## Introduction: Turn a TI Graphing Calculator Into an Intervalometer and Create Time Lapse Videos

I've always wanted to make time lapse videos, but I don't have a camera with an intervalometer feature built in. In fact, I don't think very many cameras come with such a feature (especially not SLR cameras).

So what do you want to do if you want to make time-lapse videos? You can buy a commercial intervalometer (yeah, right). You can check out some instructables like this one and make one yourself out of electronic components.

But what if you don't have the time/skills necessary to build one? You just want something quick and cheap.

Well, you can actually use a common TI graphing calculator (I don't know of any high school student without one of these) and hook it up to any camera with a remote shutter release socket. It's quite easy, and depending on your camera can require no electronic work at all.

## Step 1: Parts Needed

Here's a list of parts you need:

A TI graphing calculator - I'm using the TI-83+. I haven't tested my code on any other model, so I can't guarantee it will work.

Camera with remote shutter release socket - I'm using the Canon EOS Rebel. This has a 2.5mm socket that you can use to connect to the calculator. If your camera does not have a 2.5mm shutter release socket, you will need to create some sort of link cable that can connect the two together.

## Step 2: Program the Calculator

Depending on your calculator, this process might be a little different. The following directions are for the Ti-83+. I will try to get instructions for different models, but I will also have to convert the program to work with them also.

1) Turn on your graphing calculator (duh)
2) Press the PRGM key
3) Press the Right arrow twice to highlight the tab at the top titled "New"
4) Press ENTER
5) Enter in a name (I used "Camera")
6) You are now ready to insert the following program. The functions prompt, while, for, and end can be found by pressing the PRGM key again. The function Send has to be selected by press 2nd -> 0 (catalog).

Here is the program:

: Prompt A
: While 1
: For (H,1,A,1)
: End
: Send(A)
: End

This is a very simple program. I wrote one once that kept track of how many images were taken, displayed the estimated time remaining, etc, but it seems that it drains too much battery life and for some reason the calculator actually slowed down after a certain number of images. It might work better if you write the program on a PC in assembler, then send it to the calculator, but you need a special link cable, and that kind of defeats the point of this instructable.

Update:

The above code is claimed to work on both TI-83 and Ti-84 models.

Thanks LightShadow756 for sending me the following code for theTi-89:
(Program)

camera(pics,delay)
Prgm
0->x
While x < pics
For y,0,delay,1
EndFor
Try
x+1->x
SendChat a
Else
ClrErr
EndTry
EndWhile
EndPrgm

(End Program)

## Step 3: Making the Connection!

This step should be pretty easy depending on what kind of camera you have. Most TI calculators have a 2.5mm audio jack used for linking two calculators together. It turns out my EOS rebel uses the same type of jack, and there is no conversion required.

However, if your camera uses a different size audio cable, you might need to use a adapter. Even worse, if it uses a different shape connector, you might have to buy or make an adapter (I know cameras like the canon 10D have shutter release plugs that are specially made for them, it's very hard to find these types of connectors).

## Step 4: Set Up Your Shot.

This is where the fun starts. Don't plug in your calculator yet.

First, decide what you want to photograph. If outdoors, try to do this at a time where lighting conditions remain fairly constant. Also, try to shoot away from the sun.

Set up your shot - Use a sturdy tripod and don't zoom in too tight. Don't forget that things can change over a long period of time.

Focus - After focusing, switch your camera to manual focus, or use a lock focus feature if your camera has one. This step is very important because your camera might decide to focus on something else in the picture if your subject moves. It won't look very good if the focus is rapidly changing in a video. Also, if you're photographing the sky and there are no clouds in the frame, the camera won't be able to focus on anything at it might not take a picture at all.

Set the exposure - This step might be even more crucial than the focus step. If your camera has a manual exposure mode, or a lock exposure mode, it is very important that you use it. Like with the focus, exposure can change over time and it doesn't look good at all when your video is getting brighter and darker very quickly.

Set Quality - Depending on your camera and how much resolution you want, you will need to adjust your picture quality. My canon rebel can take pictures up to 6.3 megapixels, but this is very unnecessary if I'm going to make a small video to put on youtube.
Also, depending on your computer, it will take a LONG time to open up 200+ photos taken in the highest quality.
So, I usually turn my quality down to the lowest setting.

Some optional steps
Turning picture review off - If you want to save battery life by not having the LCD turn on every time you take a picture, remember to turn the image review off.

Turn camera sleep off - If you're going to be taking pictures with very large delays in between, you'll need to turn your camera sleep mode off. (This will drain battery faster though. If you're really worried about this you can actually modify the program to "wake up" the calculator before attempting to take a shot, this way you can keep the calculator in sleep mode. However, I think this is unnecessary).

## Step 5: Shoot the Photos!

This part is fairly easy:

Connect your Camera and Calculator - Use the link cable from part 3 to connect the two

Start the program - Turn on your calculator and press the PRGM button. Find the program you made on the list, and press enter.
On your screen, you should see the prompt "A=?". Enter in the amount of time you want in between the pictures. Note: this is not the amount of time in seconds. I think about 100 of these make a second, but this can change depending on battery life and your calculator model. If you don't want to think about this conversion every time, you can add a small piece of code in the program to do it for you.

Press Enter - Your camera should start snapping away! Now sit back and relax and make sure nothing explodes.

Turn the Program off - When you're done shooting, you can turn the program off by pressing or holding the ON button. You will see a prompt that says "ERR: BREAK". Just highlight Quit and press enter. The program will now be stopped and you can turn your calculator off.
If you want to restart the program, all you have to do is press ENTER again, you don't need to go to the program dialog again.

## Step 6: Compile the Video!

Now that you have all your pictures, all you need to do is put them together into a video. There are many ways you can do this.

Youtube has a guide to compiling a video using Windows Movie Maker here. What I don't like about this though is that you can't easily change the framerate of your video, so the final product will look slow and choppy.

Personally, I like to use QuickTime Pro from Apple (as much as I don't like Apple...)
First, copy all of you photos onto your computer hard drive and put them into a folder.

You will probably want to resize all of your photos beforehand. This will prevent your computer from freezing up if it tries to open up too many large photos with quicktime. I suggest using Windows XP PowerToys image resizer which you can download directly here. It's very easy to use and you can resize all your photos in a snap.

Next (if you're using Quicktime Pro), go to file > Open Image Sequence. Select the first image from your video, and press Okay. Your video should be automatically created!
Then, select File > Export. This is where you might have to play with the settings. If you want to upload your video to YouTube, I suggest looking at this page.
If you want your video to be streamlined for Youtube, select "Movie to MPEG-4" in the export dialog, then click the Options button to change more options around. I've included a picture with some settings, but I'm not very good with video stuff, so please experiment to find what suits your needs.

If you want a higher quality video, I'd suggest AVI or a Quicktime Movie format, but once again I'm not very good with this so please experiment.

If you don't want to "buy" Quicktime Pro though, there are many other options. It's really beyond the scope of this instructable though, so I'll leave that up to you. A quick google search for "Stop Motion software" should yield plenty of results.

I won't go much more into this as it will vary greatly depending on your setup.

## Step 7: Enjoy!

Here are a couple finished videos I've made using this method.

It would also be nice if anyone who knows how to program later model calculators (Ti-84, 86, and 89) could write some programs to do the same thing. I could probably write the programs but i wouldn't have any way of testing it.

Have Fun!