Funny you should raise this as I think the film base is a bit flimsy. Why? Well my neg carrier is glassless and I've never experienced any problems with any films except 120 Delta 3200. I could not get a focused print. Eventually I watched the film under a grain magnifier when making an exposure and saw the film base move out of focus with the very minimal heat the enlarger bulb was putting through it. A bit like a tranny popping in a projector but less so.(posted 8507 days ago)Bri