Panasonic MOS sensor cameras and 940nm illuminators?

[ddbear 0]

I have Panasonic WV-SC385 PTZ cameras. These have the newer Panasonic MOS sensor. Does anyone know how well these cameras perform under 940nm IR? The product spec sheet says they work with 850nm but I think they should "unofficially" work at higher wavelengths. Should I expect the sensitivity dropoff for 940nm compared to 850nm be around 50% dimmer for a given wattage illuminator?

[dvarapala 0]

FWIW, I have a 940nm RayMax illuminator and all of my cameras with switchable IR cut filters are sensitive to that wavelength. I don't have an 850nm illuminator for comparison, so I can't comment on the sensitivity drop-off aspects.

[cglaeser 0]

Should I expect the sensitivity dropoff for 940nm compared to 850nm be around 50% dimmer for a given wattage illuminator?

 

Absent any specs, that's a good rule of thumb.

[ddbear 0]

I'm also wondering, besides the dimmer illumination, whether 940nm has any quality differences compared to 850nm? Let's say for example the relative dynamic range, hot spots, reflectivity from objects interfering with the quality, etc.. 850nm vs 940nm..

[LittleScoobyMaster 0]

I have this exact same camera and was wondering the exact same thing about using it with a 940nm instead of an 850nm. It does very well with 850nm but I am in the market for a couple more ir illuminators and I really want the stealthier version. Did you end up just testing it or did you go with an 850 instead of the 940?

 

ftp://ftp.panasonic.com/pub/Panasonic/business/security/spec_sheets/WV-SC385.pdf

 

I don't see on the spec sheet how we can know without doing our own testing. Anyone know? If not, may just order both to test.

 

This seems to be the only ir info on the sheet:

 

Color: 0.5 lx, B/W: 0.06 lx at F1.6 (Shutter: 1/30 s, AGC: High),

Color: 0.031 lx, B/W: 0.004 lx at F1.6 (Shutter: 16/30 s, AGC: High)

[MaxIcon 0]

There are few relevant specs given for most IR illuminators. I'd like to see them spec the total IR output power and the beam angle, since that would let you compare illuminators easily, but nobody does this.

 

There's little difference between 850nm and 940nm except for the sensor sensitivity and visibility to the human eye. Beam angle is determined by the LED's spec - you can usually buy the same LED in multiple beam angles.

 

Likewise, IR output power is not very related to the input power; a 1W LED can have a huge range of actual IR output. Actually testing IR output is tricky. Decent IR power meters can cost thousands of dollars.

 

It's a jungle out there, and you pretty much have to buy something and test it to see how it works for you.

[cglaeser 0]

Likewise, IR output power is not very related to the input power; a 1W LED can have a huge range of actual IR output. Actually testing IR output is tricky. Decent IR power meters can cost thousands of dollars.

 

Another way to manage power is to sync the IR with the sensor. Messoa does that with their latest LPR camera. The electronic shutter speed is relatively fast to minimize motion blur of moving vehicles, and the IR does not need to be powered while the "shutter" is effectively closed.

 

Best,

Christopher

[LittleScoobyMaster 0]

I'm also wondering, besides the dimmer illumination, whether 940nm has any quality differences compared to 850nm? Let's say for example the relative dynamic range, hot spots, reflectivity from objects interfering with the quality, etc.. 850nm vs 940nm..

 

Just completed a test of 940nm on this camera (Panisonic WV-sc385).

 

Failed miserably with the IR-200-940 ir illuminator. Not sure how other 940's will fare with this cam. Hopefully much better.

[cglaeser 0]

Failed miserably with the IR-200-940 ir illuminator. Not sure how other 940's will fare with this cam. Hopefully much better.

 

Of course sensor sensitivity will vary, but as a general rule, the sensitivity at 940 nm will be roughly half that of 850 nm. Or said differently, 940 nm will require roughly twice the power output. Similar to the human eye, sensitivity starts to fall off at those longer wavelengths.

[ak357 0]

 

Just completed a test of 940nm on this camera (Panisonic WV-sc385).

 

Failed miserably with the IR-200-940 ir illuminator. Not sure how other 940's will fare with this cam. Hopefully much better.

Do your self a favor

and Google

CCD Sensor QE (Quantum Efficiency)

and look very close at graph's showing variation of quantum efficiency with wavelength of a CCD

[LittleScoobyMaster 0]

 

Just completed a test of 940nm on this camera (Panisonic WV-sc385).

 

Failed miserably with the IR-200-940 ir illuminator. Not sure how other 940's will fare with this cam. Hopefully much better.

Do your self a favor

and Google

CCD Sensor QE (Quantum Efficiency)

and look very close at graph's showing variation of quantum efficiency with wavelength of a CCD

 

I glanced over this one: http://blog.astrofotky.cz/pavelpech/?p=864

 

Interesting topic. Not sure I understood all of it but if the takeaway is to have a specialized camera for different needs, that's understandable. But, since 850nm works very well with my WV-sc385's, I think I will most likely just order more of the same and not bother with 940nm. I want IR that all my cams can use and 850nm seems to be an ok compromise. What needs to happen for all future cameras to be able to see 940nm adequately?

 

I didn't quite catch that from the article but I'm sure it was in there somewhere.

[MaxIcon 0]

There were 2 basic conclusions from the data in the paper:

 

- Different sensors have different sensitivities (but we knew that already).

 

- The sensitivity to 940 nm is about 1/2 to 1/3 that of 850 nm.

 

What this means: whatever camera you have, you'll lose half to 2/3 of the sensitivity going from 850 nm to 940 nm at the same radiated IR power. The rule of thumb is half the sensitivity.

 

Now you're back to the problem of knowing what the radiated IR power is for both illuminators so you can compare apples to apples.

 

If the demand grows enough for 940 nm, we'll see improvements in sensor IR sensitivity, more efficient 940 nm LEDs at lower cost, or both.