Ethos 21mm for spectacle wearers

[astronymonkey]

Hi all,

I currently use a 28mm WO UWAN as my widefield eyepiece in my 16inch lightbridge and love the widefield view it gives but at f4.5 the lightbridge gives it a 6.2mm exit pupil which is a bit too big for me.

Im considering the 21mm ethos to give a smaller exit pupil and similar field of view but im wondering  what they are like for spectacle wearers. I wear specs for observing as I have astigmatism but I didnt want to mess on with the dioptrix system so I wondered how tight the eye relief was with glasses on......any thoughts ?

cheers

[alan potts]

AM,

I know this is a bit of a half baked way of doing it but as I have done my reviews for site I checked all of my eyepieces that are not Radians Delos etc for useability with my own glasses. Now I am fully aware that not all glasses sit in the same place on a persons face, some frames would be better than others. My reading glasses are fairly small and close, at least I think they are. I could not see anywhere near all of the FOV with then on, I doubt if it was even the FOV that the 82 degree eyepieces offer. The ER is stated at 15mm and I do not think this is enough, however I hope someone else can prove otherwise for you.

I wonder if this is why Sir Patrick used a monical?

I hope this is of some help to you.

Alan.

[DirkSteele]

I own the 21mm Ethos (though do not wear glasses), and I have to say, just from where I am holding my eye when using it, I have to agree with Alan.  It will be a bit tight for glasses not allowing you to fully take in the awesome 100 degree field.  Perhaps the dioptrix option is the way to go.  I have heard it is a great option and easy to use.

[michael.h.f.wilkinson]

I haven't looked through an Ethos, but I have used an 82deg EP with 15mm eye relief (the Meade 14mm UWA), and I already struggled to see the full FOV. More annoyingly, my glasses kept nudging the EP, causing vibrations. I since replaced it with a Nagler 12mm T4 with 17mm eye relief, which is enough. I am steering clear of the 100mm EPs until they get more eye relief (if that is at all possible).

[Damo636]

With my glasses on I estimate I can take in about 90% of the afov of the 21 & 13mm, the 8mm approx 80-85%. I don't have astigmatism though and can remove my glasses while observing.

[NGC 1502]

I've never looked through a 21mm Ethos, but have looked though clubmates 13mm & 8mm Ethos on several occasions.  But all the Ethos range are listed at 15mm eyerelief.  With my specs on (thin reading glasses pushed close to my eyes) cannot see the whole 100 deg field.

Without my specs, I have absolutely no problem being aware of the field stop in all directions, fantastic view.  Some report not being able to see the whole field with no specs, but a lot depends on face contours, how deeply set your eyes are etc.   If you are able to, then try before you buy (difficult for some I do realise).

I must emphasize, when I say being aware of the field stop, it's there in my periphery vision without actually looking at it.

All the best with your choice, Ed.

[astronymonkey]

Thanks for the replies, I suppose if im not going to get the full 100 degrees then I might as well stay with the 82 degree eyepieces like the T4 naglers which I suppose arnt a bad alternative and they have a better eye relief. The reason for considering the wider fields was to allow a better exit pupils for the similar widefield views but it looks like ill have to compromise on fov to get the exit oupil down .... at least ill save a few quid.

cheers

[swamp thing]

I use a 31mm T5 Nagler in my larger scope. Yes the exit pupil is too big, but I really couldn't care less. If I'm hunting something small and faint there's more chance I'll find it in the larger FOV it offers. Once located I can swap to an ideal exit pupil to examine it.

Your 16" can afford to lose a bit of light when you use a finder/wide field eyepiece too. I'd keep your UWAN and enjoy it. They're great eyepieces.

[Damo636]

The 26 Nagler would bring the exit pupil down to about 5.5mm, not a huge decrease but I feel would be ok for most users. The tfov is practically identical to that of the Ethos and it has enough eye relief for use with glasses. Just some food for thought!

[Scooot]

That's why I bought the 26mm nagler. I use it with dioptrx but I just held it up to a light and looked through it with my glasses. With the eye guard down I can just about see the whole field stop. Although I have to have the specs lens tight against the eye guard.

[alan potts]

What about the 22mm Nagler, Michael uses one and he wears glasses. Not an eyepiece I have but reviews are very good.

Alan

[michael.h.f.wilkinson]

The 22 Nagler is great, the eye relief is good enough for me to raise the eye cup by one or two clicks. I have also used Olly's 26mm T5 and had no problems with that.

[astronymonkey]

I think the 22mm would be at the sweet spot for me as it would give an exit pupil of just under 5mm and has good eye relief. I did consider the explore scientific ones but they dont seem to have the eye relief im after

I just love the wide field views of the uwan that I have but I from my calculations , if I only have 5mm pupil then the 6.2mm exit pupil of the uwan means I loose nearly 20% of the exit pupil which stops the scope down to 12.9inches. This is the equvalent of a 35% mirror area loss which is quite a bit......does my maths sound about right on this? If so can I expect to see a brighter image in the 22mm ?

if im right then a 22mm may have to be bought before kielder in a couple of weeks !

cheers