POLL: What Shade Of Welding Glass For Backfocusing?

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.


The #1 reason I know of why it persists is because the vast majority of installers will NEVER roll back out to a job at night, drag out their extension ladder, open up housings and go to the rest of the trouble of refocusing cameras at night. And most of the few who would ever have the desire to do so work for bosses or companies that would scoff at the notion of paying the extra labor cost to have it done - especially since it would typically mean giving up that tech for at least part of a day during normal working hours that week, or having to pay overtime. I can honestly say that in 14 years of installing and servicing surveillance systems, I have never yet encountered a customer who answered "yes" when I asked if anyone has ever setup up their outdoor cameras at night. In fact, I don't recall ever having one even say a technician had stopped by post-install to check the quality of nighttime recordings.

I have not used a welding glass for a long time. I think the one I used to have was a #5, but i'm not certain. I got whatever was recommended to me by a surveillance industry "old-timer" many years ago. In most cases I have the luxury of being able to make return trips at night for the few outdoor cameras I install these days that are not equipped with a good auto-focus function. Having made dramatic improvements in numerous systems installed by other companies over the years - even including many brand new installations - simply by properly setting up the cameras, I would rather see a tech get out a welding glass and use it than to just focus a camera "naked" in bright sunlight and assume that means the camera is well set up. I would love to hear others chime in on this topic - I have always had a sense there is more I should know about it. For instance, for those who swore by the welding glass approach in years past, how was that affected as aspherical and IR rated lenses became inexpensive and commonplace?

"vast majority of installers will NEVER roll back out to a job at night, drag out their extension ladder, open up housings and go to the rest of the trouble of refocusing cameras at night"

who does that anyway... isn't that what autofocus and teamviewer was created for so we don't have to do that...

if the good lord had intended us to walk he wouldn't have invented roller skates... willy wonka

all kidding aside back when i did carry welding glass i had two pieces... i believe a 5 for outdoor adjustments and another for hallway cameras... was recommended by the manufacturer...

haha! So you're saying wear roller skates while Team Viewing through a #5... no, wait...

No, but if you find the welding glass hard to hold, just buy a welding helmet and wear that. Then you are seeing everything through the welding glass and your hands are free.

You're welcome for the helpful tip ;)

I have only found it useful when the camera is an SD coax camera without auto backfocusing. They are pretty inexpensive and I bought a bunch of shades to try. I believe I have tried 5 and 7. I would need to check since I leave them in my backback in their own section so they aren't all scratched up. The main reason I like them is when I have an ICR filter on the camera, I use the filter to open the iris and enable the filter. I have found that there is a difference in focus between them.

I have also checked remotely at night to make sure the focus is good and the IR is working well. I know some cameras will allow you to go in the menu and force the nigh mode settings, but I find it easier with a shade filter.

I am always open to trying other methods, but I try to always make sure the cameras look good at night by reviewing them at night.

I tried a couple different shades and found #5 to be about the only usable one - everything else was too dark, even in bright sunlight (of several shops I tried, only one had anything lighter than #8, and #5 was the lightest they had). I've actually found it more useful to just hold my sunglasses in front of the camera.

AF and ABF are nice, but not universally available. Remote focus is even more rare (so far).

Frankly, the main reason for the dark glass is to force the iris to open fully to minimize the depth of field for "worst case" focusing... but I've found most AI cameras have the ability to turn off the iris control (usually labelled "ESC", either on a DIP switch or an OSD menu), or if not, have an "IRIS LEVEL" adjustment... either of which allow you to TELL THE CAMERA to fully open the iris. Since most of these can also control the exposure via shutter speed and/or AGC (necessary to accommodate manual- or fixed-iris lenses), doesn't this really make the dark glass unnecessary on all but a very few cameras with very limited capabilities?

When an iris, auto or not, is fully open, many cameras overload in bright light. The overloaded image blooms so much, focus is impossible. I've found the only way to compensate is to cut the amount of light received by the camera. Though neutral density filters would be a better choice, their $50 to $150 tyypical price makes two-for-$5 welding glass inserts far more cost-effective, especially since they tend to get lost or broken regularly.

I can't think of any model of cameras I've used recently, that weren't at some point or another fitted with a lens that didn't have an adjustable iris at all... none of them ever had an overexposure issue that the ESC and/or AGC didn't compensate for. Maybe there were a few cheap ones back when I started in this biz (10 years ago), but nothing that immediately tweaks my memory. I still have old Panasonic, Sanyo, Sony, and other brands sitting in a box, with things like fixed 6mm f/1.8 lenses that have no iris adjustments.

remote access and remote zoom and focus - all from the comfort of my couch at night ;)

Are u talking about Avigilon again ? :)

Stop please

hehe Alex would I do that? ;) I do have a welders glass in my truck and I cant remember the last time I had to use it. so happy to be done with analog especially in the winter on a 40ft boom lift adjusting a 50mm lens in a clamshell housing that likes to block the shot with its sun shield

I never found that using a welding glass was accurate enough in many cases as the nightime enviromental lighting affected the back focus even thought the glass fully opened up the iris while setting up the back focus. I agree with Paul that good ridence to the 'olden days' of having to endure the cold, wet and winter conditions resulting in moisture and condensation in the camera housing. I wonder how many installers now choose a camera type by the ability of autofocus functionality.

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