> I'm amused at the use of quotes around "grading" :-). Yup ... I've "developed" this strategy for a number of reasons. Most too obscure and without pedagogical (!!!) merit. OTOH I have been "grading" my classes in a similar way for many years and I probably am not going to change to a more conventional "point" system as most of my fellow intructors use. My grading is more psychological than numerical. > Was the Lartigue reference to his photo of car No. 6 in a race? That's > what I think of as the most famous photo "exploiting focal-plane shutter > distortion", and it's by him, but I don't know if that's what you were > thinking of. Yes. When the "lecture" about FP shutters was given the Lartigue photogrpah was mentioned. It was not shown though. Will there be initiative on student's part? Who knows. > I'm not at all clear what's going on in #27, either. The highlights of the bullet make a "blur" on the "wrong" side of the bullet. "Speed lines" as drummed into our heads by illustrators should trail a moving subject and not lead it. But as the flash falls off in output the highlights of the bullet reflect useful light for a longer time than the shadows and as the light level is dropping the bullet is moving forward and so one ends up with blur on the wrong side. > Another question brings up a question I've had for years about sound > triggers: Where can one buy one? I've never seen anything closer than a > kit. I might still be able to put an electronic kit together and make it > work. Well, I usually use a tape recorder that on detecting sound triggers a sensitive gate SCR which fires the flash. I've also recently built one based on an integrated circuit audio amplifier but when I made a second one patterend after the first one it failed to perform - frustrating. http://people.rit.edu/andpph/text-cheap-sync.html http://people.rit.edu/andpph/text-audio-sync-circuit.html http://people.rit.edu/andpph/text-PC-flash-sync-socket.html I can sugggest two commercial sources you may want to look into. www.quaketronics.com sells a nice unit for about $100 www.hiviz.com (associated with Lauren Winters of NC High School of Science I believe) sells kits at quite reasonable proces. The device cursorily described in the following article responds to light, sound and dark activation and also can function as an intervalometer plus it can be equipped with solid state "switches" or mechanical ones (the latter more suitable for camera triggering - if you have a camera that can easily be triggered from an external switch closure). http://people.rit.edu/andpph/text-cross-beam.html andy
