Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

Glasses whilst observing

steve_bham

Recommended Posts

Stephen

Stephen

Posted
Posted

I wear my glasses as it's a better experience for me. Adjusting the focuser doesn't work for everyone.

It's going to depend on your glasses design, but I could work with an eye relief of 16mm min. Anything less and it wasn't a fun experience for me.

Link to comment
Share on other sites
NGC 1502

NGC 1502

Posted
Posted

I have mild astigmatism, it is apparent with large exit pupils 5mm plus. With exit pupils of around 3.5 to 4mm or smaller it is not seen, stars look sharper than at very low power.

I do like 20mm eyerelief even if I'm not using glasses. My high power eyepieces have 10mm eyerelief, but with small exit pupils of 2mm or less, many folk that need to use glasses at lower powers are ok at high power without specs.

Exit pupil is easy to work out, divide your scopes aperture by the magnification in use, example :-

250 mm scope at 100 x - 250/100 = 2.5 mm exit pupil.

Regards, Ed.

Link to comment
Share on other sites
umadog

umadog

Posted
Posted

Ed's right. Experiment with the exit pupil. The other equation for exit pupil is eyepiece focal length divided by telescope focal ratio. So if you stop down the telescope you're increasing the focal ratio and so decreasing the exit pupil diameter. For that reason the image gets dimmer but the magnification stays the same. In this way, you can find the point at which your astigmatism is no longer a problem. Probably by about 2 or 3 mm you will no longer notice it. At 1 mm it should have vanished. So for planetary viewing you are hopefully good without glasses and shouldn't have an eye relief concern. At lower powers you may have trouble.

Another option is Televue's Dioptrix correctors for astigmatism. Probably they're not cheap but they are adjustable. If your astigmatism is worse than about 1.5 diopters then you may benefit from them. I've heard from a friend who uses them that they work very well.

Link to comment
Share on other sites
Carbon Brush

Carbon Brush

Posted
Posted

Excellent advice from the above.

There is a completely different approach that you might like to try.

Contact lenses. These will correct for astigmatism.

There are several benefits (for me anyway).

I don't have to worry about eye relief, thus widening eyepiece choice.

I can get right up to an eyecup to shield from stray light

I don't get spec lenses misting from breath bouncing back off scope parts.

If I have to go into the house, again no misting, and I can wear sunglasses.

OK sunglasses on a winters night looks no dafter than our 'keep warm' gear!

If you decide to try lenses, discuss the choice with the optician. Some lenses have a limited choice of astig correction angles, where others have a wide choice. If you have never used them, they can take a bit of getting used to. But we are getting into another discussion here.

David.

Link to comment
Share on other sites
RikM

RikM

Posted
Posted

I used to wear contacts and it was quite a nice observing experience but I only use binos at that time. Long story short I had to stop wearing contacts and switch back to glasses for health reasons and I find it nice to observe with them than without. I use 20mm eye relief EP's but a bit less would be fine I am sure. I don't know where the limit is for me but 15mm eyerelief is too tight to see the whole field on an ultrawide. e.g. a 16mm plossl is perfectly fine but a 24mm Panoptic is right on the limit, an 82° 8.8mm I can only see the centre of the field.

Eyepieces seem to be a very personal choice so the best bet would be to try before you buy.

Link to comment
Share on other sites
steve_bham

steve_bham

Posted
  • Author
Posted
Excellent advice from the above.

There is a completely different approach that you might like to try.

Contact lenses. These will correct for astigmatism.

There are several benefits (for me anyway).

I don't have to worry about eye relief, thus widening eyepiece choice.

I can get right up to an eyecup to shield from stray light

I don't get spec lenses misting from breath bouncing back off scope parts.

If I have to go into the house, again no misting, and I can wear sunglasses.

OK sunglasses on a winters night looks no dafter than our 'keep warm' gear!

If you decide to try lenses, discuss the choice with the optician. Some lenses have a limited choice of astig correction angles, where others have a wide choice. If you have never used them, they can take a bit of getting used to. But we are getting into another discussion here.

David.

Ive tried various contacts to correct the astigmatism but just didn't get on with them.

Although the lens are weighted it can take a second for them to adjust and that gave me cracking headaches!

I'm going to buy one HR eyepiece to test if I can get on with the 16 mm eye relief.

Link to comment
Share on other sites
lifeonmars

lifeonmars

Posted
Posted

I am quite new to astronomy but blindly(pardon the pun) observed with my glasses on. when i took my glasses off for the first time and re focuussed to compensate I was staggered how much better the view was.

I too suffer from astigmatism in one eye I haven`t really thought about it or noticed any visible difference ,next time i am out I will see what difference I achieve by switching eyes at the eyepiece.

Link to comment
Share on other sites
pallas15

pallas15

Posted
Posted

I find that i can see better at the scope without my glasses.No reflections or light issues at the eyepiece.I also see more objects in the sky without specs once become accustomed to the dark..when i replace my specs i lose a lot of the fainter stars.

Link to comment
Share on other sites
Stargazer33

Stargazer33

Posted
Posted

I have very slight astigmatism and I find it much more comfortable to view without my glasses. As mentioned above I get a much greater FOV when I can put my eye right up to the eyecup, there is very little stray light and I feel much more as though I am in the image rather than outside of it. Sorry about that, getting a bit philosophical there!

The only time I find it a problem is if I am setting the view up for someone else to look at the image.

Link to comment
Share on other sites
ely_ellis

ely_ellis

Posted
Posted

I am quite short sited with astigmatism and have to wear glasses all the time.

At the moment when I observe I do both ways, I try with glasses on and again with glasses off. There doesn't appear to be much difference but unfortunately I can never reach a pin sharp image.

I have seriously considered laser eye surgery as I have read some reports from amateur astronomers that it opens up a whole new universe. It is costly, but it could solve a lot of problems.

My main problem is that if I have been looking close up without glasses, even when I put them back on my eyes take hours (not minutes) to be able to re-focus again. I assume this is due to my age and hardening of the lenses of my eyes.

Of course if I want to do imaging, then a whole new problem comes into play as I have to look through the camera viewfinder with my glasses on otherwise if I focus without glasses, then the captured image would NOT be in focus.

Try crouching down on your knees, with your neck bent double trying to look through a camera viewfinder without any eye relief!

Unfortunately there is no definite answer to the original question, you just need to try the different ways of doing things. Even a slightly out of focus, miss shaped cluster of stars looks fantastic.

Martin

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.