Tuesday, October 04, 2011

How GBTimelapse 3.1 uses your GPS coordinates to reduce flicker

GBTimelapse 3.1 comes with a powerful new feature called AutoRamp, which I’ve mentioned in some previous posts here and here. AutoRamp is engineered to reduce flicker in several different ways - it’s a unique tool unlike anything else on the market, as you’ll see here....

In this post, I’m going to show you how inputting your GPS coordinates into the software can dramatically reduce flicker at sunrise and sunset. There’s some powerful mathematics and a great deal of research backing up this tool, but it’s very simple for you to use.

Behind the scenes in GBTimelapse 3.1, AutoRamp uses a moving average of past luminance values to calculate the correct exposure settings for the next image. This method works fine unless the scene brightness is changing rapidly during a sunset or sunrise. When the sun is below the horizon during twilight, the exposure can change by up to two full f-stops every ten minutes. Bad news for a time-lapse!

Here’s how GBTimelapse 3.1 is a gamechanger: if you’re in a situation with rapidly changing brightness, simply input your GPS coordinates. With this info, the AutoRamp function will predict the correct exposure by calculating the sun’s changing elevation relative to the horizon.

Wow! In other words, to give you the best exposure at sunrise or sunset, enter your GPS coordinates. The software will then anticipate the movement of the sun, adjusting your exposure accordingly.

It’s easy to get your GPS coordinates. Under the Tools/Options menu, check the Location tab to see this Windows form and use Google Maps to find your coordinates...

Also, make sure your computer clock and time zone are also set correctly. The current sunrise and sunset times are shown - make sure they are correct.

To use the location information, check the box labeled “Use Sunrise/Sunset compensation” under the AutoRamp tab. Have fun with your time-lapse!

1 comment:

Aaron D. Priest said...

I have wanted this feature on my Nikon D700 for a very long time!!! Sigh....... :-)