I am looking for a wide angle lens for my D90, between 12 and 18mm focal length, preferably a prime, because I like fast(er) and cheap(er) lenses.
Any recommendations ?
While I generally encourage people to consider primes over zooms, you're definitely in the territory here where zooms start to become more plausible. Before getting into that, a recommendation:
Your best bet is probably a DX zoom in the 10-24 range. You'll lose a stop of speed compared to the 14mm prime (most are f/4), but they will be much cheaper (~50%) and a little wider. I've never tried it personally, but the Tokina 11-16mm has a good reputation.
On to the comparison. Primes, like you say, are typically cheaper, faster, and of higher quality. But when it comes to ultra-wides, the situation changes a little, as ultra-wide primes have never been at the level of simplicity and well-corrected design that's been possible in the 35mm+ range, and zooms are rapidly improving. Sticking to Nikon only, here's the interesting comparison:
Zooms: Nikkor 14-24mm f/2.8 $1800 Nikkor 12-24mm f/4 DX $950 Primes: Nikkor 24mm f/2.8 $425 Nikkor 20mm f/2.8 $600 Nikkor 14mm f/2.8 $1700 Fast Primes: Nikkor 24mm f/1.4 $2100
So even considering only the 14mm area, the fancy, fast zoom is the same speed as the 14mm prime, and only barely more expensive (one downside: much larger). Throw in even one other prime in the range it covers, and it's cheaper in absolute terms. The DX zoom is half the price, only one stop slower. Quality is harder to show in a chart, but Nikon says the 14-24 is as sharp as the primes in that range; pretty bold, but going on the review/testimonials I've read, they seem to be living up to that particular claim rather well.
Late to the party, but the obvious choice is the Tokina f2.8 11-16mm.
Cheaper, faster, and sharper (really!) than anything in that focal length except for the Nikon and Canon 14mm primes (which are rather expensive for most people). Ken Rockwell did a fairly detailed review of it. I certainly like mine.
I believe there are no wide-angle primes specifically for APS-C cameras. There are zooms that start at 10 or 12 mm. The widest available primes are 14mm and those are full-frame and very expensive. I suggest you look into Nikon or third-party ultra-wide DX zooms. Some reviews can be found at photozone.de.
As of April 2, 2013, the answer is a Tokina AF AT-X 124 PRO DX II 12-24mm. (Tokina will introduce a newer lens this month) The DX II WILL autofocus with the Nikon D3100 and D5000, both are adequate cameras. Keeping in mind that an APS-C censor is already "cropped" from a full 35mm equivalent, wide is not as wide in real values, it's an equivalent in DX. ALL the reviews of UWA lenses I've read point to this lens for quality of build, and images. There really isn't an (affordable) prime lens for an APS-C (Nikon DX) other then a 10mm fisheye. Tokina 11-16 will not autofocus, Tamron is not quality in 10-24mm, and the 10-24mm Nikon is twice the price. Most reviews I've read by owners, and Ken Rockwell, who gives the best advice for me, the prosumer/better than average photographer but not able to spend like a pro type, say that their wide angle lens stays at the 10mm range on their camera with the Nikon 10-24, and they REALLY like having the 2 extra mm on the wide end, and image barreling (distortion at the edges) is normal and within acceptable limits, especially if you are able to correct for this in camera or on a pc. I, after much research will go for the Nikon 10-24mm, cause I wanna shoot WIDE and can afford the extra $400. Best for the money hands down the Tokina AF AT-X 124 PRO DX II 12-24mm. Found one used on craigslist for $350. I gave up my search for a prime.
If you do end up going with a zoom, look at the older Sigma 10-20mm and the Tokina 12-24mm.
I also looked into this issue for quite a few years, since my D70s. If for automatic focusing prime lens, the only option seems to fit this question in a reasonable price would be the old Sigma 18/3.5 or 18/2.8 lens. I did used the 18/3.5-af for a few times and it's not a bad stuff for its price, which usually around $150. The Sigma 18/2.8, however, I only saw MF version once and I cannot confirm whether it has a af version or not. Yet the Sigma 18/2.8 seems to be even older and cheaper then the /3.5 lens.
Also if you have $200~250 budget then you can go and buy the Tokina ATX Pro-17/3.5 ASPH. It is a very fine lens and in fact I still keep the Tokina 17 now because it's good for full frame as well -- and it is the last 17 or 18mm AF prime lens in production until 2006.
If you expand you option a little bit then you can go for the Sigma 20/1.8, which you still have equivalent 30mm on aps-c camera, and its a HSM lens so it's faster. But it'll double the price up to $500 or more.
The only 14mm AF prime lens beside the legendary Nikon AF 14/2.8D-ED would be the Tamron SP-14/2.8 af lens. In fact the the Nikon 14/2.8 is acturally oem of the tamron 14/2.8 so they're the same optic and performance.. and also the same price.. It would be no necessary to spend $2000 on a APS-C camera prime lens.
I am in the same position now where I am looking to replace my
Tokina ATX 116 - 11-16mm f/2,8 and despite you said you prefer primes you also said because it is cheaper.
The answer of ex-ms still applies and you can see the cheapest are the zoom and not the primes. Finding a (fast) prime 11mm for a low budget is even impossible. There is a prime
Zeiss 18mm f/3.5 for around 1'300 $ but this a manual focus lens.
In 2015 Tokina released an upgrade of the ATX 116:
Tokina AT-X 11-20mm f/2.8 PRO DX which seems to fit the best your requirements:
And to finish, the performances chart seems to be very good and sharp.
In the second hand market you can perhaps find some
But I doubt the quality fits the current digital cameras (perhaps still OK for a D90) and due to the rarity of such lenses the price would not be so cheap. And as you can notice, there's nothing faster than f/2,8 for the range 12mm-18mm, then I think the best option is the Tokina.
You will save a bit of money for the 11-16mm, but you have a shorter focal range, but as I owned it previously I can say this was a very good lens for a DX cameras.