Eye damage

[Tifstorey]

Hi folks,

I don't know if this is a common-sense kind of issue or what, but after looking at the moon last night for a minute or so through my scope, i found myself a bit dazed by the brightness of it.

Now, obviously i know not to look at the sun, but i didn't think the moon would be bright enough to damage your eyes. It was very bright last night.. Is it a case of 'if you think it's damaging, stop'?

Is there anything i can do to lower the brightness of objects i'm looking at?

Cheers

[Mark at Beaufort]

I think if you look at the Moon on a regular basis over a period of time I think eventually it might cause you problems. Most lunar observers buy themselves proper moon filters or neutral density filters. FLO stock these items as do must astro retailers. Here is a link to FLO - Moon & Neutral Density Filters

Mark

[Cornelius Varley]

Looking at the moon will not damage you eyes, it just ruins your night vision. A neutral density moon filter will reduce the brightness of the moon and keep your night vision.

Peter

[Space Bat]

You should use a Moon filter for observing the moon past Qtr. As you will strain your eyes and in some cases damage some of the receptors in your eye especially if using lower magnification where you are observing more light and over time this will cause problmes.

For bright planets you should be ok and coloured filters are used to provide better contrast and pick up on the features of the planets.

Chris

[Tifstorey]

Thanks alot

Will check out those filters definitely.

[brianb]

Looking at the moon will not damage you eyes, it just ruins your night vision. A neutral density moon filter will reduce the brightness of the moon and keep your night vision.

WHS.

The Moon is no brighter than a landscape in full sunlight. In fact it's darker 'coz most of the Moon is as black as coal ... even bright sunlight off snow won't permanently damage your eyes, though you may get a very painful affliction called "snow blindness" which can render you essentially sightless for a day or two.

But using a Moon filter is sensible if you want to preserve your night vision. The best colour for this purpose is deep red (Wratten 29) though many people prefer a neutral density (grey) or green filter for viewing the Moon.

[LukeSkywatcher]

It's weird because i found observing the moon the other night with my 130P a lot more comfortable then with my 90EQ, even without using the moon filter.

Any science behind this?.......refractor V's reflector,larger apeture spreading light out more?

[Macavity]

I think one might be wisely circumspect and definitely CAREFUL re. any action that might jeapordise one's eyesight. Nevertheless, I recently came across an article that at least SPOKE about potential dangers of (solar) retinal damage. On a personal level, I tend to respond more to (at least attempted) quantitative analysis and explantions of the dangers involved.

Galileo, solar observing, and eye safety

Maybe some of the references cited etc., may be of help?

[TheThing]

It's been said before (indeed, in this thread!) and it's worth repeating: -

Viewing a full moon can be uncomfortable but it will NOT harm your eyesight.

[yeti monster]

As an interim measure, you can reduce the aperture of your scope to around 25mm, by placing a cover, over the objective/OTA, that has a 1" diameter hole cut into it. If you are using a reflector, make sure that the hole is off-centre.

You will find the glare greatly reduced, and the contrast increased.

[Space Bat]

Simple rules of thumb...

When observing do you have an after glow effect where a bright disc is still observed for longer than a minute?

Did you feel discomfort or slight pain in the eye when observing ?

If so slight damage has occured (Your body knows how to look after you just as you blink when seeing a bright flash) - not enough that you would notice - but keep doing so and yes over time you will damage your eyes...not that you're going to go blind from looking at a bright moon.

There I have said it - Looking at the full moon can damage your eyes...Use a £10 filter because just the fact of straining your eyes is enough to tell you something isn't right..

[brianb]

When observing do you have an after glow effect where a bright disc is still observed for longer than a minute?

Give it half an hour and the rhodopsin which sensitises the retina will replenish itself (unless you have a serious vitamin A deficiency). That's not damage, it's simply the eye adjusting itself to brighter light levels. The brightness of the lunar surface is just the same as fairly dark rock in sunlight on Earth, and your eyes can cope with that for many years without damage - they evolved in an environment deficient in RayBans.

[Ogri]

Well, I'd exercise caution. My eyes are a mess, admittedly (acute glaucoma in both, and a laser eye op that went badly wrong which welded the internals up while the pupil was dilated for the operation - so neither can shut down any more).

I set up dads Christmas present before Christmas Eve, a Heritage 130p, with a Meade moon filter.

And got arc-eye for my troubles, and took the last high strength painkiller yesterday (still slight discomfort but not enough to warrant the painkillers).

That says the light strength is indeed there to do damage. Thankfully normal pupils do respond quickly, but even so, damage can indeed become apparent even if it takes decades to cause issues.

There's a lot to be said for wearing anti-UV, anti-glare glasses, from a young age, to protect those valuable assets for the long term.

It took nearly 10 years after the operation for me to work out the coatings with my optician (plus have good enough coatings start to become available), to be able to even go outside unless it was heavily overcast (I got to love the rain, because rain meant no pain).

Flourescent lights are extremely dodgy too.

I am hoping that a long chat in the next couple of months with my Optician, might allow me to get some suitable coatings put onto blank filters, so I can partake in the hobby.

I'm also beginning to think in terms of something like a Meade ETX 60/80 as maybe not having over the top light gathering, and maybe it working ok with custom filters (plus avoiding anything in the direction of the moon, like the plague). It'll be a right pita to spend money and not have it usuable though.

Take care, your eyes are worth looking after.

[Budding Star Gazer]

WHS.

The Moon is no brighter than a landscape in full sunlight. In fact it's darker 'coz most of the Moon is as black as coal ... even bright sunlight off snow won't permanently damage your eyes, though you may get a very painful affliction called "snow blindness" which can render you essentially sightless for a day or two.

But using a Moon filter is sensible if you want to preserve your night vision. The best colour for this purpose is deep red (Wratten 29) though many people prefer a neutral density (grey) or green filter for viewing the Moon.

Snow Blindness can cause lasting effects depending on exposure time there have been cases over the years of people left with life long damage

[TheThing]

Isn't snow blindness a lack of vitamin D or some such, rather than an effect of reflected sunlight?

[brianb]

Isn't snow blindness a lack of vitamin D or some such, rather than an effect of reflected sunlight?

No, it's reflected sunlight off snow or ice - many mountaineers & almost all polar explorers have direct experience.

Deficiency of vitamin A does cause a loss of dark adaptation (and other vision problems as well in the long term) but unless you're anorexic you will almost certainly be getting enough vitamin A and/or beta carotene (which the body can turn into vitamin A) in your diet.

[Jim M]

Give it half an hour and the rhodopsin which sensitises the retina will replenish itself (unless you have a serious vitamin A deficiency). That's not damage, it's simply the eye adjusting itself to brighter light levels. The brightness of the lunar surface is just the same as fairly dark rock in sunlight on Earth, and your eyes can cope with that for many years without damage - they evolved in an environment deficient in RayBans.

When observing a full Moon (127mm Mak 25mm ep) I get a short sharp pain in the eyeball someplace. I would dread to think how bright and painful it could get when looking through something much larger.

On a side issue for anyone else reading this snow blindness is primarily concerned with reflected UV rather than visible light.