Wearing glasses and eyepieces

[Coolhand1988]

5 hours ago, JOC said:

This another thread in what is a popular subject on SGL.  I am a spectacle wearer I have a respectably strong prescription and a touch of prism in my lenses.  There is an awful lot of mathematical stuff written about what people should and shouldn't be able to see through EP wise both from the perspective of wearing your specs at the EP if you need to wear them normally, not wearing specs at the EP if you normally need to wear them and even similar conversations from people that don't normally wear glasses yet still struggle to see through some EP's.   Eye relief def. plays a part, but at the end of the day everyone is different and what works for one person may for any number of reasons not work for another.  I am def. neither a regular telescope user nor any form of expert in the matter, but I have a mixed box of EP's including some good branded ones and would like to offer up my common sense based observations on the basis of my own experience.

1.  The only EP I've ever completely failed with is a 10 or 11mm Televue Plossl which had eye relief of about 7-8mm I bought that second hand and resold it at no loss.  On that basis maybe things with longer eye relief are easier to use overall whether you wear specs or not and I think from what I read that seems true.

2.  Just because an EP works for someone it might not work for you.  Try buying EP's second hand, try them and resell what doesn't work for you.  Once they have reached second-hand price they seem to change hands at around that mark ad infinitum within a reasonable time period.  You can read threads like this all day, but even if you buy something that someone recommends it might not work.

3.  Don't assume that because you have to wear specs day to day, that you need to wear them at the telescope - I often remove mine and just adjust for focus with the telescope.  FWIW I also find that if I am snorkelling I don't need my specs on to see enough with - looking through the water makes a huge difference.  There are def. some things that you might find you can take specs off for.  A bit like removing them to thread a needle.  Some prescriptions are designed for short and some for long distances, not to mention varifocals - it therefore stands to reason, that not all specs might lend themselves to use at the EP - try taking them off and see how you get on.  

4.  I personally find I get on best with the 'hover above the EP' approach - I am no big fan of the rubber EP guards and mostly fold them down whether I have my specs on or not.   I guess if you are a DSO nut then perhaps the light exclusion from the eye cups is useful, but I am not that dedicated.  FWIW a couple of cheap bar stools one set higher and one set low is a useful investment to sit on and helps you stay still when 'hovering'.  Another advantage to hovering is you are almost automatically compensating for a  little bit of the focus esp. if you don't have your specs on.  However, just because it works for me it might not work for you.  Get a couple of second-hand EP's and get out there.  If they work for you in some way hang onto them - if they don't sell them on and have another bash.

Thanks for your very detailed advice.

I completely agree about deciding to wear or not wear glasses when observing and first hand experience when trying out different eyepieces.

If I was short sighted, i'm more in favour not to wear glasses when observing. That's just my day to day experience being long sighted. 

It will be interesting to see how low on eye relief I can go and still observe comfortably at the eyepiece.

Thanks

[Bivanus]

@Coolhand1988 what I've found out in my curent travell - that also makes me a bit slow on the answers - is that on the other side of the pond the Tele Vue Plossls 32mm and 25mm are well regarded by eyeglass user astronomers in general and  by binoviewer users in particular. Since I'm still eyeglassles 😅I went the Nagler way for now , with a 24mm Panoptic to boot .  

[Coolhand1988]

7 hours ago, Bivanus said:

@Coolhand1988 what I've found out in my curent travell - that also makes me a bit slow on the answers - is that on the other side of the pond the Tele Vue Plossls 32mm and 25mm are well regarded by eyeglass user astronomers in general and  by binoviewer users in particular. Since I'm still eyeglassles 😅I went the Nagler way for now , with a 24mm Panoptic to boot .  

 Hi

I did have a detailed look at the Televue Plossels. The 55mm version is already on my list.

If I decided to go down the bino route at some point, the TV plossels are at a budget where I can purchase two EPs for bino viewing.

Thanks

[dweller25]

I use TV Plossls down to 20mm, I tried the 15mm’s but the eye relief was too small when wearing glasses.

[Coolhand1988]

1 hour ago, dweller25 said:

I use TV Plossls down to 20mm, I tried the 15mm’s but the eye relief was too small when wearing glasses.

There are a few sites like FLO, which give their EP range information on eye relief.  The 15mm TV plossel ER is 10mm. The 20mm ER is 14mm.

It has been mentioned on this thread that the same ER will differ from person to person.  If you can go down to 14mm of ER wearing glasses, then you have more EP options.

I will start at 20mm ER, then buy a couple of TV plossls( 25mm and 20mn ) to test my minimum ER for wearing glasses.

Thanks

[John]

Plossls have eye relief that is around 70% of their focal length. 

The eye relief stated can be misleading if the eye lens top surface is heavily concave or the eye lens is inset below the eyepiece top or below an inflexible eye cup. Actual useable eye relief can be somewhat less due to these factors. 

Edit: apologies - I am repeating what I have already posted earlier in this thread 🙄

Edited October 16, 2023 by John

[Louis D]

20 hours ago, John said:

Plossls have eye relief that is around 70% of their focal length. 

The eye relief stated can be misleading if the eye lens top surface is heavily concave or the eye lens is inset below the eyepiece top or below an inflexible eye cup. Actual useable eye relief can be somewhat less due to these factors. 

Edit: apologies - I am repeating what I have already posted earlier in this thread 🙄

True.  I've got a pair of 26mm Sirius Plossls that are not usable with eyeglasses because of eye lens recession.  I've measure the pair to have only 11mm of usable eye relief.

Even my GSO and Sirius 32mm Plossl pair each have only 15mm of usable eye relief due to eye lens recession.  They are usable with eyeglasses.

My 20mm SVBONY 68° Ultra Wide Angle pair have 14mm of usable eye relief and are comfortable to use with eyeglasses.  So far, these are my favorite pair for BVs.

My vintage ~17mm Bausch & Lomb Wide Field 15x pair of microscope eyepieces have 19mm of usable eye relief and are a close second favorite pair to use in a BV.  Since they are designed to minimize RMD, AMD is more obvious.  However, I've never noticed this issue BV'ing.

[Coolhand1988]

On 17/10/2023 at 13:43, Louis D said:

True.  I've got a pair of 26mm Sirius Plossls that are not usable with eyeglasses because of eye lens recession.  I've measure the pair to have only 11mm of usable eye relief.

Even my GSO and Sirius 32mm Plossl pair each have only 15mm of usable eye relief due to eye lens recession.  They are usable with eyeglasses.

My 20mm SVBONY 68° Ultra Wide Angle pair have 14mm of usable eye relief and are comfortable to use with eyeglasses.  So far, these are my favorite pair for BVs.

My vintage ~17mm Bausch & Lomb Wide Field 15x pair of microscope eyepieces have 19mm of usable eye relief and are a close second favorite pair to use in a BV.  Since they are designed to minimize RMD, AMD is more obvious.  However, I've never noticed this issue BV'ing.

Interesting. I have read that stated eye relief can vary somewhat from true eye relief. With small to medium focal length eyepieces, a Barlow can increase the eye relief as well, where a Tele-extender does not.

The televue Delites and Delos EPs have the actual stated ER, according to reviews and testers.

The Baader Morpheus reviews have the stated ER as well, but I believe the smaller Focal length EPs needs the rubber eye guard down for this?

The above eyepiece brands and types are my preferred choices, along with a couple of long focal length plossls.

Thanks