Tag Archives: movement

Time Stacks

One of the great things about developing a repertoire of tools  and tricks for processing photos is applying those tools in creative ways. While we were furiously working on Advanced Stacker PLUS for creating star trails and processing night sky images, one clever fellow: Matt Molloy gained great acclaim by stacking sunset and sunrise shots of clouds skittering across the sky. Matt Molloy coined the phrase Time Stacks for that type of image.

Phoenix Leaping

Phoenix Leaping – 20 separate frames combined in Lighten Mode plus an extra foreground frame.

Where Steven lives in the Silicon Valley, it is difficult to get good conditions for clouds. Indeed, the San Francisco Bay Area has so many blue sky days that having clouds is a stretch – in the Bay Area the options are either low thick clouds (fog), or zero clouds. However occasionally conditions are right – or Steven travels where conditions are right – for creating these shots. Of note are dry climates with mountains and high winds during seasons with moderate moisture in the air. In March in Palm Springs, California, for example Steven watched as clouds formed due to the uplift of the Mt. San Jacinto mountain range and dissipated quickly as the young cloud wandered eastward away from the peak. Literally you could watch clouds form and dissolve in a matter of minutes. In the image above, you’ll notice that some low clouds moved slowly and didn’t dissipate. Because the denser low clouds were in the shadow of the mountain they grew dark and ominous.  You can see more variations on the same theme by checking out this set of images.

Exit Criteria

Exit Criteria – Alviso, California on one of the few days when clouds were present

What Conditions and Equipment Do I Need?

  1. You need partially cloudy skies and the clouds can not be slow creepers. The clouds should be vigorous sailors. How fast? Fast enough to cross a significant field of view in about 20 to 30 minutes. They need to move into an open area of the sky – clouds moving over other clouds won’t be as interesting.
  2. Like any compelling shot, the frame should include a worthwhile foreground.
  3. And finally, it helps if these conditions all occur near sunset or sunrise so you can get extra color in the shot.


  • You will definitely want to use an Intervalometer (or an on-board Intervalometer if your camera has one). Shooting at regular intervals results in a more pleasing outcome.
  • A sturdy tripod is also a must.

What Settings Should I Use?

  1. Select a moderate aperture (f/8, for example), and a low ISO (200). The goal is to get a shot that is relatively long to get a little cloud blur from the cloud motion.
  2. Since most interesting results occur right at or after sunset, start the exposures at 1 to 2 stops over exposed. Subsequent shots will get darker and finally dark to a point where the images will be too dark  to use (e.g. 2 stops under exposed).
  3. While it may be tempting to adjust the exposure during shooting, we have found that strategy does not work well.  You never really know which shots you will want to combine. Therefore it is best to do large sets (40-50 exposures) all using the same settings.
  4. Change settings (and optionally re-orient your camera), then get another substantial sequence.
  5. Be sure to include an exposure optimized for the foreground in the beginning and/or at the end of each sequence.

The trickiest part is selecting the interval between shots. The speed of the clouds across the frame is the key here – and that can vary dramatically depending on your conditions. One possible method is to shoot once every other second, then cull out the interval that works best (which could be 10 or 20 second intervals), but a less memory and processing intensive approach may be to use 5 or 10 second intervals between shots (or longer if your clouds are sluggish).

Also keep in mind that not all clouds will move at the same speed (or in the same direction!), nor will they be illuminated alike.

How Do I Process the Shots?

This is actually the easy part: use the same tools you would use to create star trails. That is, stack the images in Lighten mode. Understand that if clouds move over clouds the net result is sometimes quite unexpected – the brighter clouds (regardless of color) win.

How Processing Was Completed (Click for larger image)

Above is a snapshot illustrating how this shot (62 frames in the life of clouds) was finished in Photoshop. Two image contrast enhancements were added. The bottom layer is the stacked (lighten mode) image, the next image up is the intentionally over-exposed foreground. Notice that the “Darken bright foreground” is linked to effect ONLY the foreground image. Also note that darkening, and in many cases increasing contrast has the affect of increasing color saturation. No saturation or vibrance enhancements were done here. As with Star Trails, we also recommend that you do not alter any of your shots before you stack them – stack them in their raw form with NO adjustments. The result will look flat until you apply manual corrections and curves, but by not altering your shots before hand, the stack will work better and you are far less likely to introduce strange artifacts.

Variations on Time Stacks

Of course your Time Stacks do not have to be daylight subjects like this solar eclipse which was shot with a solar filter for all the shots except the last which was taken at sunset.

Annular Eclipse Sequence [C_040079+5s]

Time stacks can also include night events like a lunar eclipse

Plan C: San Jose City Hall Eclipse Sequence

Get creative and try other Time Stacks and share with us what you get as a result via comments!

Want to see the technique preferred by Matt Molloy, master time stacker? See his tutorial here.

Road Trip: Eastern Sierra, California

Do you know how to get permission” … is how it began.  And this question set in motion a two-and-a-half day trek with 16 hours (800 miles) of driving plus the usual sleepless nights.  The first night found us shivering at Mono Lake.  I knew it would be cold, but it was colder than I anticipated and my 7 layers of clothes were just barely keeping the frigidity at bay.  Unfortunately due to a low fog that crept in and the aforementioned bracing cold, we were unable to hang out until moonrise which that night was to be at 12:20 am.

Takeaway: Always be prepared for 20 degrees lower temperature than the forecast!

After sleeping in, and grabbing breakfast we took a long drive to Bishop by going through Benton and stopping at several Petroglyph sites.  There were some remarkable locations I’d never seen before along the route, including a place that looks strongly like the formations at Alabama Hills.  Unfortunately the photos I took with my Spyglass application were never saved… we’ll be talking about Spyglass in the future, so stay tuned.

Andy stares down #13

Andy stares down #13 as the sun sets.

The second evening we found ourselves at 7,200 feet elevation where clear skies turn a noticeable purple after sunset. But I talked Mr. Mean 🙂 into remaining until at least moonrise which on that night followed the rise of Sagittarius.

The Milky Way rises over the 10.4 meter radio telescopes at Cedar Flat, California.

The Milky Way rises over the 10.4 meter radio telescopes at Cedar Flat, California.

Here is a short timelapse from which the above is taken:

Awake All Night (PS CS6 version) from Steven Christenson

For a slightly different take including an additional sequence, see here.

The Route


WIth Tioga pass closed, we traveled through Sonora Pass on the way out and by accident through Carson Pass on the way back.  There was precious little snow anywhere except in Carson Pass.  The area around Caples Lake was particularly nice.

Caples Lake, Ebbetts Pass, California. This is a little bay in the lake the lakes is MUCH larger.

Caples Lake, Ebbetts Pass, California. This is a little bay in the lake. Caples Lakes is MUCH larger.

The shoreline of Mono Lake with a large Tufa formation and stars of the North Western skies.

The shoreline of Mono Lake with a large Tufa formation and stars of the north western skies.

By the way, I’ve referred to Andy as Mr. Mean only because he was insistent that I not pay for the gasoline for this long trip.  I don’t think he really has a mean bone in his body. Meanwhile, you might want to check out his antics on his blog: PhotoshopScaresMe.com