USB microscopes for very small SMT

I meant to ask if anyone here has had laser eye correction, what effect that has on close-up work. I am short-sighted ATM.

I've worked in the area, almost ALL the MDs wore spectacles. There are pros & cons, they obviously felt the risks were > the benefits.

I take it you're VERY near-sighted?

You're not quite of retirement age, I don't think?

When you reach that age, have cataract lens replacement, on the gov's dime... although you should check, your insurance might cover it.

...Jim Thompson

Ah, there's the rub...

You see, Pam DID have a cataract surgery, from a 'reputable' doctor. It was just before she lost about 40% of her remaining sight... :-(

Charlie

"Reputable" doctors give me a plain, literally.

I'm allergic to acetaminophen (Tylenol, and noted in BOLD on my chart), so the hospital staff gave me Percocet after my hip replacement :-(

Now a "reputable" doctor says I have an inflamed prostate... I say I have a hernia, but am being ignored. I'm going to take my business elsewhere... it's really fun to tell them to their face that you think they're incompetent ;-)

...Jim Thompson

So much for spell checkers ^^^^^--- should be "pain"

...Jim Thompson

I'll bet that it weird out doctors to be treated like replaceable parts. Then a doctor that won't listen to patients is a fool, ones that listen too carelessly will get replaced as well.

Nope, a doctor who regularly spends more than x minutes per patient will get replaced :-(

Laser eye correction? It adjusts your focal length. Permanently.

If you're young and still accommodate (can vary your focal length by contracting your eye's ciliary muscle, warping its crystalline lens), you'll still have a range of distances that will be in focus.

Once you get a bit older everyone loses that variable-focus ability, and your eyes' focus will be set to one distance. That fixed-focus is called 'presbyopia.' Starts setting in about 40 years, and is usually solidly fixed by 55 or so.

So, if you're presbyopic and you get laser'd for 'distance' vision--e.g. focused at infinity--near objects will be blurry. You'll need reading glasses / magnifiers.

If you're young and can still accommodate 4 or 5 or 10 diopters, you'll have some years before ... you'll need reading glasses to see up close.

Or you can get laser'd and ask to stay nearsighted.

Or wait for the almost inevitable cataract surgery, and ask for a replacement lens that makes you ... whatever you want.

I think the ideal focal distance = reading distance, say 40-50cm or so. That's -2.5 to -2.0 diopters. That way you can read and see most things even without glasses.

My two eyes are naturally both nearsighted, but one more than the other. That's called 'monovision'. I can choose the best for the task, which I find handy. It's also an option of surgery, to get one eye set to 'far,' and the other to 'near,' but many people hate it and simply, biologically, cannot ever adapt. YMMV.

HTH, James Arthur

I'm 44, but have been nearsighted since 10 or so ("3.5"?). Also quite astigmatic. So when I am working with small parts I often look over the tops of my glasses so I can use my natural very short focus.

I guess I could also get prescription glasses optimised for very short focus too - but then they might be useless for anything further away than the end of my arm!

Now that sounds like a good engineering solution! Should be similar to me leaving a contact lens out, so could I try it for a while :)

Yes, thanks.

IMO for doing surface mount work, anything over 5x magnification is overkill. So my question would be what the *minimum* magnification would be. Additionally, at lower magnifications how much of the work area would be displayed?

Just got mine... quite good, but the further away the target is, the harder is is to focus. Quite a bit of backlash on the focus ring too. Tricky at

Getting laser'd for 'far' vision would be exactly like not ever being able to look over your glasses.

If that "3.5" means -3.5 diopters, you'd be able to focus clearly up to about 30cm. That's not very short-sighted, that's considered mild. -10 diopters (10cm) is considered 'high' myopia.

Exactly true. 'Reading' glasses, though, are cheap, and an assortment of them is the usual solution to this problem.

Far-sighted people are focusd beyond infinity. In old age they can't see anything clearly--not even in the same room-- without some sort of glasses. And, the closer they bring something, the blurrier it gets.

I prefer nearsightedness. At least that way I'll always be able to clearly see the things that are right in front of me. And walk up to something to see it better, if need be. And I can read.

But, if I hunted for a living I might choose differently.

Cheers, James Arthur

I was sort of hoping that as I aged I would tend to get more "farsighted", so there would be some point when my vision was perfect! Even if only for a few months :)

But it would seem I will just lose the ability to change focus, so will be permanently focussed on a point somewhere not far from the end of my nose. Oh Well..., better that, than focussed at a point past infinity as you say below.

Thanks for the explanation.

Minimum magnification is 20 but if, as someone in a German NG wrote, it works at 5" or more away it might just work. Thing is, there is almost nothing available from the mfg and they did not respond to email. Usually that is a no-no for me but it seems it's about the only such product out there in a reasonable price range (where you don't mind if it gets busted or "lost").

Supposedly it can focus at infinity which would (theoretically) mean I can place it even farther away. If the LEDs aren't strong enough I'll just use a separate strong halogen light.

Hey, someone's got it, great! If it really can focus at 150mm and lowest zoom that'll be fine. Even if tricky and with rickety focus wheel, I'd just leave it there pretty much forever. Couple of questions:

Can you easily see 0402 or smaller parts at 150mm, good enough to guide a solder iron?

Where did you order it?

Maybe one can hack it and kludge a better lens onto it. Tried that with a web cam but that didn't work, the cheapo CMOS sensor in there just did not cut it.

Here's a nice one, but I somehow doubt it fits your budget (especially since they don't advertise the actual price-- the VHX-600 is probably well into 5 figures):

Best regards, Spehro Pefhany

That would be way above budget plus those often aren't suited for larger working distances. I can't get a 16" by 16" circuit board under it but I have to ;-)

In article , snipped-for-privacy@interlogDOTyou.knowwhat says...>

You're supposed to screw *IN* the light bulb.