lens aperture selection (2 replies and 1 comment)
which opening do you prefer at night?
Is there any quality change to the image when we shoot in full open than above apertures like 4 or 5.6?
There is no such rules which is apt for day or night. It's all belongs to personal choices. Difference in aperture change the depth of field. Higher the opening results shallow depth of field. Basically during night scenes all prefer higher opening for reducing noise in the image.
Wider apertures alone don’t reduce noise unless the extra exposure allows you to select a lower ISO.
You pick an f-stop to light to based on practicality, what you are balancing to (if your scene is partially lit by practical sources with certain light levels), and the amount of depth of field you want, either for aesthetic or storytelling reasons, or practicality again.
As for technical quality, most older lenses are a bit sharper closed down two-stops from wide-open but many modern lenses are still pretty sharp wide-open, that’s not a major concern. However focus-pulling is a lot more critical when shooting wide-open so obviously if the shot is out of focus there is a visible drop in technical quality.
Some people believe that the image has more contrast as you stop down and again, while a few lenses might get slightly milkier wide-open, and flare more, most of that issue is perceptual — if the image has shallow-focus then the highlights and shadows in the out of focus areas will blur together and look lower in contrast. But the contrast of the subject in focus doesn’t really change.
There is also a lighting issue in that at wide apertures and/or high ISO’s in low light, the camera picks up more ambient light in the shadows that would normally drop off or be overpowered when lighting to higher levels, so again, the contrast levels might change even if the contrast of the lens hasn’t changed.