IPVMU Certified / IPVM Admin | 10/30/13 05:07pm
Disclosure: I hate the casual recommendation to use 'welder glass inserts' to simulate nighttime conditions when focusing cameras. Why? You tell me:
Welder's glass is designed to filter and darken a wide range of very intense (brighter than sunlight) electrical arcs or plasma flames. And is commonly available in 15 or 20 different shades:
Yet the sun's light (whether direct or indirect) varies widely in the field. Do installers match different shades of inserts according to just how intense light is where the camera is hung? Do they really understand just how dark a scene gets at night?
In my experience, no. Rather they carry around a scratched-up, dirty, greasy shard of tinted glass in a toolbag and think it is a required tool when focusing cameras.
I'm not saying the practice is bad, just how it is mistakenly simplified and mindlessly, routinely done. What I am saying that welding glass is not required and probably is a waste of time. Actual nighttime backfocusing is better, and the whole exercise may not even be needed with autofocusing cameras. So why does this particular 'pro tip' continue to exist?
Am I wrong here? Someone set me straight.