Tag Archives: flash photography

Let’s Make Some Noise!

I’m still getting used to my new CameraAxe5 Arduino shield and what it can do, so I thought I would take things slowly and try some simple experiments first. Today’s plan was to have the camera and flash fire when I clapped my hands – just like the perfect servant it should be!

In order to keep things as simple as possible, I decided not to photograph moving objects to begin with, but got Gerald Jr to pose for me in my little portable studio setup. He stands and does what he’s told. The CAS5 and sensors/outputs were set up as follows:

Sensor input and device output setup for Microphone experiments
Sensor input and device output setup for Microphone experiments

This is how the values were set on the Advanced Sensor Menu of the CAS5:

Device1 Device2
Trig Sen Sensor1 Sensor1
Delay ms 000.0 500.0
Bulb sec 02 00
Prefocus No No
Sensor1 Sensor2
Trig Type Threshld Low
Trig Val 080/26 000
Power On On

Device 1 (Camera)

Trig sen – set to trigger from Sensor 1 (the mic)
Delay – 0ms – the shutter opens immediately when the sensor detects above its threshhold (see below)
Bulb sec – 2 – hold the shutter open for 2 seconds
Prefocus – no, don’t attempt to focus (was set to manual on lens)

Device 2 (Flash 1)

Trig sen – set to trigger from Sensor 1 (the mic)
Delay – 500ms – the flash fires half a second after the sensor detects/opens the camera shutter – this is to allow for shutter lag in the camera, so it should be fully open by the time the flash fires
Bulb sec – 0
Prefocus – no

Sensor 1 (Microphone)

Trig type – threshld – the microphone triggers the devices once the detected volume exceeds the trigger threshold (set below)
Trig val – 080/26 – the ambient noise in the room was around 20-30 units (the second value), so I set the trigger threshold value to 80. Noises exceeding this (like a hand clap or cough!) would trigger the devices
Power  – on

Sensor 2

Nothing connected

So, without coughing too loudly, I clapped my hands and my robotic minions took this lovely little picture of Gerald Jr posing for the camera:

Gerald Jr says Hurrah!
Gerald Jr says Hurrah!

Here’s a little video showing the setup in action:

I realise it’s early days yet, but I need to get to grips with the basics before I dive headlong into colliding water droplet territory! One step at a time…

200ms delay - not enough action in the frame
200ms delay - not enough action in the frame
500ms delay - all the action has happened
500ms delay - all the action has happened

Later on, I used a similar setup to the above for my Day #1402 shot of falling pasta. This time, I set the camera to 4s exposure, with a 2s delay on self-timer and manually firing the shutter with the remote release. Once the camera warning light went out after 2s, I dropped the pasta onto the background. The flash was set to fire after 300ms of delay via the CameraAxe, so that there was still some pieces in mid-air. This delay was worked out by trial and error – firing immediately gave too little in shot, and firing after about 500ms meant it was all stationary on the floor.

The room was dark enough for a 4s exposure to register a black frame without any flash going off – the camera was at ISO 200 and f/14, with the two flashes set to 1/128 power. I had found previously that firing the camera via the Arduino setup and having less than 500ms delay wasn’t giving enough time to allow for shutter lag. But with a much longer exposure and manual firing, I still had “time” to set the flash off via the microphone hearing the pasta hitting the deck, before the shutter closed again after 4s.

My Year In Pictures

After my enforced rest with my broken elbow/bashed knee last year, I decided that I would try to keep a photographic diary of 2008 – taking at least one picture every day, even when I’m just slogging away with work and not going anywhere interesting.

So far, I’ve managed to keep it up. I’m not sure they will all be masterpieces, but it’s an interesting challenge to keep the momentum going, and not forget to take a shot each day.

You can see the results at my new blog, My Year In Pictures.

I’ll still be writing bits and pieces here, but that will be more concerned with general photographic topics. I hope you enjoy reading both!

My Flash Is Dead (Nearly)

My Canon Speedlite 540EZ is now officially a dinosaur. I’d suspected as much a few months ago when I went to use it with my EOS300D and nothing happened. That is, the pilot button on the back would fire the flash when charged, but the camera wouldn’t. It was the first time I’d attempted to use it with the digital body, and (stupidly) I’d not tried it out before going somewhere where I really needed it. So I had to manage, and vowed to test it again soon.

Various factors made me forget to do so, until yesterday, when I remembered to try it again. The same result. At least in all the auto/semi-auto modes I tried. I didn’t have a huge amount of time to play further and have not tried full manual yet. But I’ve just googled for compatability issues between the two, and it seems it’s never going to work any better than in full manual mode. I have to set the shutter speed, aperture and flash power all by hand. Damn.

At first, I thought it was just Canon’s sneaky marketing scam to get you to buy a new flash for the sake of it, but reading a couple of articles has tempered my cynicism a little. Steve Dunn (4th post down) explains here why it won’t work in any mode except manual. Basically, its an old flash which only understands TTL or A-TTL metering which relied on measuring the light reflected off the film during exposure. And of coures, digital doesn’t have any!

So it looks like I’ll have to think about buying new flash gun if I want to use fully automatic metering. I’m wondering whether to bother, bearing in mind how often I actually use a flash. And with the abililty to change ISO rating on a per-frame basis with digital, plus a half-decent image-stabilised lens, the occasions I’ll need it are probably diminishing.