[bullitt_60]

I have the 10-20 f4.5-5.6, but that was mainly a cost issue for me. I didn't realize the 8-16 filter issue. At what focal length is the filter not visible?

[Digitalis]

I prefer the better resolving power and 8mm , myself.

Technically the sigma 8-16mm f/4.5 -5.6 isn't really any sharper than any other UWA lens - it simply is more consistent across the frame. At f/8 the sigma 8-16mm resolves 54 lp/mm on average which isn't spectacular* to put this into perspective: my SMCP-K 50mm f/1.2 @ f/8 can resolve 98 lp/mm, my FA31 at f/8 can reach 118 lp/mm and the FA77 at f/8 can reach 105 lp/mm

At what focal length is the filter not visible?

Any focal length longer than 14mm - and you have to use the expensive slim framed filters in a 72mm filter thread.

That is a rockin image, digitalis!

Thanks Mike, you have shown some excellent work yourself using wide angle lenses.

* To be fair I averaged the resolution figures because my copy of the sigma 8-16mm was slightly decentered, an optical fault that my K5IIs made blindingly obvious. ( A tradeoff for having no AA filter is that all your lenses have to be really good) The overall resolution of this lens is probably higher - but only marginally.