then shouldn't you be the one getting an eye exam? :D :P

[Steffen]

My guess would be a poor/defective sample. Sample variation is still a big issue in this industry (esp. in the "affordable" price brackets), and equipment reviews rarely pay enough heed to that.

Any review rating that is based on a single sample of the reviewed item should be taken with the proverbial grain of salt, until substantiated by similar ratings given by others.

Cheers
Steffen.

[Camelopardalis]

I'm probably due :lol:

But I also use a scope corrected for field curvature...

[Astro_Bot]

Field curvature has been reported many times in the ES 82d 14mm by many reviewers. So has flaring from off-axis bright objects in the "old" ES 82d 8.8mm, since corrected by a revised baffle/field stop design.

[Camelopardalis]

But does that automatically mean I'm wrong? :confused2:

Maybe it's worst in a Newtonian and all the reviewers had Dobs? That'd be a useful data point, and helpful to the OP.

[Astro_Bot]

There's are factors such as visual accommodation (i.e. you may have better and/or different-shaped eyes to other reviewers), target viewed and expectation to be considered.

I wouldn't say you're wrong, merely in a teensy, tiny minority ... :D :P

I reviewed in an f/10 ACF SCT and f/7.5 refractor, but there have been reviews in Newtonians as well.

But, hey, what would I know? I actually liked Tron: Legacy. ;)

[AG Hybrid]

Nawwww. My ES 14mm 82 has noticeable field curvature towards the outer field. It could also be an aberration magnified by coma as well. I should try it in the ES coma corrector. It should clear things right up.

[Camelopardalis]

:lol: I can live with that. I liked Tron Legacy too ;)

[MortonH]

The reports of field curvature in the ES82D 14mm eyepiece didn't stop me buying one for my slower scopes. But in faster scopes I've read it can be a problem.

My 14mm ES82D is perfect in a f/12 Mak and good in a f/7 refractor. However, the other day I did solar observing with my ZS66 (f/5.9) and noticed that sunspots were in focus on one limb of the sun but very slightly out of focus on the other side. The difference was focused out with a very minor adjustment. Perhaps this is the FC of the eyepiece?

[stephenb]

I've spent most of the afternoon digesting the latest replies, including Astro Bots :lol: and it is starting to gell with me. Yes I tend to agree, i've always thought to myself that the AFOV is not a critical element and more of a comfort element of the eyepiece.

I've taken in all your advice, comments and recommendations - cheers to you all. Today I've ordered the ES 18mm 82D from VTI Optics. This hits 131x. I was surprised that they offered a very competitive price (AUD $212) compared to the overseas stores (e.g. OPT USD $190 + shipping)

[Camelopardalis]

Congrats Stephen! Look forward to hearing what you think of it :thumbsup:

[stephenb]

Thanks Dunk, I know your advice was to with the 14mm and not the 18 (too close to the 27mm Pan?) however I thought I'd look at a 4-piece set 80x, 130x, 180x & 220x. :)

[Varangian]

I suggest you look through one in a fast newt like I was and like OP is, which is what I have done with the 14. I mentioned that I was using other ES EPs in a fast scope. You could even try reading the entire thread maybe? :question:Better still look at a heap of reviews on the 14 on this forum - in particular Bambury's who uses this EP in fast newts like the OP.

[stephenb]

The ES 14mm 100D has been recommended by my telescope maker so I am 100% confident I will not see any "seagulling".

Edit: Varangian, if you have any links to reviews on IIS I'd be happy to read them (I've done a quick search this morning and located this thread from Erick (http://www.iceinspace.com.au/forum/showthread.php?t=45759&highlight=explore+scientific) and John Bambury's post (http://www.iceinspace.com.au/forum/showpost.php?p=451476&postcount=4)
Cheers

[Varangian]

Yes the 14 mm 100 is perfect I have it myself and I said as much in my earlier posts. As per earlier posts I'm talking about the 14 mm 82 that you mentioned in one of your earlier posts. sheez.

[Varangian]

Hi John, I have a CC and it does fix the majority of the problem I had with the ES 82 14 mm. My advice was based on use of the 14 mm 82 without a CC however. There are plenty of EPs out there around 14 mm that you can use on a fast newt without a CC - even though many Dob owners will not use much above this FL without one.

My original advice was based on my personal experience of the ES 82 14 mm with a fast newt. I purchased it under the assumption that the entire 82 ES line was very good but when I tried it in the 4.9 not only did I see sea gulling across the outer 25% but also blurred vision. At first as suggested I thought it was my scope so I collimated about 3 times and tried again - same problem. Then I started to panic about my eyes! I jumpoed on line and found a plethora of reviews on this EP in fast newts and 95% of them recommended to stay away.

[stephenb]

Sorry, John, I understand what your saying. Miscommunication ,:thumbsup: But you are correct, the 100D reviews I am finding this morning across the interwebs are very encouraging.

[Varangian]

Stephen, I'll look for the review at lunch time today. I remember coming across a thread recently when I was looking for reviews on the 6.7 82 ES where Bambury states that the designers were 'drunk' when they designed the 14 mm 82:lol: Again, his experiences of it were in a fast newt and mine were the same when I tried it at Heathcote a while back. Other Dob users on the night felt the same.

Not sure if it was CN or IIS but I'll try to find it as it's a great and informative thread for those in the market for a new ES EP.

[stephenb]

Cheers, John, I'm yet to get this dob up to Heathcote due to transport issues, but maybe one day soon....



Interesting USD prices for international postage on the 100D 14mm ES:

Eyepieceetc.com $399 + 83.51 postage

OPT Telecopes: $399 + 64.31 postage

I did communicate with Don Pensack from eyepiecesetc.com who incidently was extremely helpful and he apologised for the postage costs, but I understand that's the fault of USPS - not the retailer's.

I will check with VTI and Extravision today on their availability....

[Don Pensack]

My original advice was based on the idea that a particular scope should start out with a 1X/2X/3X magnification scheme, where X= a particular number based on the aperture. For instance, on an 8", X=50, on a 12.5", X=70, and on an 18", X=80.
That's because the larger scope can use higher magnifications and for the same f/ratio, larger scopes have higher magnifications at the same exit pupil.

Is that all the eyepieces you would need? Probably not as seeing conditions are rarely the same everywhere (people under very steady skies tend to use higher magnifications) and you might find yourself wanting a magnification in between two that are derived this way.

Such a recommendation flies in the face of exit pupil considerations.
Take the 18" f/4.5 scope with a Paracorr. The effective f/ratio is f/5.18,
so a 2mm exit pupil would be a 10.4mm eyepiece = 228X. Most places, that would be too high a magnification for a mid-power eyepiece, even though it is a mid-sized exit pupil.
so though the exit pupil idea seems to work well for small scopes, it doesn't seem to work very well on large scopes, which is the reason I came up with a 1X/2X/3X idea for a basic set of eyepieces to build a collection around.
In my scope, that was 70x, 140x, 210x, or 26mm, 13mm, 9mm and I have built around that idea by splitting the 9mm into an 8 and 10mm and going beyond in the high end to 6 and 4.7mm.
But the idea of a basic set of 3 around which you can build a collection is not a bad one.

And if you choose to use exit pupils to do so, that's fine, but just remember it doesn't work very well in big scopes. I have a friend with a 28" f/4.2 scope. With a Paracorr, his focal ratio is f/4.8. A 9.6mm eyepiece would yield 358X. Where he observes, he can use that magnification fairly often, but not much higher. But that's a 2mm exit pupil, which is mid-power by exit pupil standards.

[Camelopardalis]

4-piece set sounds like a plan Stephen :thumbsup:

From the sounds of things, a coma corrector would be a good addition to the collection too, of you're ordering from the US anyway...

[killswitch]

Wow its gone up in price. Just last year, i picked up the ES 14mm 100d Argon from AgenaAstro for $299 + $45 shipping (USD).

One thing about the 100d eyepiece is that they are heavy and can throw your scope off balance.

[MortonH]

Anyone asked VTI when/if they're getting the 14mm 100D back in stock?

[Varangian]

Yes I only have a 12" and that is the smallest scope I would use it on. I have to use counter weights when I use the 14mm 100 which is a bit of a pain...



James was o/s when I spoke to him a month ago and said he was replenishing supplies of the 82 series by the end of May. I'm not sure about the 100 series though :question: An email will clear that up.

[Astro_Bot]

I think I need to correct a misinterpretation of my post ...


Don, if you're referring back to my post, with its advice to use f/stop intervals based on exit pupil, as you seem to be, you're overlooking a very important step.

The first step I recommend (as do many people) is:



In this scheme, you would use the f/stop interval (exit pupil) to fill-in between the magnification extremes, hence whether the smallest exit pupil is considered mid-sized or not is irrelevant.

The absolute size of the exit pupil has to be considered anyway - that's largely how an owner would arrive at the lowest practical magnification along with consideration of effect of a central obstruction (if any). In your method, you address this with a "look up table" of aperture vs. lowest magnification, and whilst that's certainly one way to go, IMHO, it's an unnecessary approximation that doesn't suit all users, although as an eyepiece vendor, if you're there to apply it to each purchaser, I'm sure it would work well. For everybody else, better to calculate exit pupil and use it directly. (In Stephen's case, he already had a 27mm Pan with 6mm exit pupil, so that was not an issue here).

The bottom line is that, whatever method is used, it remains only a rough guide, and neither of us is Stephen. :)

[garin]

Hi Stephen,
I suspect your 18" is an SDM like mine.
In the brief time I've had mine (about a month and a half) I've found the eyepieces I'm favouring are my 13mm Ethos and the 8mm Ethos, I am missing my wide field view and tried another club member's 26mm Nagler and that was really nice, I also found the original Meade QX 26m I sold with my Lightbridge wasn't bad.

[stephenb]

From VTI today, they no longer carry it in thier stock line as there was no demand for it. Extravision hasn't got back to me so I guess it's over to eyepiecesetc.com

ES 18mm 82D should be her early next week. Standby for a review in the coming weeks :thumbsup:

[brunono2]

Agena astro is one of the best USA suppliers of astro equipment including ES eyepieces -delivers usually the next day after the order placed; low freight charges and excellent attitude and response if you have any issues with items received

The ES 14MM 100 is USD 399.99

Cheers

BRUNO

[stephenb]

Yes, I've been watching Agena Astro for other products, Bruno. I saw their range of e/ps but I was undecided. I'll take another look at them today. :thumbsup:

[Astro_Bot]

I've been trying to remain vendor-neutral in recent times, but, since you've raised the topic ... I've had excellent service from Agena Astro (including for ES eyepieces) and can highly recommend them.

[Varangian]

Despite about an hour searching I cannot for the life of me find this post by John B. I came across it looking for reviews on the 6.7mm ES but have had no luck following up. Maybe John B will read this thread and provide his views on the 14mm 82 ES at some stage...

[stephenb]

Thank anyway for your efforts, John.

The ES 18mm arrived today after placing the order on Thursday (including a day for the bank payment to clear). I'll give it a go this evening on the Moon, Mars, Jupiter and Saturn.

I also ordered a pack of 4 eyepiece screw bolt containers but unfortunately the ES and the TV 27mm Pan do not fit in them! Oh well. Looks like I'll have to flog them off on IIS Trade Section ;)



Both VTI and Extravision are not stocking this one...