cglaeser

It may be helpful to visualize the inverse square law. Suppose you want to butter your toast with a butter spray gun. Suppose the butter spray pattern will precisely cover a single slice of toast when held one foot from the toast. Now, suppose you want to butter four slices of toast the same time. All you have to do is arrange the four slices in a 2x2 pattern and move the sprayer two feet from the toast. You have doubled the distance between the sprayer and the toast, and 1/4 of the butter is falling into each slice. That is the inverse square law. In other words, there is a relationship between the distance and the amount of butter (light) that falls on a given area. If you double the distance, you reduce the light on a given area by a factor of 2 squared which is 4. If you triple the distance, you reduce the light on a given area by a factor of 3 squared or 9. This law is well known in the field of photography, and such BS would be ridiculed as a joke in photography marketing literature. Security camera manufacturers assume that security camera installers know very little about light, and much of the security camera marketing literature is near worthless. Lux ratings don't mention shutter speed or aperture, IR Illuminators give an arbitrary distance without any mention of assumed camera or lens specifications, varifocal lenses don't mention aperture for the full zoom range, and the list goes on and on. It's pathetic. Security camera installers with a background in photography don't know whether to laugh or to cry when reading these specifications. Best, Christopher

Are the DVRs at one location connected to one LAN, or are the DVRs at four locations behind four different LANs? Best, Christopher

Well then, by reversing the inverse square law, it should burn a hole through your retina at 30 feet. Apparently, the inverse square law isn't really a law. It's more of a suggestion, which the photons are encouraged to follow but are free to ignore. Best, Christopher

CAI makes a device called Webcontrol. http://www.redhillnetworks.com/products/webcontrol/index.html At $35 they are so cheap I purchased one about a year ago but have not yet played with it. It has 8 digital inputs, 8 digital outputs, and a few analog inputs. It has a web browser interface and supports several protocols including SMTP. Time permitting, I look forward to testing it. Best, Christopher

I saw a report about a year ago about the development of a system that tracked customers in a store and used analytics to try and determine if and when customers needed assistance from the sales staff. There are times when customers want to browse on their own and there are times when customers want to be approached by a sales person to provide assistance. This system was being designed to address that issue. Best, Christopher

The specs say the UF500 is rated for 3,000 hours. That's not very long. How often do you replace the bulbs? How much do you pay for replacement bulbs? Best, Christopher

Wow, 44 IP cameras, that's a huge project for a first time DIY project. Heck, that's a big project for many installers. Best, Christopher

It depends on what you want to look better. Six illuminators on a home where one will do doesn't have much curb appeal. Best, Christopher

While some cameras can record directly to a NAS, you don't want to do it that way, particularly for a large number of cameras. The VMS should control the recording, which includes such mundane tasks as file system organization and file naming, reusing storage, etc. Exacq is a good choice. They offer servers, or you can license the software and build your own servers. Best, Christopher

I may have isolated the problem so I'll post the solution for future reference. The 502 is capable of producing multiple streams, including JPEG and two H.264 streams. Several weeks ago I was doing various experiments and comparing the detail of JPEG vs H.264. At the conclusion of the experimentation, I set the camera back to JPEG. Although the Exacq server was only accessing the JPEG stream, the camera continued to produce the H.264 stream, even though it was not being consumed, apparently causing the intermittent problems. Yesterday I set the H.264 configuration to off, and it appears that the camera has not had a hiccup for about 24 hours. I am running JPEG with maximum detail at 1.3 megapixels (I use 1.3 mp instead of 3 mp for improved night performance). It can run 15 fps, as best I can tell, without any problems. Fingers crossed. If the problem was indeed caused by the H.264 configuration, then I would submit this is a defect. Over the course of several hours, the JPEG stream would slow to a crawl, motion was not detected or stored, and then an hour or more later the camera would heal itself, only to repeat the cycle again a few hours later. FWIW. Best, Christopher

That's pretty good for 30W. What is the beam width? Best, Christopher

Well, I dropped the fps from 15 to 10 and the JPEG compression from 10 to 8, and that did not seem to help. It's starting to slow down again, and motion is not being recorded as it begins to choke. Three other cameras, all different types, continue to run fine. Best, Christopher

That looks exceptional! Thanks for posting. Best, Christopher Edit: BTW, what is causing the white horizontal bands? Is that street lights or camera or something else?

How can you compare DOF without any mention of features like sensor size and aperture? Best, Christopher

The web user interface on my Netgear ReadyNAS RAID storage allows me to review the SMART information for each disk drive in the array. In particular, I monitor the Reallocated Sector Count, and if this number begins to increase, I consider replacing the drive. Is there a Windows application that shows the SMART information for hard drives? I tried using the Seagate utilities some months ago, but as I recall, these utilities did not show the Reallocated Sector Count or other SMART information. In addition, the ReadyNAS has an email notification feature that will send me an email message if the Reallocated Sector Count increases on one of the drives. Can you recommend a Windows utility that will monitor drive health and send a notification or pop-up when a drive is experiencing problems? Can the Windows event log send notifications on some types of events? In summary, how do you monitor drive health to prevent complete failure? Same questions for Ubuntu. Best, Christopher

Have you tried it yourself? Have you reviewed the specifications? B&W is 0.2 lux. Do you know the shutter speed used for that 0.2 lux? Axis lux ratings are so poor, they never specify the shutter speed. In some models, they were using a 2 second DSS for their lux specs. A couple years ago I called Axis and discussed the lack of shutter speed in their specifications. They said they were implementing a new lux rating scheme, and all future cameras would be specified with no slower than 1/6 second shutter speed. So, let's assume the Q1755 specifications is 0.2 lux at 1/6 second. That's 1.0 lux at 1/30 second. Do you think that's good low light performance? Best, Christopher

OK, yeah, that makes sense. The voltage in the secondary coil is proportional to the voltage in the primary coil and the number of turns in each, but otherwise they are isolated. Thanks. Best, Christopher

A rather simple question, just curious. When connecting two or more DC devices (e.g. two devices communicating via RS232) and one or more of the devices have a separate DC wall-wart power supply, and the wall-wart AC plugs are not polarized, how is it that the ground of the two devices can be connected together without a potential between them? Can the DC output float separate from the AC wall-wart input? Best, Christopher

OK, assume money is not an object. Which Axis do you recommend for low light? And no, you can't pick a thermal. Best, Christopher

Do you think MP cameras can match the motion sensing capabilities of PIRs and IR Beams? Best, Christopher I think he means you could do the same as you would with $150 bullets Perhaps, but he mentioned "all forms of alerts if there's movement", which sounds like he is suggesting that cameras can do the work of PIRs. Best, Christopher

That's what I'd like to know. My Panasonic 502 MP camera sees as far as the edge of the street light. My Redwall PIR sees 300 feet beyond the street light into total darkness. A small army of burglars could dance a jig undetected by the 502 just beyond the street light, but no one makes it past the Redwall. In the next few days I need to knock down a wasp nest that is growing near the 502, causing countless false motion alarms during the day. The Redwall is unaffected with zero false alarms. This talk about MP cameras replacing high-end PIRs looks good on paper, but in real world scenarios, um, good luck with that. Best, Christopher

Do you think MP cameras can match the motion sensing capabilities of PIRs and IR Beams? Best, Christopher

Axis makes quality products. Low-light performance is typically not that great. Best, Christopher

If you need to go wireless, then your best option is probably the Optex VX-402RI PIR with Inovonics transmitter, and the Inovonics EN4204 receiver, or if you need relays, then the EN4204R. You should be able to get the PIRs for about $170 each and the receiver for about $120, more or less. Best, Christopher

What's the $500 for? An Optex 402 is under $200, and a Crow Daredevil is $100. Best, Christopher