I use a Viper and am quite happy with it. The lens cap has a pinhole which I use most of the time for the added depth of field. I can get it to focus at about 18" - beside using it to load sheet film holders, I use it to check development. I use dip tanks so I can pull a sheet out and see if I need to adjust the developing time. I have yet to notice any fogging issues - I am using it without any filter on the IR light.