Eye relief differences in different people?

[Zeta Reticulan]

7 minutes ago, Don Pensack said:

Huh?  The rubber is glued to the threaded ring, and there is no grease at all.

There was on mine. I replaced the original with the new 'foldable' Baader eyecup. I folded the rubber and it detached from the ring, which had a lot of grease in the threaded metal ring part where it threads into the eyepiece itself. It isn't glued as far as I can see.  I spent a lot of time cleaning this grease off the eyepiece. After this incident I decided to use it unfolded. It works fine. As long as I don't pull the rubber off the metal ring. 

[badhex]

Finally got the last eyecup/extension I needed for the APM 24mm UFF:

[ED Splitter]

Interesting thread to read. Eyepieces are very personal. Too much discussion is made on eye relief. Not sure all manufacturers measure this equally or even regard it to be the same thing. Ultimately there is always a compromise. 

[Don Pensack]

17 hours ago, ED Splitter said:

Interesting thread to read. Eyepieces are very personal. Too much discussion is made on eye relief. Not sure all manufacturers measure this equally or even regard it to be the same thing. Ultimately there is always a compromise. 

Eye relief is the distance from the top center of the eye lens glass to the exit pupil.  It is the industry standard.

However, there are factors that affect how useful that eye relief is:

1) the depth of the eye lens below the rubber eyecup.  Many long eye relief eyepieces have their long eye reliefs destroyed by a too-deep eye lens.

2) Whether the eye lens is concave, flat, or convex.  Some older designs seemingly have no eye relief  but are still usable because of convex lenses.  Some more modern designs seem to have less eye relief due to concave eye lenses.

3) The shape of the top of the eyepiece.  If a folded-down eyecup still sticks up several mm, that will reduce the effective eye relief.

     Effective eye relief is the distance up from a folded down eyecup to the exit pupil.  I have seen effective eye reliefs really bite into the mfr's eye relief significantly.  The 24mm APM Ultra Flat Field eyepiece has a 29mm eye relief,

     but the effective eye relief is only about 18mm because the eye lens is deep in the eyepiece and the rubber eyecup doesn't fold completely flat.

     Even with that, the 18mm effective eye relief can be too long when the eyepiece is used by a non-glasses wearer (see Badhex' post).

4) Some companies have tried to measure the effective eye reliefs of their eyepieces and post those figures because it is relevant for glasses wearers.  But this figure, if not also quoted in combination with the mfr's eye relief,

    is misleading to those who view without glasses.  Take that APM 24mm.  If all you saw was 29mm, then most would think the eye relief was excessive.  But it's only about 18mm for glasses wearers, and some glasses wearers couldn't use it.

    And non-glasses wearers might still find the 18mm excessive, or be scared away from the eyepiece altogether by seeing the 29mm figure.

 

I advocate that all eyepiece companies advertise both actual and effective eye relief figures, which would help all of us decide if the eyepiece is suitable for our uses.

But, as they say, if wishes were horses, beggars would ride.😄

[ED Splitter]

8 minutes ago, Don Pensack said:

Eye relief is the distance from the top center of the eye lens glass to the exit pupil.  It is the industry standard.

However, there are factors that affect how useful that eye relief is:

1) the depth of the eye lens below the rubber eyecup.  Many long eye relief eyepieces have their long eye reliefs destroyed by a too-deep eye lens.

2) Whether the eye lens is concave, flat, or convex.  Some older designs seemingly have no eye relief  but are still usable because of convex lenses.  Some more modern designs seem to have less eye relief due to concave eye lenses.

3) The shape of the top of the eyepiece.  If a folded-down eyecup still sticks up several mm, that will reduce the effective eye relief.

     Effective eye relief is the distance up from a folded down eyecup to the exit pupil.  I have seen effective eye reliefs really bite into the mfr's eye relief significantly.  The 24mm APM Ultra Flat Field eyepiece has a 29mm eye relief,

     but the effective eye relief is only about 18mm because the eye lens is deep in the eyepiece and the rubber eyecup doesn't fold completely flat.

     Even with that, the 18mm effective eye relief can be too long when the eyepiece is used by a non-glasses wearer (see Badhex' post).

4) Some companies have tried to measure the effective eye reliefs of their eyepieces and post those figures because it is relevant for glasses wearers.  But this figure, if not also quoted in combination with the mfr's eye relief,

    is misleading to those who view without glasses.  Take that APM 24mm.  If all you saw was 29mm, then most would think the eye relief was excessive.  But it's only about 18mm for glasses wearers, and some glasses wearers couldn't use it.

    And non-glasses wearers might still find the 18mm excessive, or be scared away from the eyepiece altogether by seeing the 29mm figure.

 

I advocate that all eyepiece companies advertise both actual and effective eye relief figures, which would help all of us decide if the eyepiece is suitable for our uses.

But, as they say, if wishes were horses, beggars would ride.😄

I agree. 

[badhex]

2 hours ago, Don Pensack said:

Eye relief is the distance from the top center of the eye lens glass to the exit pupil.  It is the industry standard.

However, there are factors that affect how useful that eye relief is:

1) the depth of the eye lens below the rubber eyecup.  Many long eye relief eyepieces have their long eye reliefs destroyed by a too-deep eye lens.

2) Whether the eye lens is concave, flat, or convex.  Some older designs seemingly have no eye relief  but are still usable because of convex lenses.  Some more modern designs seem to have less eye relief due to concave eye lenses.

3) The shape of the top of the eyepiece.  If a folded-down eyecup still sticks up several mm, that will reduce the effective eye relief.

     Effective eye relief is the distance up from a folded down eyecup to the exit pupil.  I have seen effective eye reliefs really bite into the mfr's eye relief significantly.  The 24mm APM Ultra Flat Field eyepiece has a 29mm eye relief,

     but the effective eye relief is only about 18mm because the eye lens is deep in the eyepiece and the rubber eyecup doesn't fold completely flat.

     Even with that, the 18mm effective eye relief can be too long when the eyepiece is used by a non-glasses wearer (see Badhex' post).

4) Some companies have tried to measure the effective eye reliefs of their eyepieces and post those figures because it is relevant for glasses wearers.  But this figure, if not also quoted in combination with the mfr's eye relief,

    is misleading to those who view without glasses.  Take that APM 24mm.  If all you saw was 29mm, then most would think the eye relief was excessive.  But it's only about 18mm for glasses wearers, and some glasses wearers couldn't use it.

    And non-glasses wearers might still find the 18mm excessive, or be scared away from the eyepiece altogether by seeing the 29mm figure.

 

I advocate that all eyepiece companies advertise both actual and effective eye relief figures, which would help all of us decide if the eyepiece is suitable for our uses.

But, as they say, if wishes were horses, beggars would ride.😄

One potential solution would be for EP manufacturers to provide a removable eyecup and adopt a thread standard like M43 for medium and large sized EPs, and a smaller one for smaller EPs. It might not fit every use case but it would certainly help. 

[Don Pensack]

2 hours ago, badhex said:

One potential solution would be for EP manufacturers to provide a removable eyecup and adopt a thread standard like M43 for medium and large sized EPs, and a smaller one for smaller EPs. It might not fit every use case but it would certainly help. 

This is an industry that can't standardize filter threads.  Standardize eyepiece barrels?  ¡Buena suerte, amigo!

[Zeta Reticulan]

I dream of standardised filter threads. lol

[badhex]

16 minutes ago, Don Pensack said:

This is an industry that can't standardize filter threads.  Standardize eyepiece barrels?  ¡Buena suerte, amigo!

Indeed. I don't have the agena astro astronomy threads page bookmarked for no reason - but one can dream! 

[Mr Spock]

Standardise things? Try looking at invoices. 300 different companies will have the invoice number in 300 different places 

[Zeta Reticulan]

300 different companies? Everyone knows 99% of all astronomy equipment is made in one giant underground robotic factory in China!

[HollyHound]

On 04/08/2022 at 20:55, Philip R said:

Assuming you purchased your TeleVue Radian new, did it include a pupil guide in the box? [image and instructions below].

TV Radian Eyepiece Instructions.pdf 938.47 kB · 130 downloads

I too would get a blackout when using my 6mm Radian with my ETX105 before I added/re-modded the rear end/visual back.
Using the supplied pupil guide should eliminate it. 

Just happened upon this thread... I had no idea what that little black disc was in the Nagler 22mm box (I've just packed it all back for sale) 🤔

Now I do, thanks very much for this snippet of information 😁

Edited October 28, 2022 by HollyHound

[HollyHound]

Duplicate post!

Edited October 28, 2022 by HollyHound
Duplicate post

[Don Pensack]

2 minutes ago, HollyHound said:

Just happened upon this thread... I had no idea what that little black disc was in the Nagler 22mm box (I've just packed it all back for sale) 🤔

Now I do, thanks very much for this snippet of information 😁

Just be aware that it can cut into the field unless it is used near the exit pupil position.  Since it is only going to be used by non-glasses wearers on a very long eye relief eyepiece, the eyecups are going to be raised up quite a bit anyway.

It rests on the rubber and helps the novice find the exit pupil when the exit pupil is high above the glass.

More experienced observers or glasses wearers would not need it.

[HollyHound]

1 hour ago, Don Pensack said:

Just be aware that it can cut into the field unless it is used near the exit pupil position.  Since it is only going to be used by non-glasses wearers on a very long eye relief eyepiece, the eyecups are going to be raised up quite a bit anyway.

It rests on the rubber and helps the novice find the exit pupil when the exit pupil is high above the glass.

More experienced observers or glasses wearers would not need it.

Thanks for the useful information @Don Pensack 👍

I primarily use XWs and DeLites (which have excellent eye relief), plus some Masuyamas (also decent)... it was really curiosity as to what that little device was for 🤔

Tele Vue really do thing of (almost anything) 😁

[Stephenstargazer]

I cant add much to the science of eye relief, but my personal experience is frustrating. With my Vixens (classic 20 mm er) my eye drops nicely on the un folded eye cup and away I go. With all those adjustable Televues (long Panoptic, Delos, Delite) I have to set them right down. Same applies with some but not all binoculars. 

Seems my sockets may be a bit deep and I dont fit wide eyecups. I am not a glasses wearer (yet.....) but that would be problematic. 

Tele Vue think of everything but not everybody ? ☹️

Edited November 7, 2022 by Stephenstargazer

[Don Pensack]

Judging from responses over the years, I'd guess that eye relief can vary from 11-30mm and be usable by someone who wears glasses.

What is appropriate for you will have to be determined by you.

That someone who does not wear glasses could use an eyepiece with 20mm of eye relief while touching the eyecup is either an indication of a very deep eye socket (as you suggest),

or an eyepiece that doesn't really have a full 20mm of eye relief, or an eyepiece whose eye lens is very deep in the eyepiece.

Those reasons are why a one-size-fits-all approach doesn't work, even if the idea of a 20mm eye relief as a starting point is a decent one.

[Stephenstargazer]

Have we any comment from those who wear contact lenses? It seems this would be better than glasses but perhaps it does not help if you need to correct astigmatism? I have a little but only noticeable on large exit pupils. I have used Dioptrix, but then the eye relief is reduced about 5mm.

Whilst 'one size fits all ' is not possible there are some designs that are less critical on eye placement. These are comfortable to use I find. The adjustable TVs are not one in my case.

[Louis D]

Toric lenses work for some folks, but not others, for astronomy observing.  They are weighted at the bottom by making them thicker so they will rotate to the correct position for astigmatism correction when looking horizontally.  The problem arises when looking mostly downward into an eyepiece.  The contact lens will then start to rotate out of best correction position for some people because gravity is acting on the lens as a whole to pull it off of the eye.

I haven't tried contacts at all, myself.  I get pinkeye infections far too easily without them whenever I get a head cold.

[Stardust1]

I observe sometimes with contacts and sometimes with glasses. I don't use eyecup extenders for the Morpheus eyepieces. I have no issue with the eye relief. Though the Morpheus 6.5mm is more challenging when using glasses. The Morpheus 17.5 and 12.5 are glass friendly, I can take the whole AFOV with ease and without any eye strain. 

I do have some eyepieces with tight eye relief, like the XO 5 and 2.5 mm. The eye relief of the XO 5 is at the limit, but still doable. 

[Don Pensack]

In an earlier post, I commented about the difference between Design Eye relief (measured from the glass) and the Effective eye relief (measured from the rubber eyecup--the important measurement for glasses wearers).

Here are some measurements I and others made:

Eyepiece............eye relief/depth of lens/effective eye relief

APM UFF 30.0           22.0        -4.90     17.10
NAGLER 22.0            19.0        -3.00     16.00
MORPHEUS 17.5      23.0        -2.30      20.70
MORPHEUS 14.0      18.5        -2.30      16.20
MORPHEUS 12.5      20.0        -2.30      17.70
APOLLO 11.0            18.0        -3.70     14.30
MORPHEUS 9.0        21.0        -1.90      19.10
ETHOS 8.0               15.0        -3.20      11.80
APM XWA 7.0           13.0        -4.00      9.00
MORPHEUS 6.5        18.5        -1.70      16.80
ETHOS 6.0               15.0        -3.10      11.90
ETHOS SX 4.7          15.0        -5.25      9.75
MORPHEUS 4.5        17.5        -2.10      15.40
ETHOS SX 3.7          15.0        -5.20      9.80

APM UFF 24.0           29.0      -12.4     16.6

APM UFF 18.0           20.0        -4.3     15.7

x-Cel 25.0                  16.0        -2.2      13.8

x-Cel 12.0                  16.0        -2.0      14.0

x-Cel 9.0                    16.0        -2.0      14.0

APM Super Zoom      19.0        -2.5     16.5

 

8mm Delos is 1.9mm eyelens depth  Effective eye relief 18.1mm

9mm Delite is 3.1mm eyelens depth  Effective eye relief is 16.9mm

10mm Pentax XW is 4.9mm eyelens depth  Effective eye relief 15.1mm

 

[NGC 1502]

For us eyepiece junkies what a fascinating thread😊   Some rambling comments for what it’s worth…

I don’t need eyeglasses to observe, but I use reading glasses for everyday use.

My 3-6 Nagler has 10mm ER and I find zero problems in use…but if I do use reading glasses I can see the whole 50 degree field with the rubber eyecup folded.

I own all focal lengths of TV Radians except the 3mm.  As long as the click stop eyeguard is properly deployed I don’t have problems with eye positioning.  I do accept others have problems.

The original TV Nagler 4.8mm gets lots of complaints about tight eyerelief.  When I owned one I found the eyerelief adequate for me without glasses. The problem I did have was constant fogging of the eye lens in damp conditions due to the close proximity of my eye.  Apart from that it was an excellent compact high power eyepiece.

My 35mm Panoptic is a lovely eyepiece.  But reading various threads I discovered there were 2 versions. It would seem that both versions were optically the same. The difference was that early versions had the eyelens more deeply recessed than later versions.  What year the change occurred I do not know.

I have a set of original Vixen LVs. I like them a lot, especially the 30mm LV (this is not the later 30mm NLVW)  In use I find the 30mm LV so wonderfully easy to use, my eye goes immediately to the right position. The 60 degree apparent field looks far larger than it is, in fact I prefer it in use to my 27mm Panoptic.  And the 27 Pan is wonderful in other ways…

I could ramble further, maybe later….

 

 

[badhex]

34 minutes ago, NGC 1502 said:

For us eyepiece junkies what a fascinating thread😊   Some rambling comments for what it’s worth…

I don’t need eyeglasses to observe, but I use reading glasses for everyday use.

My 3-6 Nagler has 10mm ER and I find zero problems in use…but if I do use reading glasses I can see the whole 50 degree field with the rubber eyecup folded.

I own all focal lengths of TV Radians except the 3mm.  As long as the click stop eyeguard is properly deployed I don’t have problems with eye positioning.  I do accept others have problems.

The original TV Nagler 4.8mm gets lots of complaints about tight eyerelief.  When I owned one I found the eyerelief adequate for me without glasses. The problem I did have was constant fogging of the eye lens in damp conditions due to the close proximity of my eye.  Apart from that it was an excellent compact high power eyepiece.

My 35mm Panoptic is a lovely eyepiece.  But reading various threads I discovered there were 2 versions. It would seem that both versions were optically the same. The difference was that early versions had the eyelens more deeply recessed than later versions.  What year the change occurred I do not know.

I have a set of original Vixen LVs. I like them a lot, especially the 30mm LV (this is not the later 30mm NLVW)  In use I find the 30mm LV so wonderfully easy to use, my eye goes immediately to the right position. The 60 degree apparent field looks far larger than it is, in fact I prefer it in use to my 27mm Panoptic.  And the 27 Pan is wonderful in other ways…

I could ramble further, maybe later….

We all love a good ramble on here 🙂

Really interesting to read everyone's different experiences even with the same EPs. Yet more evidence of how highly personal observing often is! 

[PeterStudz]

21 hours ago, Louis D said:

Toric lenses work for some folks, but not others, for astronomy observing.  They are weighted at the bottom by making them thicker so they will rotate to the correct position for astigmatism correction when looking horizontally.  The problem arises when looking mostly downward into an eyepiece.  The contact lens will then start to rotate out of best correction position for some people because gravity is acting on the lens as a whole to pull it off of the eye.

I haven't tried contacts at all, myself.  I get pinkeye infections far too easily without them whenever I get a head cold.

I have a toric lens for my left eye which is dominant and so it’s my observing eye. Out of interest I’m right handed. Most right handed people will have a dominant right eye. And dominant left if left handed.

Generally I only wear contacts for sport and only occasionally for astronomy. And my daughter prefers to observe with her glasses on, so I’ll wear mine so I can see in the same way she can. But to be honest I don’t notice any astigmatism when observing with or without contacts or when wearing glasses. 

Most of my eyepieces are BST StarGuiders. For glasses I personally wish that the eyecups weren’t quite so deep. Often I’ll remove them for easier viewing. 

Not sure why but one thing I have noticed. I’ll see more floaters when observing with or without contacts. Less with glasses. 

Edited November 9, 2022 by PeterStudz