Eyeglasses

I have a couple of apos and some very nice eyepieces, but the weak link in my optical train is my spectacles. In everyday use it is natural for them to become scratched, marred, or otherwise flawed. I have been toying with the idea of buying a special pair of glasses which I will keep aside until I go out observing. This pair will receive special care and handling, and will be kept as clean and unmarked as my scopes. Does anyone else go to these lengths, or is this a common practice for those of us who are hopelessly myopic?

Walter

If it makes you feel better, I got contacts just for observing... I love that spacewalk feel and you really can't get it with glasses on.

Cheers,Eric

I find that eyepieces were a leading destroyer of my eyeglasses. My current glasses are the most destruction resistant I've ever had. They have a "quartz" coating which is anti-scratch, but they have no anti reflection coatings.

The "quartz" coating has done wonders to prevent scratching. I do see reflections in the lenses at times of planets, but not usually bothersome. The scatter has been very low compared to what I had been used to since they are so much less scratched.

I'm old enough to need bifocals and also have some astigmatism in one eye. Is it a problem? Yes, a little. But not one that has bothered me enough to attempt specific solutions. The only thing I have ever done about the issue is to refuse to wear plastic lenses. They scratch.Period. Amen.

At lower powers I use longer eye relief oculars and at higher magnifications with smaller exit pupils I simply take the glasses off. It is nice to have a loop holder to let them dangle around the neck.
Larry

Walter-

I have two pairs of glasses, a rimless pair for work etc. which have terrible achromatic abberation....I highly recommend anything but rimless glasses for observing unless they are made from something other then high density poly-carb. My other pair is a black thick rimmed glass pair with the most expensive coating the manufacturer offers. Although I wear them on some occasions when not observing I mostly purchased them with observing in mind and they work fantastic. I don't wear them on rainy/snowy/dusty days so I rarely take a cleaning cloth too them and this helps preserve their coatings. Glass definitly has better light throughput then any of my past plastic lenses. I found with contacts my astigmatism wasn't corrected well enough even with a touric? lens, not to mention the lens didn't breath enough for my comfort at the eyepiece.
Make sure that if you decide to purchase a second pair with astronomy in mind you get a larger lens to cover your naked eye field. I always hated my last pair which cut off the bottom 20% of my vision.

-Chris

Hi Walter.

I also have a 2nd pair of glasses. My first pair, the one I wear "around" and to work, has trifocals for close, computer, and far vision. The central correction for the computer work *really* gets in the way of observing at the eyepiece. The second pair, which I use only for astronomy, has bifocals for star atlas reading and "distance" correction that I use for observing. This system works quite well for me and, if you find a convenient way to pack your 2nd pair (with your eyepieces, say), it doesn't require much extra effort. The downside, of course, is that it's expensive to get the 2nd pair of glasses.

By the way, I often take the 2nd pair on trips as a spare in case something happens to my primary pair.

I've discussed contacts with my eye doc but haven't gone that route... For what I do all day, I'd have to wear glasses over and above the contacts and it seems pointless to use both kinds of eye gear.

Hope the hymns pick up the spirits. If not, try the other way.

John

Regarding astigmatism; at Low powers where your exit pupil is in the 5-7mm zone you will notice your optical defficiency more then at higher powers/ smaller exit pupils. For example, on a f4.5 scope with my 30mm 84* = exit pupil of 6.6mm I must use my glasses or the field gets bad as you move off center. Yeah that's a fast dob, but the astigmatism in the eye is usually much worse. When I use my 14mm for a 3.1mm exit pupil glasses are an option and I usually reomove them, no point in wasting any light

For more on exit pupils and effects on the eye please read pages 45-48 of the Observers Handbook from the Royal Astronomical Society of Canada.

-Chris

Are you using glass lenses or plastic? I use glass lenses and find that with reasonable care they do not become scratched or other wise flawed for several years....

jon