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17mm Ethos to Compliment 26mm Nagler?

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#1 HellsKitchen

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Posted 04 May 2021 - 12:24 AM

Good day folks

 

I've been using my Nagler for several sessions now, and after a "false start" I am growing to love it dearly. Even though my main forte is 300x+ viewing of planetary nebulae, my skies are dark, and I certainly love my widefields. Infact, in my 72mm refractor, the 26mm Nagler is beyond fun, it kicks ****, and makes for a fantastic session of cruising the Milky Way and the LMC. The Whole LMC is right there in the field, complete with the bar, and with a UHC, more knots than an old pile of rubber bands. 

 

Now, I am considering buying a 17mm Ethos. In my spreadsheet, it makes sensible compliment to the 26mm Nagler with my scopes. For a start, the weight is near identical. Magnification and TFOV is a sensible step. I'm just looking for opinions and experiences, entertaining reading material, before I send 1000 gold coins on their way like confetti. 

 

Mein scopes are 8", 12", 130mm Newts with F/L's of 1200, 1328 and 650mm, and small F5, F6 refractors.


Edited by HellsKitchen, 04 May 2021 - 12:33 AM.

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#2 gnowellsct

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Posted 04 May 2021 - 12:35 AM

Looks like its $760

 

100 degrees * 17mm fl = 1700

82 degrees * 26 = 2132

 

This is a quick and dirty way seeing that the numbers say you will have a noticeably larger fov in the Nagler 26.  You don't have to bother calculating the full true field to a particular telescope doing it this way.  (Ethos 21 mm would be so close to the Nagler as to indicate you should pick one or the other)

 

and of course you will have higher magnification in the Ethos.  

 

Having eyepieces in the mid 20s and upper teens makes sense among those who are building a complete set of focal lengths.    If you collect this kind of glass you're building an upper tier set.  Enjoy.

 

Greg N


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#3 HellsKitchen

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Posted 04 May 2021 - 12:39 AM

760 US = 1000AUD. 21mm Ethos is not on my radar, I would just be duplicating my Nagler for an absurd amount of money and weight.

 

Nah, I'm not looking for something with equal or bigger tfov than the 26 Nagler, just a logical addition to it. 


Edited by HellsKitchen, 04 May 2021 - 12:40 AM.

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#4 areyoukiddingme

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Posted 04 May 2021 - 12:54 AM

Seems to be a pretty close jump for these scopes.

 

I assume the F4.4 would get a coma corrector and be 1542mm, so 59x to 92x, and exit pupils would be 5.14 and 3.35. 

 

I use an 1826mm 12.5", and find more often than not I jump from 31 Nagler to 12.5mm Nikon HW. So with a bit less focal length, I suspect a 13 Ethos might get more use.

 

Of course, really depends on what else you have in your eyepiece case, and what you prefer for exit pupil.


Edited by areyoukiddingme, 04 May 2021 - 12:54 AM.


#5 ButterFly

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Posted 04 May 2021 - 12:54 AM

Without knowing anything more, I'd say 13 Ethos.  Anything else can change that.

 

I call the units for those resulting numbers in post #2 "jumbos".  It's a scope independent way of looking at your eyepieces as a set.  Crunch those numbers for all you other eyepieces and see where a prospective new member fits into your set.  At lower power, steps in jumbos are more important to frame things.  At higher power, the steps in magnification become important to beat seeing.  In the middle, there is the middle with all the compromises.

 

I use a 21 Ethos (similar jumbos to your 26 Nagler).  The 13 Ethos is a great jump after that.  It's my most used eyepiece under my dark skies.  At 1300 jumbos, the closest Nagler equivalent is the 16mm.  But again, the rest of your eyepieces matter.  They are a set just like your telescopes are a set.  Each addition should have its place and not be too redundant.


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#6 gnowellsct

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Posted 04 May 2021 - 10:15 AM

At last someone figured out a way to make Pentax xw oculars look like cheap affordable eyepieces
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#7 brentknight

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Posted 04 May 2021 - 11:22 AM

I use my 31T5 and 17E, but feel they are still pretty close. The 31T5 is just so darn heavy that I'll often skip the extra field for the convenience. The 13E might be a better choice...
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#8 SeattleScott

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Posted 04 May 2021 - 01:19 PM

The other obvious contender is the 17 Nikon HW. Not sure about weight, it is more expensive, I think it might be hard to get optimal Paracorr setting exactly dialed in on Dob, but it is supposed to be best in class. Haven’t used it just suggesting a possible alternative.

Scott

#9 areyoukiddingme

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Posted 04 May 2021 - 01:29 PM

The choice seems to come down to exit pupil preference, and whatever else is in the case.

 

I have both the Nikon HW, and while I think the 17/14 is the better of the two, I find for my F5.75 (with coma corrector), the 12.5 is a better exit pupil match.

 

So if the motivation here is to have a hyperwide because it's close to an optimal ~2mm exit pupil, then the 13mm is probably the better choice. Given the F4.4, and 10mm would actually be closest to optimal.

 

But if that position is already held by another eyepiece, well I can see how a 17 would fit.



#10 payner

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Posted 04 May 2021 - 01:51 PM

As noted above, one of the advantages of the Nikon 17-mm HW is it has an EiC tele-extender that makes for a 14-mm HW. The tele-extender gets out of the way and provides for two focal lengths in one eyepiece. The Nikon 12.5-mm HW has an EiC tele-extender and makes for a solid 10-mm HW. 

 

Some additional choices there to ponder.

 

Randy



#11 DRodrigues

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Posted 04 May 2021 - 05:02 PM

The ES92 17 or 12mm are alternatives to Ethos, if preference goes to eps with better eye-relief - usually those using eye-glasses when observing, like me.



#12 Markovich

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Posted 04 May 2021 - 09:00 PM

I have the 26mm Nagler and a 10mm Ethos- Im looking at a used 17mm Ethos to fill the gap in the near future. The 13mm might just a tad too large of a jump from a 26mm.


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#13 Jon Isaacs

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Posted 05 May 2021 - 06:12 AM

I'd like to know more, what other eyepieces are in the picture?

 

That said, I find the 21 mm Ethos - 13 mm Ethos a bit too big a step, workable but not optimal.

 

The 26 mm -13mm is a factor of 4 in brightness, that's too big for me.

 

Jon



#14 JuergenB

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Posted 05 May 2021 - 06:18 AM

17.5 mm Morpheus?

 

Juergen



#15 HellsKitchen

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Posted 05 May 2021 - 07:27 AM

I've considered the Nikon, but the price and weight have put me off. The ES are too heavy aswell. I'm starting to think 13mm might be more logical. The 17mm is only 25x more than the Nagler, may well not be the level of difference I intend for the price of admission. What about the APM xwa 13mm? I've done some reading on it here, and saw good things. Much cheaper way than an Ethos to introduce myself to the 100* foray, and to see how well that focal length compliments the Nagler. 

 

Currently I have 1.6, 2.4, 3, 4, 5, 6, 7, 9, 13, 22mm eyepieces in 1.25". The <9mm are Delites and 13, 22mm are LVWs. At the end of the day I am sort of looking looking to have a 1.25 inch and 2"/widefield set. Most of the time with the 1.25 inchers I am in the single digits (using the 22mm as a finder) on small objects. My rationale is weight, form factor and balance would be less of an issue depending on the type of observing I am doing than if I had a mixed set, as I don't plan to swap between those 1.25 inch eps and heavier hyperwides every 5 mins. If I am doing higher power stuff, there is a common regime. If I switch to lower power, widefield, large DSO observing there would also be commonality there between a hyperwide and the 26 Nagler. A 13mm hyperwide should be a whole different experience to the LVW. 


Edited by HellsKitchen, 05 May 2021 - 07:48 AM.


#16 areyoukiddingme

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Posted 05 May 2021 - 01:39 PM

That information makes me think that something around 13 is the better place to go. 

 

I'm assuming that the F4.4 (F5.06 with coma corrector) and the F6 are commonly used scopes.

 

In that case, the simple double the F-ratio heuristic makes sense. A 10mm might be best with the former, but a 13 wouldn't be far off, and will suit the F6 (which I'm assuming is not going to be coma corrected).

 

I haven't tried the APM 13, but have tried the 20, and compared multiple times with the 21 Ethos. They are very close for me in 12.5 F5, and the APM is lighter and a bit more comfortable to use. The ethos may have the edge on sharpness, but it's not a big difference, at least not with my scopes.



#17 brentknight

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Posted 05 May 2021 - 02:06 PM

I have the 26mm Nagler and a 10mm Ethos- Im looking at a used 17mm Ethos to fill the gap in the near future. The 13mm might just a tad too large of a jump from a 26mm.

I have the 8E, 13E and the 17E, and then I have the 31T5.  For me, there is very little point while observing a target in going from the 31T5 to the 17E and then the 13E.  I'll either start out with one or the other (as the finder) and switch to the 13E or the 8E depending on the target.  In the Dob, I'm actually using the 17E more than the 31T5 as the finder, just because the Nagler is so heavy.  If the APM XWA 20mm ever comes back in stock, I'll grab it and consider using it instead of either the 17E or the 31T5.  I'll continue to use the other two, but just with my AT72EDII for wide-field viewing.

 

The point is that in common use that unless the target is relatively large, the difference in the view is still pretty minor between the 31T5 and the 17E.  I think between the 26 Nagler and the 17E, that you would end up rarely using the 26mm.  The 26mm is the problem.  Replacing it with the 17E or the APM equivalent might get a more usable range.  Or maybe even consider the APM XWA 13 and the APM XWA 20 (that pair would be cheaper than a new 17E by itself).



#18 Markovich

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Posted 05 May 2021 - 06:00 PM

Well, initially after buying the Obsession, I had the 31mm Nag, a 17mm T4 Nag and a 10mm Radian.

It was a really good change between eyepieces. The 17 Nag and I didn't gel and I sold it. I still use an OLD 19mm TV WideField but its not optimal for the Obsession. That eyepiece is used mostly in the SCTs. The 31 Nag was outstanding ( and still is) but I traded to the 26 to save some weight. 

The 26 Nag- 17mm Ethos-10 Ethos- 8mm Delos should be fine for me.


Edited by Markovich, 05 May 2021 - 06:01 PM.


#19 ButterFly

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Posted 05 May 2021 - 06:19 PM

Without knowing anything more, I'd say 13 Ethos.  Anything else can change that.

 

 


Nah, I'm not looking for something with equal or bigger tfov than the 26 Nagler, just a logical addition to it. 

 

I completely misunderstood your question, then glossed over this like it was nothing.  Oops!  What threw me off was that a 17 Ethos has fewer jumbos than a 26 Nagler, so it always has a smaller true field of view in any scope.  I thought you were looking for a smaller true field of view as a complement.

 

I agree that a 31 Nagler type would be too close to your 26 Nagler for general use.  Swapping the 26 Nagler for a 31 Nagler or ES 25/100 is the expensive solution.  41 Pan / 55 Plossl types are not appropriate for your f/5 and below scopes.  Maxing jumbos needs glass, and that gets heavy and expensive for lower f/ratios.



#20 Deep13

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Posted 06 May 2021 - 12:07 AM

For my 12.5" f/5, I use a 27 Panoptic. My next lowest power EP is a 14 Delos. I used to have a 22 Pan., but I never used it. So I think a 13 Ethos makes more sense than a 17.

#21 areyoukiddingme

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Posted 06 May 2021 - 12:24 AM

I think a 31, 17, 10, 6 sequence makes sense (although the 10/6 jump is bigger than I like).

 

with 1542mm of FL, that gives 50x, 91x, 154x, and 257x.

 

But with a 26 as an anchor, then 13, 8, 6 seems to work:

 

that gives: 59x, 119x, 193x, 257x, which looks like a nice set of jumps.



#22 HellsKitchen

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Posted 06 May 2021 - 03:12 AM

A 12 and 17mm ES92* just appeared on the local classifieds, could get both for the price of a single Ethos. But the 1100g weight is, well, I don't know. That is essentially 50% increase over the already somewhat grenade'y 26 Nagler. Still, could it be a be a divine sign? I did try the 26 Nagler with paracorr in my 5" Newtonian riding on a GSO Voyager with no problems. The long ER sounds attractive, I personally don't like being squeezed against an eyepiece, for reasons including fogging in cold weather, and chance of skin or eyelash oils getting on or near the lens. I've used LVWs and Delites, and the ER really gelled with me. 

 

On the other hand, the 13mm APM Xwa is looking attractive aswell. Could get one for 227 euros, but can't calculate the shipping because APM won't let me add it to cart because no stock! I could order one from the US for $299, but would really need to find some other stuff I want need to add to the order to justify the shipping costs. 

 

But, here is the thing. Those ES eyepieces can be resold for no loss shall they not work out for whatever reason. It could technically be considered as a "try before you buy".


Edited by HellsKitchen, 06 May 2021 - 03:25 AM.


#23 HellsKitchen

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Posted 06 May 2021 - 03:40 AM

I completely misunderstood your question, then glossed over this like it was nothing.  Oops!  What threw me off was that a 17 Ethos has fewer jumbos than a 26 Nagler, so it always has a smaller true field of view in any scope.  I thought you were looking for a smaller true field of view as a complement.

 

I agree that a 31 Nagler type would be too close to your 26 Nagler for general use.  Swapping the 26 Nagler for a 31 Nagler or ES 25/100 is the expensive solution.  41 Pan / 55 Plossl types are not appropriate for your f/5 and below scopes.  Maxing jumbos needs glass, and that gets heavy and expensive for lower f/ratios.

 

No, infact you actually understood my question correctly! Basically what I am looking for is a hyperwide eyepiece or two to compliment the 26 Nagler, but at shorter FLs, which obviously will yield smaller tfov's . The idea is to have a hyperwide eypiece for DSO an Milkyway observing that compliments the Nagler, and what I meant by that is get a logical increase in magnification with a 100* AFOV. I got a 26 Nagler instead of the 31 mostly due to exit pupil and price(!). Anything lower than my 26 Nagler would be merely a finder eyepiece, as opposed to an observation eyepiece due to my current scope's F ratios, exit pupil, and my observing style. There would be a few exceptions, but nothing to justify a cost of the 31 Nagler or equivalent ES or a 41mm Panoptic. I would however not be averse to grabbing a 40mm 68* for around A$100-200 for those odd occasions, but not a penny more. 


Edited by HellsKitchen, 06 May 2021 - 03:41 AM.

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