I have the lensbaby sweet 35 in a composer pro, build is not bad metal mount the rubber on the grip ring is a bit cheap though unfortunately no AF confirm chip so no exif data or aperture info
strangly though the meter in the viewfinder seems accurate on the 5Dmk2, havent used it on the mk3 infact havent used it for a while
it has 12 circular apperture blades and the bokeh is amazing from it out of focus areas goes to mush
it nice in that the aperture control is a ring on the front rather than the silly plates of the other version
at f2.5 though its quite soft, also at this aperture there is not alot in focus it seems the depth of field is shallower than for a conventional lens at 2.5 it seems shallower than a 50 f1.4 wide open
so stopping down a bit really helps clear things up
its a fun lens to have when out to dinner with friends around a table as the 35mm on full frame is quite good and you can get some really cool shots
i think they do an 80 now as well however they are quite expensive for what they are
as for using i find the easiest way to shoot is to have the lens centered on your subject, focus then move the camera trying to keep the lens in the same spot to change your composition
i havent tried it with my brightscreen yet i was wondering how it would go since the bright screen has the focus assist elements in the center where as the lensbaby has an unusual focus system perhaps the EGs screen would work better with this lens but I'll have to have a go with the brightscreen and see
its a cool effect lens and if you love bokeh and buttery oof elements you will love this lens
i only use it wide open if i'm chasing every last scrap of light though