The three things that matter in photography of edges

[Cyrano]

Light, light, and light.

Top lighting only:



Top lighting + back lighting: 



Top lighting + back lighting + side lighting:



I believe this image shows the result of stropping at too high an angle.

[grepper]

Mr. Cyrano, what microscope did you use for those images?

I completely agree Lighting is everything.  Here's one with top lighting only.  Lots of reflection, detail is lost and the edge is not illuminated well to show detail.

   

Here's one with a great burr using a little top lighting and more side lighting. 

   


Bottom light without top or side lighting just shows a silhouette of the blade.  Sometimes getting the light right can be a bit tricky to avoid reflection from the grind of the bevel.  I just use a USB microscope and have found that it requires requires a bit of trial/error to get the light just right.  But getting it right makes all the difference.

[Cyrano]

These images were created using a Dino-Lite AM7915MZT.

[Jan]

Mr. Cyrano, Mr. Grepper I fully agree with you that lighting is everything. Much better results are achievable when you replace the photons by electrons.

I like the scale in your images, Mr. Cyrano. It is important to know the absolute dimensions of the imaged edge features/defects.

Jan

[Cyrano]

... Much better results are achievable when you replace the photons by electrons.

Are you lucky enough to have an SEM at hand? 

I, alas, do not. If I were more industrious, I could bring samples to a local university lab. That would offer some value, but trial-and-error learning would be expensive and slow.

[Jan]

I'm roughly in the same situation as you.

Jan

[Cyrano]

Then you, sir, are demonstrably more industrious than me.

[grepper]

I had looked at Dino-Lite a few years ago and thought they were overpriced for what you got.  FWIW, I still think they are.

However, that said, I checked out their current models and it looks like they have come a long way and now have features not found in any other USB microscopes that I am aware of.

The coolest and most impressive is automatic focus stacking.  That is a huge boon for microscopy.  Dino-Lite calls it Extended Depth of Field (EDOF).  It’s a common technique in photography, especially in macro photography, usually done in post with software such as: https://www.heliconsoft.com/heliconsoft-...con-focus/ However, this manual process is more time consuming than having it automated in the camera.

Especially in microscopy, depth of field (DoF) is extremely narrow.  When the edge of a blade is in focus, even a tiny distance up the bevel is blurry and out of focus because the DoF is so narrow.  Focus stacking works by taking a shot focused on the edge of the blade, then another shot focused a little way up the bevel, then a little further up the bevel, etc.  Then all of the images are stacked together effectively producing an extended depth of field so that the entire object is in focus a lot like using a smaller diameter aperture.  Apparently Dino-Lite has automated this process and produces a single, focus-stacked image.  Very cool indeed.

This means that the Dino-Lite models with EDOF also have auto focus.  This is commonly found in just about all digital cameras, but not so in USB microscopes.  It’s a huge advantage because manually focusing the little scopes can be a hair pulling freak show.  Auto focus is great when using the scope for inspection, especially when sliding the specimen under a fixed position mounted scope.  

I noticed that for a hundred bucks of so more than the Dino-Lite AM7915MZT, they now have USB 3.0.  About time, USB microscopy guys!  USB 3.0 has been around for a long time, but very few USB scopes offer it.  If the hardware in the scope can keep up with the interface, it would end the hideous lag in the image display as the specimen is moved under the scope.  

Currently I don’t think Dino-Lite has any competition as far as features go, and can therefore get the $1300.00+ asking price.  The focus stacking feature alone might make it worth it.  

My only problem with Dino-Lite is still their asking price.  For instance, for only $200 more there is this:
http://www.amscope.com/microscopes/40x-1...amera.html

It has a 14mp camera compared to the Dino-Lite 5mp.  True objective lenses, 1600X optical compared to the Dino-Lite 220X, focus stitching software, x/y stage, filter holder and all the stuff that professional metallurgical microscopes provide.   That’s a lot more scope for then money than a Dino-Lite, but the Dino-Lite has some advantages that reasonably priced metallurgical scopes do not.

Does it have auto focus?  No.  Automatic focus stacking producing a finished image automatically?  No.  It only as a 40mm working distance while with a hand held scope like the Dino-Lite it can be placed on any object regardless of size.

I hate getting excited about microscopes.  Every time I start checking them out I want to get a hole saw, drill a large hole in the side of my wallet and hook it up the dust collector hose.

Those are great images, Mr. Cyrano.  I’m jealous.  

[Cyrano]

Grepper,

In evaluating the value of Dino-Lite vs. other USB microscopes, I also consider these factors:

* The quality of the optics. I have not done any direct comparisons between my Dino-Lite and other high-end USB 'scopes, but my Dino-Lite is in another league entirely when compared to inexpensive USB 'scopes in terms of image quality.

* The quality of the service and support. From personal experience compassing many interactions over the past 2.5 years, I can vouch for the excellence of support from both the USA distributor and from the manufacturer in Taiwan. Hardware issues have been resolved immediately via expedited replacements. Software issues have been resolved typically within a couple of days (!!!) via downloadable updates. 

In evaluating the value of Dino-Lite vs. conventional 'scopes with digital cameras (like the AmScope you reference,) I also consider these factors:

* Size: The Dino-Lite 'scope is tiny, and fits easily in a corner of my office desk. A full-sized optical microscope would require its own workbench. 

* Flexibility of sample positioning --> flexibility of lighting: Where a conventional 'scope requires the sample to be on its stage, the Dino-Lite easily accommodates having a sample held 200 mm above the desktop, in any spatial orientation, with nothing else nearby. This allows nearly unlimited control over lighting. 

Regarding focus stacking: 

I've found Dino-Lite's embedded EDOF algorithm is good, and usually yields results comparable to stacking in Photoshop. 

I use Photoshop when making images requiring extremely large DoF beyond the range of automatic EDOF. 

Single exposure:



Focus stacked in Photoshop: 



Regarding focusing: 

My Dino-Lite not only offers autofocus; it also offers manual focus via keyboard/mouse control over its internal focusing mechanism. This allows precise manual control of focus without touching the 'scope. This feature works brilliantly, and I use it exclusively for most of my work. I use mechanical focus only for high-precision linear measurements, as the internal focus mechanism introduces a small uncontrolled variation in magnification.

[Larrin]

The AmScope you linked to doesn’t say but I believe the 100x objective is oil: https://www.amazon.com/AmScope-ME300TZA-...B00GGY10IK

Typically light microscopes don’t go over 1000x without oil which may mean th max useable magnification is much lower than advertised