The front element won't budge and I didn't have a lens cap anyhow. I'm not sure what size lens cap would fit either. I'll probably only use this at home anyways, but the front element will twist on and off easily. As long as I don't put the plastic ring with the writing back on it. There is like a permanent fingerprint on the front element and you're right about not using it much. Now I have a decent macro lens.
I gotta get pretty close and move back and forth to focus.
I'm not the best at testing, but here is a quick try.
35mm f/22
50mm f/27
60mm f/22
80mm f/22
80mm f/5.6
80mm f/11
80mm f/22
80mm f/32