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 post

A 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.

Introduction

Smartphone 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 grime

It'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.

Blur from focus

If 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 movement

In 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.

If your subject can't stay put, take lots of photos. Afterwards, you can select the best one where they happened to remain still.

Detail

The 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:

The 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:

It'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):

Much 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:

Often, 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 around

You 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 it

The 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.

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:

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.

Megapixels

Pixels 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:

Why 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.

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:

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. And they look perfectly charming. If they were blurry, they'd be unusable, but when all the pixels are crisp, the photo is still able to take on a life of its own.

Megapixel marketing

I find it frustrating that phones use their megapixels as a marketing tactic when it's really not that relevant to photo quality. The sensor size is much more important, because you need a bigger sensor for those pixels to be able to resolve detail. If 64 megapixels is enough for a $10,000 professional camera setup, there's no way it's useful to have 200 megapixels on a phone.

The default setting on phones is to save storage by only using 12 megapixels, so unless you've changed settings, the 200 megapixel phone loses 94% of its megapixels as soon as you press the shutter. Bad deal!

Exposure

Exposure is a fancy word for brightness; it's how light or dark your photo is. If it's too dark, it won't be very eye-catching, but it's not the end of the world. If it's too light, the colours will be distorted by "clipping" (parts that got so bright they became white), which looks particularly bad for skin tones. Phones are pretty good at picking exposure for you, but they sometimes go too bright, so tap on the area of interest and use the slider to make it darker if needed. (Don't see a slider? Search [your phone model] camera change brightness.)

Cameras generally struggle with scenes that have both very dark and very light parts, such as forests which are quite dark apart from very bright beams of light streaming through the leaves. Human eyes tend to see the picture as a whole, but cameras over-emphasise the contrast, giving spots of light that look unnatural. It's very difficult to take realistic-looking photos in this kind of environment.

Another difficult situation is sunlight falling directly onto a person's face. For example, it was difficult to photograph this man's light skin under the sun in front of the dark green hedge.

Unfortunately, I just lied to you. These photos weren't taken on a phone, they were taken on a dedicated camera, which makes a big difference here. All smartphone cameras (but not dedicated cameras) use a feature called "HDR", which stands for High Dynamic Range. It secretly takes multiple photos with different exposure levels, then combines them into a final image, taking the properly exposed parts from each.

In theory, by making the shadows more subtle, HDR photos can better match how the human eye perceives light. In practice, each phone processes HDR differently, so the effect depends on what you have. Here's a simulation of HDR from editing my last photo:

Even with HDR, bright light directly on a person's face creates difficult conditions for the camera. To give your camera the best chance, see if you can move your subjects to a shaded location, swap places with them, or wait for cloud cover.

A note on software processing

In the age of AI- ok, I'm not starting this section with that damned sentence. Point is, smartphone cameras have tiny, limited hardware, and they try to make up for that using a lot of software processing to enhance image quality and detail. These enhancements exist on a spectrum. The simplest ones merely tune settings, while the most drastic ones use machine learning or generative AI to make up detail where none existed.

• Auto white balance - estimating what the colour tones are supposed to be and changing them to fit
• HDR - taking multiple frames and neutralising the brightness away from extremes
• Night sight - merging light across frames with a tone map to make it look like night
• Built-in detailed images of the Moon superimposed on your photos of the Moon
• Whatever's going on with Google Pixel AI generation

I won't make a value judgement on this - you need to decide for yourself which kinds of software processing you're okay with and which ones you aren't. If you don't want AI-imagined detail saved into your photos, find the relevant settings (e.g. "Intelligent Optimiser" or "Pro Res Zoom") and turn them off. If you don't want any frame stacking, you'd need to use a dedicated camera instead of a smartphone, because a smartphone without HDR isn't viable.

In conclusion

With your existing phone, keep these simple tips in mind for better quality photos:

• Wipe off the lens before each photography session
• Tap on your subject (on their eyes if it's a person/animal)
• Hold still
• Take multiple photos and pick the best one afterwards
• Use a location with soft, indirect light
• Adjust the brightness, taking care with skin tones

And here's what you should look for if you're buying a new phone camera:

• Larger sensor (check this on GSM Arena)
• Look at sample photos online (each device has a unique look)
• Megapixels do not matter

Great job on making it to the end! With this newfound knowledge, you'll be able to take a really crisp photo. Now you can upload it to Instagram, where it can be downscaled, compressed, AI-enhanced, compressed again, and finally viewed on a budget smartphone on minimum brightness with its screen covered in fingerprints.

Don't ignore art

Those are the rules, but breaking the rules is fun. Take photos that are way too dark or bright. Smear fingerprints on the sensor to create streaks of light. Change the white balance to purple. Wave it around when it says hold still. Zoom in beyond what's reasonable. Appreciate the smudges from nighttime noise reduction. Nobody can stop you. If you've got settings, you might as well change them.

— Cadence