More light?

[LUV2TINKER 0]

I'm currently using an F1.4, 3.5-8mm DC auto iris lens (also have a lens just like that but with video auto iris lens) attached to my b/w Ultrak KC4300, 1/3" CCD, box camera to monitor my vehicle at night. I only use it on 8mm, because that's the perfect size for my application.

But I'd like a little more light entering the lens.

Just wondering if I could get more light at night by using a fixed, 8mm, F1.2 lens.

[mobbarley 0]

I'm currently using an F1.4, 3.5-8mm DC auto iris lens (also have a lens just like that but with video auto iris lens) attached to my b/w Ultrak KC4300, 1/3" CCD, box camera to monitor my vehicle at night. I only use it on 8mm, because that's the perfect size for my application.

But I'd like a little more light entering the lens.

Just wondering if I could get more light at night by using a fixed, 8mm, F1.2 lens.

 

Absolutely, but the difference between 1.4/1.2 is not going to be dramatic.

If there is no light in the garage then no camera / lens will be able to see without some kind of illumination.

[Soundy 1]

F/1.4 to f/1.2 is only half a stop, meaning about 50% more light... realistically, like mobbarley says, it probably won't make a substantial or even noticeable difference.

[Stanislav 0]

The difference between F1.2 and F1.4 depends of current light level and camera sensitivity. If there is a bright region on the scene then current camera exposure can be limited by this region and changing lens will not improve image at all.

If the scene is low illuminated uniformly, you can expect theoretically difference as shown on the images.

But real difference can be a little more because varifocal lens probably transmits less light than equivalent fixed F1.4, it has more complicated construction and more optical losses than fixed lens. Also the F1.4 value in varifocal lens spec F1.4, 3.5-8mm can be applied to 3.5mm focal length. With 8mm focal length the F number can be worse.

 

[jeanne_hsu 0]

why not buy an IR illuminator?

just like this

[LUV2TINKER 0]

Thanks guys. That helped me to understand how it works.

 

What is that software those screenshots were from?

[MaxIcon 0]

If you want to try out an inexpensive IR illuminator before springing for the good stuff, Amazon has one called the YY Trade IR30 that is under $20 and works very well for the price. It doesn't come with a PS, but runs from a standard 12v camera power supply, and has a photocell to turn it off at night. I get pretty good range and illumination from mine.

 

Read the reviews on Amazon to see people's experiences.

 

ETA: There's a link to Stanislav's awesome software in his sig.

[LUV2TINKER 0]

I looked at those IR illuminators on Amazon a while back. I'm trying to avoid those as much as possible, because there's a pretty big dynamic range of reflectiveness in things in the image in this application. And there's *almost* enough light to capture the images without resorting to that using just the camera, and without needing too much assistance from the AGC in the camera.

 

That screenshot Stanislav posted just blew me away when I saw it - with all those parameters, like the IRE %, S/N ratio, etc., that change when you change something. I mean, I know those are theoretical, but that would still give you a rough idea of how it would come out. I'll bet there are really interesting formulas built into it.

[Stanislav 0]

That screenshot Stanislav posted just blew me away when I saw it - with all those parameters, like the IRE %, S/N ratio, etc., that change when you change something. I mean, I know those are theoretical, but that would still give you a rough idea of how it would come out. I'll bet there are really interesting formulas built into it.

 

Please see my article Illumination and camera sensitivity in CCTV. Therein is some information how these images are simulated.

*IR illuminators can be modeled too.

[MaxIcon 0]

If you don't want to go IR, the best bet would be to find a 1/2" camera with excellent low-light performance (lots of recommendations for those around here), and put the fastest lens you can on it.

 

I have an old Panasonic WV-CL924A with a F/0.95 lens that gives pretty durn good low light performance, but it still needs some ambient light. It's a fair bit more expensive used than your Ultrak, but they show up used on ebay pretty regularly (where I got mine, back in the day), and can be found for well under $200, often with lens (but maybe not the lens you need).

 

Lots of used 1/2" lenses going cheaply, too (stick with the good brands), as 1/3" is a lot more popular these days.

 

Another option, if IR washout is an issue, is to reduce the output from the IR emitter, or put a diffuser over it to reduce the glare (but reducing throw at the same time).