# How can I get a large depth of field at night?

I am new to photography and have a question on aperture. What if I wanted to take a picture with majority of the picture in focus, but at night time, so I can't have the aperture too high, because it's focus would be narrow, but I can't have the aperture too low, because it wouldn't allow much light, resulting in a dark image ? How would one balance this ? Can you balance this ?

• Photography is the art of choosing compromises in a way that reflects your vision. Nov 29, 2023 at 21:05

Depending on the subject you can add more light, in the case of interior photography. That is what flashes and continuous light are made for.

But on an exterior, you use a slower shutter speed and a tripod. You can also use a higher ISO, but the time the sensor or film is exposed is the basic option.

Considering aperture alone, the only way to "balance" the tradeoffs aperture changes incur is a technique called hyper-focus; which is a balance of focal length and subject distance to manage the depth of field.

For this example I'll assume you have an APS-C camera. If you have a 50mm lens set to f/16 the hyperfocal distance is ~ 25ft. And if you focus at 25ft everything from 12.5 ft to infinity will be w/in the depth of field (acceptably sharp; not critically sharp). If instead you use f/8, the hyperfocal distance is 50ft and DOF extends from 25 ft to infinity.

Those numbers are just a SWAG using the Focal length as a percentage of itself at f/16... i.e. 50% of 50mm = 25ft @ f/16. If you use a shorter FL the hyperfocal distance is closer. E.g. 40% of 40mm = 16ft. Or even easier, just drop a zero from the FL; e.g. 4x4=16.

If you have a different size sensor you need to start with a different aperture; e.g. f/11 for 35mm/FF, f/22 for M4/3. And because it is a SWAG, and judging focus distance is difficult, you want to error by focusing a little long if the near DOF is important.

You can also use an app on your phone or online to calculate the hyperfocal distances for your lenses at various apertures... I've known some that have put that information on the lens cap for select apertures.

How would one balance this? Can you balance this?

You do it by balancing your camera and lens on a stable mount, such as a quality tripod. This allows one to extend the exposure time far longer than would be practical when holding the camera by hand.

You then use a technique to release the shutter that doesn't induce camera movement. I prefer a wired remote shutter release. Some folks prefer wireless remotes. Others use the camera's self-timer or built-in intervalometer, if the camera has one. All have their own sets of advantages and disadvantages.

There is yet another approach specific to digital photography,stacking.

The idea behind stacking is that multiple (sometimes a whole lot) of pictures are taken and the multiple pictures are digitally aligned stacked and merged into one picture.

Depending on the techniques and algorithms used, stacking can:

• Act like a long exposure (without a tripod)
• Denoise many high ISO shots to produce an equivalent low ISO result
• Stack slightly different focuses to produce a high depth of field result

With DSLR cameras, this requires post processing many images on a computer to produce these stacked results.

Have you ever noticed that friends with high end iPhones seem to be able to take better pictures in low light without even trying? This is because the iPhone is actually taking multiple pictures and stacking them in-camera without you ever even realizing what it's doing.

I can't have the aperture too low, because it wouldn't allow much light, resulting in a dark image

Well, then you just use a longer exposure duration of course (i.e. slow shutter speed) – to allow more light into the camera over time. Or a higher ISO setting – to make the sensor more sensitive to the (low levels of) light coming in.

Exposing correctly at any time requires balancing aperture, shutter speed and ISO against the light levels in the scene. If you have to use a particular aperture value due to other requirements (here, depth of field), then you just use other variables to balance the exposure.

The rule of thumb around shutter speed is as follows... Get the reciprocal of your focal length (e.g. focal length of 50mm, the reciprocal would be 1/50). Now, if your shutter speed reaches 1/50 or longer, this is likely to be too long to hold steady without assistance. So, this is where a tripod (or a beanbag resting on a wall, etc) comes in handy.

There's no rule of thumb necessarily around how high you can set your ISO before noise in the image reaches unacceptable levels. For this, you're going to have to use some trial and error yourself, to see what ISO settings are acceptable for you, or search online for what other users of your particular camera model find acceptable.