Lenses, 12m x 0.5 with infrared cut

[Gator 0]

I'm looking for a source of thread in board camera lenses that have an infrared cut filter built in. Some of these board cameras have the IR filter built into the pinhole lens or have no filter at all. I would like to buy an assortment of different focal length lenses for my cameras and I need the IR cut to improve the color quality and sharpness.

 

I searched IR cut MTV lens on eBay and I find people advertising lenses that pass infrared as being "IR CUT".

 

Does anyone know where to buy these? Or is there a way to add a filter in front of the ccd on cameras that don't have the filter built into the sensor?

[Baylab 0]

There is some kind of "Day & Night" filter, which can block some Infra red except a window at 850nm (with a window width of 30-50nm). Most of low end day and night camera use this kind of filter. With such a filter, you don't need any switching mechanism, however, since live vegetation has extraordinary high reflectivity to infra red radiation, you can't get good colour reproduction in under bright sun light for tree and grass.

 

Therefore, if you really need high quality image/video for day and night, you might have to use a mechanical filter switching module.

[Gator 0]

Thanks. You know a lot about lens technology. I didn't know there were lenses designed to pass that narrow spectrum in addition to the visible end.

 

I found two infra-red cut filters on ebay. One is a small element you place in front of the sensor. I've bought one to try. The other has an electronic drive to slide it back and forth. For my use, the fixed one will do. I'm using a small board camera indoors and the IR is throwing the color off a bit.

 

What is the color response for the 12mm x 0.5 lenses that are marked VIR? Are they just optimized for IR, or do they also include filtering?

 

Is there advantage to use a "megapixel" lens on a 600tvl camera?

[Baylab 0]

For any ordinary optical glass, the spectrum responses at visible and near IR band are quite similar, that why some blocking coating is needed to get good colour reproduction.

 

You can expect marginal improvement when you choose the megapixel rated M12 lens. such improvement might be unnoticeable from naked eye.

 

A real visible / IR lens should be optimized for FOCUSING （not just the spectrum response), that means, when you switch from visible light to IR illumination , there should be no noticeable focusing shift.