ES82 30mm - CA

[Wardr77]

Hello all,

Looked at the moon last night through my recently acquired ES82 30mm; just about got the whole thing in the FOV, but I did notice a lot of yellow/orange colour flare around the edges of the moon, is this normal do you think? I expected there would be some but this was quite significant. This EP is great on clusters, starfields etc, but for our neighbour i felt the trusty plossls were better.

Scope used was an F10 SCT

Thanks

[rwilkey]

Hi Wardr77, not had any problem with the 30mm, though not tried it specifically on the Moon, would not have thought that target would be beneficial with this type of ep, more for deep sky and starfields etc.  Still, an intersting report, thanks for posting.

[damnut]

Hi Wardr77,

Cannot think what is happening there. The SCT at F10 is very forgiving of eyepieces, and the ES 82 30mm is an excellent ep.

[spaceboy]

Some of the ES range do suffer lateral colour around the edges. I had a 30mm ES 82° for a little while and I was not overly impressed with it although ES have been known to let some poor examples slip through QC. On this occasion though what you are experiencing wardr77 sounds to me like the normal lateral colour is being emphasised by a warm eyepiece or scope optics, maybe even atmospheric diffraction ? (This only tends to happen when the object in low in the sky though.)

[Wardr77]

Hmmm a little concerning then. It was a warm and breezy night last night and I did notice that the stars were not the crystal like points of white light I normally see. Additionally the moon was 'boiling' somewhat and was still quite low when I was viewing it. Perhaps I'll try again when the seeing is better.

Thanks for your replies

[Dude_with_the_tube]

could be seeing conditions what affects your views.I had both Meade 5000 series 30mm UWA and have ES 30mm 82 deg and both showed exceptional quality.In F10 you shouldnt have any issues with ES 30mm.

Reading your comment above,i am declined to think that seeing conditions did affect everything.Low positioned targets are never the best.

[alan potts]

Like Dude With the Tube I had the Meade 30mm UWA and never saw any problems, a very good eyepiece though rather heavy.

Alan.

[Wardr77]

Like Dude With the Tube I had the Meade 30mm UWA and never saw any problems, a very good eyepiece though rather heavy.

Alan.

Hello Alan,

I have not noticed any issues with DSO's or stars, unless a bright star moves to the extreme outer edge of the FOV then I see colour flaring, but figured this was normal due to the large FOV. Have you observed then moon directly with the meade without any colour issues?

Thanks

[Dude_with_the_tube]

Hello Alan,

I have not noticed any issues with DSO's or stars, unless a bright star moves to the extreme outer edge of the FOV then I see colour flaring, but figured this was normal due to the large FOV. Have you observed then moon directly with the meade without any colour issues?

Thanks

i have done that with both Meade and ES and can confirm no false color or any other artifacts observed on moon due to very low power.Scopes used:10" F4.7 dob;14"  F4.6 dob  and multiple refractors from F8 down to F14.4 

You will not have a "perfect" flat field from 30mm 82 deg eye piece.there will be a slight field curvature in these 82 deg ep`s,and as a result there is a possibility of having distortions on the outer edges only due to EP being very wide FOV.Is your scope colimated????Have you tested colimation?

[Wardr77]

Not perfect if I'm to be honest. Checking against Vega the other night I did detect that the obstruction shadow is very  slightly shifted to right and down a bit. At first glance it looks fine, but it probably does need a very fine tweak. Is this likely to cause the issue I'm seeing then?

Thanks

[alan potts]

I had at the same time the 31mm Nagler and the Meade 30mm and I think here we are talking about where you place a star like Vega. Now I often do this and without doubt did on my review of the 24mm UWA Meade. If I recall the was a tiny amount of a coma like fault, but not coma, on the bright star at the very edge and I mean, if we imaginary calibrate 1-10 acorss the FOV, I'm talking about something that is visible at 0-0.5 and 9.5-10, in these areas.

Now the Nagler was almost perfect in this area but it is over twice the cost and has great edge distortion. I still think this 30mm model is a very good eyepiece even with this very minor fault.

As also stated by Dude with, is you colimation spot on, this can have a dramatic effect on these issues. I have fallen into the same trap, using the same scope night in night out, never a thought of is all OK, then you checkit and wow, I have a new scope 

[Roy Challen]

Hello all,

Looked at the moon last night through my recently acquired ES82 30mm; just about got the whole thing in the FOV, but I did notice a lot of yellow/orange colour flare around the edges of the moon, is this normal do you think? I expected there would be some but this was quite significant. This EP is great on clusters, starfields etc, but for our neighbour i felt the trusty plossls were better.

Scope used was an F10 SCT

Thanks

While I wouldn't say it was a lot, I did have exactly the same as you described - yellow fringe around the moon, with the moon filling the whole view. This was with the 8.8 82 degree in my f/16.4 frac. I don't find it objectionable but everyones eyes are different.

[Don Pensack]

This lateral color aberration of the exit pupil, yielding a "ring of fire" is also found in the 31mm Nagler as well as some other ultrawide eyepieces.

This isn't a problem unless the eyepieces are used in the daytime, or at night on the Moon.

Used for deep sky, it usually isn't visible.