How close should my eyes be to a stereo microscope? - Page 1
Forum section: electronics / general

author: HobGoblyn
author_rank: Unknown
timestamp: January 29, 2020, 03:25:58 pm
content: Might seem an odd question, but I've spent ages trying to google this and cant find an answer.I have a new Swift S41 microscope. I wear varifocal glasses.I've only tried out my microscope a couple of times, each time I removed my glasses, and almost had my eyeballs touching the rubber eyepiece.Watching various TV dramas with actors playing forensic scientists, I noticed they always have their eyes about 2.5cm - 5cm (1" - 2") away when looking through. OK they are actors and not really looking at anything, but it got me thinking.Watching a few youtube channels, I notice that most also don't put their faces right up to it, however some do.So I tried to google various things like "how to use a microscope" and virtually all of them were telling me about preparing to correctly view slides etc in something like a biology lab. I can find no definite answer as to what the correct way is.Or is it one of those things that's simply down to personal preference?Thanks

author: retrolefty
author_rank: Super Contributor
timestamp: January 29, 2020, 03:34:40 pm
content: Key search term is 'eye relief distance'.https://en.wikipedia.org/wiki/Eye_relief

author: jfiresto
author_rank: Frequent Contributor
timestamp: January 29, 2020, 04:38:31 pm
content: Quote from: HobGoblyn on January 29, 2020, 03:25:58 pmYour microscope may have copied an old ocular design. By the mid-1980s, the "big four" (Leica/Wild, Nikon, Olympus and Zeiss) had gone to "high eyepoint" oculars that project an image high enough above the ocular that you can wear glasses and still get the full field of view. They are usually marked with an eyeglass symbol and accept rubber eye shield extensions that block light straying into your eyes if you don't wear glasses.

author: mcovington
author_rank: Regular Contributor
timestamp: January 30, 2020, 03:21:16 am
content: What he said. The usual design spec nowadays is 20 mm, eyepiece lens to eyeball. Some older eyepiece designs have much less eye relief, down to 5 mm or even less.You might consider a new pair of eyepieces for your microscope if the ones in it have insufficient eye relief.

author: Berni
author_rank: Super Contributor
timestamp: January 30, 2020, 06:11:27 am
content: Depends on the design a bit, but it often feels like you should be up close even if you shouldn't.You get a wider field of view by pressing your eyes right up against it so it seams like its the right way to use it. But often doing that causes other issues like stereoscopic images not quite lining up properly, harder to focus etc...Also chair height is a critical thing with microscopes. It needs to be high enough that you have to tilt your head forwards a bit to look down. You can still see the image when looking from a too low angle but it won't be as good. Microscopes for PCB work tend to require a tall chair do to the large working distance under it to let you work comfortably, so the entire microscope body ends up rather high up.

author: mcovington
author_rank: Regular Contributor
timestamp: February 14, 2020, 03:16:12 am
content: With all the eyepieces I've seen on microscopes and telescopes, except for a few super-cheap ones, you *don't* get a wider field of view by pressing your eye closer. You may actually get a narrower field of view. There is a correct eye position, typically 20 mm behind a good microscope eyepiece, maybe 10 mm behind a cheap one.I am very familiar with telescope eyepieces (I write books on amateur astronomy). Somewhat less familiar with microscope eyepieces, but all the ones I have seen are similar.