What makes a good smartphone camera?

There are lots of things that affect the quality of photographs. The biggest one is the skill of the photographer behind the camera.I don't have any tips for that, so for the rest of this blog I'll be looking from an unfeeling perspective at camera hardware and technology.Perspective of this postA phone photographer is likely a tourist and family member who mainly wants to record memories, like landscapes they saw and people they know. They are not an artsy photographer using creative techniques or playing with light to make unusual shots for an art gallery. These two goals may conflict.As a basic example, the artsy photographer may actually want certain elements in the shot to be out of focus, to draw attention to what's left. Meanwhile, the family member wants everything to be in focus so they can clearly identify the people, place, event, and reminisce on the occasion in years to come.Also, I won't be discussing videos today.IntroductionSmartphone cameras are often advertised in terms of their megapixels, but other technical attributes are far more important for the visual quality of a photo. There's also some things to consider to do better with the camera you already have.Blur from grimeIt's better if the picture is clear. I'd wager that if you took a photo on your phone and looked at it and it was blurry, you'd be irritated and want to re-take it.With smartphones, the most common cause of blurry pictures (or streaks of light across them) is because you got fingerprints or oil or dust or food or anything on the glass. It's easy for a phone lens to collect grime over time. Always wipe the glass before taking a photo! If you don't, you'll see a general blurry mistiness, and lights create diagonal streaks.This is an extreme example because it was raining straight onto the glass, but it matters for regular pictures too. Taken by me, July 2025.Blur from focusIf parts of the photo are out of focus, they will be blurry. Smartphone cameras have excellent autofocus and a wide depth of field, so usually this is fine, but here are some things to watch out for:Tap on your subject to make the phone focus there. If it's a person or animal, tap on their eyes. For general scenery the phone should figure it out for you.

There is a minimum focus distance of several centimetres. If you're photographing something really small, like a mushroom, beetle, or flower stamen, you may need to move back a little to get it in focus at all. The minimum distance changes when you zoom, so try a few different zoom levels.Many phones' front-facing cameras have fixed-length focus instead of autofocus. If this is the case, you won't be able to take close-up or landscape photos with the front camera, and tapping won't make a difference.Blur from movementIn the darkness, your camera will need to use a longer shutter speed (that means capturing light for a longer period of time) to get more light for the photo to look bright enough. Any movement (of you or your subject) during this time will be blurred. You can solve this by holding the camera really steady (prop the long edge on a flat surface if possible) and telling your subject to stay put.It doesn't speak English. 1/7 shutter speed, taken by me, Jan 2026If your subject can't stay put, take lots of photos. Afterwards, you can select the best one where they happened to remain still.DetailThe raw light values seen by the camera sensor have a lot of noise or grain in them, but you don't see this in the photos that are saved. Here's an example:taken by me, March 2026The end result looks fine, but if I go back to the raw light values seen by the camera sensor and zoom in on the guy's blue puffer jacket, here's what that looks like:close-up of raw image with no noise reduction, 2:1 pixel zoom, ISO 800, AMaZE demosaicingIt's all fuzzy! What gives?All of the circuitry controlling the light-sensitive elements picks up some amount of background noise.By photographing in bright environments, there's lots of light available, which "drowns out" the comparatively small amount of noise, giving you a clean looking photo. But when photographing in dark environments, there isn't much light to go around, so the natural noise in the sensor has a much greater impact.

Regardless of how much noise there is, you won't get to see it in your finished photo, because the camera will automatically process the image and do noise reduction to try to make it all smooth instead of grainy. Here's a before/after of that close-up with noise reduction applied (settings manually tuned):2:1 pixel zoom, left: AMaZE, right: noise reduction + VNG4Much smoother! But that's the problem: smoothing it out loses some of the detail. Looking closely at a different part of the photo, you can see that some of the detail of the veins in the leaves has been smoothed over, crunched, smudged, and lost:2:1 pixel zoom, left: AMaZE, right: noise reduction + VNG4Often, it's possible to retain detail while smoothing over the noise, but it really depends on how noisy the photo was to begin with. If there was more noise, it's a lot harder to recover detail and much more likely that things will look smudged. Noise is an issue in the following situations, when there's not enough light:Darker environment, less light to go aroundYou might be able to move closer and zoom out (which makes the smudging less apparent), use flash for extra light (best indoors), or wait for a brighter moment (e.g. clouds covering less of the sky). If your phone has a "night sight" mode, try that out! It uses exposure stacking to take multiple frames and add them together, combining the light from each one. Remain very still for best results.Physically smaller camera sensor, less light hits itThe camera sensor is a physical thing. It reacts to photons hitting it. If the camera sensor is physically larger, that's a bigger "catchment area", so more photons will randomly hit the sensor as they're bouncing around.The biggest sensors are found on big boy cameras, but even within smartphones, there's still a lot of variation in camera sensor size. That has a huge impact on how much detail your photographs have.Comparison of different phones. Both are 1:1 pixel zoom, 3x telephoto, extremely close focus distance.In these zooms, you can see that the top picture generally looks okay.

There's a decent amount of contrast, you can see the depth in the plant matter, and there's fine detail visible on the wriggly brown bits (at least on the parts that are in focus). However, the bottom picture is a lot more fuzzy, has less detail, no crisp edges, and generally looks flatter and worse overall.Why are they so different? They have a lot in common: both smartphones with the 3x lens, both 12 megapixels, and both use Samsung-brand sensors. The big difference, and the cause of the poor quality, is the sensor size. The top picture was taken with Nothing 3a Pro, which has a sensor size of 1/1.95" (big). The bottom picture was taken with Samsung S24, which has a sensor size of 1/3.94" (small). Here's what that looks like visually:Not actual size (but to scale). The telephoto sensor in the Samsung S24 sees 4x less light than the telephoto sensor in the Nothing 3a Pro.4x less light means 4x more noise, which means lots of detail will be lost from having to do 4x as much noise reduction. The sample above was in good daylight conditions, and it's much worse at night. For some night samples and more information about why sensor size matters, watch this really excellent video by Simon Bernlieger. If you're looking to buy a new phone, the same man has a smartphone buying guide based on sensor size.MegapixelsPixels are the individual coloured points that are recorded into the image. Megapixels counts these in millions. Remember that since images are two dimensional, if you make it 2x taller and 2x wider you have 4x the megapixels. Here's some numbers for scale:MegapixelsComparison2"HD" 1080p YouTube video4Phone screen84K TV screen12Phone cameras (on default settings)16-40Mid-range dedicated cameras50Phone cameras (on max settings)200Certain high-end phone camerasWhy more megapixels in camera than screen?So if you had an 8 megapixel image on a 4K TV, it would look sharp.

If you had a 50 megapixel image, it would still look like 8 megapixels because that's all the TV can display, it wouldn't show any finer detail.So why do they make cameras with lots of megapixels if you can't actually see them all on the screen? To let you zoom in without losing detail. If you have a 12 megapixel image and a 2 megapixel screen, you'd be able to zoom in to show a small part of the image without it being blurry from resolution issues.Looks great!This is especially important for phone cameras, because the only way they can zoom is by cropping off the edges. If they start with a lot of megapixels, they'll still have some left after you've zoomed in.It's also good to have more megapixels if you plan to print your photos, because printers are higher resolution than screens.So more megapixels, more zoom, more better?Not necessarily. The extra pixels only matter if they display useful information. If your image is blurry to start with, it doesn't matter how many megapixels you have - they're all going to be blurry. This means megapixels only matter if you've already cleaned the lens, held still, and got enough light in the shot to avoid losing detail due to noise. Consider this very green cat:Photo and cat provided by a friend, used with permission.This photo is 16 megapixels, which should theoretically look great on any display. But even just opening it without zooming you might be able to spot some technical defects straight away. Several parts of the cat, especially her fur, look smudged and not full resolution. The smudging is very apparent if you zoom in and look at the bridge of her nose, the fur below her chin, or her right eye (considerably noisier than her left eye). These pixels are easily covering your display, so you might expect the photo to look sharp, but since they're displaying blocks of colour instead of useful information, counting megapixels is not a good metric of image quality.I have a Game Boy Camera, one of the earliest consumer digital cameras, which takes photos at a whopping 0.014 megapixels.