Can someone please educate me on the Dahua Exposure settings? :)

TheE

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My question within the exposure settings deal with "Manual" and "Shutter Priority". Basically which one should I use, and please educate me on why they seem to act in the opposite way.

Within "Shutter Priority" when I lower the shutter, the picture gets brighter as I believe should happen when you lower a shutter speed. But, in "Manual" everything is opposite -- the higher number brightens the image and the lower numbers darkens the image.

Any input or suggestions to dummy this down for me so I can understand what's happening would be greatly appreciated.

Thanks for your time!
 

Mike A.

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It's similar to setting priority modes and ISO with a DSLR if you're familiar with that.

- In Auto mode, it selects shutter and gain (not truly so but gain being basically equivalent to ISO for explanation purposes here).

- In Shutter Priority mode, you set the shutter speed, it adjusts the gain to try to best accommodate that setting.

- In Gain Priority mode, you set gain, it adjusts the shutter.

- In Manual mode, you directly set both.

Just checked one of mine and I don't see the "opposite" effect that you describe in Manual mode. If set to say 1/30 and with all of the same settings otherwise, as expected it's a brighter image than if set at 1/120. Could just be a quirk in whatever firmware.
 
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Rebelx

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But, in "Manual" everything is opposite -- the higher number brightens the image and the lower numbers darkens the image.
That's correct. Higher shutter speed will reduce exposure ie brightness. Lower shutter opposite.

I suspect the gain adjusts the aperture of the lens. I could be wrong. Higher aperture number reduces light in photography. Gain could otherwise mean ISO in which case higher numbers will make the image brighter but more noisy.
 

Mike A.

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I suspect the gain adjusts the aperture of the lens...
Gain is an amplification of the signal that's more similar to ISO.

Not clear on exactly how aperture works in these cams myself. Physically it's fixed so there is no true variable aperture (at least on most all typical cams). At least at one time they called what now is labeled Gain Priority "Iris Priority" which would be the same as aperture priority in a DSLR/film camera:
"Iris Priority: Prioritizes the iris setting (aka F Stop) and automatically adjust the shutter"
Which makes me think that there is no aperture setting at all beyond the cam as it comes, it's just using gain as a way to simulate some general equivalent in terms of light level/sensitivity.
 
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Rebelx

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Physically it's fixed so there is no true variable aperture
I see thanks!

In that case only ways to change the exposure(brightness) is to change shutter speed or gain (ISO equivalent).
 

Mike A.

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I see thanks!

In that case only ways to change the exposure(brightness) is to change shutter speed or gain (ISO equivalent).
I think that's right. All being digital/electronic equivalents. You can directly alter "shutter" and/or gain. Then there are the various image settings for brightness, contrast, gamma, etc., noise reduction(s), and IR and other compensations (BLC, HLC, etc.) which work on top of that to digitally enhance the image.
 
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