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. Cataracts (1 Viewer)

Binastro

Well-known member
. There is a very interesting article in the Sky and Telescope magazine for September 2014. Page 34.

It is of great relevance for astronomers but also may be for other users of binoculars.
It describes the diffraction spikes that occur after normal cataract surgery, which most people seem not to understand or just ignore.
But apparently, if you understand the problems and have a good young eye surgeon who is familiar with the latest techniques, these diffraction spikes can be more or less eliminated.

It is perhaps not suitable for the squeamish, but the outcome was very good.
 
I don't have cataracts, but my astigmatism can be pretty stout. Without my glasses, a crescent moon will have about 6 points with the body of the image scattered all over.

Bill
 
Thanks for posting. I've been lurking here over several years, as well as making the occasional contribution or query. I've marvelled at the detailed knowledge and awareness posters here have about binoculars - to the extent that I've started wondering why I don't see some of the effects described.

I'm now 76, suffer astigmatism and have worn bifocals since my 40s. I wear my bifocals when using binoculars, and eye relief is very definitely a factor for me. At my last visit to the opticians I asked whether I had cataracts. To my surprise, he pulled up equipment (slit-lamp) which he'd never used on me before, and found evidence of cataracts forming, but still at a level which didn't benefit from surgery. I certainly wouldn't want to end up with diffraction spikes, as I still do a small amount of star gazing.

My current binoculars include Nikon 10x42 Monarch DCF, Opticron HR WP 10x42, and Bushnell Elite ED Prime 8x42 - bought in that order. All are in pristine condition. Of these, I find the Bushnell Elite ED Prime the best, and easiest to use. The Opticron HR WP are better for me when I use them on a tripod, but their field of view is noticeably narrower than I like. At a quick glance, all of them seem sharp enough over a reasonable area.
 
I only see them in my left eye, and only with a very bright, small source, at night ... something like a street light at a quarter of a mile or so.

They really don't bother me.

They just are.
 
The 10X42 SE had no spikes whatsoever on bright light sources, my Minox Porro however is fraught with them. If the glass is immune to them, then I guess my eyes are also.
 
bh46118,

What are the specifications of the Minox Porro?

Are the light sources point objects or slightly extended?

I don't know the reason for your findings, but I always thought that everyone except for children saw some spikes with bright point sources.

It could be that a point source is expanded into a sizeable disc with some binoculars eliminating spikes?

Some modern binocular optical elements are nowadays apparently not ground but rather pressed? into shape and the surfaces are not truly smooth.

P.S.

If your eyes don't focus exactly and you see the T.V. green or red ready light expanded, is it perfectly round in each eye with no nodules.
If you are an artist could you sketch the out of focus discs if you see them.
I am not an artist, but have many eye imperfections with the expanded discs.
I cannot remember if I saw no spikes when young.
 
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Prism intrusion into the optical pathway is the culprit according to what I've read on Cloudy Nights and AllBinos. I'll post some links soon. I do see spikes with the naked eye, but the SE eliminates them. That's probably one of the reasons why they are so prized for Astronomy.

bh46118,

What are the specifications of the Minox Porro?

Are the light sources point objects or slightly extended?

I don't know the reason for your findings, but I always thought that everyone except for children saw some spikes with bright point sources.

It could be that a point source is expanded into a sizeable disc with some binoculars eliminating spikes?

Some modern binocular optical elements are nowadays apparently not ground but rather pressed? into shape and the surfaces are not truly smooth.

P.S.

If your eyes don't focus exactly and you see the T.V. green or red ready light expanded, is it perfectly round in each eye with no nodules.
If you are an artist could you sketch the out of focus discs if you see them.
I am not an artist, but have many eye imperfections with the expanded discs.
I cannot remember if I saw no spikes when young.
 
In post 2 of this thread http://www.cloudynights.com/topic/304296-minox-bd-10x44-bp-vs-nikon-10x50-action-ex/?hl=%2Bbd10x44bp#entry3887837 the poster describes what I see through mine. To my eyes they are near "Alpha' in some ways for daytime viewing, but I don't think they quite cut it for astronomical use.


Prism intrusion into the optical pathway is the culprit according to what I've read on Cloudy Nights and AllBinos. I'll post some links soon. I do see spikes with the naked eye, but the SE eliminates them. That's probably one of the reasons why they are so prized for Astronomy.
 
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