It's a unique lens for special purposes, but it's very sharp. Open aperture is only F8, so guestimate works well. You can bracket focus slightly if you are not sure, but depth of field at F8 and below is acceptable. You can shoot this lens at 1/60 as mirror slap and shutter vibration are minimum. Ideally you would lean on something to support yourself and you can stop down to 11 or 16 and still get razor sharp pictures. Or use a tripod, of course.
