Author Topic: What's the highest magnification you use on a microscope and why?  (Read 351 times)

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Offline badrequest400Topic starter

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Someone on a different forum was asking for soldering microscope advice. I only ever use my 10x lenses since 20x is unnecessary to me and has too limited a field of view. The person on the other forum ignored this advice and went for a model offering up to ~700x magnification! It made me wonder what that's even useful for. What is the highest magnification people here use [for electronics] and specifically what for?

« Last Edit: Yesterday at 07:01:47 pm by badrequest400 »
 

Online jpanhalt

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Re: What's the highest magnification you use on a microscope and why?
« Reply #1 on: Yesterday at 06:00:08 pm »
The resolving power of a light microscope is limited by the wavelength of light used and the optics.  The highest practical resolution of a light microscope used in pathology is about 100X with oil immersion objective, which has a much higher refractive index than air, followed by a 10X eyepiece to give about 1000X magnification.  Many pathologists go no higher than 63X (X10). PS: The shortest wavelength of visible light is about 400 nm = 0.4 micron.  Some bacteria push that limit.  A red blood cell is about 7 micron in diameter.

The magnification can be virtually any claimed number, but that doesn't mean better resolution.  It's like magnifying a bit-mapped image until you are looking at a single pixel.  In my experience, cheap video microscopes (eBay and Amazon) are like pinhole cameras.  They give a lot of distortion and way too much magnification without raising the camera to a height much higher the the tiny stand allows.

I agree with your lower estimate.  With my Nikon dissecting microscope (I prefer light to video), I have 10X eyepieces and usually use 0.9X to 1X for the objective, rarely going above 2X.  The maximum is about 4X.
« Last Edit: Yesterday at 06:04:50 pm by jpanhalt »
 

Offline thm_w

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Re: What's the highest magnification you use on a microscope and why?
« Reply #2 on: Yesterday at 09:01:35 pm »
700x is usually for biology as mentioned above. I don't even know how you'd use that for soldering.
The most for soldering I'd go to is around 30x for really close inspection (zoom range 3-30x). As you say 10x eyepiece is the one to use.

But if we are talking bare dies, Shariar has some good demos of what is possible. I think he was in the 100x range?
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Offline magic

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Re: What's the highest magnification you use on a microscope and why?
« Reply #3 on: Yesterday at 09:11:23 pm »
Is it a purely optical microscope (you look into a tube with glass in it) or some digital gadget with a screen or USB/HDMI output?

The latter may boast crazy magnification numbers which are not necessarily comparable with traditional magnification specs of optical microscopes. OTOH a conventional microscope with 700x mag is too much for wirebonding, let alone soldering :P And you likely won't find a stereoscopic microscopes with such magnification, and working distance will be for all practical purposes zero.

BTW, the magnification of optical microscopes (and magnifying glasses) is defined as approximately how larger the object appears to be compared to viewing it with naked eye from 25cm distance.
« Last Edit: Yesterday at 09:29:50 pm by magic »
 

Offline joeqsmith

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Re: What's the highest magnification you use on a microscope and why?
« Reply #4 on: Yesterday at 09:13:03 pm »
About 2.5x to 50x depending what I am working on.  There have been times I would have liked to go up higher but not 700x.   

Offline twospoons

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Re: What's the highest magnification you use on a microscope and why?
« Reply #5 on: Yesterday at 09:32:03 pm »
I work in the range 10x to 40x, depending on what i'm doing.  I use 20x eyepieces and a 0.5x Barlow over the objective for a longer working distance, makes getting the iron in there much easier.
 

Offline Zero999

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Re: What's the highest magnification you use on a microscope and why?
« Reply #6 on: Yesterday at 09:41:12 pm »
Note this isn't a matter of the magnification factor, but the smallest detail, which is dependant on the wavelength. Illumination with a violet 400nm LED will be able to achieve much greater resolution, than an incandescent lamp or white LED, which has much longer wavelengths.
 

Online watchmaker

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Re: What's the highest magnification you use on a microscope and why?
« Reply #7 on: Yesterday at 11:08:18 pm »
I have used scopes for at least 20 years in watchmaking.  I do general bench work at about 15x with the scope set at 30X and a .5x barlow (15x widefield eyepieces.  For inspection, I have a SZ7 and we use it to 70x.  At the lathe, I may go to 40X.

It is a function of field of view, magnification/resolution image brightness, working distance, and head position (the lower the barlow, the higher the scope needs to be).  Generally anything that sez it yields over 100x for under a couple grand is a toy.

Change mag range with barlow, not eyepieces  For my money, the BL15X ultrawides are the best value for money. Large exit pupil, field of view and bright. Many are used by astronomers.

I am talking optical scopes by the way.
Regards,

Dewey
 

Offline Smokey

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Re: What's the highest magnification you use on a microscope and why?
« Reply #8 on: Yesterday at 11:32:17 pm »
I've always found the best stereo inspection microscopes to be the 0.7 to 5x zoom with 10x eyepieces.  That covers like 90% of the soldering and rework jobs.  The other 10% is picked up with a 0.5 barlow.
 

Online Alex Nikitin

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Dewey knows what magnification I likely to use for soldering and inspection  ;) . I do use however up to x400 (x40 x10) magnification on my metallurgical microscope for checking the gap condition on magnetic heads for tape recorders.

Cheers

Alex
 

Offline CatalinaWOW

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For soldering and similar fabrication I completely agree that modest magnification is sufficient.  Failure diagnosis also can require finding tiny cracks or voids and really has no limit on magnification which is useful, including use of electron microscopes.  And once upon a time, when manual wire bonding still happened magnifications in between those ranges where useful.

 

Online jfiresto

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Yeah, you would need a compound microscope with oil immersion and a minuscule working distance to get 700X – which makes me wonder if the OP's colleague got a video microscope with 700X magnification w.r.t. a large screen.

No one has mentioned the challenge of vibration with a stereo microscope at much lower magnifications upwards of, say, 20X. Mine can only reach 62X and that took a massive stand to make tolerable.

-John
 

Offline magic

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You don't need immersion. Rule of thumb is 1000×NA so you only need 0.7NA. Plenty of dry objectives can do that.

Working distance is only a matter of money, here's 5mm if you want ;)
Horizontal field of view 0.18mm.
 
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Online jfiresto

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Well, you have convinced me that I know nothing about modern compound micro$copes, for which I thank you and I mean that sincerely. I would love to see a drawing of the 50X Mitutoyo's optical train.
-John
 

Online Phil1977

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As others already mentioned, the dream magnification ratios of digital microscopes are usually pure fantasy. Fantasy of the kind if you would connect the video output to a video beamer and shine the image onto the neighbour building then you get this and that magnification...

What I usually look for is
- the size and quality of the imager unit, take something with at least 1/2.3" chip and a low latency HDMI output. 4K is nice to have for digital magnification and taking pics or movies, but 1080p is absolutely sufficient for hands-on-stuff.
- a lens with a optical magnification range from around 0.5 to 5. Cheap lenses do this by changing the focal distance, better ones have a "zoom" allowing magnification without changing the focus.
- Every old 21"- or 24"-computer screen is better than small displays sold with cheap microscopes. If you want to do yourself a favour, buy a new screen for PC work and use the old one at the microscope.

If you check these points I assume you will get a well usable solder microscope. Forget completely about "non-optical" magnification factors.

Or, if you want to spend more money, get a purely optical stereo microscope from a "solid" brand. The price is much higher, but good and crisp stereo magnification with a factor of 5x-20x is a really stunning dive into the 3-dimensional object under observation. Probably not necessary for solder stuff, but anyhow, it´s very fascinating. And long time working with a digital screen is much more convenient than looking through an eyepiece, so a really well equiped lab may have both systems...

Purely optical microscopes with magnifications of 100 or more again an own world, but practically only usable for absolutely flat objects like cross-sections or biological stuff. Even the roughness of a non-soldered PCB board is sometimes to much height difference to be focusable in such a microscope.
 

Online tszaboo

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I only ever go to 45x magnification, my work scope has a 10x fixed lens and a 0.7x-4.5x adjustable lens in series.
You might want to have higher magnification to look at cracked capacitors of 0402 or 0201, not as a daily driver, definitely not for soldering or solder inspection.
 


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