How can I detect when a Nikon D7000 has actually taken a photo for Arduino automation?
Asked 5/7/2014
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I want to automate a turntable-style shooting setup with an Arduino and a Nikon D7000: rotate an object with a stepper motor, trigger the camera, then rotate again. I can trigger the camera over infrared from the Arduino, but I also need a reliable way to know that the exposure actually happened before moving to the next position.
The built-in flash will be raised to trigger remote Nikon flashes, so I may not be able to use the hot shoe in a normal way. I considered using a photodiode to detect the flash burst, but I’m looking for a simpler or more reliable signal from the camera. Is there a practical way to detect shutter/exposure completion externally?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
12y ago
2 Answers
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Easiest is to use the camera hot shoe even though you don't have much space. You can probably find a non working flash for nothing. Separate the flash from the hot shoe and use the hot shoe portion as an ultra low profile adapter for your electrical signal. Circuit should go to ground during flash.
Also most DSLRs have an led light that shows the activity when the image is being written to the card. You may not want to start taking your camera apart but you have a trigger with that light circuit. Any sort of photo detector could be used externally if you want to stay out of the camera. Choose a gel filter the same color as the led and extraneous room light or flashes will not give you a false count if you set the gain on your detector properly.
Originally by user27866. Source · Licensed CC BY-SA 4.0
user27866
12y ago
0
Generated from our catalog & community — verify before relying on it.
A practical answer from the community is to use a camera-generated signal rather than trying to infer it indirectly.
The simplest hardware method is the hot shoe: the center contact is effectively shorted to ground when the flash fires, so your Arduino can detect that event. If clearance is tight, you could use just the low-profile hot-shoe foot from an old or broken flash as an adapter.
If you don’t want to use or modify the hot shoe, another workable option is to monitor the camera’s card/activity LED. That light indicates the camera is writing the image, which is a strong sign the shot was taken. You can detect it externally with a photodiode or phototransistor aimed at the LED. To reduce false triggers from room light or flash, use an optical filter matching the LED color and set the detector sensitivity appropriately.
Compared with detecting the flash burst, monitoring the activity LED is likely easier to isolate from your lighting setup.
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