Night Time Aperture

[DisneyDetective]

In regards to the aperture while taking night time photos, does it change ie is it near impossible to take a photo with the foreground object in sharp focus and the background is blurry?

 

[ukcatfan]

The time of day is not directly relevant to the aperture you use, but it might typically be the opposite of what you think. Opening the aperture allows for faster shutter speeds and makes the depth of field shallower. Use the aperture you want and then adjust the shutter, ISO, and flash use to get the shot you want.

 

[zackiedawg]

Exactly - as UKcatfan says, the aperture properties remain the same whether it's day or night, and a lens' ability to render shallow depth of field remain identical day or night. If you can get a nice sharp subject with a nice out of focus background with a particular lens during the day, and try it at night, with the same aperture settings you can get the same result.

It mostly comes down to what you are trying to achieve...when doing night exposures, many people favor the saturation, the color, and the light streaks that long exposures provide, but with a wide open fast aperture, you can't expose for as long since you're bringing in so much more light. But sometimes you may go out with the expressed goal of achieving night photos with shallow depth of field, in which case pick a lens with a fast aperture and good out of focus qualities, and have fun. A few quickie examples I've tried at night with shallower depth of field:

 

[DisneyDetective]

Thank you very much for your help!!

 

[boufa]

Never mind... I had a great explanation of depth of field, and shutter speed, etc, but after re-reading a post that read like a first graders homework, I decided to delete it. Sorry. The long and short is that when you have the lowest f stop you can use to hand hold the camera AND freeze the action, you will very unlikely have so small of a depth of field to get anything other than most of the parade float in focus.

The only offset to this, and it is somewhat limiting, is that you could use a high ISO. This will give you a few more stops of shutter speed, which will allow you to change the apature. Even a tripod will not help, because while you would gain the ability to get the depth of field you want, anything in motion will blur due to the parade moving.

There is 1 other option... you could set up a tripod and take photos of the parade, using a decent shutter speed. Then without moving the tripod or the camera (this is critical) you could take the background photo with a longer exposure (after the parade is over). Then combine the 2 images in post production.