I shoot 5x7. Lenses in the 135-150mm range that cover well are relatively scarce, especially considering the number of options in that range. I don't remember enough details about lens design to confidently explain why, but there's something about lens design that explains it, trust me There are a few, of course - I'm currently eyeing the original Fujinon 150/5.6, later versions of which lost about an inch of image circle. It's definitely a useful focal length, one I'm especially interested in given my fondness for 65mm on 6x8cm.

I only know about all this from spending entirely too much time reading about 5x7 gear, so I'm curious, are there similar coverage "gaps" among other formats? Apart from ultrawides, which become increasingly scarce as your film holders grow...