G'Day Suzanne just as a matter of interest I have a digi blue that I use just for that reason and that is to fine errors in the stamps,the last one I posted was an R8c which is a revenue stamp,this was suppose to have a double and the digi blue confirmed it didn't.
The first photo is of the microscope then I'll post a photo of what you can expect using a microscope,this one is magnified at 10X.


I do have a stamp that was magnified at 60X an early 1cent,sorry I can't remember which one it was but it had an error that you can only see with a microscope.

There is another thread with the photo's of the format of the digi blue and what it looks like on screen but with the alzheimer's I can't remember what thread it's on.
regards Harry
