This is a photo I took during Veterans Day last year and it was a good candidate for the etching effect. I loaded the photo into photoshop and used the smart sharpen tool turning it way up to 415%, then I went to the filter gallery and selected the torn edges effect. I played around with the sliders until I got the looked I wanted.
This is a photo I downloaded from the internet, so I could practice with the effect. The background in this photo was very dark. I followed the same procedure as the first photo and then added a step. I inverted the photo, so the light areas would be dark and the darker areas light.