Digital scopes came up in another thread and I thought that the topic deserved a thread of its own.
Magnification of what is happening at the cutting edge of a tool while sharpening is, in my experience, an invaluable aid to know how and when you have achieved a sharp edge. Arm hair shaving might be sufficient information for some, but some of us like to know more about what is happening at at the micro level at the very cutting edge.
There is a limit to how much you can see with a handheld optical loupe with typically 10X to 60X magnification. At times I like to see more detail than the loupe can provide about what is happening down closer to the micron level. The new and relatively cheap digital scopes (sometimes referred to as USB scopes) provide the next economical step up from the optical loupes.
I've gone through various digital scopes, but with mixed success. Besides being invaluable for seeing myself what I'm achieving with my sharpening methods, these digital scopes provide a means of communicating with others the results (or not) I'm getting from my sharpening methods.
There are many digital scope options on offer out there and without any recommended specifications on what to look for it is hard to know what is a good starting point for this purpose.
One of the issues I have found is the limited depth of field at higher magnification making it hard to clearly see all of the area being looked at.
Another issue with the cheaper ones is the coarseness of the focussing mechanism.... take your hand away from it and it is immediately out of focus.
Some of the offerings claim magnifications up over 1,000X, but IME, that is way above anything that would be useful for this purpose. What is the maximum magnification that would be useful for this purpose?
Lighting is the other aspect in using these economy scopes... some have too many LED light sources so that it is impossible to see a single reflection and remove all but one and it is not bright enough to see at higher resolution.
What is our collective 'insights' (excuse the unintended pun) into what we need to avoid buying what is in effect a stocking stuffer.
To kick off, here is a posting by David Weaver (D.W) from another thread that is currently running on this forum, here.