Hi, John -
That is one of the reasons I reduced and compressed the images on our screen saver content preview sites. If the photos are small and a bit fuzzy, there's not as much incentive to "borrow" them. That was easier for me than watermarking or using other security measures. The full-sized, uncompressed images will be MUCH sharper, though nowhere near the quality of the reproductions in Tom's book. Roger says borrowing images from a screen-saver is not at all easy, and the average railfan is not likely to have the tools available to do so.
In general, I don't mind other people posting A FEW of my pictures for NON-Commercial purposes, so long as the subject is identified correctly and credit is given. Seeing a link to the organization owning or running the pictured locomotive(s)- such as C&TS and The Friends, the Nevada Northern, or the Golden Gate RR Museum - also tends to calm me down a bit.
- Russ