We have only five signed O.T. Frasch images in the range from 500 to 599, plus one unsigned image of Mt. Rainier with a caption in writing that strongly resembles his. The five signed images are in the range from 500 to 509 and show scenes in Moscow, Idaho, the site of the University of Idaho. Two of the images have black boxes where the emulsion was scraped off. We've seen a version of one image with the emulsion present; it has the signature of another photographer. Thus we wonder if Otto actually took these photos.
Decades with images:
A selected image from the range 500-599: