> On 22 April 2018 at 02:28 Mark Roberts <postmas...@robertstech.com> wrote: > > > So yesterday was "studio shoot" day for some of my photography > students (and some from another class). Needless to say, it was a > massive amount of work. But it was still fun and educational. > > Since we had to work with a lot of students we split things up and had > them shooting in groups of 3 or 4 at a time. We standardized the > lighting setup with a couple of Alien Bees with umbrellas (the school > doesn't have any soft boxes). I had every student set his/her camera > to manual exposure, ISO 100, 1/125 shutter speed and f/8. And since > the school only has one radio trigger we had everyone use their > camera's pop-up flash to optically trigger the main strobes. > > This setup worked well. Except when it didn't. Some cameras just > didn't get along with this and produced dark photos. In fact, some > (not all) produced uniformly dark shots even after changing aperture. > I'd have two students with budget Nikons set to identical > configurations and one would work perfectly and the other wouldn't. > (Unfortunately, due to the number of students coming through, I didn't > have time to make a list of cameras that exhibited the problem and > those that didn't.) > > After she shoot was all done I think I worked out what was going on: I > believe it was caused by the pre-flash that DSLRs use to meter before > the main flash. I don't know the details but I suspect the pre-flash > was triggering the studio strobes before the shutter had a chance to > open. Of course, when you're on manual exposure there's no reason for > the camera to have a pre-flash at all, but it may be left on because > the manufacturer didn't want to add additional code to the firmware > (in the case of the cheapest cameras). The cameras that seemed to > yield a uniformly dark exposure regardless of aperture may have been > operating in manual mode as far as ambient light was concerned but > modulating flash power independently. > > Anyway, we solved the problem by letting any student whose camera had > trouble shoot for a while with the radio trigger. > > Whew. A lot of work. But very gratifying in the end. Glad the > semester's almost over.
Interesting phenomenon. If that had been me, with my present cohort, half of the studio gear would have been broken. They are getting worse as the year progresses. I can't wait for it to be over. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
