da15 produces great results even wide open, no worries.
but there is nothing 'not to slow', compact and reasonably priced in that segment. maybe da21 is the closest match, or manual focus 20mm?
i use old manual focus 24/2.8. a bit narrower but very good results. and not hard to find 24/2 if you want faster.

ciao

Hello

There is a zillion tests and shootouts of this sigma, also compared to other similar devices online. I read way to many of them.
I got sigma because i got it really cheap, new. Only shoot few test shots with tamron.
Sigma is focusing much faster then *50-135. Not sure for tamron. Used it in theater, focuses very good also in low light, very reliable and silent.
It has 0.29 macro, shoot big spiders, lizards and butterflies. Reported to be a bit soft at 200mm at mfd and wide open as well, never had problem with that.
I think that 'being soft' problems mostly origin in back/front focus issue.
Used it for almost 2 years only with success. But i do not shoot sport or birds in flight.

[IMG]http://i329.photobucket.com/albums/l378/s57l/palagruza/kuscar2.jpg[/IMG]

ps. i think you can't go wrong with either
good luck

hello

i use protection filter, witch adds 3mm and puts the filter thread on the same level with sliding hood, so any cap would do, but i use original screw-one. but i think even without filter, there is enough space for clip-on cap.

edit: just saw, you are looking for push-on. i am not sure, but looking at the lens, push-on cap is not really possible...