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Higher power eyepieces

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#1 ApexAZ

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Posted 17 May 2021 - 12:32 PM

Hi all,

 

I got 2 eyepieces with my new telescope:  Celestron x-cell lx 9mm and ultima edge 30mm.  I wear glasses and have astigmatism and already am struggling with the eye relief on the 9mm.  The 30mm has been great.

 

I've been looking at televue ethos eyepieces and I have a few questions:

 

1. What should I aim for in regards to comfortable eye relief while wearing glasses?  I'm interested in the televue ethos 6mm, or possibly 4.7mm and each have an eye relief of 15mm; I'm just not sure if that's sufficient?

 

2. Exit pupil on both the 6mm and 4.7mm are close to 1mm, give or take.  My 30mm has an exit pupil of 6mm as a point of comparison.  Is 1mm too small to be practical?  Should I find something closer to 9mm like what I have but better?  My scope is a 12" dob with 1525mm focal length.

 

3. The ethos eyepieces seem to be 1.25" with 2" adapters.  Does this matter, or should I try to find something that is native 2"?

 

Thank you all!

 

 



#2 havasman

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Posted 17 May 2021 - 12:43 PM

No eyepiece below 16mm @ 82o AFOV needs to be a 2" eyepiece nor does it offer any optical advantage at all.

 

If you're going to wear glasses while observing and want a short focal length Televue eyepiece, what you want is from the Delos line. They are extremely good eyepieces. There is a very capable and experienced group of observers that are convinced the Delos are optically superior to the Ethos line.

 

For higher magnification I have 6, 4.7 and 3.7 Ethos and 3.5 & 2.5T6 Naglers and use them all. I also have 8mm Delos and it is very good. I dislike long eye relief eyepieces generally. The Delos' adjustable eyecup works very well for any eye relief preference. I suggest you might start with a 10, 8 or 6mm Delos. A 10mm/6mm jump is very useful when observing DSO's with a Dob such as yours.

 

Whether a 1mm exit pupil is too small depends mostly on your observing conditions. Some site conditions better facilitate high magnification  observing. Sometimes relatively inexperienced observers may find it difficult to observe with small exit pupils because they can't keep track of them with their eye as it (the eye) moves around. For an experienced observer with a decent site 1mm is usually not considered particularly small at all.


Edited by havasman, 17 May 2021 - 02:07 PM.

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#3 cst4

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Posted 17 May 2021 - 01:19 PM

TV Delos

Pentax XW

Baader Morpheus

 

If you like your 30mm then I think you would really enjoy any of the above lines.  I believe glasses can be worn with any of them but you may want to check me on that as I don't wear them.


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#4 SeattleScott

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Posted 17 May 2021 - 01:23 PM

Ethos don’t have enough eye relief to see the whole view with glasses. Delos would be more the ticket if wearing glasses. There are a few other excellent options also if you aren’t married to Televue.
Celestron Xcel LX typically have just enough eye relief to take in the whole view with glasses. At least for most users. You say you are struggling with the eye relief. Are you having problems getting close enough with glasses to see the whole view? Or are you having problems with the view blacking out if you don’t keep your eye in the right spot? This is a common issue for beginners using wide angle eyepieces. If you like the 30mm, then maybe something with a bigger eye lens would help. Such as Delos and a few others.

Scott
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#5 ButterFly

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Posted 17 May 2021 - 01:45 PM

Ethos should be tried first if you wear glasses.  I do and I very much enjoy them.  Looking directly at the field stop near my nostril is a challenge because my glasses get further from my face on the opposite side by the stem.  The rest is fine.  I bring one with me when glasses shopping to check the field stop.  I don't like giant 80's glasses anyway, so it doesn't limit my choices much.

 

You can get excellent seeing.  I got the 6 as well when I moved to AZ.  In my 15" with a Paracorr, the 8 is about 230x and the 6 is about 300x.  I barlow both when I can, and that's quite often.  M51 at 300x in a 100 degree eyepiece is spectacular from a dark site.  Jupiter comes alive over 500x.  I use barlows to get that high up.

 

The benefit of the 2" mode is support, and no need for the adapter.  A 2" widefield can get heavy.  Dangling a barlowed 13 Ethos of a tiny 1.25" diagonal is a little scary.



#6 John Huntley

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Posted 17 May 2021 - 01:53 PM

I have the 6mm and 4.7mm Ethos and also the 7mm, 5mm and 3.5mm Pentax XW's. For the glasses wearer I think the Pentax XW's (and similarly the Delos 6mm and 4.5mm) will be more comfortable to use than Ethos's and will offer equal if not slightly better optical performance.

 

My 12 inch dob is F/5.3 and the above 7mm - 4.7mm focal length eyepieces get lots of use on the right targets under decent seeing conditions. The 3.5mm Pentax not quite so much but still is useful under excellent conditions.


Edited by John Huntley, 17 May 2021 - 01:54 PM.

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#7 ApexAZ

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Posted 17 May 2021 - 02:20 PM

Ethos don’t have enough eye relief to see the whole view with glasses. Delos would be more the ticket if wearing glasses. There are a few other excellent options also if you aren’t married to Televue.
Celestron Xcel LX typically have just enough eye relief to take in the whole view with glasses. At least for most users. You say you are struggling with the eye relief. Are you having problems getting close enough with glasses to see the whole view? Or are you having problems with the view blacking out if you don’t keep your eye in the right spot? This is a common issue for beginners using wide angle eyepieces. If you like the 30mm, then maybe something with a bigger eye lens would help. Such as Delos and a few others.

Scott

A little bit of both, but I keep bumping the eyepiece with my glasses.  I don't have this problem with the ultima edge 30mm at all.  I don't even really need to touch the cup to view, but even if I do end up moving closer in, it's a nice soft rubber that I don't have to worry about scratching my expensive RX lenses.  I don't need to touch it, but I have to get so close that I often end up do touching it on accident and I just worry about scratching my glasses mostly.

 

I have the 6mm and 4.7mm Ethos and also the 7mm, 5mm and 3.5mm Pentax XW's. For the glasses wearer I think the Pentax XW's (and similarly the Delos 6mm and 4.5mm) will be more comfortable to use than Ethos's and will offer equal if not slightly better optical performance.

 

My 12 inch dob is F/5.3 and the above 7mm - 4.7mm focal length eyepieces get lots of use on the right targets under decent seeing conditions. The 3.5mm Pentax not quite so much but still is useful under excellent conditions.

Something like this? https://www.bhphotov...iece.html/specs

 

Dangling a barlowed 13 Ethos of a tiny 1.25" diagonal is a little scary.

I'm not sure what you mean by this?  I wish I could try an ethos before I buy, as they are stupid expensive.  What I do know is that my ultima edge with 20mm eye relief is very comfortable for me to view, so maybe I should just get the delos.  The lx 9mm is 16mm of eye relief and I seem to bump it constantly.

 

I suppose eye relief is probably more important than the greater 100 degree AFOV of the ethos?  My assumption is all the AFOV in the world probably won't matter if I keep banging my glasses into it trying to see.

 

As a side question, how does barlow affect viewing?  Does it lower brightness/contrast.  The ability to get multiple magnifications from my eyepieces is appealing, but I'm not sure what the downside would be, if any?


Edited by ApexAZ, 17 May 2021 - 02:36 PM.

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#8 ButterFly

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Posted 17 May 2021 - 03:35 PM

Wide field eyepieces are big and heavy.  It's good to have a 2" focuser/diagonal supporting them rather than a 1.25".

 

A good barlow shouldn't affect the eyepiece.  It dims just like any other dimming from going to higher power.  I use a screw on 1.25" Baader Hyperion barlow.  The 8 and 6 barlow just fine.  The 13 is heavier, so I don't, but I can.  A 2" barlow is a whole lot more weight.  A 2" barlow and a 21 Ethos is over 5 pounds.  Balancing a dob with that is a huge challange.  I use the barlow to get those steps in mag to beat seeing anyway.  I'm fine with just a 1.25" barlow.

 

Star parties are hopefully going to start up again soon.  If you will buy new, I'd say hang tight for a little longer.  If you buy used, you can sell it again for not much loss if it doesn't work out.



#9 Astro-Master

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Posted 17 May 2021 - 03:36 PM

I would replace your 9mm Celestron x-Cel lx with a Morpheus 9mm with a wider 76 degree apparent field of view, and a true field of view of 27 arc minutes, with a comfortable 20mm of eye relief.

 

The 9mm with your 12" F/5 will give you an ideal 1.8mm exit pupil with a power of 169x for great views of DSO's.  The Morpheus eyepieces at $240. is a very high quality eyepiece at a bargain price.  If you try and like the 9mm Morpheus the 6.5 Morpheus would be another good eyepiece for your scope.


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#10 ApexAZ

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Posted 17 May 2021 - 04:21 PM

I would replace your 9mm Celestron x-Cel lx with a Morpheus 9mm with a wider 76 degree apparent field of view, and a true field of view of 27 arc minutes, with a comfortable 20mm of eye relief.

 

The 9mm with your 12" F/5 will give you an ideal 1.8mm exit pupil with a power of 169x for great views of DSO's.  The Morpheus eyepieces at $240. is a very high quality eyepiece at a bargain price.  If you try and like the 9mm Morpheus the 6.5 Morpheus would be another good eyepiece for your scope.

Backorder Backorder Backorder...Yeesh :(



#11 Dave Mitsky

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Posted 17 May 2021 - 05:26 PM

Backorder Backorder Backorder...Yeesh frown.gif

Unfortunately, that's simply the way it is since the pandemic affected the amateur astronomy market.



#12 cst4

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Posted 17 May 2021 - 05:47 PM

Backorder Backorder Backorder...Yeesh frown.gif

Keep an eye on the classifieds or put out a want add for something.  Not a whole lot is in stock these days and buying used may be your only option.  My recommendation would be just to jump on the first Pentax XW, Baader Morpheus, or Tele Vue Delos you see for sale in the classifieds at about 14mm or shorter.  Morpheus are probably the cheapest new and are my favorite of these.  Also the widest AFOV.


Edited by cst4, 17 May 2021 - 05:47 PM.

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#13 MitchAlsup

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Posted 17 May 2021 - 06:43 PM

No eyepiece below 16mm @ 82o AFOV needs to be a 2" eyepiece 

The 9ES120 actually does due to its 120º light path to the exit pupil.


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#14 MitchAlsup

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Posted 17 May 2021 - 06:55 PM

1. What should I aim for in regards to comfortable eye relief while wearing glasses?  I'm interested in the televue ethos 6mm, or possibly 4.7mm and each have an eye relief of 15mm; I'm just not sure if that's sufficient?

 

2. Exit pupil on both the 6mm and 4.7mm are close to 1mm, give or take.  My 30mm has an exit pupil of 6mm as a point of comparison.  Is 1mm too small to be practical?  Should I find something closer to 9mm like what I have but better?  My scope is a 12" dob with 1525mm focal length.

 

3. The ethos eyepieces seem to be 1.25" with 2" adapters.  Does this matter, or should I try to find something that is native 2"?

1) 20mm is the required minimum for wearing glasses at the eyepiece.

 

2) 0.5mm Exit Pupil corresponds to the 50× per inch of aperture rule==maximum magnification

7.0mm corresponds to the eye's pupil of a young fully dark adapted eye.

 

2 again) you are going to want a lowest power EP, a stepped set of EP magnifications/FoVs through the mid-range (say 50% more magnification per step), and a closer spaced set of magnifications for the high power end (20% to 25% per step). At the high magnification end of things, some night will allow you to use a 6mm others a 5mm and still others only a 7mm. When operating at high power one wants to use as much power as they sky permits.

 

3) All of the 1¼-2 Ethoi can use barrel extenders so you can make them 2" only--you might as well put parfocal rings on them at the same time so you can swap EPs without moving the focuser much.


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#15 havasman

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Posted 17 May 2021 - 06:59 PM

The 9ES120 actually does due to its 120º light path to the exit pupil.

Yes, and that would be an example of why I qualified the statement by including an approximate AFOV range. It didn't seem to me the OP would be in the market for that outlier eyepiece.

 

I spent a few months with one several years ago and found it interesting but not for me. I thought if all my observing was from a light polluted site it would be very beneficial, maybe even a one-piece eyepiece kit.


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#16 Dave Mitsky

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Posted 17 May 2021 - 07:29 PM

Have you considered the Tele Vue DeLites?  They have a slightly larger apparent field of view than the Celestron X-Cel LXs and 20mm of eye relief.

 

Astronomics has the 9mm DeLite in stock at the moment.

 

https://www.astronom...5-eyepiece.html


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#17 CHASLX200

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Posted 17 May 2021 - 07:46 PM

My fav's were the 3mm Radian and 3mm Delite as well as a 2.5mm Vixen LV from years ago.  And i really use these high power eyepieces a lot.



#18 Sarkikos

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Posted 18 May 2021 - 09:04 AM

1) 20mm is the required minimum for wearing glasses at the eyepiece.

 

Required by whom?  Required eye relief while wearing glasses can vary widely among individuals.  "20mm" is the oft-quoted standard, but it is not universal.   I can keep my eyeglasses on while observing through some eyepieces which have eye relief as low as 10mm.  It's best for individual observers to experiment a little to find out for themselves.

 

Most eyepieces with very short eye relief also have short focal lengths and are high power eyepieces.  Many people with astigmatism won't need to wear eyeglasses while viewing through these in any case.

 

Mike


Edited by Sarkikos, 18 May 2021 - 09:06 AM.

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#19 Sarkikos

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Posted 18 May 2021 - 09:19 AM

Hi all,

 

I got 2 eyepieces with my new telescope:  Celestron x-cell lx 9mm and ultima edge 30mm.  I wear glasses and have astigmatism and already am struggling with the eye relief on the 9mm.  The 30mm has been great.

 

I've been looking at televue ethos eyepieces and I have a few questions:

 

1. What should I aim for in regards to comfortable eye relief while wearing glasses?  I'm interested in the televue ethos 6mm, or possibly 4.7mm and each have an eye relief of 15mm; I'm just not sure if that's sufficient?

 

2. Exit pupil on both the 6mm and 4.7mm are close to 1mm, give or take.  My 30mm has an exit pupil of 6mm as a point of comparison.  Is 1mm too small to be practical?  Should I find something closer to 9mm like what I have but better?  My scope is a 12" dob with 1525mm focal length.

 

3. The ethos eyepieces seem to be 1.25" with 2" adapters.  Does this matter, or should I try to find something that is native 2"?

 

Thank you all!

How bad is your astigmatism?  The narrower the exit pupil, the less you will see the astigmatism from your eye.  The shorter the focal length of the eyepiece, the narrower will be the exit pupil.  Chances are you won't even notice your astigmatism with eyepieces at 6mm focal length and shorter.  So you might not even need your glasses, and can use eyepieces with shorter eye relief. 

 

1mm to 0.5mm exit pupil is a good range for planets, the Moon and planetary nebulae.  In your scope, that's a 5mm to 2.5mm eyepiece, 305x to 610x.  But you will need good to excellent seeing to support those magnifcations.

 

Mike


Edited by Sarkikos, 18 May 2021 - 09:20 AM.

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#20 ApexAZ

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Posted 18 May 2021 - 12:08 PM

How bad is your astigmatism? The narrower the exit pupil, the less you will see the astigmatism from your eye. The shorter the focal length of the eyepiece, the narrower will be the exit pupil. Chances are you won't even notice your astigmatism with eyepieces at 6mm focal length and shorter. So you might not even need your glasses, and can use eyepieces with shorter eye relief.

1mm to 0.5mm exit pupil is a good range for planets, the Moon and planetary nebulae. In your scope, that's a 5mm to 2.5mm eyepiece, 305x to 610x. But you will need good to excellent seeing to support those magnifcations.

Mike

I don't have my rx info in front of me, but it's bad enough I can't seem to wear wrap around rx sunglasses with highly curved lenses, despite them saying they can now correct for it. I can seem to see ok in my LX 9mm without my glasses tho. Maybe not quite as well, but enough to see.

Edited by ApexAZ, 18 May 2021 - 12:08 PM.


#21 Sarkikos

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Posted 18 May 2021 - 12:10 PM

I don't have my rx info in front of me, but it's bad enough I can't seem to wear wrap around rx sunglasses, despite them saying they can now correct for it. I can seem to see ok in my LX 9mm without my glasses tho. Maybe not quite as well, but enough to see.

If your vision is OK through the 9mm eyepiece without glasses, it should be even clearer through eyepieces with shorter focal lengths.

 

Mike


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#22 Passerine

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Posted 19 May 2021 - 06:46 AM

What Mike explains is really good to understand.  I have mild/moderate astigmatism in both eyes.  Someday I may try 1 o 2 special eyepieces that require me to remove my glasses.  An eyeglass lanyard might be handy if you need to remove your glasses for some of your eyepieces.

 

Generally my preference is to keep my glasses on most of the time.  I enjoy star hopping, constantly looking at the part of the sky where the scope is pointed. I also need or prefer my glasses when I'm reading star charts or using the Nexus DSC.  And especially at dark sky locations, I often just pause, quit thinking and gaze at the beauty of the whole sky...  So far all my eyepieces have long eye relief.

 

Dave


Edited by Passerine, 19 May 2021 - 07:00 AM.

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#23 Sarkikos

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Posted 19 May 2021 - 08:00 AM

What Mike explains is really good to understand.  I have mild/moderate astigmatism in both eyes.  Someday I may try 1 o 2 special eyepieces that require me to remove my glasses.  An eyeglass lanyard might be handy if you need to remove your glasses for some of your eyepieces.

 

Generally my preference is to keep my glasses on most of the time.  I enjoy star hopping, constantly looking at the part of the sky where the scope is pointed. I also need or prefer my glasses when I'm reading star charts or using the Nexus DSC.  And especially at dark sky locations, I often just pause, quit thinking and gaze at the beauty of the whole sky...  So far all my eyepieces have long eye relief.

 

Dave

These are the same reasons why I prefer to keep my glasses on whenever possible at the telescope.  :waytogo: 

 

But I do have a few "special" eyepieces that force me to remove the glasses.  The eye relief is just too short for me to keep the glasses on and still see the entire field of view.  So I also have the eyeglasses on a lanyard, just in case I have to take them off.

 

I also take the glasses off when I'm trying to see very faint DSO or very fine structure on planets.  

 

Mike



#24 Passerine

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Posted 19 May 2021 - 10:27 AM

That's a good point about removing glasses in order to see more detail on planets.  I need to remember that.  Also I need to make a point to take my glasses off with all my eyepieces and learn exactly what my own limit is for my astigmatism affecting the view.  I've been over-committed to keeping my glasses on so I don't even know.  In this recent post Don Pensack figured out his limit is an exit pupil of 1.7mm or larger (glasses needed).

 

Dave


Edited by Passerine, 19 May 2021 - 10:28 AM.

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