After a flight of more than 3 hours duration over an ‘easy’ target (http://www.flickr.com/photos/bblakecambridge/6147138957/) with different permutations of exposure control ( auto-focus, manual focus fixed to infinity, shutter priority, aperture priority, AF area mode, fixed ISO, PL filter on/off etc.) produced a very mixed batch I have had to look at the rig again.
I was fortunate to have a good wind and plenty of space to walk the kite and rig up and down. I found the camera would just refuse to shoot in some aspects and perform well in others. No amount of silent cursing would get the thing to work on nadir shots but, if I tilted to the horizon, it would (somewhat sluggishly) oblige. The very wide 10.5mm fisheye lens did better than the AFS35mm ‘prime’ but there were many times I was just left jerking the stick and screaming at it to shoot.
I’m not a big fan of the fisheye view and even re-projected to a more human perspective the aberration at the edges is awful but at least I was getting a more responsive camera with it. I was able to satisfy myself the IR LED was not at fault, I could trick it into running constantly using the trimmer control: no this is a camera problem. To investigate further I decided ( somewhat reluctantly as there is a weight penalty at this point) to see what happens with servo control of the shutter.
Now I discover the problem. The D5100 sometimes needs a bit of processing time with the shutter release held down to shoot. With the servo ‘finger’ I can emulate this action exactly and its clear there needs to be a split second lag for ‘dark’ exposures with the button held down – the IR release was not doing this so it would shoot only if the exposure setting agreed with the camera metering calculation ( or re-calculation in the case of a moving camera!)With the shutter servo fitted I can just about close the lid on the box!
So with a 8-12mph SEasterly blowing I set off to see what I can get. I get the Picavet in a tangle and, as I sort it out the Sun slides behind a cloudbank that stretches upwind to the horizon: with the little time I have I get the rig aloft and shoot. The shutter is working flawlessly I can hear it zztclak! zztclack! zztclack! as it drifts off down wind with the rising kite.
The pan gear jams, I haul down, tighten the gear on the servo and start again, my receiver screen blacks out: I haul down, tweak the wiring and start again…
…10 mins and 209 shots later:
….yes! and I’m able to pick out the sharp shots taken as the camera swings about on its cats cradle. The shot rate for ‘fine ‘JPEG is 4fps.Any wind from the East round here is rough so it was nice to see the new GS1 do its thing, I still need more stability in the pan axis but now I think this DSLR lark is working properly. I still think I’ll ditch the Picavet and gear down the pan ratio …oh and try and wait for better light too!