Dealing With Huge Amount Of Varying Light?

In my current work environment which is a casino. There is a huge amount of varying lighting conditions. The slot machines with all the neon lighting and various other lighting issues. My question is would it be better to have a small FOV ie; less lighting issues ..maybe or have a wide FOV and try for the best possible iris setting?

NOTICE: This comment was moved from an IPVM Course Discussion.


Belvie, Very good question!

In general, there is a real issue when the lighting is a scene varies a great deal.

Recall that a camera can only have a singular shutted speed / exposure for the entire FoV/scene. For example, let's say the camera selects a 1/200s shutter speed. That will work well for capturing the bright areas and not having them be washed out. However, the tradeoff is that dark areas may be underexposed.

When you have significant variations of light, the best solution is true multi-exposure WDR.

Related, this is a fundamental weakness of panoramic cameras as the FoV area is so wide the probability that the camera has to capture very bright and dark areas simultaneously is quite high.

So if you can constrain a camera to only a similar range of light levels, great. But that may not be logistically feasible as you might have bright areas right next to dark ones.

The best bet is to go for true multi-exposure WDR cameras.

Wake up Carl.....it's your turn at the wheel. :)

Zzzzzzzzz... Huh?

Belvie,

We typically don't use WDR functions. I've found they typically cause contrast to go down which yields a "washed out" picture. Our casino is generally well-lit though a bit on the dark side. As far as the flashing lights on slots, etc., we try to avoid them as much as possible by zooming in or cutting off the lights. If we have to cover areas with flashing lights, etc., we typically use iris settings to compensate.

One huge tip: try to avoid using AGC at all, or if the camera has variable AGC, set it at less than 10-12db. We also prefer manual iris lenses to auto-iris. If pressed with auto-iris, we often set the iris in the menu to manual. We usually start with the iris wide open (for depth of field reasons when focusing) and close it enough to give the best picture. We also use faster shutter speeds on occasion.

Again, AGC is the worst offender when dealing with casino cameras and lighting, whether it be slot machine banks, WAP slot machine faces or gaming tables. The only time we actually use AGC is for area overviews in particularly dark areas.

One more tip:

Watch your shutter speed(s). We always turn off DSS because it can make a 30fps stream actually deliver a lower effective frame rate than expected. We also often switch the shutter to "Manual" and use its speed to control image brightness. The lowest acceptable shutter speed in our case (we record and view all cameras at 30fps) is 1/30, though we can use higher speeds in areas with more light.

"We also often switch the shutter to "Manual" and use its speed to control image brightness."

If the shutter is set to manual, then are these cameras auto-iris? Otherwise, if it's manual shutter and manual iris, it's going to have big lightning issues.

Often not. Our preference is manual iris but unfortunately, the vast majority of dome cameras only come with auto-iris lenses. But no, we've found that, properly programmed, auto-iris lenses do play well in "manual" with manual shutter settings. Keep in mind that most indoor areas have a constant level of light 24/7/365.

We do try to use manual iris lenses whenever possible. One reason is that slot areas often have flashing lights and active displays, which can cause auto-iris lenses to "pump", making the scene brighten and dim constantly. Manual settings overcome that.

On a related note: I find it unfortunate that more and more manufacturers are utilizing power zoom/focus lenses. In my opinion, that severely restricts our options without providing any real benefits:

  • Power zoom/focus lenses are not easily interchangeable, making it necessary to select the correct camera model for each application, rather than one camera and choice of lens. This also can affect "camera re-purposing", whereby we re-aim a camera at a different area, often requiring a different lens. This process is further complicated by power zoom/focus cameras' limited choice of lenses.
  • Power zoom/focus lenses have fewer choices of focal lengths versus C/CS-mount lenses. I haven't found many cameras offering <3mm->10mm power zoom/focus lenses. Typical choices are 3mm-9mm and 10mm-~20mm. That leaves out very wide lenses (aka Theia 1.8-3mm) and very narrow lenses (aka 5mm-50mm) which we often use.
  • For our purposes, power zoom/focus lenses don't save on installation time. We are very critical with our aim/focus/zoom settings and to obtain our preferred FOV, it is necessary to adjust aim and zoom/focus alternately. It's not easy to do that in the field so we have to adjust zoom/focus while at a workstation while the field tech adjusts aim and camera orientation - a two man job.

NOTE: 2.8mm-12mm or 3.3mm-12mm lenses fill our "sweet spot". They can fulfill 80%-90% of our needs. That range is common in C/CS but very uncommon in power zoom/focus lenses. We currently use many Computar 2.8mm-12mm manual iris lenses on analog cameras (including our Vitek VTD-A2812 domes) and have found that Arecont MPL33-12A 3.3mm-12mm MP lenses fill the bill for MP IP cameras.

On another related note: Arecont MPL33-12A lenses cost in the $115-$125 range, depending on source. They are actually Evetar M127VM3312IRCS lenses re-branded by Arecont. I believe other manufacturers may offer the same lens as an option but not separately so we are "stuck" buying the Arecont lenses. Evetar will only sell to us direct from China, requiring the complexity of importing (something I discussed in another thread). Does anyone have another (read cheaper) U.S. source?

Does anyone know of another company who makes wide angle varifocal MP lenses? Theias are darned expensive and we don't really need the fisheye correction capability.