What is bulb ramping?

Question

What does the term bulb ramping refer to and what does it bring the world of time-lapse photography?

It seems you need a specific type of intervalometer for bulb ramping. How do these differ from the average intervalometer?

Answer

Bulb ramping, or bramping, is a means of automatically adjusting exposure settings to maintain a specific exposure value (EV) throughout the duration of a time-lapse sequence. Bulb ramping intervalometers can be simple and cheap, or complex and expensive, depending on the results they can provide. Cheaper ones, and many DIY projects that you can follow to build your own, tend to produce fairly apparent jumps when exposure settings are changed, resulting in less-than-ideal results when a time-lapse sequence is stitched together into a video. More expensive intervalometers that offer bulb ramping capabilities tend to produce much finer adjustments over more frames, greatly reducing or eliminating visible jumps in exposure value in the final video.

Its somewhat possible to achieve bulb ramping with a normal intervolometer and automatic settings in a camera body. Things like auto ISO and a priority mode will usually achieve some degree of bulb ramping...but the results are often unpredictable. Using automatic and priority modes sometimes limit your options as well...such as only outputting JPEG images, or being limited in how much "ramping" can occur, etc. If you want the best results, buying or building a high quality bramper that supports fine adjustments over the duration of a time-lapse sequence will be necessary.

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Are Intervalometers different for standard Time-Lapse and HDR Time-Lapse

Question

I am a Nikon D90 user and fairly new to photography. I am considering purchasing a wired remote shutter release as intervalometer for taking time-lapses. However since I'm also a fan of HDR, it will be a matter of time before I want to experiment with HDR time-lapse.

My question is, will any intervalometer work the same? Or do I need an HDR-specialized intervalometer?

An example intervalometer I had my eyes on that is relatively cheap and has the full features: http://cgi.ebay.com/130338921382

I have also seen expensive ones mentioning they take HDR time lapse: http://www.promotesystems.com/products/Promote-Control.html

Thanks in advance. :)

EDIT:

I was inspired by Philip Bloom's HDR Time-lapse tutorial and it seems like his intervalometer(s) do more than standard interval with auto-bracketing on camera. Instead of "[ev0] [wait] [ev-1] [wait] [ev+1]...", it seems like his intervalometer(s) are doing "[ev0] [ev-1] [ev+1] [wait]...". Is that right??

EDIT2:

After reading John Rappold's article, I think the reason most shutter releases ask you to set to bulb mode is so it can accurately time the shutter open time. Does this mean if I set "hold time" to 2 seconds, use continuous mode and takes 3 brackets of 0.25sec, 0.50sec, 1sec, it will produce the desired result I seek for??

Answer

Based on the Promote Control page, it sounds like its HDR capabilities are limited by the camera. Some cameras may support a continuous stream of bracketed shots, while others may require a pause between each. I figure that is because some cameras support burst-mode bracketing, while others require separate shutter releases for each shot of a bracket.

Based on Philip Bloom's 'HDR' timelapse video, I'm not really sure I see anything there that probably couldn't be achieved with single RAW frames from a camera with decent enough dynamic range. Most HDR images are not actually physically high-dynamic-range...they are low dynamic range images tone mapped from high dynamic range images. According to DxO Mark, the Nikon D90 has about 12.5 stops of dynamic range, which gives you quite a bit of headroom to eek out a quality "HDR" video comparable to Philip Bloom's with single shots.

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How can timelapse sequences be shot without in-camera support?

Question

How can timelapse sequences be shot without having in-camera support for it?

Which third-party tools are recommended?

Answer

I have a Canon TC80N3, which works as a remote shutter, can do hundred of exposures at a timed interval (aka time lapse), a long delay before taking a shot, and very long exposures (ie, greater than 30 seconds that the camera can do).

They seem to be quite difficult to get new nowadays - but they do have them on eBay.

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Timelapse without in-camera support

Question

How can timelapse sequences be shot without having in-camera support for it? Which third party tools are recommended?

Answer

I have a Canon TC80N3, which works as a remote shutter, can do hundred of exposures at a timed interval (aka time lapse), a long delay before taking a shot, and very long exposures (ie, greater than 30 seconds that the camera can do).

They seem to be quite difficult to get new nowadays - but they do have them on eBay.

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Can anyone suggest an intervalometer for the Nikon D90?

Question

I was wondering if anyone had suggestions for intervalometers for a Nikon D90. The D90 lacks a remote port, so it has to be triggered either by USB or IR, which limits the 3rd party remotes it is compatible with quite a bit.

Answer

The Nikon D90 can in fact accept a wired remote. It plugs into the GPS port which is the second rubber-covered area on the side of the D90. While some cameras have separate ports, the D90 uses this single port for both purposes.

Here are a couple options from Amazon:

• Satechi TR-M Timer Remote Control for Nikon D90
• GSI Super Quality Multi-Function Timer Remote Control Shutter for Nikon

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