1/4" vs 1/2" lenses

[martinibianco 0]

Hello

 

Are there any technical disadvantages/restrictions if a CCTV camera with a 1/4" instead of a 1/2" lense is used?

[survtech 0]

The lens should match the camera. If you were to use a 1/4" lens on a 1/2" camera, you would see a "tunnel effect" on the screen, meaning the picture would not fill the whole screen; it would appear as a round picture within the rectangular screen. The bigger the difference between lens size and imager, the smaller a fraction of the screen would be filled.

 

On the other hand, you can use a 1/2" lens on a 1/4" camera. The amount of light passed to the imager would be less but a 4mm 1/2" lens, for instance, on a 1/3" camera would show the same field of view as a 4mm 1/3" lens.

 

Also watch out for "C" mount vs. "CS" mount lenses and cameras. You can put a "C" mount lens on a "CS" mount camera if you add a 5mm spacer (CS Adaptor). You can't, however, use a "CS" mount lens on a "C" mount camera under most circumstances.

[martinibianco 0]

Thanks a lot for the answer.

I'm comparing CCTV cameras with 1/4" lenses to cameras with 1/2" lenses, not to change the lens on a camera from 1/4" to 1/2". The cameras I'm looking at are either 1/4" or 1/2" - one system.

 

I rather have the feeling that 1/2" cameras will somehow be phased-out and only 1/4" CCTV cameras will remain on the marked.

 

So what is the difference between these two systems? Is a 1/4" camera better or worse compared to illumination and other technical data?

 

 

Thanks a lot in advance and best regards

[ClosedCircuitCom 0]

the larger the imager the better picture you will get

[survtech 0]

the larger the imager the better picture you will get

Not necessarily! There are 1/3" cameras that are better than most 1/2" cameras. Few, if any, companies have put any recent development work into 1/2" and larger cameras except megapixel; and those are mostly CMOS, rather than CCD.

 

What I assume you mean is that you are comparing cameras with a 1/4" imager vs. a 1/2" imager. For most applications, I would choose a 1/3" camera as the best balance between cost and capabilities. 1/4" cameras typically don't perform as well and 1/2" may or may not, depending on the type and manufacturer. And you are right, I doubt that 1/2" analog cameras will be much of an option in the future.

 

For instance, Ganz discontinued their 1/4" domes (ZCD3000 series), in favor of 1/3" domes (ZCD5000 series).

[CameraGimp 0]

Assuming you are looking at imagers from the same family the only difference if the imagers are different sizes is sensitivity.

 

They are built the same, they have the same number of pixels so a bigger sensor will have bigger pixels and that will be more sensitive.

 

Obviously comparing a 1/4" Exview to a 1/2" CMOS isn't fair and all bets are off.

[ClosedCircuitCom 0]

ikegami continues to produce cameras with a 1/2 ccd and continues to build on them

[survtech 0]

You're right, they are one of the very few. So does Watec/Genwac and a few others. We really like the Ikegami cameras - excellent low light and AGC characteristics and a 10-year warranty on many. Our only issues are their color (most are white) and their odd size, similar to the Sanyo "cube".