Question about Aperture for Low Light

PhoT0GR@p3R · Aug 7, 2023

I have a question regarding aperture. If I have a lens that has a larger aperture at 2.8 and I am at a low light situation do I open it up all the way to account for the lower light? For example if I am doing a night city scape shot and I am using a tripod I would want to go to a lower aperture to capture the most detail and increase my shutter speed to compensate for the lower light I know I am ok.

Now if I don't have a tripod or want to make the foreground say a railing in front of me blurry and focus at a wider aperture at the horizon to make that the focal point, will the shot come out ok if I can get away at a shutter speed fast enough not to use a tripod (with inbody stabilization)?

I understand that a wider aperture will give me a shallow depth of field, but I also want to know how to apply it properly in a low light situation. Here are some shots I took in Paris last month on vacation in the catacombs underground with low light. I went with the maximum aperture that I could get away with at the focal length setting. [Nikon D5300 18-55mm VR II kit lens]

ISO 2500 18mm f/3.5 1/13 sec

ISO 2500 18mm f/3.5 1/13 sec

ISO 2500 48mm f/5.3 1/20 sec

Ozzie_Traveller · Aug 7, 2023

G'day Traveller

As a series of generalisations go ...
Every lens will show its best corner-to-corner sharpness in the middle of its aperture range. So your current lens will give you its best sharpness in the F8 area. Away from these apertures the lens will give good sharpness in the centre and (under a microscope) that sharpness will fade a bit as you move towards F2,8 at one end or F22 at the other end of the aperture range

DoF is another matter altogether, and you choose DoF as a matter of priority when needed / or not needed, and live with the sharpness that the lens gives you along the way

Once you are on a tripod, the need to -always- use F2,8-F4 apertures is less needed as you can extend the shutter time quite easily, and so F8 - F-16 even for a night pic is quite acceptable

Just a tip for tripod pics of street scenes ... because the scene contains more 'dark bits' than 'bright bits', the camera will try to brighten up the dark bits and they will / may turn a 'mushy-black' colour. I get best street scenes by setting the EV+/- to minus 1, and then the dark bits of the street scene stay dark

As to your pics above-
They seem okay and are probably very similar to ones I would get if I were there alongside you

Hope this helps
Phil

Grandpa Ron · Aug 15, 2023

I have run the ISO up and and shot photos by moon light, albeit a bit noisy. I always have a tripod handy, but when I am walking or sightseeing, I use my hiking staff as a mono-pod.