Monthly Archives: July 2010

Creating a Time-Lapse Calculator with Excel

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A quick way to perform movie-making calculations.

One of my hobbies is photography and I dabble occasionally with time-lapse. In time-lapse photography, you set up a camera on a tripod to take a photo at a set interval, like every 15 seconds, over a long period of time, like hours. When you’re finished, you take the resulting images and compile them into a movie using each photo as a movie frame. The length of your movie is dependent on the number of shots and the number of frames per second (fps) at which they are compiled.

I wanted to be able to easily calculate various values for a time-lapse movie project based on certain values I provide, which I call “assumptions.” For example, how many seconds between shots if I want 1200 shots over 3-1/2 hours? How long would a movie be if I took shots over 10 hours with 15 seconds between shots and compiled them at 30 fps?

This is basic math, but with a twist. I wanted to be able to solve for any one of three source photo values given the other two values:

  • Time period, in hours
  • Seconds between shots
  • Number of shots

Given that information, I also wanted to be able to solve for either of two resulting movie values:

  • Frames per second
  • Movie length, in seconds

Time-Lapse CalculatorThe resulting Time-Lapse Calculator shown here does the job.

The formulas I put in the green cells are shown below. The IF function tests to see if cells are empty and uses the test result to determine whether it needs to perform and display a calculation. For example, in cell D6, it checks to see if B6 is empty; if it is, it calculates the result based on B7 and B8. Because the last two formulas require data from either cell B8 or D8, they also test to see which one contains data. The result is a nestled IF statement.


D6=IF(B6="",B8*B7/60/60,"")
D7=IF(B7="",60/(B8/B6/60),"")
D8=IF(B8="",B6*60*60/B7,"")

D11=IF(B11="",IF(B8<>"",B8,D8)/B12,"")
D12=IF(B12="",IF(B8<>"",B8,D8)/B11,"")

You can download a password-protected copy of the worksheet here. (The password is not available for distribution.)

After completing this worksheet and beginning to write about it, I realized that it’s not everything I envisioned. What I really wanted was to calculate one of the following based on the other three:

  • Time period, in hours
  • Seconds between shots
  • Frames per second
  • Movie length, in seconds

I’ll likely work on this in the future. If I finish it, it’ll appear here on Maria’s Guides.

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How to Hide Farmville (and other Annoying Games) from Your Facebook News Feed

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This should make Facebook a little more bearable for people who use it for business.

I just got back on Facebook. It was a tough decision. What helped make it tolerable to go back to Facebook was my discovery that I could hide posts related to Farmville, Mafia Wars, and other time-sucking games I really couldn’t care less about.

It’s easy:

  1. In your News Feed window, when you see a post about a game you don’t care about, point to it. A Hide button appears.
    Hide Button
  2. Click Hide.
  3. The item disappears and is replaced with a series of buttons like the ones shown here. Click the button to hide the game.
    Click Hide
  4. A note like the one shown here appears. Ignore it and it will go away.
    It's Gone

From that point on, you won’t get any posts related to that game.