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XW 30mm + ES100 20mm = Ethos 21mm?

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#1 bazookaman

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Posted 19 January 2021 - 01:15 PM

I'm seeing the Ethos 21mm is on "sale" for $854. That's more than twice as much as any of my other ep's, which I already consider expensive. However...

 

My Pentax 30mm XW I like in general, except it seems that the wide exit pupil really shows my astigmatism as an annoying inability to focus to pinpoint. I either get an annoying spike at the 4 o' clock position, or slightly out of focus star. I feel either way is a compromise and it's annoying and frustrating. I hate that my eyes can't take full advantage of this awesome ep. And after using the 100° and 82° ep's, 70° feels a bit tight.

 

At just a slightly smaller tfov, but a much larger afov, the ES100° 20mm gets more use than my 30mm XW. I actually mostly use the 30mm when the 20mm fogs up. It's sharper to my astigmatic eye and I like the greater mag and the much wider view. I use a paracor 2 so both are sharp to the edge afaict. But the 20mm background is much brighter than the 30mm for some reason. I figure it's some sort of optical malady due to design. That's it's major drawback for me. Also, if I flip the rubber cup out, I cannot see the field stop so I never use it.

 

I find the two ep's to be redundant due to almost identical tfov. I'm thinking about selling both and getting the optically E21. I've read it is optically superior to the ES100 and I definitely prefer 100° over 70° and the exit pupil should be similar to the ES100 so as not to make my astigmatism apparent. I wouldn't break even, but it'd be close enough to consider it a wash for me. Am I overlooking something? Would this be a grievous mistake?



#2 junomike

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Posted 19 January 2021 - 01:19 PM

I've had both (ES 20 100, E21) and prefer the E21 for it's darker background and Star Presentation.  I (like you) found the ES 20 100 had a "grey" like background however other than that the I didn't note too much difference.


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#3 areyoukiddingme

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Posted 19 January 2021 - 01:33 PM

In that range, you can't beat the E21. The APM 20/100 comes closest, and beats out the ES 20/100.

 

Alternatively, look into a dipotrix for your XW to clean up the astigmatism.


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#4 SeattleScott

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Posted 19 January 2021 - 01:44 PM

The XW has 20mm eye relief so you should be able to wear glasses with it to resolve the astigmatism issue.

Scott

#5 bazookaman

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Posted 19 January 2021 - 01:45 PM

In that range, you can't beat the E21. The APM 20/100 comes closest, and beats out the ES 20/100.

 

Alternatively, look into a dipotrix for your XW to clean up the astigmatism.

Thanks guys. I saw mention of the dioptrix (sp?) before, will check it out now.



#6 bazookaman

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Posted 19 January 2021 - 02:11 PM

That also makes me wonder if my glasses will better correct astigmatism than my contacts. I suspect they do. I don't like the thought of wearing glasses while observing, especially just for one eyepiece. But it'll be good to know. Looks like it might be a good night to try it in the driveway.


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#7 SeattleScott

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Posted 19 January 2021 - 02:22 PM

Maybe you need to update your contacts prescription?

#8 bazookaman

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Posted 19 January 2021 - 02:41 PM

Maybe you need to update your contacts prescription?

It's very possible, it's been a while and I usually extend the 6-month pack to last about 3x longer than they're supposed to.

 

In either case, I've talked myself into making the switch to the 21e! Thanks for the help.


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#9 faackanders2

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Posted 19 January 2021 - 07:37 PM

I'm seeing the Ethos 21mm is on "sale" for $854. That's more than twice as much as any of my other ep's, which I already consider expensive. However...

 

My Pentax 30mm XW I like in general, except it seems that the wide exit pupil really shows my astigmatism as an annoying inability to focus to pinpoint. I either get an annoying spike at the 4 o' clock position, or slightly out of focus star. I feel either way is a compromise and it's annoying and frustrating. I hate that my eyes can't take full advantage of this awesome ep. And after using the 100° and 82° ep's, 70° feels a bit tight.

 

At just a slightly smaller tfov, but a much larger afov, the ES100° 20mm gets more use than my 30mm XW. I actually mostly use the 30mm when the 20mm fogs up. It's sharper to my astigmatic eye and I like the greater mag and the much wider view. I use a paracor 2 so both are sharp to the edge afaict. But the 20mm background is much brighter than the 30mm for some reason. I figure it's some sort of optical malady due to design. That's it's major drawback for me. Also, if I flip the rubber cup out, I cannot see the field stop so I never use it.

 

I find the two ep's to be redundant due to almost identical tfov. I'm thinking about selling both and getting the optically E21. I've read it is optically superior to the ES100 and I definitely prefer 100° over 70° and the exit pupil should be similar to the ES100 so as not to make my astigmatism apparent. I wouldn't break even, but it'd be close enough to consider it a wash for me. Am I overlooking something? Would this be a grievous mistake?

the 20mm background/contrast is definitely darker than the 30mm background/contrast; this plus the extra magnification is what Al Nagler called the Majesty factor.  Unless you are looking at the bright milky way like M24 star cloud and not a dim object.

 

I have the ES 20 100AFOV and it is not sharp to the edge with my f4.1 dob; even Paracor II doesn't correct it (but goes from 90% to 95%).  Eveyone on cloudly nights says TV 21mm 100 AFOV Ethos doesn't have this issue, and since you like 100AFOV and are willing to spend (trade) for it go do it.

 

P.S.  I'm keeping my ES 30mm 82AFOV 5000 UWA.


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#10 Echolight

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Posted 19 January 2021 - 08:18 PM

My APM HDC HWA 20mm 100 degree eyepiece looks funny until my eye is fully dark adapted. I notice that if I use it when I first go outside, the outer 20% or so is gray. But after a while the background looks evenly dark though it.

 

I'm sure the Ethos would be better. But I think I'd opt for the ES92 17 if I were to make a switch. But even $550 plus tax would be pushing way past the limit of reasonable for me. And both the 21 Ethos and ES92 17 are far beyond the weight window I set for balancing purposes.

 

Maybe a used 22 Nagler or a new 20 LHD....

 

Nah. I'll just stick with the HDC 20.  

 

A 10-ish mm hyperwide or ultrawide is probably next on my list. The 10mm Ethos fits inside my weight window..., unless I am gifted an Apollo 11. But the HDC 9mm is still a third the cost and suppose to be better than the longer focal lengths in the line. Oh well. I'm in no hurry to figure it out.


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#11 John Huntley

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Posted 19 January 2021 - 09:15 PM

I have the 21mm Ethos and the 31mm Nagler. Under my skies the 21mm Ethos gets a lot more use with my 12 inch dobsonian. Darker background skies = a little easier to pick out the fainter DSO's.

 

I did have the 20mm ES / 100 and thought that nice but the Ethos is a touch better. Easier to see the full field of view with the Ethos.

 

I also have the ES 17mm / 92 which is very close to Ethos performance levels I feel. Closer than the ES 20 / 100 perhaps ?.

 

None of these are in any way poor eyepieces though. Amazing that we have these choices really smile.gif


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#12 Jon Isaacs

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Posted 20 January 2021 - 01:25 AM

I have the 21mm Ethos and the 31mm Nagler. Under my skies the 21mm Ethos gets a lot more use with my 12 inch dobsonian. Darker background skies = a little easier to pick out the fainter DSO's.

 

I did have the 20mm ES / 100 and thought that nice but the Ethos is a touch better. Easier to see the full field of view with the Ethos.

 

I also have the ES 17mm / 92 which is very close to Ethos performance levels I feel. Closer than the ES 20 / 100 perhaps ?.

 

None of these are in any way poor eyepieces though. Amazing that we have these choices really smile.gif

 

I have both the 31mm Nagler and the 21mm Ethos and I had the 20mm ES 100 degree.. 

 

For me, the Ethos is sharper at the edge (Paracorr 2 in scopes around F/5).  With ES 20mm, I could not see the edge of the field of view without peaking and when it peaked, what I saw wasn't so pretty.  With the 21mm Ethos, I can see the entire field in one glance and what I see is nice and clean. 

 

I use the 21mm Ethos as my finder most of the time if I am not using the 13mm Ethos... The 31mm Nagler which filled that role when I had the 20mm ES 100 degree, is used as finder only if I am having trouble locating an object.  

 

Jon


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#13 havasman

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Posted 20 January 2021 - 02:32 AM

It's very possible, it's been a while and I usually extend the 6-month pack to last about 3x longer than they're supposed to.

 

In either case, I've talked myself into making the switch to the 21e! Thanks for the help.

I really didn't expect it and really didn't even want it to be so but to my eye the 21 Ethos is the best eyepiece I have ever used. It's very comfortable, extremely sharp and just flat **** good in every way I seem to care about. It isn't yet my favorite eyepiece, but it's in front to be best. I've had several in the class. The ES' gray haze was a problem for me. The William Optics, the 1st of the class I tried, was fine but didn't fit my face so I got the ES. The APM, chosen over the ES in head-to-head, was really good and when I used it for about a year I found I used the focal length more than ever. But then I got the Ethos and it's all over. To my mind XW 30mm + ES100 20mm < 21E.

I really recommend you stay up with your appointments with your ophthalmologist. It's an ocular hobby. Good contacts work well and I've never observed w/o them. Getcha some before you give up and wear glasses.


Edited by havasman, 20 January 2021 - 02:34 AM.

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#14 bazookaman

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Posted 20 January 2021 - 10:20 AM

I really didn't expect it and really didn't even want it to be so but to my eye the 21 Ethos is the best eyepiece I have ever used. It's very comfortable, extremely sharp and just flat **** good in every way I seem to care about. It isn't yet my favorite eyepiece, but it's in front to be best. I've had several in the class. The ES' gray haze was a problem for me. The William Optics, the 1st of the class I tried, was fine but didn't fit my face so I got the ES. The APM, chosen over the ES in head-to-head, was really good and when I used it for about a year I found I used the focal length more than ever. But then I got the Ethos and it's all over. To my mind XW 30mm + ES100 20mm < 21E.

I really recommend you stay up with your appointments with your ophthalmologist. It's an ocular hobby. Good contacts work well and I've never observed w/o them. Getcha some before you give up and wear glasses.

I was thinking about getting an appointment, it's been a while. Probably close to two years.



#15 Sarkikos

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Posted 20 January 2021 - 11:07 AM

Keep your astigmatism-correcting eyeglasses on while viewing through the XW30.  The eye relief is 20mm.

 

Another option is to see if a Dioptrx will fit the XW30.

 

Mike


Edited by Sarkikos, 20 January 2021 - 11:09 AM.

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#16 ubernator

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Posted 21 January 2021 - 03:46 AM

Thanks guys. I saw mention of the dioptrix (sp?) before, will check it out now.

 

 

Keep your astigmatism-correcting eyeglasses on while viewing through the XW30.  The eye relief is 20mm.

 

Another option is to see if a Dioptrx will fit the XW30.

 

Mike

Dioptrix will certainly NOT fit on an XW. It will fit on ES because they have a similar style flange that holds the eyecup that TV eps have, but you lose a few MM of eye relief due to the recessed lens.

 

Just wear glasses with the 30xw, unless you, like me have self diagnosed astigmatism and have never gotten glasses for it.


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#17 Sarkikos

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Posted 21 January 2021 - 07:31 AM

I have myopia, presbyopia and astigmatism.  So I usually wear my eyeglasses when viewing through eyepieces.  It just doesn't make sense to spend all that money on well-corrected telescopes and well-corrected eyepieces, but then don't correct your eyes.  shrug.gif

 

Yes, I know you can adjust the focuser to compensate for myopia or presbyopia.  But the focuser won't help me see the sky clearly "naked eye" or read charts.  For that I need my eyeglasses.  And I don't like flipping my glasses on and off.

 

I only take the glasses off if

 

(1) the eye relief on an eyepiece is very short  (I can keep my glasses on for eye relief as short as 10mm)

(2) the observation requires maximum contrast (planetary detail) or maximum light throughput (very faint fuzzies)

(3) a Dioptrx is on the eyepiece (I keep a Dioptrx on my 31 Nagler and 41 Pan)

 

Mike


Edited by Sarkikos, 21 January 2021 - 07:36 AM.

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#18 bazookaman

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Posted 21 January 2021 - 11:40 AM

I appreciate the input. I don't normally wear my glasses and the last thing I want is one more thing to struggle with. I don't like the thought of having to press my eye against my glasses and glasses against an eyepiece. I know a lot of people do it but I generally don't like wearing glasses. I'd rather just get the 21E (which is on it's way) to replace my current 20mm and 30mm, and not have to worry about any of it. And will get a boost in IQ too. Less weight in my case, one less eyepiece to worry about, no noticeable astigmatism, better IQ, and I get close to breaking even. Seems hard to beat.


Edited by bazookaman, 21 January 2021 - 11:40 AM.


#19 CrazyPanda

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Posted 21 January 2021 - 12:52 PM

The difference in brightness due to the exit pupil differences between the 30 and 21 is significant 2x brighter view in the 30 than the 21. This means it may be more appropriate for high quality line filters like a Lumicon O-III, which really craves big exit pupils.

 

In my F/5.2 coma corrected scope, I have a 35 Pan, 31 Nag, and 21 Ethos, and each have their place when it comes to the application of nebula filters.

IMO it would be a loss of a tool to replace both the 30 and 20 in your kit with just a 21E. The 21E in an ~F/5 scope is good with a UHC filter, but I find it's a bit too dim for a good O-III filter. I use the O-III at the 31 and 35 focal lengths almost exclusively.


Edited by CrazyPanda, 21 January 2021 - 12:55 PM.

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#20 KJL

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Posted 21 January 2021 - 01:46 PM

Dioptrix will certainly NOT fit on an XW. It will fit on ES because they have a similar style flange that holds the eyecup that TV eps have, but you lose a few MM of eye relief due to the recessed lens.

Wait, that's not correct.

The two relevant links are here, but Don's response a couple posts down from that are also relevant.


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#21 Jon Isaacs

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Posted 21 January 2021 - 02:54 PM

The difference in brightness due to the exit pupil differences between the 30 and 21 is significant 2x brighter view in the 30 than the 21. This means it may be more appropriate for high quality line filters like a Lumicon O-III, which really craves big exit pupils.

 

In my F/5.2 coma corrected scope, I have a 35 Pan, 31 Nag, and 21 Ethos, and each have their place when it comes to the application of nebula filters.

IMO it would be a loss of a tool to replace both the 30 and 20 in your kit with just a 21E. The 21E in an ~F/5 scope is good with a UHC filter, but I find it's a bit too dim for a good O-III filter. I use the O-III at the 31 and 35 focal lengths almost exclusively.

 

When using narrow band filters, those larger exit pupils can come in handy, it depends on the object.  

 

However... 

 

It is my thinking/experience that eyepieces like the Panoptics, Ethos's and Naglers are not necessary with filters.  The filter reduces the brightness of a star by 2-3 magnitudes and so off-axis astigmatism and coma are much less apparent.  And since the goal is to see the nebulosity, a simple eyepiece like a 32mm Q70 can be quite effective.  

 

Jon


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#22 bazookaman

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Posted 21 January 2021 - 05:57 PM

Thanks, I hadn't considered filter use as I haven't ever used a 2" filter. I have an O-III (1.25") but rarely use it. I'm not all that concerned with filters at this time.



#23 Jon Isaacs

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Posted 21 January 2021 - 08:12 PM

Thanks, I hadn't considered filter use as I haven't ever used a 2" filter. I have an O-III (1.25") but rarely use it. I'm not all that concerned with filters at this time.

 

If you like to look at the Veil and such, filters make a big difference.  With a 2 inch O-lll filter, I can see the Veil in my 10 inch Dob from my urban San Diego backyard. 

 

From a dark sky, it really brings the Veil alive.

 

Jon 


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#24 bazookaman

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Posted 21 January 2021 - 11:57 PM

If you like to look at the Veil and such, filters make a big difference.  With a 2 inch O-lll filter, I can see the Veil in my 10 inch Dob from my urban San Diego backyard. 

 

From a dark sky, it really brings the Veil alive.

 

Jon 

I've never had any luck with the big ones other than Orion. I was told to not even bother. Was that bad advice? I think my driveway measures 18.7 iirc, with lots of coach lights on everyones driveways. My backyard is better (no direct lights) but it's not worth dragging the bucket out there.


Edited by bazookaman, 21 January 2021 - 11:57 PM.


#25 bazookaman

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Posted 27 January 2021 - 02:33 PM

Sorry for the clouds guys.

 

thumbnail_20210126_150707.jpg

 

Might get first light Sunday. I'll update my first impressions.


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