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WarrenM

lens - DC and ESC

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I have done quite a bit of searching and haven't come up with any good explanations of what they do and why one would be preferred over the other in different settings. Would someone care to talk about the two.

 

My interest stems from a camera (vbm-24vf) placed in a shadow looking into a sunny spot. It looks better in daylight with the DC brightness turned down a bit but if it is turned down a couple clicks past default the camera won't switch back from B&W at night to day. I haven't tried ESC mode yet..... thought I would ask before wearing my screws out

 

Thanks

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DC refers to the DC-voltage drive for an auto-iris lens. If you dial down the lens aperture too much, the image won't get bright enough again for the camera to switch out of night mode.

 

ESC is Electronic Shutter, which to put it simply, controls brightness by electronically adjusting how much light the sensor collects.

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Is DC default because it is generally better then ESC... or when would someone want ESC. I couldn't tell the difference in them but haven't tried it over a 24 hour period to see all light levels.

 

Thanks.

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With ESC, you always have the same amount of light hitting the sensor... the only thing that changes is the time period where the image is "read". If you open a manual iris all the way up to let more light in at night, it may be getting TOO MUCH light during the day, and the image will be washed out, since the sensor does have a limit on how much light it can handle.

 

With an auto-iris lens (there's a "video" type as well, but "DC" is far more common), the lens iris is opened and closed automatically in response to changing lighting conditions, thus allowing a greater range of light to be handled properly.

 

Think of it this way: assume your light can vary from 0 (pitch dark) to 100 (a white surface in direct sunlight). Now assume your sensor can handle a range of 0 to 80. If you put a lens that lets the full amount of light through, any brightness over 80 will just be washed out. If you close the lens's iris down so it reduces the 100-level light to 80, then anything below 20 is effectively lost, and everything else in between is reduced by 20, so as things get dimmer, you lose detail. (Note: this is HIDEOUSLY over-simplified, light levels and sensor response both being anything but linear, but you get the idea, I hope.)

 

With an auto-iris lens, the lens can close down automatically in bright light to reduce the maximum light to whatever level you set, and then open again when it's dim to let the maximum through.

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i am gonna resurrect this post, i have been having the same problems with my cnb vcm-24vfs, the image that i get during the day, looks very detailed, BUT, the items in the image has a blooming effect, not very detailed...

 

i have tried very hard to correct this issue, i stumbled upon the same settings as the original poster did, i set it to DC, and lowered setting below default, sure enough the pictured looked light years better, but the next morning the cameras wouldn't switch back to color, which was very disappointing...

 

i have even considered hiring someone to come and setup the cameras, i refocused several times, that didn't help, so i know its not that, its the settings of the camera..

 

can the camera be left in ESC, will that provide a better image, more detail?

 

any input would be greatly appreciated...

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Bumping this to the top, in hopes of an answer, I am just now tinkering w/ my first VCM, and want to know more.

i am gonna resurrect this post, i have been having the same problems with my cnb vcm-24vfs, the image that i get during the day, looks very detailed, BUT, the items in the image has a blooming effect, not very detailed...

 

i have tried very hard to correct this issue, i stumbled upon the same settings as the original poster did, i set it to DC, and lowered setting below default, sure enough the pictured looked light years better, but the next morning the cameras wouldn't switch back to color, which was very disappointing...

 

i have even considered hiring someone to come and setup the cameras, i refocused several times, that didn't help, so i know its not that, its the settings of the camera..

 

can the camera be left in ESC, will that provide a better image, more detail?

 

any input would be greatly appreciated...

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i am gonna resurrect this post, i have been having the same problems with my cnb vcm-24vfs, the image that i get during the day, looks very detailed, BUT, the items in the image has a blooming effect, not very detailed...

What are the DNR and SBLC settings?

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