Cellphone cameras: how good are they?

(Originally written in Feb 2012.)

I have been interested in photography since I saw my dad clicking our pictures when I was perhaps a few years old. I've been carrying around a camera without adult supervision since I was perhaps 15. Now, when half my life is spent, I see a new world of photography where people whip out their cellphones and click pictures using those tiny lenses.

I got a modern smartphone last year: the HTC Desire HD with an eight-megapixel camera and 720p video shooting ability. This cellphone's camera is supposed to be pretty good as cellphone cameras go. And during the last year or two, I've heard increasing comments from non-photo-enthusiast friends about the adequacy of cellphone cameras.

  • "Can you really make out the difference between a cellphone-clicked photo and a thirty-thousand-rupee (US$700) digital camera photo?"
  • "All those manual controls are okay for you, but I am a non-technical person. I just want to point and press the shutter."
  • "Most photos are to be published on Facebook and then forgotten anyway, so do you need any better quality?"
  • "Does it make a difference whatever quality shit you're talking about when all I want are some photos of my kids? I'm not into that high art-shart thing like you, you know."

Having heard these comments long enough, I decided that I'll try to put up some sample pictures to help you decide whether the quality difference matters to you. I have decided a long time ago that it matters to me. In fact, even modern digicams cannot give me photos of the quality I like -- I use film SLRs, and will switch to digital SLR only when I can afford a full-frame DSLR.

I am different from my non-photo-enthusiast (henceforth NPE) friends in one more way: I don't think viewing a photo on a computer screen is good enough for the pleasure of a good photograph. I need to see a print, at least 8"x10". (Many of the photos I like have been printed and framed at sizes of 24"x36". I love them. I stare at them every day.)

The rest of the article is for my non-photo-enthusiast (NPE) friends. See the photos for yourself and decide what's good enough for you. Whatever floats your boat.

All the small photos below are linked to the original unretouched photos. Some of the original big photos are quite large (5MBytes or more), so be prepared when you click on the small photos and download the full-size ones.

Some cellphone camera photos

To begin with, let us look at some cellphone photos which most of you will consider technically excellent.

Punchy, high-contrast image, with deep shadow areas and brightly lit patches. The camera is at its best with scenes like this.

This one too is nice, though it's low-contrast. Nice subtle shades, colours, and details. But there's more to them than meet the eye, as we will see. Let us start digging a bit deeper.

Let's look at the third one:

This was clicked in the open one evening, at a resort. Looks quite good, no technical problems with it. Sharp, detailed, etc. But look closer now: here's a piece of the picture, at its real size and resolution:

The yellow leaves appear smudged. It's as if there is posterisation: a phenomenon when colour in the photo appears in blobs, losing subtle shading and changes in hue. I had never seen this with digicam photos earlier, so it caught me by surprise. Even the blades of grass show clear signs of this blobbing... they have lost detail.

Let's go to the fourth sample. A shot of a few kids in a classroom. This is the kind of photo most NPE parents vociferously claim are "all they want to click". They claim they are simple people who don't understand all this art-shart stuff about photography.

Let's look at a small piece more closely now.

Look carefully at the blotches. Is this good enough for you?

Some friends say "Oh, but this was a dimly lit scene. You are just stacking the odds against the camera and then blaming it for poor quality." So here's another example, much more brightly lit. Yet another ordinary photo clicked by an ordinary parent who wants to freeze images of his kid for his old age. Nothing arty-sharty here.

And here's a detail from a brightly lit portion of the photo.

A quick examination of the faces of the kids shows a blotching which is, well, unacceptable to me. Also see how the brightly lit areas on the cheek of the kid on the left are completely blindingly white. Ditto, parts of the right-side kid's face. They look like they are suffering from some skin discolouration.

I feel like asking my NPE friends: "Can you afford to give your child anything but the best??" (from those ads of expensive, pretentious, privately-run play schools).

By this time, I had begun to notice a trend with my cellphone camera photos:

  • Blotching, posterisation, leading to loss of detail
  • "Blowing out" of the highlight areas, where the brightly lit areas become one blob of pure white and lose all detail.

Some digicam photos now

Here's a digicam photo, clicked indoors on a December morning in Calcutta with an overcast sky outside. Light, as is expected, was low. The camera was in auto-everything mode. The digicam used is the Canon SX40HS.

A few things I like about this photo:

  • the colours are very natural
  • there is no colour cast: the white balance has been detected correctly by the camera
  • the sharpness in the areas on which the lens has focused is stunning

Here's a detail from the laptop bag in the foreground.

See how clear is the weave pattern on the fabric of the bag. The shot was clicked hand-held, but I suspect the IS (image stabilisation feature) of the camera kicked in, minimising the effect of camera shake. If you have the patience, scroll up to the first photo on the page (the one with the monkey wearing dark glasses) and download the full-size photo by clicking on the small one. Then zoom in and examine the grey corduroy fabric of the trousers in the bottom left of the photo. Compare that sharpness with this one of the laptop bag here.

Any NPE with a fully automatic digicam can get photos of this quality today.

A side-by-side comparison

So, to highlight the issues more clearly, I decided to do a side-by-side comparison. I clicked one subject with two cameras, entirely with automatic settings. I first clicked with the digicam, in fully automatic mode just like my NPE friends would. I then clicked the same scene with my cellphone camera.

Here are the photos. No points for guessing which one is from which camera.

In case you were wondering, my cellphone camera gives me 8MP images, and the digicam here gives me 12MP. But the megapixel count is not a factor for image quality at all. I have obtained equally good images with five-year-old digicams giving 3MP images.

I feel this is sufficient data for you to make up your mind.

Why I use 35mm SLRs

I will not go into this subject in detail, because this page is for my NPE friends. However, I will show one or two photos below. No cellphone camera can click these, and very few (and expensive) digicams can perhaps click them, if at all. However, they are passe for old 35mm film cameras, and also for modern digital SLRs (if you have a full-frame DSLR). If you stretch a bit, such photos may be possible using the cheaper small-sensor DSLRs too.

All these were clicked using a Canon AE1 Program, a film SLR camera manufactured in the early eighties. It's available today in the used market for about US$100, in excellent condition. The film used is very mediocre supermarket-grade Kodak Gold, which limits the quality of the image. The negatives were developed and scanned using a 4000dpi Nikon film scanner, giving me 24MP images (in case you are into the megapixel wars).

Here's a detail from one of the photos:

The slide in the playground was made from some sort of fibre-based plastic material, very smooth on top and very fibrous below. The almost tactile feel of the fibres in the detail, with multi-coloured strands, is exactly how it appeared to me when I saw it and touched the surface.

What's so special about these photos?

Look at the photo of the father and son on a rock. Click on it, and let the larger image download and fill your screen. You will then notice how the background is blurred and the two people are sharp. This gives the photo an almost three-dimensional feel. This blurring of the background is impossible to get with a small lens. It's totally impossible with cellphone cameras and small, cute digicams. It may be somewhat possible with larger digicams with large lenses, and with small-sensor DSLRs. And it is completely routine with full-frame sensor DSLR cameras and 35mm film cameras. This three-dimensionality is one of the big reasons I hate small toy cameras of all kinds -- I need it to make photos interesting. And this phenomenon (the photo enthusiast types call it "shallow depth of field") is only available with physically large-diameter lenses.

Download and examine the full-size image of Hawkeye, the confused Alsatian pup. Zoom in and examine the region at his eyes. See how sharp those eyes are. Then zoom out and look again at the background. See how blurred it is. This photo was clicked on the rear seat of a car. The background is about three feet behind Hawkeye's head, and yet see how blurred it looks. This makes the pup's head stand out from the background.

Hawkeye's photo could not have been clicked without a fast lens -- a large lens. I guess it was clicked at an aperture of f/2.8 or thereabouts. Such large lenses are not even built for most digicams. Therefore, shooting in the dark interiors of cars is a difficult gamble for cellphones and small digicams. This low-light shooting is the second reason I need large lenses for. And large lenses mean large cameras like inexpensive thirty-year-old 35mm film SLRs or horrendously expensive full-frame sensor modern digital SLRs (in the Canon stable, they start with the EOS 5D at about US$2,000 for body only).

Every professional news photographer uses digital SLR cameras. Every run-of-the-mill newspaper carries photos with shallow depth-of-field which no digicam can capture. Every NPE friend of mine flips through or reads newspapers. Yet they never ask why their own cameras cannot click such photos.

What's the difference due to?

Here's a bit of the technical explanations behind the differences.

  • Lens size. A larger-diameter lens allows shallower depth of field in your photos if you want them. This allows your photos to acquire that three-dimensionality I described above. Cellphone makers are proud of how small and sleek their phones are. None are proud of how good the cameras are. Small and sleek bodies do not permit the inclusion of good lenses.

  • Lens quality. A lens needs to correct a lot of optical errors and distortions to capture a sharp image. You cannot build a low-distortion lens unless you craft it out of multiple pieces of glass, stuck on top of each other, in complex designs. A cellphone camera does not have space for a complex and carefully designed lens. A digicam has much more space for a complex lens, but there too, the smaller cigarette-packet-sized ones have worse (simpler, smaller, cheaper, lighter) lenses. The bigger digicams have better lenses. That's why they're heavier, larger and more expensive.

  • Focusing. A lens needs to be able to focus on one part of the scene, leaving other parts out of focus. This gives the image its blurred backgrounds. Modern digicams and SLR lenses can focus -- they have moving parts. Cellphone cameras, with a few notable exceptions, have no moving parts. Therefore, all parts of a cellphone-cam image are equally sharp -- or equally blurred, as you may call it.

  • Sensor size. This is for digital cameras. Larger sensors mean more detailed, sharper pictures. Sensors are arrays of tiny electronic thingies called "cells". Each cell-thingie receives a tiny bit of light and records it in the camera's memory. Small sensors have these cells so tiny, so closely packed together, that light tends to spill from one cell to the next, blurring everything. That's where the cellphone camera's blotchiness and posterisation comes from. Larger sensors have larger cells, thus making it easy for each cell to record its own independent bit of light. Full-frame DSLR cameras have sensors 24mm x 36mm in size. So they capture images with fine shades of colour, fine detail, with great accuracy. Just like 35mm film cameras of thirty and forty years ago, but for a lot more money.

Some of my NPE friends worship at the altar of the God of Technology. They claim "But all this will get better with every six months. See how fast technology changes." I agree, in part. Digital sensors will get cheaper, therefore larger sensors will become more common. But optics is not improving much. The quality of 35mm lenses peaked by about 1980, and has stayed there. The best lenses of twenty years ago are as good as the best today. And the basic laws of physics, which govern shallow depth of field or distortion in lenses, will not change. Too bad.

I end my story now with a sample of a photo clicked by the digicam I used earlier. This shot is a good example of how much detail a modern fully automatic digicam can capture, something that cellphones cannot even dream of.

Have fun!

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