For several years I had believed that shooting a medium format camera at high ISO would yield terrible results. Most likely there would be no point in trying, I thought. However, a few days ago I nevertheless brought the Pentax 645Z and the Pentax 25mm f/4 out into the darkness where the zoombies reign — in my imagination anyway. I would have loved to have an ultra-wide-angle f/2.8 lens on the 645Z. That would assuredly have been an advantage. On…