Its been my experience that wide angle lenses tend to be a bit pricey. Your $100 budget may be a bit low, however waiting and watching the marketplace, evilbay and craigslist, may produce a find. There are several suggestions however that tend to be in the lower price range - at least used.
DA 16-45/f4 - is an excellent lens, and with its wide end at 16mm it is in the wide area. You can find it used for about $250. I would check the market place here on the forum. Its resolution and sharpness is very good. There are a lot of these lenses out there, and since it has been discontinued, I have watched quite a few of them go across the market place. At 16mm, I would think that this will probably be one of the most inexpensive high quality wide angle lenses you will be able to find - other than manual focus and possibly M42 lenses.
Zenitar-K 16mm f2.8 Fisheye - its a fisheye, however it is very useful. New, they go for about $200, but they again can be found in the marketplace.
DA 10-17 Fisheye - Again its a fisheye, with a field of view from 180 to 100 degrees, but on the long end, the fisheye effect is diminished. Its a very good lens, but it is a specialty lens. Again the marketplace.
Then comes the hard part. The wide angle rectilinear lens (non fisheye) that are 21mm and below. These tend to hold their price, and the price is relatively high (above $250 for the most part). The Pentax lenses run the highest, however the Sigma lenses though running less still offer great quality and very good value. So here is somewhat of a list - I do not guarantee that its complete, and I am sure where I was lacking others will fill the voids...
- DA 14mm f2.8 - discontinued but is suppose to be excellent - same physical size as the DA 12-24, need to find one
- DA*15mm f4 - excellent small prime
- FA 20mm f2.8 - discontinued, excellent low light
- DA* 21mm f3.2 - excellent, light weight, a small bit of distortion
- SMC K 18mm f3.5 - discontinued, excellent - no AF, need to find one
- SMC A 20mm f2.8 - discontinued, excellent - no AF, need to find one
- Tokina 17mm f3.5 - discontinued, excellent, large lens (about the size of 12-24), no AF, need to find one. I see a couple become available every few months
- Lentar (Tokina) 21/3.8 rumored to be relative inexpensive
- DA 12-24 - excellent, rivals primes in IQ, 100 - 60 degrees FOV
- Tamron 10-24 - reported to be not as good as Pentax and Sigma
- Tamron 11-18 - reported to be not as good as Pentax and Sigma
- Sigma 10-20 - excellent
- Sigma 12-24 -excellent,
- Sigma 8-16 - new just announced
Wide angle lenses tend to have a very large depth of field and as such, auto focusing in really not necessary, thus manual focusing will help with the budget. I think I would tend to look for M42 lenses in trying to hold down the cost.
Here is a link to an old Pentax Lens site, that you can search for good WA lenses that you might find available.
... hope that helps...
Last edited by interested_observer; 07-04-2010 at 06:50 PM.