Use a TI-83 Plus to take Hour-Long Exposures

I looked forever for info about doing this but only found stuff about the intervalometer. So I'm making this video to help other people who want to use their graphing utility for shooting on bulb mode.

This is how you can use your TI-83 Plus Graphing Calculator to take pictures of the stars (especially during next week's annual Perseid meteor shower) at long exposure lengths.. without having to pay ridiculous amounts of cash for a remote shutter.

All you need:
TI-83 Plus Graphing Calculator (Works on some of the other ones, too... I think)
Canon digital Rebel (I'm using the 550D/T2i; I think they all have the 2.5mm audio jack for its remote shutter though)
2.5mm audio cable (male to male)
Tripod

Total Cost: About 3 bucks

The Program.. I messed with the intervalometer program for about an hour before coming up with this one...
********************************************************************
:Prompt S
:S*1.1904→S (the arrow is above the "on" button)
:For(N,1,S,1)
:Send(A)
:End
********************************************************************

Execute the program.. When prompted for S, enter your desired exposure time (in seconds)

Make sure your shutter speed is set to BULB
If you find the time you set is too long, you can always cancel the shot by hitting the "ON" button on your calculator.

Point your camera to the sky and enjoy.

EDIT: Make sure the second line of the code is
:S*1.1904→S
I had the wrong number in the calculator on the video. It's NOT 1.25.

Category:

Howto & Style

Tags:

• canon
• rebel
• t2i
• ti-83
• plus
• graphing
• calculator
• bulb
• remote
• shutter
• long
• exposure
• meteor
• shower
• program
• intervalometer

[burnout616]

One thing I noticed however is that the exposure time does not always match the input time. Is this because of the variable 1.1904? What does this value control?

[WookieeCookies]

@burnout616 Yeah, I've noticed it, too. The third variable ('S'),when in in TI's 'For loop' syntax, determines how long the variable A will be sent (at least with this use of the 'For loop'). I had an original number (1.25), but it was wrong. I put in a 400 second exposure with S@ 1.25 and and checked the true exposure time in the photo data. Cross multiplied and solved for X, which gave me 1.1904.

[WookieeCookies]

@WookieeCookies The loop is dependent on the calculator's clock speed. I noticed the TI-84s are about twice as fast as my 83+. I think there are lurking variables that effect the given clock speed. (Perhaps memory usage bogs it down? Not sure)

[roberttice]

how do you get the arrow after 1.25

[WookieeCookies]

@roberttice read the video info.

[squirrelgecko]

YOU ARE MY FAVORITE PERSON IN THE WHOLE WIDE WORLD!!!!

If I knew you, I would bake you cookies. Thanks for the script!

Instead of the sky, I'm off to the storm sewers to paint with some light!

[WookieeCookies]

@squirrelgecko Nice. I'm glad someone has benefitted from this xD. Yeah, I use this setup during meteor showers... but I'm yet to capture one ._. --Being in the city doesn't help. Closest so far was a huge fireball right in line of my lens as I was about to start exposing! Doh. Anyways, have fun! I expect cookies, too.

[burnout616]

I couldn't find anything on a long release shutter until this. Perfect

[ChemicallAli]

The problem im having with the edited script is that, it is a second off the number i put in the calculator, so 3 = 2 seconds.

[jamieboyrockon]

@roberttice It's the button that says "STO->"

[ktrwcm2010]

urgh I have a problem. I have xsi and ti 83. did all the settings correctly, but it wouldnt take photos in given interval. It would take a picture instantly when I connect the cable, but it takes only one shot and no more after that first shot. Does anyone know how to fix this problem? thanks