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What does 4~9mm Vari-Focal DC Auto Iris Model mean?

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The cameras I am interested in come with a 4mm lens standard, but can be upgraded to a 4~9mm lens. Most cameras have a 3.5mm lens. How much wider of a view will a 9mm lens give, and does this mean the camera angle can be changed by turing the lens? Thanks.

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Sorry VST_Man....I think you meant to say 4mm is wider than 9mm?

 

The higher the focal length of the lens, the narrower the field of view & the larger the target appears.

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Yes, a 4mm is wider than a 9mm. I think VST knew that, he just needs grammer check...

 

Also when comparing cameras, make sure your comparing a 1/3" sensor to a 1/3" and not a 1/4", and vice versa.

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ok, now I'm confused. I want the view from the cameras to be a wide angle. In that case, do I need a 4-9mm variable lens, or just the 4mm lens? I only need the 4mm lens, right? 9mm would give me a more narrow view, correct? Are there any examples on the net of what different mm lenses look like in actual pictures? I have found a few that show frames per second on video, but I have never found examples of what the picture looks like with various size lenses.

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If the price difference is small then get the vari-focal since it gives you more flexibility in setting your scene width. Otherwise if you just want the widest angle stick with the 4mm.

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LOL, that 3.6mm looks like a 2.8mm, only flipped ..

normally the roundness is the other way around ..

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