Is that an IR filter glued to the back of that M12 lens???

[stroonzo 0]

Taking a lens out of a Dahua 3200 dome (which is an electronic day night camera) I find there to be a reddish thin filter attached to the back of the lens. Is this an IR filter? If so, then doesn't that completely negate the electronic day night functionality? I mean, I understand the difference in electronic vs mechanical (where you here the filter kick into position). I read that electronic day night was supposed to not use an IR filter lens and compensate for this in daylight hours by color filtration:

 

...However, digital day/night cameras (or electronic day/night cameras) are also available, which electronically adjust colors during the day, instead of using an infrared filter. This allows the digital day/night cameras to deliver similar benefits of true day/night cameras, but at a lower cost. Without the need for a physical filter, digital day/night technology can also be leveraged for smaller form factors, such as bullet cameras.

 

http://www.supercircuits.com/resources/blog/day-night-cameras-the-best-of-both-worlds

[buellwinkle 0]

According to the specs on Dahua's website, it says Auto(ICR) which is a mechanical IR Cut Filter, just a different abbreviation which means IR Cut filter Removal. You can usually tell because you'll hear a click when then camera switches and even is some you can see it switch in one of the frames being recorded.

 

Electronic IR is bogus as it has a permanent IR filter for during the day and switches to B&W at night, There isn't a camera made with IR LEDs that has a permanent IR filter, that would defeat the purpose of the IR LEDs. Also, there's no good way of compensating through image processing to correct for colors skewed by not having an IR filter because it's a changing variable.

[stroonzo 0]

The specs for the state: IPC-HDB3200C Day/Night Auto(Electronic)/Color/B/W. From this can I assume then that the lenses on those domes are using a built in filter and that is the reddish glass glued on to the back of lens (the backside of the lens visible when the lens unscrewed)?

[MaxIcon 0]

Yeah, that's what it sounds like, since this camera doesn't have IR LEDs. If there's a movable IR filter, you'll hear a click as it switches between day and night, as Buellwinkle says, and you'll also see it between the lens and sensor, with 2 wires going to it. The glued-on filter is the cheapest way of adding it.

 

You could check by putting on a different lens to see if the daytime colors change, showing more purple where IR is strong. I have a few cams with no IR filter, and one cam I removed the fixed IR filter from, and they vary quite a lot in how much the daytime colors shift.

[blakem 0]

I haven't tried it, but to test if you have an IR filter installed you could point a TV remote at the camera and press a button. You should see the IR LED light up if there is no filter.

[buellwinkle 0]

I'm sorry, you didn't have the full model number before and they make several cameras including a dome with the 3200 designation, but no, that's a day only camera, no mechanical IR Cut Filter, it has a permanent IR filter and at night you can chose to have it switch to B&W but really makes no difference, it's immune to the effects of IR light because of that IR filter and you need white light to assist it.

 

Actually it has poor low light sensitivity as compared to their 1.3MP Aptina used in the very similar looking but indoor only dome I reviewed earlier this year from Q-See. Also, they started making new models that nobody talks about here but they have a new 1080P and 3MP Aptina sensor so they seem to moving away from the Sony Exmor. the models end in 1, like ipc-hfw3200c is now a ipc-hfw3201c. I have not seen these yet through my U.S. distribution channel but I can get them from my Asian distribution channels. They have their mini IR dome that was previously available only in 1.3MP not is available in 2MP (1080P).

[stroonzo 0]

For testing, I put a 6mm, IR compatible lens on the 3200 mini dome. The night time usage is improved, but trying to run color in the day is useless of course. So much for being an E-Day/Night. I'll post some pictures for comparison once I finish all of the testing. I am going to see how the mini dome responds to an IR Illuminator at night, how it runs during the day in night mode (B&W), and do some shutter speed comparisions to the other dome covering the same general area.

 

In the end, I may find the dome to be a useful conversion to a full-time B&W camera.

[MaxIcon 0]

I haven't tried it, but to test if you have an IR filter installed you could point a TV remote at the camera and press a button. You should see the IR LED light up if there is no filter.

 

You'll always see the LED light up due to the brightness of the LED at the emitter, I've found, but it'll be much brighter without the IR filter. All my cams leak some IR with the filter in.

 

A better check is to use the remote like a flashlight. Without an IR filter, you'll see the beam spot on whatever you point it at, and you'll see little or no beam with a filter in.

[blakem 0]

You'll always see the LED light up due to the brightness of the LED at the emitter, I've found, but it'll be much brighter without the IR filter. All my cams leak some IR with the filter in.

 

A better check is to use the remote like a flashlight. Without an IR filter, you'll see the beam spot on whatever you point it at, and you'll see little or no beam with a filter in.

 

Ahh, thanks, that is a good trick to know in the future.