USB Microscope

[Cyrano]

... The lighting intensity and angle, relative to the angle of view from the camera itself, is the most tedious and challenging part of getting a good picture, or at least a picture which clearly shows the details you want to highlight ...

Just so. Getting the right composition is a matter of seconds; getting the right lighting is a matter of many fiddly and often frustrating minutes.

... And depth of field is secondarily a challenge, being extremely shallow at such magnification ...

Have you tried focus stacking? My 'scope does this automatically with good results. I can get even better results by stacking images manually in Photoshop.

Single image, looking down at a knife tip pointing up:

Stacked images:

... The biggest drawback with my particular unit is the coaxial built-in light source. I usually rely on some secondary light source instead, turning the unit's own coaxial lighting down/off, because it's sourced too close to the center axis of the unit as a result of it's narrow design. It's basically like shining a penlight into a mirror, in trying to illuminate the bevels on a freshly-sharpened edge. Some sort of oblique lighting, coming in from the side, usually works much better.

That's my experience exactly.

My 'scope offers some remediation by allowing the coaxial LEDs to be toggled on/off in quadrants. Depending on the magnification in use (which determines working distance and thus determines angle of illumination,) this can offer some degree of directional lighting. I've shown this in my images above.

My 'scope also offers polarization. This can be effective when the surface details of interest have a different texture, or a different spatial orientation, from other areas in the image field.

For oblique lighting, I use a blunt instrument and a scalpel. The blunt instrument is a conventional gooseneck microscope illuminator. The scalpel is DIY: a tiny LED, powered by two AA cells.

 

[TigFur]

I have plenty of flashlights that let me set the brightness to what i need, finding a difuser should be no problém so i will experiment with that.

Wow that fcus stacking Picture is amazing. Sadly photoshoping it might be a too time consuming to use while sharpening. I will look into that as well once i get the scope.

 

[Cyrano]

... finding a difuser should be no problém so i will experiment with that ...

I've found that while almost any translucent material will work, some work much better than others in terms of light uniformity, intensity loss, amount of diffusion, etc.

The best I've used is this material.

 

[Cyrano]

Here's another example of focus stacking combined with if-I-had-hair-on-my-head-I'd-tear-it-out lighting:

This shows an edge I reprofiled on a Worksharp Ken Onion/BGA tool. You can see I formed nearly a mirror edge at the apex, but left a much rougher surface near the shoulder.

 

[Twindog]

^^^

Is that a kind of burr forming along the shoulders?

 

[kreisler]

the red rectangle in the bottom left stating "0.2mm" can't be correct. It would mean that the edge has a width of 0.3mm . Is that the case?
3.0mm is a more realistic edge width.

 

[bucketstove]

the red rectangle in the bottom left stating "0.2mm" can't be correct. It would mean that the edge has a width of 0.3mm . Is that the case?
3.0mm is a more realistic edge width.

Hehe all you have are choppers and scandi knives? No fine edge kitchen knives?

If your edge is 3mm "wide",
at standard safe angle of 15dps,
that means your edge is 1.5mm thick
If you have a crazy 20dps angle, that makes it 2.052mm thick
Correction its a lil bit thicker 15 at 3 is 1.608 and 20 at 3 is 2.184

Thats some prybar scandi nightmare very durable

Or its a 1dollar 1mm kitchen knife you reprofiled to 10dps yourself

Now 20 at .3 is 0.218 mm ( 0.0085826772 inch or 8/1000 inch )
or 15 at .3 is 0.1608mm ( 0.0063307087 inch or 6/1000 inch )
this is a very thin edge, but doesn't tell you anything about the primary grind which could be a scandi but should be flat ground at 2-6dps

 

[kreisler]

Your maths is good, great stuff. With such small measures my geometry calculations become off haha.
I only said 3.0mm to make my point that the actual edge width is probably not 0.3mm, by looking at that photo.

 

[TigFur]

So i have received the andostar microscope a while ago.
I do not like it and i do not recommend it for this purpose.
It is VERY cumbersome to use:
- Focusing on high magnification moves it all over the place
- The lag is horrible - On the smallest resolution it is okay but you cant really see much, on anything else it just takes a while and on the highest resolution it takes like three seconds.
- The first two points work remarkably well together, against the user. You erally cant focus well if your Picture moves AND it takes three seconds to see the results of your adjustment.
- Software wise its kind of okay... Well the fact that you need a computer nearby makes it also cumbersome but that was obvious and expected
- The magnification is not very good. I have decided to focus it to a certain point using the transparent attachment availible, and that is a good way to make it usable as now you can press it against anything and it will be in focus. That however only lets me use a small magnification.
If i tried to do the best magnyfication i can, i need a very good contrasting object that i can focus on and that is flat if possible. A ruler is basically perfect, an edge of a knife is the exact opposite.


- It has a very shallow depth of field - If you do decide to use the best magnyfication and go through all the trouble of focusing you will find out that even the height difference of grain in a sabitoru rust eraser is a big distance, that of course is a minor issue.



So for shiny knife edges it is very bothersome to use. There is however a use for it, i was able to read a few letters on old coins that i was not able to read with a jewelers loupe. And the view of some things can be interesting. As long as you dont need a big mahnification is it easy to use (if you set the focusing point at the end of the tube and have an object that is flat)

- There really is almost no space to fit an external light source when you focus to the biggest magnification
Here some examples of a knife edge using the transparent tube and thus a small magnification:


It is a nice magnifying glass but not a microscope and did not help me progress in sharpening at all.

 

[TigFur]

Here are some random pics, the best i took and those took very long to make.
The crack in the razor can be seen with the naked eye pretty easily and the Picture after that is an attempt at the biggest magnification of an edge with external light, took a few hours and i was not able to focus at the spot that i marked because it kept moving away.

 

[kreisler]

Great photos T TigFur , thanks for taking the efforts to shoot them, nice share! Fantastic magnification, much higher than my portable microscope. It is hard to understand why your new microscope isn't suitable for our purpose. We take your word though, no problem!

I find my 8$ microscope absolutely suitable and easy to employ for our purpose, as long as i don't try to shoot photos of the magnified knife edges. The latter is possible but a pita and not the intended way of product employment.

As i posted yesterday, i don't do ambitious sharpening sessions anymore (like Ruixin sharpener and or PTS method), unless there is no other way around it. That's because i don't (want to) see my occupation with knives and sharpening topics as hobby, because it really isn't, for me at least. Meanwhile i see it more as pastime, skill, utility, some fun, routine, with a clear goal in mind: maintaining an acceptable sharpness level with the least amount of efforts and time investment. Learning the skill, gaining the experience, insight, knowledge through practice and microscope, buying all the accessory items from so many sources, etc … took me 1 or 2 years, can't remember, and could have been called my new hobby back then. Now i am past that point and i won't dig deeper into the knife/sharpener/steel topics. The microscope is still a helpful tool during ambitious sharpening sessions; just for regular edge maintenance i prefer to do the quick-check method with flashlight and apex light reflections. And it was very(!) enlightening to learn (with the help of my checking methods) that a single slice through a magazine paper sheet can/will degrade the knife edge, did you know? (Depending on the knife steel quality, of course) This observation was true for my Firebird 440C knife and my super old cheap kitchen knife. Just saying, given how easily a perfect edge gets degraded (e.g. through the standard paper slice test), i don't see the point anymore (well, not anymore!) of spending so much time and efforts on achieving that perfect edge. Instead, my leather strop maintains a polished sharp apex with ease, which is all i ever wanted before i got drawn into the whole world of knives and sharpening topics years ago.

Or maybe i should buy a paper sharpening wheel and the Spydie Sharpmaker and make a new hobby out of it.

 

[Cyrano]

So i have received the andostar microscope ... The lag is horrible - On the smallest resolution it is okay but you cant really see much, on anything else it just takes a while and on the highest resolution it takes like three seconds.

I know you understand photography and microscopy well, but just in case you hadn't already thought of this:

Is the lag related to exposure time, where a long shutter speed is constraining the video frame rate? If so, throwing more light on the subject may help.

Given the constrained geometry for lighting, the DIY LED illuminators I showed earlier in this thread might prove useful.

 

[TigFur]

Well the photos are okay as long as the object has enough contrast and you are willing to spend 20 minutes for it.

Is the lag related to exposure time, where a long shutter speed is constraining the video frame rate? If so, throwing more light on the subject may help.

No this is definately a lag of the processing, there is plenty light from the microscope itself.

 

[JD Spydo]

A couple of years ago I was doing some contracting work for a Doctor friend of mine and he showed me his lab. All of the optical equipment he had was made by ZEISS and NIKON. I got to check out both makes of microscopes and they both seemed to have good optics. Don't know if they would be good for knife edges or edged tools in general but both of those microscopes seemed to be high quality units from what I could tell.