The effects of dirty eyepieces: advice sought

[Dragons Egg]

Due to my proven inability to do this myself, I'm about to send some of my eyepieces (2 ES 82s & a TV Ethos 21mm) off to be professionally cleaned. If that doesn't solve the problem, then I'll submit all three of my scopes to the same treatment, including my NP101. Before I do this, however, I would like to know just how dirt and grease visually degrades the performance of an eyepiece lens. (Google doesn't seem to understand this question). For what it's worth, what I see is astigmatism in a given star-field, especially towards the edges. Hitherto every star was tack sharp right across the field, but now I can no longer keep the ones near the edge of the field properly in focus with those in the centre. The discrepancy is subtle, but once spotted it's impossible to ignore. Also there's a faint 'sparkly' effect whenever I'm panning the scope, which has nothing to do with atmospheric scintillation. Grease? Dirt? Traces of cleaning fluid? This degradation is replicated on my ES Mak-Newt, as well as the two refractors. So I can only put it down to the EPs. . . at least for now. If the problem extends to the scopes themselves, then potentially I could be in real trouble, of course. But, hey, one step at a time. In passing this has been such a disheartening experience that I came close to giving up astronomy altogether. Since then my enthusiasm has rekindled somewhat since buying a pair of small image-stabilised binoculars (Canon 12x36). Even so, as wondrous as these bins are, they also remind me that there's an outstanding issue that still needs attention.

My apologies for banging on like this, but stargazing-wise this last eighteen months hasn't been a happy experience for me. So any input would be extremely welcome. Thanks for reading this 'cautionary' tale.  

 

[F15Rules]

Hi Graham,

I'm sorry to hear of your problems..if you were previously getting great images with your equipment, it begs the question "What has changed?"..

So, firstly, can you actually see any signs of dust, dirt or grease on the eyepieces or your scope optics? In my experience it takes a LOT of soiling to degrade your images noticeably. Also, you mention noticing this more to the edges of the field? It does sound odd as I'd expect dirt related soiling to affect all of the field, assuming that the soiling is evenly spread around?

Secondly, I hate to ask this, but could it be your own eyesight that is changing/has changed? I ask this, as I myself have had noticeable degrading of the sight in my right eye in the last couple of years, to the point that my former main observing eye (my right) cannot usually give me the very sharp focus it used to give - and I have had to retrain my left eye, which is noticeably better than my right, to be my main observing eye.. so worth considering an eyesight check, if only to eliminate that as a possible cause?

Usually, cleaning a lens is not a difficult process, and if you search on the telescope or eyepiece forums on SGL, I'm sure you will find lots of good advice as to how to do it yourself..just a bit of care and attention with good quality materials such as Baader Wonder Fluid and Cleaning cloth being used.

Good luck and I hope you can get to the bottom of the problem.

Dave

[Louis D]

You didn't say if you wear eyeglasses and if so how strong your astigmatism is and if you have presbyopia.  Do you need to refocus stars center to edge that you didn't use to have to?  If so, you may be getting presbyopia and can no longer accommodate near/far focusing.  If that is the case, you'll need to find flatter field scopes and eyepieces.

Astigmatism in you eye would be visible center to edge and would be stronger in lower power eyepieces.  This doesn't seem to be the case based on you description.

The scintillation is worrisome.  I recently had vitreous detachment diagnosed in my non-observing eye which causes random flashes in my vision.  It has to be watched to make sure it doesn't lead to retinal detachment.

Definitely get to an optometrist for a thorough eye exam.

Edited August 21, 2020 by Louis D

[Sunshine]

If your eyepieces were soiled enough so that the image was degraded, then I'm inclined to think you would have had no doubt it was your eyepieces, it would have to be that bad. Recently, i have found that i could not bring stars at lower powers to a proper focus, i was afraid my scope was at fault. It is not, astigmatism was the culprit as i can focus just fine at higher powers.

[Ruud]

What puzzles me is that your binoculars don't cause you any problems while everything else does. 

Your binoculars have an exit pupil of 3mm. Could you please try an eyepiece-telescope combination that has the same exit pupil? Does your experience with your binoculars change if you look through one  tube only, or if you stop the objective lenses down to 12mm so that they give you  a 1 mm exit pupil?

How does panning look through the binoculars with the image stabilisation turned off? Do you see any of the strange effects you get from your other instrument? How does your experience with your binoculars change if you look through one  tube only?

Have you cleaned your binoculars yet? Could you upload a photo of the eye lenses of your ethos 21 and your binoculars next to each other?

Your experience with your binoculars might indicate that your eyes and optical cortex aren't the source of the problems, but it is important that you rule out any health issues with your visual system. Discuss the matter with your GP.

About your proven inability to clean your eyepieces: How have you been cleaning them?

One standard method is 
-  blow off any particles with a blower
-  push loose any remaining particles with a soft brush
-  clean the lens with some cotton, moistened with a solvent like alcohol
-  wipe dry with very soft tissue paper (kleenex regular is recommended)
-  streaks are removed by fogging the glass with your breath and wiping it dry with a tissue
-  blow off any lint left by the tissue paper

Small optical elements are relatively impervious to heat stress and can be coated at high temperatures, resulting in hard, scratch resistant coatings. Eyepieces are  made with cleaning in mind and the outer coatings are quite durable.

ES suggest that you clean their eyepieces by holding them under running water or give them a bath like in this video: https://www.youtube.com/watch?v=PG9ywpAZOao The relevant section starts after about 16 minutes.

 

 

 

 

 

[SiriusB]

From what you've described, (astigmatism) it doesn't sound like dirty eyepieces to me

I'd expect dirty EP's to lessen contrast.

FWIW A good few years ago i bought a camera lens that looked like it had seen serious professional use, Nah!,~abuse.

I only bought it because at the time that focal length almost never came up 2nd hand & was NLA new.

The lens was scratched, the lovely multicoating was all but non existent, the focusing sloppy, the camera shop were obviously a bit embarrassed selling it as they insisted on sending for a CLA before i bought.

All that said, i never noticed it took worse pics than my mint or near mint lenses.???

Make of that what you will.

[Dragons Egg]

First up: many thanks for all the helpful comments and friendly advice. No, I never wear eye glasses when observing (I do wear specs, but only for reading purposes). So far I've had none of the above problems, either with my IS binoculars, or possibly more testingly, while looking through a friend's mounted Orion Resolux 15x70 bins. Perhaps more puzzling still is the fact that a recently acquired 6mm Delos works just fine on my ES 80mm triplet. Is this because I've never 'cleaned' it? Or would the 80x magnification/reduced FOV it delivers to the scope render the problems less visible? I have no ready answers to both questions. I've not yet tried the Delos out on the other two scopes, though I intend to do so asap (weather permitting). Yes, as has been pointed out, it's possible the problem could originate with my eyes, after all, especially given that I'm now in my late sixties. Meanwhile, depending which comes first (again largely hinging on the weather) I'll seek a second observer's opinion on my equipment and see what gives, while keeping open the option of sending off the above three mentioned EPs to be cleaned. As a side note, given that the exit pupils of the Canon binos are 3mm, it so happens that one of the above trio of EPs, namely the ES 14mm, offers a 2.9mm exit pupil on my ES Mak Newt. Unhappily it's also the worst offender out of these three EPs, which is a real pain, given that it's the one I use the most often. Finally, I've made a note to get my eyes checked out! Again, thanks for everything. 

Clear skies!