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Archive for May, 2011

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One of the best things about digital media is the ability to place information into the file header called EXIF data, and one useful bit of information that can be stored is the longitude and latitude. Having the GPS coordinates embedded into the file header means that you can go back to a photo from 3, 4 or 6 years back and you can find out where you took it and best of all most photo sharing websites will display a map of where you have taken photos. There are a few ways of doing this, some cameras have built in GPS but these are very expensive and tend not to work very well, a separate GPS tracker but this is just another item to carry around and will probably set you back £100 or you could use your smart phone which you would most probably have with you at all times anyway.
Most smart phones nowadays have built in GPS and will track your movements when you want them to (or even when you don’t most probably), you don’t have to have a flashy iPhone; all you need is a phone that will export a GPX track. I do have an iPhone and unfortunately you’ll have to buy an app that will record your tracks in GPX form, I tried using several free but these were fairly clunky and didn’t work that well. After much research I bought “Geotag Photos Pro” and at the time of purchase was £2.39, but it really is a great app, the interface may seem a bit basic but don’t let that fool you!
When it comes to Geo Tagging the main thing to remember is to make sure that the camera time and phone time are in sync; the phone will log the GPS data and attach a time stamp to the coordinates and the geotagging software will try to match the time of when the photo was taken to closest time stamp in the GPX file (this is what the exported GPS data is called).

When “Geotag Photos Pro” is launched you will see the following screen:

The first things to do are to set the how often the GPS loction is logged. One of the best things about this app is that it doesn’t leave the gps on, it will just turn it on when it is time to record a coordinate, so if you want to preserve battery life and you’re not moving around set this to every few minutes, but be aware that this won’t be very accurate if you are on the move. Here is what the screen like, I’ve set my phone to log every 30 secs.

Also you’ll need to sync the phone and camera time, press settings on the Geotag Photos Pro home page and you’ll see this:

Now go into setup camera time and set the time on your camera to what is displayed here.

Once you’ve set the auto log and set the camera time create a new trip and press record.

When you’ve finished logging your trip you can go into trips log and this will look like

The other good thing about this app is that you don’t need to upload the data to a website to obtain the track (although you can for archieve purposes), by pressing the blue circle you will have options of deleting/rename a trip or exporting the trip via email or itunes.
You can also check whether or not you have uploaded the trip to the Geotag Photos Pro website, if you have a symbol of a house with a tick it means that the trip has been uploaded.

To upload your trip go back to the home screen and press settings & upload, you will need to have an account setup do this, if you dont have one select “Link with Geotagphotos.net”, once your account has been set up go back a page and select upload logged data and then start upload. When the trips have been uploaded you will be able to delete them off of your phone and they will still be available on the Geotagphotos.net website.

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Another important part of water drop photography is making sure that the water flows through the solenoid at a constant, the beauty of using an Arduino to control the setup is that everything is repeatable but this can only be achieved if the water pressure stays constant!!
A mariotte Siphon can be used for this and will ensure that the water flows at the same rate regardless of how much fluid is in the vessel. I decided to use a 50ml syringe to hold the liquid, it might not sound like a lot but you wont need a 500ml drink bottle when all you are doing is releasing a drop of water at a time!

There is plenty of information on the internet about “Mariotte Siphons”, I found these websites useful and it should give you an idea of how to construct something

Mariotte Siphon
Mariotte Bottle

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Okay, now we have the circuits designed and built they need to be mounted in the box and wired up.

I divided the box in to two halves, the bottom half will have the Arduino and strip board mounted, and the top half will have the connectors and switches mounted.

The Ardunio has three mounting points and I decided to mount this flat inside the box, you will also have to consider the fact that you will need access to the USB port and the power connector. The way that I did this was to cut 2 holes into the side of the box and the held the Arduino in place, I then drilled through the holes that are already in the Arduino through into the base of the box. Here are some photos to give you an idea of what I did!


Then I cut the strip board to size so that it would fit in the slots provided and would still allow me to put the lid back on. Once the strip board has been cut to size you should be able to crack on with building your circuit! Here is a photo to show you how mine looked, please note that at the time of taking this I hadn’t built the solenoid circuit.

The last thing to do was make a rough sketch of how I wanted the connector and switch layout to look. I then made a scaled diagram to make sure that everything would fit, measured and cut the relevant holes. Another couple of photos to show you how the finished box looked. I wouldn’t use those big audio connecters again as they are an over kill and they take up unnecessary space!

Here is the finished Box; you’ll see two 3.5mm stereo jacks, these are for triggering the camera and flash guns. The 3 pin XLR is for controlling the solenoid and the 5 pin XLR is for the sensor. The switches perform a few operations and more info can be found on the Programming page.
On the side of the box are 2 power connectors, one is 5V for the Arduino and the other is 12V for the solenoid; there is also a USB socket which is on the Arduino itself and is used for uploading programmes.

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