Ethos / Delos / Pentax XW on moon

[Moonshane]

For some time now I have been harping on about issues I had with my old 13mm Ethos and 'blotches' of colour when looking at the moon. It's hard to describe really but manifests itself in the form of quite different shades in different areas of the moon when using these eyepieces. When looking intently at one spot, the detail is ultra sharp and contrasty as you'd expect but when you move your eye around the blotches of brownish grey or even pinkish brown 'flick' into place. Using my 17.3 Delos last night for the first time, the symptoms were the same. The view through my 15mm plossl match it for every aspect other than field of view in my 120ED refractor with the added benefit of not having the issues described above.

I am not fussed really as I didn't buy this eyepiece for lunar observing but felt I'd post this in case anyone is.

Don't get me wrong, for everything other than the moon (including the sun) this is a spectacular eyepiece (as is the Ethos, and also it may of course be my eyes. The issue only manifests itself for me with my old 13mm ethos, my 17.3 Delos and also my 26mm nagler but not my 12mmT2/ 9mm or 7mm T1.

I wonder if the Pentax XWs with their excellent transmission etc will create similar issues for me. I fancied a 10mm Delos but might go for the 10mm XW if I can find one and try one before I buy.

Any thoughts?

[michael.h.f.wilkinson]

I haven't seen this effect in either the Delos 8mm I have or the XW7 and XW10 I have. I am really surprised the Delos 17.3 has this issue

[Moonshane]

I suspect it's my eye - maybe I should try using the other one as a test? I have seen it on several different eyepieces and scope types though. I did have an ocular migraine (just one, ever) a few years ago which created rainbow zigzags in my eyes and tunnel vision.

[estwing]

I love the moon in my 13e...but as you say it's not for everyone

[nightfisher]

Shane, if this is an issue with you dominant observing eye, I would think it would show with most eyepieces though different focal lengths may have an effect, if your not seeing this with plossl at 15mm it would hint at your vision being good, however do you wear contacts? Just a thought as to wether these might play a part

[DRT]

Shane,

Are you using an ND filter (or similar) when viewing the Moon? Could it be that these eyepieces with higher light transmission are allowing a significantly brighter image to reach your eye and then leaving some sort of ghost image when you move to view another part of the surface?

Derek

[alan potts]

Shane,

In this area I have the 17mm and 13mm E, 12mm and 14mm D , 15mm Plossl and 16mm Nagler, I have also had for a considerable time the 11mm, 12mm, 13mm and 20mm Naglers. I have subjected all of these to views of the Moon with a fair cross-section of scopes and I have never seen anything like you describe, you have even had me looking for it.

Alan 

[John]

I've not seen the effects you describe with my Ethos's either. My 5mm XW is my favourite lunar eyepiece but, not seeing the issues you are seeing with the Ethos, I can't say whether you may find them with the XW's as well.

Looking at the eyepieces that you experience this issue with they seem to be ones with large eye lenses wheras the ones where it is absent have relatively small eye lenses. I wonder if there is a connection there ?

[Moonshane]

cheers all

I suppose it could be the bigger eye lenses although the Radians I have with their bigger lenses don't show the effect. I wish (sort of) that someone else could see this as it's very hard to explain!

[alan potts]

John may well have something there, is there another eyepiece you can try with a smaller eyelens?

Alan

[Moonshane]

The scope does not affect whether I see it. I see it (or have seen it) with my :

• 13mm Ethos
• 26mm Nagler
• 17.3mm Delos

I don't see it with my :

• 16mm T2 Nagler
• 12mmT2 Nagler
• 9mm T1 Nagler
• 7mm T1 Nagler
• 10mm Radian
• 8mm Radian
• 40mm Widefield
• 32mm, 25mm, 20mm, 15mm, 11mm TV plossls
• 7mm, 9mm, 12.5mm, 18mm BGO
• Any other eyepiece I have had. 

It seems to be restricted to new type, wide/ultrawide field eyepieces. As it happens, the 26mm Nagler eye lens is not that large. I suspect as no-one else that I am aware of sees this, that it is a mismatch between my eyes and the coatings/high transmission.

I don't use filters generally but might try my polarising filter from the Lunt wedge to see if this improves things on the moon.

[John]

Have you still got the plastic pupil guide that comes with the Radian ?

Maybe it's worth trying that with one of the other eyepieces ?

[Pig]

Shane,

It is clear to me that the problem is in fact your 13mm Ethos, you have clearly suffered an allergic reaction to it and you should stop using it immediately. As a result there is absolutely no point in you keeping it........ 

As with many unfortunate events some benefit can be found if one searches hard enough. Feeling some empathy for you I thought I would try to help you out and after making several enquiries on you behalf I have finally found someone, who just happens to be very trustworthy and reliable, that wants to purchase the Ethos from you   You could say every cloud has a silver lining

[Moonshane]

LOL

unfortunately Shaun, Olly Penrice already benefitted from the allergic reaction.

[Mr Spock]

I used to see this with my 7mm T6 Nagler and 250mm Newt, but not with my 8mm LVW.

I put it down to mild blackouts in the Nagler changing the shade and colour of the lunar surface depending where your eye is.

[Moonshane]

Good post Michael. You are probably on the right track.

[RikM]

Shane, I see this effect sometimes with my XW's in the 10". I put it down to the extra brightness as I don't see it with the same eyepieces in the Pronto.

[Pig]

Do wide angle eyepieces serve any beneficial purpose over say a 50mm FOV eyepiece when use to view the Moon ?

[jetstream]

Do wide angle eyepieces serve any beneficial purpose over say a 50mm FOV eyepiece when use to view the Moon ?

I think it depends on the scope and the aberrations/distortions that the EP/scope combo produces. To my eyes, in my scopes, some hyperwides soften the view outside the center too much for my liking negating the advantage of the wide field (lunar/planetary). I have one widefield that does not do this though...and there may be others. Mind you, when using the dob the coma free area is small anyway-this does compound EP issues at the edge. BTW I tested this in the f7ish refractors too.

As per Merlitz's illustrations we all see barrel/pincushion distortion differently, so this is a factor as well.

[John]

Do wide angle eyepieces serve any beneficial purpose over say a 50mm FOV eyepiece when use to view the Moon ?

I don't find any special benefits other than (for me) not having to move the scope quite so often - my scopes are alt-az and undriven.

On the other hand swooping across the lunar surface at 300x with a 100 degree sharp field of view is a heck of a lot of fun

The best lunar eyepiece I've owned and used is my 5mm Pentax XW. It's consistently shown me the finest detail and the most contrast on the lunar surface. Absolutely cracking eyepiece for this purpose, and many others

[Pig]

Cheers John & Gerry ...... very useful info

[Moonshane]

From my perspective the moon is best in my plossls but if you don't see the light anomalies I see the the wide field is useful on undriven mounts

[Stu]

I've not had an issue with widefields on the moon so I guess it must be an eye/brain thing.

A 3.7mm Ethos SX I had previously provided spectacular views, unfortunately my eyelashes seemed to always be in the way so I moved it on

[mikeDnight]

Ive used Naglers, Radians, Ethos, Tak LEs, Tak Hi LEs extensively but my all time favourite are my Pentax XW's, 10, 7, 5 and 3.5mm focal lengths. They have an extendable eye shield which helps the observer to keep their eye at the ideal distance from the eyelens and they are as pure as the driven snow. I doubt id ever change them!

Mike :-)

[michael.h.f.wilkinson]

I love using wide-fields on the moon. My first 82 deg EP was the Meade S5K 14mm UWA. Seeing the entire moon in a single FOV at 145x was a gobsmacking experience. It gave the view equivalent to looking out of a porthole of an Apollo command module at 2,650 km from the moon (1,650 miles). The 22T4 and 17T4 Naglers give similar result. I do like the SLV 5mm on the moon, but after using the XW7 and XW10 the 50 deg FOV feels a bit constricted.