Photo — Exposure, plainly

#photo/basics · Note 2 of 7 · part of Photography

Three controls, and each one costs you something other than brightness. That second effect is the entire craft.

Aperture

Smaller f-number = wider opening = more light and less in focus.

• f/1.8 — maximum light, paper-thin focus. At close range on the 35mm, you can miss focus between an eye and an eyelash.
• f/2.8–f/4 — a usable compromise; the lens is also getting sharper.
• f/5.6 — about the sharpest this lens gets. See Photo — Peak sharpness.
• f/11+ — diffraction starts softening everything. On 24MP APS-C the losses are visible past roughly f/8–f/11. Stopping down further does not "add" sharpness.

Shutter

The rule of thumb for handheld sharpness is 1 / (focal length × crop factor). For the 35mm on the R50: 1/(35 × 1.6) ≈ 1/56, so round to 1/60.

That is the floor for camera shake with IS off. Subject motion is separate and usually stricter:

• Someone standing still: 1/60
• Someone talking, gesturing: 1/125
• Walking: 1/250
• Kids, dogs, sport: 1/500 and up

The lens's IS buys you several stops on the first number only. It does nothing whatsoever for the second.

ISO

Raise it last, but raise it without guilt. A sharp, noisy photograph is a photograph; a clean, blurred one is not.

On the R50, roughly:

• 100–800 — clean, use freely
• 1600–3200 — very usable, especially from RAW
• 6400 — usable, wants noise reduction
• 12800+ — emergencies, and modern AI denoise makes them surprisingly viable

The order I actually set them

1. Aperture first — it is a creative choice about what is in focus.
2. Shutter second — set the floor the subject demands.
3. ISO last — let Auto ISO fill the gap, with a ceiling set.

In practice that is Aperture Priority (Av) with a minimum shutter speed and an Auto ISO ceiling of 6400. That covers most of what I shoot without touching a dial.

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