Camera Specs Explained: Megapixels, Aperture, Sensor Size and Zoom

The camera row on a spec sheet is the most over-read and least complete part of it. Megapixels get the headline, aperture appears as a cryptic fraction, sensor size is usually missing entirely - and none of those numbers, alone or together, tells you how good the photographs will be. This guide explains what each number measures, what is missing, and how to compare two phones without mistaking a big number for a better camera.

Megapixels, honestly

A megapixel is one million pixels. More pixels means more raw detail to work with and more room to crop - it does not mean a better image, because pixel count says nothing about how much light each pixel collects.

The distribution across our database is instructive: of the 47 phones we track, 32 record a 50MP main camera, 11 record 48MP, two record 200MP (the Samsung Galaxy S25 Ultra and Galaxy S26 Ultra), and one each records 64MP and 12MP. The headline resolution of a modern phone camera is therefore remarkably uniform - the differences that matter sit below it.

Two mechanics explain why the headline number misleads:

• Binning. High-resolution sensors normally combine groups of adjacent pixels into one larger "super pixel" at capture time, so the photo you share is typically around 12MP regardless of whether the sensor holds 50 or 200 million pixels. The extra pixels are used for zoom cropping and detail merging, not for a larger output file by default.
• Pixel size. Larger individual pixels gather more light, which is what improves low-light performance. Pixel size is rarely published for phones, so it cannot be compared from the sheet - treat it as unknown rather than assuming a 200MP sensor with small pixels beats a 50MP one with large ones.

Aperture: what the f-number means

Aperture is written as f/1.4, f/1.8, f/2.4 and so on, and a smaller number means a wider opening - more light reaching the sensor. Across our database, main-camera apertures run from f/1.4 to f/1.9, with f/1.8 the most common (15 phones), followed by f/1.7 (10) and f/1.6 (8).

The important caveat: the f-number is a ratio of the opening to the focal length, so it does not account for sensor size. An f/1.8 lens on a small sensor collects far less light than f/1.8 on a large one. Aperture is one input into exposure, not a light-gathering score on its own - and on phones it is often fixed, so there is nothing to adjust.

Sensor size: the number that is missing

The sensor is the part that converts light into the image, and its physical area is one of the strongest predictors of image quality: more area means more light per shot and a shallower, more natural background blur.

Phone manufacturers almost never publish sensor dimensions. That absence matters when comparing: if a specification is not on the sheet, it stays unknown. Our methodology records what is published and leaves everything else blank rather than estimating - which is why the camera rows you can see are comparable and the ones you cannot are simply not claimed.

Zoom: optical, digital and the line between them

• Optical zoom moves physical glass to change focal length, so detail is preserved.
• Digital zoom crops into the sensor and enlarges, which costs resolution.
• Hybrid zoom crops and then applies processing to rebuild detail - usable, but not equivalent to glass.

In our database, 24 of 47 phones record a telephoto camera, and the telephoto rows carry their own megapixel, aperture and zoom factor - for example the Asus ROG Phone 8 records a 32MP f/2.4 telephoto with 3x optical zoom. The main lens's own optical zoom field is recorded on only four phones, so a blank there does not mean a phone lacks zoom; it means the figure was not published. Check the telephoto row instead.

Stabilisation and video

Optical image stabilisation moves the lens or sensor to counter hand shake - it helps both stills in low light and video smoothness, and it is worth checking for on any phone you plan to shoot video with. Video ceilings are recorded per phone: the iPhone 15 records 4K at 60fps with Dolby Vision, while the Asus ROG Phone 8 records 8K at 24fps. Resolution and frame rate are choices, not a ranking - 4K60 is the practical format for most people, and high frame rates matter more to you than8K if you shoot action.

What actually decides the photo

Photographs are produced by a chain: sensor and lens gather the light, stabilisation keeps it steady, and processing decides how the scene is rendered - high dynamic range stacking, night-mode merging, subject segmentation, colour tuning. Two phones with identical sensor specifications can produce visibly different images because the processing at the end of the chain differs by manufacturer and by generation.

This is why hardware sheets cannot rank camera systems. They can tell you what is fitted; they cannot tell you how it is calibrated.

How to compare cameras honestly on our site

Our Spec Comparison puts the published camera rows side by side: main, telephoto, ultrawide and front cameras with megapixels, aperture and optical zoom, plus video resolution and frame rate. Three rules keep that comparison useful:

• Never treat a blank as zero. A missing aperture or zoom figure means not published, not absent.
• Do not use megapixels as a quality proxy. 200MP against 50MP is a cropping-capability difference, not an image-quality verdict.
• Leave image quality to testing. We record specifications and their sources - we do not run camera tests, and we do not publish scores. For how photos actually look, consult independent reviewers who shoot the same scenes with both phones.

Start with the Spec Comparison for any two models in the database, then read the telephoto and video rows - those, more than the headline megapixel count, separate a camera system you will use from one you will not.