Although I have been enjoying the recent discussions of Turbines, HDTV (a favorite of mine) and culture. I do have a general question regarding film. My daughter, who splits fairly equally between film (35mm and Polaroid SX70 for manipulation) and digital with the occasional use of one of my beatup but totally usable Rolleicords (obligatory Rollei reference). Her usual 35mm film of choice is Tri-x. Generally she shoots at 320. Over the Summer we did some push processing at 1600 in the darkroom that she and I have built up, at her request, which made her dad very pleased. The push processing was more or less educational for her and to see if I could still do it for me... In any case, the other day she ran out of Tri-x and asked me if she could use Plus-x at 400 which we had in the 'fridge, and push process and get the same results as Tri-x normally exposed at 320-400. Without really thinking it through I said no don't do that. As a good daughter, she accepted her dad's sage advice (yeah, it does happen), but afterward, I was wondering whether I was right. Over the years I have pushed TX to 1600 and even 3200, but always shot PX at 100-125. If I needed higher speed I simply used TX. Was I correct??? Thanks, Ken