I mentioned in my mini review of the Sigma 30mm that flare was a potential issue with this lens. At the time all I had noticed was the occasional aperture blade pattern. Veiling flare has now reared its head:

That’s with the hood on! The circumstances were admittedly extreme. The light from the setting sun is pouring in through the window on camera left hitting the lens just about parallel to the front element. I’d expect some flare in this situation, but the veil was dense enough to almost completely obscure the view through the finder. I’ve been spoiled by RF lenses with their tiny front elements.