Auto Iris Level - what does 0-100 mean?

[PaulS]

When enabling Auto Iris, you can change the setting between 0 and 100. But what does this mean? The usual (quite useless) Hikvision manuals say "If Auto is selected, you can set the auto iris level from 0 to 100." - not very helpful....
Can anyone help, please?
At the moment I've set to 50, but no idea if this is good/bad/indifferent for night-time images but where the camera also works in daylight (normal external environment)

 

[Digilec]

 

[PaulS]

Thanks, Digilec, but if the iris is in “auto” what happens then. I thought setting it to 50 was probably a medium DoF, but what happens “automatically”? Does the camera try to maintain that DoF but this will change when light conditions change as it opens/closes? I read that an auto iris should be used on external (outside) cameras because of changing light levels, but levels can also change a lot on naturally-lit internal ones, Shirley? Thanks for your help, Digilec!y

 

[Digilec]

 

[Digilec]

Yes, you would set the target aperture and exposure level. if the scene changes the iris and shutter speed will adjust to avoid under/over exposure from light changes. The camera above has a P-Iris, see below from Axis white paper;

1. P-Iris is a new type of iris control that is both automatic and precise. Unlike a DC-iris lens, the main task of the P-Iris control is not to continuously adjust the flow of light through the lens. The primary objective of P-Iris is to improve image quality by enabling the optimal iris position to be set so that the central and best-performing part of the lens is used most of the time. This position, expressed as a specific f-number, is where the lens performs optimally, where many optical errors are reduced, and where image quality (with regards to contrast, resolution and depth of field) is at its best. This is the default setting in a net- work camera with P-Iris.

 

[PaulS]

Thanks, Digilec. I’m interested in a wide DoF (targets can be some distance to really quite close) but trying to keep the shutter speed as high as poss at night to reduce blurring but not so fast I have to increase the Gain with it’s associated noise. I’ve learnt over the last year that this is a bit of a “black art” and trial & error is needed. I’m using Hikvision, both turrets (fixed iris) and DarkFighters (variable - but not “P”).
I’ve settled on timed switching between day/night (b/w and colour) and timed switching (slight different times to day/night) between the night & day settings (mainly FPS and Gain). At night I’m down to 25fps - any lower and it seems to blur but at higher FPS the images are too dark and noisy. It does mean every month-or-so I need to adjust the timers for the difference in daylight hours, though.
Any suggestions welcome, of course.
Thanks again,
Paul

 

[Digilec]

If detection is a requirement at night then IR is fine, for faster shutter speed to avoid motion blur I would use Raytec Vario IP IR illuminators and reduce the gain control for more clarity and less noise.

For identification at night I think you need to start with a camera that provides high quality colour images with a large image sensor at 1920x1080 (higher resolutions have smaller pixels which make them less sensitive to light). again if required add a white light illuminator to further improve image quality and adjust gain/shutter speed as required.

Ultimately more light is key.

Very best,
Michael

 

[PaulS]

I've used a pair of the Hikvision DarkFighter (1x2M and 1x3M) in key areas and there is some light available. The full-colour seems to struggle but B&W seems OK.

I've come to understand the limitations of "reasonably" priced cameras at night (basically they aren't capable).

I appreciate your input; thanks.