DA 15mm F4 Limited - Advice Please

It takes 49mm filters, which is rare for an ultra wide angle, it gives wide field of view,and is very lightweight

i took the glass out of an old 49mm filter, that screws onto the 15mm and gives clearance of the hood protrusions to fit my 49mm cokin adaptor onto which i can fit either filter holder ,standard or wide angle.tested and no sign of vignette

The 15mm is a fantastic lens for IR if you do any.....probably the best from the 20 or so lenses I have tried. No hotspots at all, and very sharp.