Tech Tip #7 - Auto Bramping

In this week’s tech tip I’ll be talking about how to take a “Bulb Ramp” (AKA Bramp) using your camera’s automatic features. This is actually one of my favorite tricks for keeping light levels smooth, even during regular daylight time-lapses, but it can also make taking sunrise or sunset time lapses much simpler. 

The Theory 

I expound on this more thoroughly in our bulb ramping tutorial but the most important thing to keep in mind is that the light levels during a sunset or sunrise are changing a lot. The traditional method for accounting for this is to use your camera in bulb mode, and have your Radian or Michron dynamically change your camera’s shutter speed throughout your time lapse. This can lead to some very cool footage, but takes a bit of thought and practice to get right. 

Auto Bulb Ramping instead works by having your camera adjust to the changing light levels by putting it into an automatic setting. This removes some creative control, generally gives you less ability to capture the full transition into stars (this one depends on your camera), and can go awry if done improperly. But it is pretty easy to set up, and will still capture most of your sunset/sunrise transition. So if like me you want to reduce your time spent thinking about the shot (or avoid a scene getting too dark as night approaches), read on! 

The Process

As you fiddle around a bit, I’m sure you’ll develop your own preferred settings (all cameras are different) and you will be limited in some settings by how bright everything is when you start out, but here’s what I recently used on my Canon T1i and Olympus XZ-1 during some sunsets: 

• Camera Mode : Aperture Priority (This will give you the most flexibility)
• Aperture : The widest you can go (at some point things will be dark)
• ISO : This one is more tricky, I generally go for 400 or 800, but auto could be a good choice as well. You can also help things out by jumping in and bumping your ISO up mid time lapse if your camera seems to be maxing out. 
• Focus : Manual (As always!)
• White Balance : Again tricky, but Auto seems to work fine for me
• Time Lapse Interval : This will depend on how long your longest exposure will be, which is hard to know, but ~12 seconds is usually safe. You can test this by putting your camera into AP mode, and taking some photos with the lens covered. This will tell you how long your camera’s longest exposure will by in this mode. 

The last thing to make sure to do is to set your camera’s metering settings. This will tell your camera what portion of the scene to expose relative to, and can make or break this process. There’s a good explanation of metering modes here, and generally speaking, you will want to use Spot metering, which lets you select a particular region of your camera’s view as the chunk of the scene to try to keep the end light level constant within. As you set up your Bramp, you will want to think about what object in your scene is the most important to keep consistently exposed (I generally go with the sky). If you aren’t sure however, or if you have a lot of motion in your time-lapse and the metering spot may move, than something like evaluative metering may be a better choice. 

The Result

In the below example, I used a 10 second interval, ISO Auto (it ranged 100-1600), and used evaluative metering (there was too much motion for spot metering). As you can see in the end of the video, the Radian’s motion seems to speed up because the end exposure of 30 seconds is too long for the 10 second interval. Because of this, only every 3rd photo commanded by the Radian is actually taken (the camera is still taking one long exposure while the commands come in every 10 seconds), and so the Radian moves three times as much per photo as it should. Were I to shoot this one again, I would use a sturdier tripod (notice the wind shake part way in), a higher ISO, longer interval, and larger aperture to reduce these issues. On the flip side, I was able to set up a 2.5 hour time lapse with fairly little effort, and caught most of a beautiful sunset! By the time I took the Radian down, it was completely dark.  

While by no means a work of art, this time lapse shows the flexibility of taking an Auto Bramp (note the consistent metering even after the sun falls behind the trees), as well as some issues that can arise. 

That concludes Tech Tip #7! I hope you found it educational and entertaining, and as always shoot us an e-mail if there is a clarification you would like, or a tech tip you wish to see! Also, we have now set up a Tech Tip compendium in case you have missed any of the older ones. 

-Steve