Monday, 6 August 2018

Using Eyeglasses with Telescopes - one solution

Well, age has caught up with me.  I started to wear eyeglasses over the last couple of years as I’ve started to struggle with close up focusing.  This was fine with reading, but now I’m needing to use glasses with my sketching.  This has created a problem when I go to and fro between sketch pad and eyepiece and now needing to lift and replace the glasses from my nose.  This is a problem not just for those who sketch, but also for those people who make observing notes, and for microscope users too.

Lifting, holding and replacing traditional eyeglasses constantly is a fool’s game.  There had to be an easier way to make the switch.

I started looking into headband magnifiers.  Many of these come with an assortment of different lenses that provide different degrees of magnification.  I purchased a set that appeared to be light weight and as an added bonus has a pair of white LED lights built in.

My initial testing at home was most promising.  This headband set has a double articulating joint which allows or the lens to be lifted and for the whole LED assembly to be lifted too, and as the lens is attached to this element, the lens is able to clear the eyepiece safely.

The ultimate proof is using the headset at the scope while doing a sketch.  I used the headset on two occasions with the supplied lenses, once with a lunar sketch and the other with a DSO session.  As it turns out, the concept is good, but the supplied lenses are not.  The lenses are designed for close up work, and these lenses are not suitable for my purposes that has the sketch pad at a longer distance than these lenses work at.

Another problem with these lenses comes from the way they are made.  As the individual lenses are attached to each other with no spacing, the field of view when using these lenses is very narrow, and ultimately impractical.

My eyeglass script is mild, and at a pinch the ready-made glasses available at pharmacies  work well for me.  So, the thought occurred to me to swap the lenses that came with the headband for one of these inexpensive pharmacy eyeglasses.  If the experiment works, I can look at making a new set of lenses of my script.  By making use of these eyeglasses, I would also make the field of view much, much larger

So, I chopped up one of the supplied acrylic lenses to use the coupling mechanism it has, and attached it to the eyeglasses also using acrylic.  The arms on the eye glasses I cut off.  If I unscrewed the arms to remove the, it would have left two long tags would become a hindrance and get in the way when moving to and from the eyepiece.

Now for the third field test and proof of concept.  This was a lunar sketch.

The result was successful.  The new lenses are much easier to use, with no noticeable eye strain, and with a much larger field of view.  With this successful test, I can look at having a new eyeglass script made up for me that I can modify to fit this headband.  Of course, not having to use eyeglasses is easier, and I will need to get used to the actions of lifting and lowering the lens, but the gain of clarity of image is well worth whatever hassles using glasses presents.  I’ll post this latest lunar sketch in a separate blog entry.


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