Are There Are Any Surveillance Cameras / Lens Over 140° But Less Than 180°?

JH
John Honovich
•Aug 10, 2014
IPVM

I am curious if anyone knows of such products. I can think of a handful of ~130° cameras but none over that until one gets to 180°

This is not a practical need for us, but we are going through the design of the camera calculator and are trying to determine if we should simply remove / disable say 136° to 179°?

Also, related, you might have noticed the math for 180° cameras is wrong, because we assume straight lines between the AoV endpoints. However, we are going to switch this to the circumference of a circle which matches our test results.

Avatar
Carl Lindgren
•Aug 10, 2014

John,

I don't think so. The widest SD lens I've ever seen is a Fujinon 1.4-3mm and the widest MP lens would be Theia's 1.8-3mm.

We used to have some 0.7x lens convertors for medium-wide-angle 1/2" or 2/3" lenses when I first started my job nearly 17 years ago but I can't find them for CCTV lenses anymore - just for digital cameras.

RW
Rukmini Wilson
•Aug 10, 2014

Widest "pro" found was the 1.3mm Theia at 135° 

Widest Non-pro was a 2.1mm at 160°

 

Which I might have dismissed totally except for the fact that it might be used in this well-known brand's product line:

Avatar
Carl Lindgren
•Aug 10, 2014

Widest "pro" found was the 1.3mm Theia at 135°

Odd, 1.3mm does not translate to 135° on any lens calculator, including IPVM's. Taking IPVM's calculations for a 1/3" sensor, the HFoV would be 123°; for a 1/2.7" sensor, it would be 132° and for a 1/2.5" sensor, 131°. But that wouldn't make any sense since the HFoV should get wider with the larger 1/2.5" sensor.

On point, other calculators, including Theia's own, say that to obtain a 135° HFoV requires a 0.99mm lens for a 1/3" sensor, 1.21mm for a 1/2.7" sensor and 1.19mm for a 1/2.5" sensor (or thereabouts).

Widest Non-pro was a 2.1mm at 160°

That demonstrates how FoV figures are typically "fudged". It is absolutely impossible for a 2.1mm lens to have a wider FoV than a 1.3mm lens.

JH
John Honovich
•Aug 11, 2014
IPVM
In reply to Carl Lindgren

I agree that calculators have problems predicting certain lenses, especially those with short focal lengths.

The AoV equation is a linear function with focal length and imager size being the inputs. Evidently, this does not match reality at the low end.

Our planned solution is to add a directory of specific cameras / lens models so people can pick the specific one they want and know the AoV is accurate.

RW
Rukmini Wilson
•Aug 11, 2014
In reply to Carl Lindgren

That demonstrates how FoV figures are typically "fudged". It is absolutely impossible for a 2.1mm lens to have a wider FoV than a 1.3mm lens.

I would tend to agree since focal length and FOV are normally described as inverse relations.

But wide-angle lenses are different because they have significant distortion which can vary greatly depending on whether they are curvilinear (fisheye) or rectilinear (ultrawide) or somewhere in between. Looking at these pictures from Theia's site shows how what is technically nearly the same FOV, but having vastly different distortion, originating from two different lens architecures (with different focal lengths.) 

Ultrawide  Fisheye 

In short using a stock lens calculator on these lenses is a little like measuring your height in a "House of Mirrors". Not to say there's no fudgery going on also, though.

SU
Stanislav Utochkin
•Sep 19, 2014

Standard lens calculators are useless for wide-angle lenses. The reason of this is a difference in technology of lenses with the same focal length. Different technologies produce different distortion levels. Thus wide angle lenses should be tested with measuring their real angles. Many manufacturers give real measured angles in lens specifications. This is good practice. Having these angles we can use them in modeling and designing.

JH
Jim Hall
•Oct 09, 2014

Computar TG2Z1816FCS Lens

JH
Jim Hall
•Oct 10, 2014

Pelco 13VA1-3 Lens

Claiming 84 to 180 degree vari-focal. I dunno who really makes it..

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