How to Spot a Psychopath

A reader writes:

"Nokia announces 808 PureView ... 41-megapixel camera(!)"

HAHAHAHAHAHA, HAHA, HAHAHAHA, HAHAHAHAHAHAHAHA
HAHAHAHAHAHAHAHAHAHAHAHAHAHA

*choke* *gasp* *groan*

When I read that I immediately thought of your "enough already with the megapixels" page. I figured I'd send you the link so you can knock yourself out. :D

And now, back to frantic laughter...

Lucio

This thing may actually be less ridiculous than it looks.

The sensor in the Nokia 808 is much larger than normal phone-cam sensors - much larger, in fact, than the sensors in almost all point-and-shoot compact digital cameras (not counting expensive oddballs like the new PowerShot G1 X).

In the inscrutable jargon of camera sensor sizes, the 808's sensor is "1/1.2 inches". This means a diagonal size of around 13 to 14 millimetres.

The "APS-C"-sized sensors in mainstream DSLRs have a diagonal around the 27 to 28mm range, and thus four times the area of the 808 sensor. "Full frame" DSLR sensors are way bigger again, but they're also way more expensive.

For comparison, the (surprisingly good) "1/3.2 inch" sensor in the iPhone 4S has a diagonal of less than six millimetres. Consumer point-and-shoots these days usually seem to have 1/2.3" sensors, giving a diagonal of less than eight millimetres. (I haven't researched this in detail, but the eight Canon consumer compacts and five cheap Nikons I just checked out were all 1/2.3.)

Fancier point-and-shoots, like Canon's PowerShot G12 and Nikon's Coolpix p7100, have somewhat larger sensors; those two both have 1/1.7", giving diagonals in the neighbourhood of nine to ten millimetres.

(The abovementioned PowerShot G1 X has a "1.5 inch" sensor, which after compensation for endowment-overstating jargon is a 23-point-something millimetre diagonal. That's very nearly mass-market-DSLR size, but you'd bleeding want it to be for a street price of $US799. You can get an entry-level DSLR with two unexciting but functional zoom lenses for that price. If you want something more compact, you can even get a mirrorless camera - a Nikon 1 J1, say - and a couple of lenses, for $US799.)

So the 808's 13-to-14-millimetre sensor isn't impressive by interchangeable-lens-camera standards, but it's pretty darn huge compared with compact cameras, and huger still by phone-cam standards. But it apparently has the same immense photosite density as the tiny sensors. So it really does have about 41 million photosites.

The 808 sensor is meant, however, to operate by "pixel binning" lots of adjacent photosites together, creating an image with a more sane resolution (apparently as little as three megapixels), but of higher quality than the same image from a tiny sensor with that same resolution.

Pixel binning is not a cheat like interpolating a low-res sensor's output up to a higher resolution. Done properly, binning really can make lots of super-small, noisy photosites into a lower number of bigger, less noisy ones.

I hope the 808 sensor actually does work better than it would if it were the same size but with bigger photosites in the first place. It seems a long darn way to go just to get a big megapixel number to impress the rubes, but stranger things have happened.

(The hyper-resolution also apparently lets the 808 use the much-maligned "digital zoom", a.k.a. just cropping out the middle of the image, without hurting image quality. Though, of course, the more you "zoom", the less pixel-binning the sensor can do. On the plus side, it's much easier to make a super-high-quality lens if it doesn't have to have any proper, "optical" zoom, and the minuscule lenses that phone-cams have to use need all the help they can get.)

The principal shortcoming of the small super-high-res sensors in phonecams and compact digicams is low-light performance. And "low light" can mean just "daytime with a heavy overcast", not even normal indoor night-time lighting.

The best solution to this problem is to avoid it in the first place by not being so damn crazy about megapixels, but that seems to be a commercial impossibility, largely thanks to my favourite people.

The next-best solution is to use a lens that lets in more light. But large-aperture lenses are much more expensive to make than small-aperture ones, and also tend to be unmanageably physically large for slimline-camera purposes. Oh, and the larger the aperture, the smaller the depth of field, which is bad news for snapshot cameras that often end up focussed on the end of a subject's nose.

Another low-light option is to use slow shutter speeds, but that'll make everything blurry unless your camera's on a tripod and the thing you're photographing is not moving.

Or you can wind up the sensitivity, and turn the photo into a noise-storm.

Or, if your subject is close enough, you can use the on-camera flash, which will iron everybody's face out flat.

(Approximately one person in the history of the world has managed to become a famous photographer by using direct flash all the time. Here's his often-NSFW photo-diary site. Half the world's photographers hate him.)

Some of the better compact digicams have a flash hotshoe on top. Bouncing the light from an add-on flash off the ceiling is a standard way to take good indoor photographs. A compact camera plus an add-on flash isn't really compact any more, though. It might be possible to work some kind of hinged flash into a phone-cam, but nobody's managed that yet.

My suspicions about the Nokia 808's low-light performance were increased by Nokia's three gigantic sample images (32Mb Zip archive)...

...all of which look pretty fantastic, as demo pics always do.

If you look closely, the blue sky is noticeably noisy, shadow detail is a little bit noisy and a little bit watercolour-ed out by noise reduction, and at 100% magnification none of the demo shots are what you'd call razor sharp, especially around the edges of the image.

But the full-sized versions of these pictures are 33.6 and 38.4 megapixels. If you scale them down to the ten-to-twenty-megapixel resolution of a current DSLR, it'd be hard to tell the difference between the 808 shots and DSLR ones.

But not one of the demo pics was taken in low light.

Nokia have, however, just added several more demo images on the 808 press-pictures page here. The new images include some lower-light shots. In every case, the lower the light, the lower the image resolution, as a result of that pixel-binning trick. But those lower-res images look good.

I'm not sure what the light source is for this one - possibly a floodlight pointing upwards at the climber - but it's 33.6 megapixels, and looks pretty good, except for some watercolour-y noise reduction on the far rock wall. Presumably the light source is pretty strong.

This seems to be an actual night-time shot, possibly taken with the on-camera flash but suspiciously nicely lit for that. It's a mere 5.3 megapixels, but not very noisy at all.

This dusk shot is the same resolution but with a 4:3-aspect-ratio crop, taking it to only five megapixels. Noise is noticeable, but not obnoxious.

These two shots are both overcast daylight and are the low five-ish-megapixel size too. Their noise isn't a big deal either.

And then there's this sunset picture, which sticks to the lower-light-equals-lower-resolution rule; it's back up at 33.6 megapixels, because it's exposed for the sunset, with everything else in silhouette.

Time, and independent review sites, will tell whether these pictures are representative of what the 808 can do. But it looks good, and plausible, so far.

Which is unusual, because odd sensor designs that're alleged to have great advantages do not have a good reputation.

Fuji's Super CCD did close to nothing in the first generation, and has developed to give modest, but oversold, increases in resolution and dynamic range.

Sony's "RGB+E" filter design didn't seem to do much of anything, and was used in two cameras and then quietly retired.

Foveon's X3 sensor genuinely does give colour resolution considerably higher than that from conventional Bayer-pattern sensors.

But, one, the human eye's colour resolution is lower than its brightness resolution (a fact that pretty much all lossy image and video formats, both analogue and digital, rely on), so higher colour resolution is something of a solution looking for a problem.

And, two, Foveon and Sigma (the only maker of consumer cameras that use the Foveon sensor, if you don't count the Polaroid x530, which was mysteriously recalled) insist on pretending that three colours times X megapixels per colour makes an X-megapixel Foveon sensor as good as am X-times-three-megapixel ordinary sensor. That claim has now been failing to pass the giggle test for ten years.

The Nokia 808 sensor, on the other hand, may actually have something to it. We've only got the manufacturer's handout pictures to go by so far, and any sufficiently advanced technology is indistinguishable from a rigged demo. But this actually could be a way out of the miserable march of the megapixels, without which we actually probably would have had, by now, cheap compact cameras that're good in low light.

Or it could turn out to just be more marketing mumbo-jumbo.

But I really hope it isn't.

A reader writes:

I am looking to buy a digital SLR camera. I am stuck between the Nikon D5000, Canon EOS Rebel T1i [also known as the EOS 500D]and the Canon EOS Rebel Xsi [a.k.a. the EOS 450D; the DPReview 500D review compares the 500D and the 450D].

I am leaning towards the XSi, however I would like to know if there is more value spending the extra bucks and getting one of the other ones. I am a beginner when it comes to photography and will use it mostly for taking pictures when travelling and family functions etc. Appreciate the guidance.

Jorge

I don't really know enough about the Nikon to firmly rule it in or out. Don't worry, though; I'm sure commenters will soon explain to you exactly why your only possible sane option is Nikon, and also how a Nikon will definitely steal your family's souls and impel their dead-eyed husks to kill and devour you at the earliest opportunity.

I can, however, tell you that the major investment for any DSLR owner isn't the camera body, it's the lenses.

(Well, actually it's perfectly possible to buy a DSLR body and a couple of lenses that cost less than the body, and then just call it a day. This almost always indicates that you should have bought a smaller, lighter, cheaper point-and-shoot camera instead.)

I presume you don't have any Nikon or Canon lenses at the moment. If you've got a friend who's got a collection of lenses for either Nikon or Canon and who's willing to loan any of them to you, though, then you should get the same make of camera they have.

(This extends to less common DSLR brands, like Pentax, Olympus and Minolta {though probably not Sigma}. Sony bought up Minolta's camera arm, so now they're "Sony Alphas" instead of Minolta Alphas, but the lens mount remains the same.)

Note also that some Nikon F-mount lenses only autofocus if you put them on a camera body with a built-in motor, that mechanically couples to the lens. The D5000, like various other cheaper Nikon DSLRs, does not have that motor, and so will only autofocus if you get lenses that have their own motor. Motorless lenses will work on a D5000, but you have to focus manually.

Manual focus can be a bit of a pain with consumer DSLRs, because they never come with the split-image ground-glass focusing screen that you need. It's certainly not impossible to do manual focus, though, especially since the camera should still be able to go beep at you when it reckons you've got the focus right. (You can also usually upgrade the focusing screen - it's not even all that terrifying a DIY job.)

Further points:

1: The Nikon and the Canon T1i (which is known as the EOS 500D, outside the USA) can capture HD video. The cheaper Canon cannot. The new wave of video-shooting DSLRs - all of which, I think, you can set to lower resolutions if you don't need HD - are a big step forward in consumer videography. They give a professional interchangeable-lens camera to amateurs. If you don't care about video, though, or prefer a pocket-sized video camera, this becomes irrelevant.

2: Resolution doesn't matter. As far as actual image quality goes, even for long-exposure night shots and high-ISO work, there's little real difference between the recent Canons - and, I'm pretty sure, the Nikon too - and models from several years ago.

This was a 30-second exposure, at 2:37 in the morning, by the light of the full moon, taken with my EOS-20D in 2005.

Another 20D shot, this time more than 40 minutes!

A five-minute exposure from my EOS-D60, circa 2002.

Really high-sensitivity image quality and noise reduction is, to be fair, slowly improving. And the highest sensitivity figure you can set is rising, too. But the difference is not very large, because of the marketing-driven megapixel mania that keeps packing more and more pixels into the sensors, even if most lenses and most photographic subjects don't have the optical quality and/or image detail to make this matter, rather than improving the pixels that're already there.

If you find someone selling a seven-year-old D60, in good condition, for $100, buy that instead of a new camera, and spend the savings on starting your lens collection.

(The second-hand market for DSLRs isn't actually very exciting. This is because DSLRs hold their value much better than most electronic devices, and even if an old DSLR is mechanically perfect it may have lots of crud on the sensor. And the price of brand new DSLRs keeps sliding down, even as more genuinely useful features like video, partially self-cleaning sensors and sensor-shift all-lenses image stabilisation trickle in around the marketing nonsense. Second-hand lenses often aren't that cheap, either, but this is compensated for by the fact that they're very often in perfect working order.)

3: Don't get only one lens, even to start with.

If you get a basic body-plus-one-lens package for any of these cameras then you'll get a perfectly serviceable little zoom lens. Photo enthusiasts love to complain about quite minor image-quality flaws, but the kit zoom lens really is just fine for most purposes.

You should also definitely get a cheap 50mm f/1.8 prime, though, for reasons I explain here.

In brief: Cheap "fast" large-aperture lens equals great portraits, with the face in focus and the background blurred.

The cheap Canon f/1.8 50mm is this one. The Nikon equivalent is this one - NOTE, however, that it's one of those motorless lenses that you'll have to focus by hand on low-end Nikon DSLRs. For candid portrait shooting this isn't actually a major limitation, since you need to jockey around anyway when using autofocus to avoid focusing on the tip of the nose rather than the face, but it's still worth noting that, as far as I know, there's no cheap f/1.8 prime for Nikon that has its own autofocus motor.

(By linking to Adorama, above, I'm making no particular recommendation of them. They're a perfectly good online photo store, as is B&H, with prices about as cheap as any dealer who isn't a scam artist - but I'm linking to them because I like their short URLs and site search. Note that I'm also linking to the USA-retail versions of these lenses; big photo stores also often sell cheaper used, "refurbished" and grey-market lenses.)

4: If you're going to shoot sport or birds or anything else that needs a telephoto lens, then you should either buy a two-lens camera kit, which usually adds a passable something-to-200mm lens to the standard little zoom lens, or buy a something-to-300mm zoom lens separately. The absolute cheapest options in this category - some under $US100 - have lousy image quality, but you don't have to pay a lot more to get a quite acceptable Canon, Nikon or Sigma. (Third-party lenses - Sigma, Tamron etc - can usually be had in both Canon and Nikon versions, and often some other mounts besides.)

Examples:
Canon 75-300mm, $US160
Nikon 70-300mm, $US155
Sigma 70-300mm for Canon, $US159
Sigma 70-300mm for Nikon, $US159

The basic something-to-200mm lenses, like the little kit zooms, also show up very cheap on eBay all the time as people upgrade their camera-and-lens kits. You'll be able to save a little money if you buy the basic lenses that way, but it's probably not going to be worth the hassle.

You can also get quite affordable image-stabilised lenses these days. Both Canon and Nikon make stabilised versions of the above cheap zooms, though this pushes the price up over $US500 without improving the actual basic optical specifications at all. The stabilisers help considerably with camera-shake, but do nothing to prevent pictures of things that are themselves moving from being blurry.

You can get the stabilised version of the basic Canon 18-55mm lens in a quite cheap body-and-lens kit, as well. Here's a refurb version of that kit, at a price that's hard to dislike.

5: Get a tripod. A cheap and nasty eBay/DealExtreme Special will do fine. Even if you hardly ever use it, it'll be $20 (or less than $15...) well spent when you finally do need it to shoot longer exposures in low light, maintain consistent framing of a sequence of shots, et cetera.

(You might also like to get a remote shutter release cable for your camera of choice, to avoid bumping it when you press the shutter button for a tripod shot. The brand-name versions can be a bit expensive, but since a remote release cable is just a switch on a wire, you can buy cheap copies with confidence.)

6: Get an add-on flash, with a swivel-and-tilt head. (Not one like this, that only shoots forward.)

Direct lighting from the little pop-up flash on your camera, or any other flash pointing forward, will get you a picture when nothing else will, but is an almost perfect guarantee that the picture will be an unsightly "happy snap".

Flash bounced off the ceiling, plus a 50mm f/1.8 wide open, are your secret weapons to take fantastic portraits indoors.

Ideally you'd want a quality flash from the camera manufacturer, that works with the wireless triggering systems that most (possibly all) current DSLRs have, and can thus be used together with any other compatible flashes you buy. But those can be a bit pricey.

Off-brand flashes that work with the Canon and/or Nikon systems exist, but are apparently often a little dodgy, and aren't all that cheap, anyway.

The next step down, which will probably suit you just fine, is a flash with no wireless-compatibility stuff, but which still supports Through-The-Lens (TTL) exposure metering. Sigma have some nice options; again, there are also more expensive products from the camera manufacturers themselves.

If you're really on a shoestring budget, you can just buy a cheap old-fashioned "thyristor" auto-flash that works with your camera.

Your camera probably won't like flashes with a high trigger voltage, but there are many flashes that do not have this problem. The one-stop Internet info depot for cheap-and/or-manual flash users is Strobist.

(The magic name of Strobist also makes it pretty easy to see if that "SpringFlower Joyshine 2001" on eBay for $15 is worth buying. Just searching for [flash name] "trigger voltage" will also usually suffice.)

OK, readers; what've I forgotten? Let's see if we can throw so much advice at Jorge that he gives up on the whole idea of taking pictures!