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Question about wearing glasses and viewing through a scope..


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Quick question.

If you wear glasses, do you need to keep them on when viewing through a telescope?

My thoughts are that you don't, and you just adjust the focus to compensate for your short or long sight. Thus you focus until the image is sharp like someone with perfect sight would, and you see the image just aswell as someone with perfect sight does. Then if someone else wants to view through the telescope they will have to readjust the focus for their eyesight.

Is that how it works?

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Yes mate, pretty much.

Some eyepieces do give enough eye relief so that you can keep them on if you wish - sometimes that's easier if your referring to a chart or sketching or something similar.

Cheers

Ant

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If you have astigmatism you need to keep your glasses on. I bought EPs with long eye relief so I could observe with glasses (and share the view easily with others) but find it much easier to just observe without glasses. I find even people with 20-20 vision adjust the focus amongst themselves so my idea of easy sharing of views without refocussing was naive I guess.

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I echo the previous comments on astigmatism.

A further complication arises if you are 'mature' enough to make use of varifocal lenses. The alignment to the eyepiece is critical. Varifocals exhibit a lot of errors off axis. This is why you have to 'learn' to use them.

I generally use contact lenses with any optical kit. There are no astigmatism problems, and no varifocal alignment problems.

A further comment is knocking lens coatings on metal eyepiece parts. Or getting rubber eyeguard 'prints' on your lenses.

Edited by DavidValentine
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Not from personal experience, but from something I read: If you are short sighted (nearsighted) or have astigmatism, you should view while wearing glasses. Otherwise, view without your glasses.

Now if I could just remember where I read that so I could attribute the source correctly.

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I prefer to observe without them, I have them on a cord around my neck and just drop them off when I'm at the eyepiece and I always know where they are.

I had experimented with contact lenses, but my problem is short sightedness and I found that I couldn't read anything close up, everything had to be at arm's length, and this was useless when I was sketching.

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I prefer to observe without them, I have them on a cord around my neck and just drop them off when I'm at the eyepiece and I always know where they are.

I had experimented with contact lenses, but my problem is short sightedness and I found that I couldn't read anything close up, everything had to be at arm's length, and this was useless when I was sketching.

I tried some longer arms then went back to specs and "granny" strap

Couple of things to watch out for getting the specs tangled around the eyepiece and also breathing on them

Steve

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I wear glasses as I have mostly astigmatism and have been told that I now need varifocals. As I believe it varifocals are three

differrent ranges of focus in one lens. Will this not cause problems when trying to look through an eyepiece i.e. unless my view is fixed through the eyepiece will it not go in and out of focus with the slightest movement of my glasses against the eyepiece ? Hope that makes sense.

Vlebo

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I'm short sighted and view with my glasses on, but thats only because if I take them off i cant see anything. When I tried to view without glasses it was fine the focus worked just as well as when I was wearing them.

but I've found it is much better just to keep them on so when I look somewhere else I do not need to put them on again.

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If, like me, you require correction for a combination of astigmatism and short sight, and you suffer presbyopia. That is require reading glasess, or a different prescription for reading, then contact lesnes are worth looking at for scope use.

Without specs or contacts, you will never correct the astigmatism. unless you happen to have a scope with the opposite of your eye defect!

If you suffer long or short sight only, then you can just adjust the scope focus to suit.

A varifocal lens is full of compromises. Particularly if it includes astigmatic correction or if it made small to go into a particular design frame. A really good illustration is if you can get hold of a 'standard' lens to correct your distance vison, and a varifocal lens. Go outside and look at distant detailed objects. Look straight ahead and you hopefully see a clear view. Now move your eyes, not your head, to view objects that are off the centre of the lens. Is the view as good? Make objective measurements because your brain will fill in the gaps and fool you. For example, can you actually read that car number off axis? In general you will see a bit of degradation with a fixed lens. But a varifocal will give you all sorts of distortions and errors. This is why the opticians tell you that you have to get used to varifocal lesnes. or putting it another way. You learn to move your head for left/right viewing and your eyeballs up/down for near/far viewing.

A conact lens will give you correction for distance and astigmatism. Scope focus setting will be similar to those who do not need correction. Reading glasses from Poundland are quite adequate for reading eyepieces, charts, computer screens, etc.

Your good distance correction means you can look at the sky to work out what is going on. Use a red dot finder without problem, etc.

If you pop back into the house, you don't have the problem of condensation on cold specs lenses.

I have tried specs, contactrs and nothing. to me contacts & reading specs are definitely the solution for any optical instrument use.

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I tried contacts a year or so ago and could not get on with them as they kept moving around on my eyeball. I was told this was due to my astigmatism. If things have changed since then and there are specific contacts for astigmatism then I would certainly be glad to give them a go and just have reading glasses for when they are needed.

Vlebo

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Hi Vlebo.

Just though a thought on contact lenses. A particular high street optician will offer you a particular choice of lenses, but not all lens types. So he will not not necessarily be able to offer you the best lens for your eye. The range of lenses will have been chosen on a commercial basis to suit most people for msot of the time and give a profit.

It is worth calling back and asking again about anything different that may be on offer. Also try a different optician. Usually one or more of the high street names are offering free trials so you have nothing to lose.

I have found (over 50 years of visits) that the quality of service and choice vary hugely between opticians. This often has little to do with the bottom line price.

You thought understanding scope optics was tough. Corrective lens choice is a minefield!

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I am short sighted with astigatism and observe without glasses. They hang round my neck on a chord during observing sessions and only go on in order to look at the sky.

I find it very useful to have a focusable finder: my first scope had a fixed-focus finder and I had to put on my glasses to look through the finder. Now I have a finder adjusted to suit my eyes, so once I've locked on to the star I want, I can take off my glasses and do the rest without them. If the star is bright enough so that I can see it as a blur then I set the finder on it without using my specs at all.

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Hi Vlebo.

Just though a thought on contact lenses. A particular high street optician will offer you a particular choice of lenses, but not all lens types. So he will not not necessarily be able to offer you the best lens for your eye. The range of lenses will have been chosen on a commercial basis to suit most people for msot of the time and give a profit.

It is worth calling back and asking again about anything different that may be on offer. Also try a different optician. Usually one or more of the high street names are offering free trials so you have nothing to lose.

I have found (over 50 years of visits) that the quality of service and choice vary hugely between opticians. This often has little to do with the bottom line price.

You thought understanding scope optics was tough. Corrective lens choice is a minefield!

I think it is time to start paying a visit to some opticians and also give some privately owned ones a check as they may be more helpful.

Thanks

Vlebo

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