Hey Aperture
Photography·7 min read

Choosing your first mirrorless camera

Sensor size, autofocus, and the handful of specs that actually matter when picking your first camera.

Start with sensor size, not megapixels

Megapixel counts are the easiest number to market and the least useful one for deciding between two cameras at a similar price. Sensor size drives low-light performance, depth-of-field control, and how forgiving a camera is when you get the exposure slightly wrong — all things a beginner runs into constantly.

Full-frame sensors give you the most latitude but cost more and pair with larger, heavier lenses. APS-C (sometimes called crop-sensor) bodies are the sweet spot for most first-time buyers: meaningfully better image quality than a phone or point-and-shoot, without the price and bulk of full-frame. Micro Four Thirds bodies trade a bit more sensor size for genuinely compact bodies and lenses, which matters if the camera you own is the one you actually carry.

Autofocus matters more than it used to

Older camera-buying advice spent a lot of time on megapixels and very little on autofocus, because autofocus systems used to be fairly similar across price points. That's no longer true. Eye and subject tracking autofocus has become one of the biggest differentiators between an entry-level body and a slightly-more-expensive one, and it's the difference between a sharp portrait and a soft one when your subject is a toddler or a pet that won't sit still.

If you shoot people, pets, or anything that moves unpredictably, prioritize a body with reliable eye/subject tracking over one with a higher resolution sensor and weaker autofocus.

In-body stabilization is worth paying for

In-body image stabilization (IBIS) compensates for hand shake regardless of which lens is attached, which matters a lot if you'll eventually buy lenses that don't have their own stabilization. It's the single spec most likely to save an otherwise-good photo taken handheld in dim light.

What to actually compare when two cameras look similar on paper

Once you've narrowed to sensor size and autofocus quality, the remaining differences are mostly about how the camera feels to use day-to-day: viewfinder resolution and lag, whether the rear screen fully articulates (useful for vlogging and awkward angles, less so for traditional stills), battery life measured in shots-per-charge rather than a marketing number, and lens ecosystem — how many lenses exist for that mount, and at what price.

ConsiderationWhy it mattersSkip if…
Sensor sizeDrives low-light quality and background blur controlYou mainly shoot in bright, even light
Autofocus trackingDetermines your keeper rate for moving subjectsYou shoot mostly static subjects (landscapes, products)
In-body stabilizationReduces blur from hand shake, works with any lensYou always shoot on a tripod
Fully articulating screenUseful for vlogging, low/high angles, selfie framingYou only shoot traditional stills at eye level
Lens ecosystem sizeMore third-party and used-lens options over timeYou only ever plan to own one or two lenses

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