HDTR Photography – Capturing Time Flow
- By: Luis Argerich
Not to be confused with HDR, HDTR means “High Dynamic Time Range Photography”, the basic concept is to create a photo that shows different states of the same scene as time passed. In our example time flows from left to right converting a daytime cityscape in a night-time shot.
To create an HDTR photo you need to take several photos of the same scene at different times. A tripod is needed and an intervalometer is a great tool to automate the capture process. If you don’t have an intervalometer just set up a time or alarm clock and take photos at fixed intervals. You don’t need to use exactly the same exposure time in all the photos, you just need to make sure the scene looks darker as time passes.
For this project we combined five images as follows:
- 4:24pm F8 1/320
- 5:30pm F8 1/320
- 6:30pm F8 1/200
- 7:30pm F8 5”
- 8:30pm F8 5”
Note the big difference from 6:30pm to 7:30pm in exposure time, as the sun set between both photos keeping the same exposure time would have made the photo totally black and useless.
Once you have the photos load all of them as layers in your favorite photo-editing software: Gimp, Photoshop etc. Add a layer mask for each photo and use a left to right gradient on each layer mask to gradually blend each photo into the next one. For our project the masks looked like this:
If the transitions are not very smooth or if you see banding in the final photo you can use a gaussian blur on the masks to make the transitions smoother. Eventually you may need to add some intermediate shots.
If you have a window or balcony and a tripod you have a fun project to try when you can’t go out to take photos. Try different focal lengths and compositions to see how they look in an HDTR image and show to your friends how you captured time in a single photograph.