Do any wide-angle primes exist?

Scam · 16 Jan 2007 at 13:53

Just wondering really.. primes seem to be cheaper than zoom lenses (as long as theyre not telephoto). But wide-angles are much more expensive to produce.

Then again, when using wide-angles you're often shooting with long exposures, so F1.8 isn't really required. So why isn't there a 10mm F5.6 prime out there? At say.. £75 or something?

(My thinking being that prime=cheap and small ap.=cheap)

Just thinking out loud really.. hope that makes some sort of sense.

rpstewart · 16 Jan 2007 at 14:12

I would think it's actually more work to make a slow wide angle than a fast one. The restriction on apertures at the telephoto end is due to the aperture being related to the focal length. A 200mm f/2 lens needs an aperture opening of 100mm hence needs a front element at least that size which means high cost and weight. At the other end it's not such a big deal, to get the field of view of a 10mm lens you need a big front element anyway which means that you don't have to restrict the aperture as much.

So why don't 10mm primes exist? I think it's just too small a market, the only bodies which need 10mm focal lengths are 1.6x crop DSLRs and for the most part these tend to be bought by users who don't buy prime lenses. The people who buy primes tend to be the folk with the pro bodies who don't need a 10mm lens, 18mm or possibly 14mm is plenty wide enough for them.

SDK^ · 16 Jan 2007 at 14:22

Canon and Sigma make a 14mm F2.8, full frame prime lens. If it's easy to make a wide aperture why would they restrict it to F5.6

FranchiseJuan · 16 Jan 2007 at 14:54

The problem is not with f stops, but with distortion. Would you want to buy a lens that creates so much distotion that is almost not rectaliniar? You can get really cheap fisheyes that are manual focus, but they are not usefull for a lot of things.

Also for the 35mm base cameras that we have, it is hard to make lenses that are really wide (wider then 12mm), and also reletively distorion free. This is part of the limitation of format. You can see that it is much easier to get a nice wide angle lens for medium or large format, as the base focal length is longer.

Jotun · 16 Jan 2007 at 15:11

There is always the Peleng 8mm which I believe can be had for ~£140 (something I'm considering myself)

Scam · 16 Jan 2007 at 15:22

Ahh i see yes. So there isn't much point making a wide-angle with a smaller aperture as its 'wide' at the end anyway?

Jotun said:
There is always the Peleng 8mm which I believe can be had for ~£140 (something I'm considering myself)

That's a fisheye though isn't it. Which is crazy distortion. Seems to be a lot different from that to, say the 10-22 or 12-24 that i love the effect of. So here's another question, when does a wide-angle become a fisheye?

rpstewart · 16 Jan 2007 at 15:25

The Peleng is a proper 180 degree fisheye though. A fisheye is far easier to make than a rectilinear lens like the Canon or Sigma 14mm.

Great wee lens though, you can get some interesting shots with it -

Scam said:
when does a wide-angle become a fisheye

There isn't a point where if you go wider it becomes a fisheye, the lens has to be designed as either retilinear or fisheye. For example the 10-22mm is rectilinear but Canon do a 15mm fisheye....

FranchiseJuan · 16 Jan 2007 at 15:26

Scam said:
That's a fisheye though isn't it. Which is crazy distortion. Seems to be a lot different from that to, say the 10-22 or 12-24 that i love the effect of. So here's another question, when does a wide-angle become a fisheye?

There is actually no point where wide angle becomes fisheye. Lenses are made rectaliniar (the term for lenses that are not fish), or fisheye.

Also you should know that fish eye lenses (especially the 15mm ones), don't have that much a fish effect on the croped cameras.