Hi All; I'm new to this forum and this is my first post: thanks to all developers and contributors for such an awesome work!
I'm using the Canon SX260HS to capture UAV photogrammetric imagery: the camera is loaded with CHDK and KAP UAV script, and is remotely controlled by a Pixhawk flight controller.
I need to improve geo-referencing of the images: to do so I placed a phototransistor (VTT7125H) just on top of the AF LED which, when activated upon shutter opening, (should) send a signal to the external interrupt pin of an ublox GPS - so camera trigger events will be recorded in the GPS log with high accuracy time-stamp.
The issue I'm stuck with at the moment is with the LED-phototransistor implementation:
- when operated in ambient light, and obscuring it with the fingers , the phototransitor correctly changes state;
- when the phototransistor is placed on the camera AF LED it fails to detect the pulse most of the time (the phototransistor is masked with black tape);
- AF LED: in KAP_UAV script the camera activates the LED choosing option # 1, 3, 5 (actually all the odd numbers up to 15 seem to work but with different behaviors); I tested the LED either in burst mode or with 2 s intervalometer, and noticed that the LED pulse durations change.
Before posting here I've been searching and googling for some time now: I've read lots of topics in this forum (mainly answered by Waterwingz), on DIY Drones forum, on TuffWing site, etc. - this is where I got most of the ideas to start building this system, but now I'm basically stuck....
Some of the questions I have:
- Based on actual working configurations that some of you have tested, are there any specific requirements/models of phototransistor to use?
- Is there a way to figure out the meaning of the different option numbers associated with the AF LED setting in KAP_UAV script? Based on the preceding, what's the best option to use to get the most precise shutter pulse? I only found this link
http://chdk.wikia.com/wiki/SX260 (LED addresses at the bottom of the page), but I'm clueless....
- Can the AF LED pulse duration be configured to be constant at each shutter event (say 300-500 ms)?
Let me know if further information is needed.
Thanks in advance for your support (and patience ;-).
Regards