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Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
gwegner Offline
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Post: #1
Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
German version of this article here.

One method that is often named in the context of day-to-night time lapses is called 'bulb-ramping'. The idea behind this is using the camera in its so-called 'bulb' mode and an external device ('bramper') to change the exposure time automatically.

While using the 'bulb' mode the camera opens the shutter curtain as long as the shutter button is pressed and closes it as soon as the shutter button is released. The mode is the preferred one when using long exposure times in conjunction with cable releases, e.g. night photography.

'Bulb ramping', using an external device, is used to 'ramp' up or down exposure times during time lapses.
Ideally this would keep continuous exposure transitions throughout the whole sequence.

The idea is not a bad one but the problems that occur are by design.
To know how much the transitions between two shots has to change, the controller has to the exposure delta that it has to change during a certain time, for example: during the next 2 hours the exposure time has to change from 1/50 to 2 seconds.
But to get to these values you need to know in advance which exposure time you would need from now on in 2 hours!

This piece of information depends on a lot of different factors, like:
  • weather (what, if the sky is cloudy in 2 hours?)
  • geographical latitude (closer to the equator the sun sets a lot faster that in central europe for example)
  • the season or time in the year
  • time of day
just to name a few.

Even if you could repeat a capture on 2 consecutive days (measuring the scene on the first day and capturing it on the second) the problem of weather changes and many other factors would remain.

Another idea used by some of the 'bramper' devices is to use a light meter (photocell) to measure the exposure times needed - with similar disadvantages as using camera internal metering: it cannot distinguish between changes that are natural/wanted (like clouds moving across the sky) or unwanted ones (like a bird sitting on the photocell).

Even if such a 'bramper' could incorporate GPS for the location and pair with a Smatphone to get weather information and the path of the sun there would still be unforeseeable variables that would interfere with a precise control of exposure.

Leaving the technical points aside, a 'bramper' is another complex device which you have to carry with you and still have the (high) chance to mess up that one sequence (in contrary to digital photography with time lapses you generally don't have a second chance to redo it with adjusted settings)

All of these problems made me develop a more flexible and simpler solution for the so called 'holy grail of time lapse photography': seamless transitions between day and night which can be accomplished without external devices.

Using this method dealing with sequences containing extreme dynamic range is a breeze as it is not prone to any of the disadvantages named above: after years of being hard to realize, now you can get the so-called 'holy grail of time lapse photography': perfect transitions from day to night or vice-versa.

The basic idea of this method is to change the exposure time or the ISO setting during the sequence as soon as you realize that the picture taken is over or under exposed to a certain degree.

To determine if this is the case, you could use the histogram when playing back your images during shooting. - another method is using the build-in metering of the camera. Don't worry - we will use it manually!

Almost every camera will show a exposure meter (either in the viewfinder or on the top LCD) during operation in manual mode (M) to show if what the camera sees is over or under exposed. Often the meter is a bar, marked with '0' at the center to mark the 'correct' exposure.

After the initial setup the meter shows the desired value e.g. '0' - in this case '0' is an example because you might want to deliberately over or under expose the sequence to keep light areas from clipping, during a sunset for example.

Now you need to remember the initial value you just set. While the scene gets darker the indicator moves to the negative section. If this indicator is at '-1' (or 'initial value - 1') you know that the current image will be under exposed by one stop - this way you know that you can compensate for exactly one stop.

Another, even better way is to check the histogram. It will work more accurate and in more darkness (the metering will stop working it it's too dark). To be able to use the histogram without touching the camera, I started a cooperation with Zoltan Hubai, the developer of the Android-App for wireless camera control "DSLRDashboard". Check out my video to learn how this works. Together with LRTimelapse 3 it makes Holy Grail Shooting a breeze: http://lrtimelapse.com/gear/dslrdashboard/

The next step is essential - you need to know exactly how to change the exposure time or the ISO on your camera by one stop (or 2/3 or 1/2 stop). Of course every camera is different at this point. With Nikon you need to turn the rear command dial by 3 clicks to the left to elongate the exposure time by one stop. Increasing the ISO by one stop is accomplished by pressing the ISO-Button and turning the rear command dial 3 clicks to the left. If you use DslrDashboard the LRTimelapse Page there will allow you to change those settings without touching the camera.

During post production with the 'holy grail' you will compensate for those jumps simply by using LRTimelapse. How this can be done exactly is explained in the tutorial video on the tutorial website.

Using this procedure correctly you will get perfect results with relatively minimal effort.

---
A very warm 'thank you' goes to the users Markus (MarkusFelix) and Olaf (splitti) for helping me translating this article to English!

The new version 2014 of my EBook Timelapse Shooting and Processing is available now,
covering all new Workflows with LRTimelapse 3! Available in English and German.

lrtimelapse.com - advanced Time Lapse Photography made easy!
gwegner.de - Fotografie, Zeitraffer, Video, Reisen.
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(This post was last modified: 08-24-2013 12:25 AM by gwegner.)
01-17-2013 07:17 AM
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JoseAlonsoLeon Offline
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Post: #2
RE: Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
Really nice write up of the process and its limitations. I have to agree totally on what you wrote and thank you for posting it. I had installed Magic Lantern on my 5DMKII because of the many features it adds to the camera and have been using several of them on a daily manner, built in Intervalometer, HDR bracketing without the 3 bracket limit, ISO changes in ramping (not bulb ramping) or 5 bracket HDR ISO change and so on. But quite frankly I never made the jump to Bulb Ramping with it because it never passed the tests I made at home and every time I went out to shoot a night scene I was never comfortable enough to trust the functionality and trust that my sequence would come out perfect. Which is why I never used it really.

I could not put the words all in a straight phrase to explain my doubts but you have done it marvelously.

I am very happy with the Holy Grail method which I also use for none Day to Night transitions but for any scene with drastic changes. It's a wonderful tool and out of ten sequences I would say 9,5 of mine all pass thru LRTimelapse. I hardly do any TL sequence without it.

By the way If you need help for translations in the future, I'll be glad to help you in English, French or Spanish.
(This post was last modified: 01-18-2013 02:01 AM by gwegner.)
01-18-2013 01:20 AM
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ridindave Offline
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Post: #3
RE: Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
Hello Gunther, hello everybody,

I'm of course a hardcore LRT user, and I also own a bramper. I guess I had my bramper before I got LRT, but it didn't take long before I realize that bramper was more or less useless, thanks to LRT.
I've made a lot of day/night transitions, the way Gunther describes it. The only refinement I add is to increment exposure by a 1/3 stop only, instead of a full stop.
This way I'm pretty sure that nothing will be noticeable, not even a slight variation in noise amount. Of course, drawback is it takes 3x more work on post...

Thanks again for your software, Gunther! Smile

David
01-18-2013 01:54 AM
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JoseAlonsoLeon Offline
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Post: #4
RE: Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
(01-18-2013 01:54 AM)ridindave Wrote:  Hello Gunther, hello everybody,

I'm of course a hardcore LRT user, and I also own a bramper. I guess I had my bramper before I got LRT, but it didn't take long before I realize that bramper was more or less useless, thanks to LRT.
I've made a lot of day/night transitions, the way Gunther describes it. The only refinement I add is to increment exposure by a 1/3 stop only, instead of a full stop.
This way I'm pretty sure that nothing will be noticeable, not even a slight variation in noise amount. Of course, drawback is it takes 3x more work on post...

Thanks again for your software, Gunther! Smile

David

I'm with you on your last comment. I prefer to minimize the jump at the cost of a few more copy/paste select and Match Total Exposures...;-)
01-18-2013 02:02 AM
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skyml Offline
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Post: #5
RE: Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
I gave up using my Little Bramper in exchange for usind a small netbook and GBTimelapse to Ramp my shots. So many more automated features besides bulb ramping... ISO Ramping, WB Ramping, Lens calibration, etc and intergration with moco devices like the Dynamic Perception MX2.
01-18-2013 10:09 AM
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BillinNM Offline
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Post: #6
RE: Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
Greetings -

My first posting here...

I'm a long-time still photographer and a new and enthusiastic timelapse maker and user of LRT. I have had some good success, including some Holy Grail transitions that have worked quite well. I am very impressed with LRT and its capabilities (thank you, Gunther!!).

I have generally been making my Holy Grail sequence exposure adjustments in 1-stop steps. I am curious ... for those of you that are using 1/3-stop steps, do you find that LRT is generally able to correctly identify those small steps and mark the correct corresponding keyframes? I am interested in trying this approach, which will no-doubt maintain a more optimal exposure level throughout the sequence, thereby requiring less exposure adjustment in LightRoom, although admittedly 3X the number of keyframe pairs to edit.

Looking forward to the arrival of my eMotimo TB3-Black to get things moving ... this TL stuff can be addictive, I am discovering!! :-)

Thanks, Bill
01-20-2013 05:37 AM
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gwegner Offline
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Post: #7
RE: Is a 'bulb-ramper' a useful tool to capture day to night time lapses?
Regarding the "detection" of the jumps: as of LRT 2.3 (I'm going to release a beta the next days) it will use Exif-Data to detect the changes, so that will be a lot more accurate than the current detection based upon the brightness changes.
So you won't have to worry, that 1/3 changes wont be notified. My experience is, that 1EV steps are sufficient in most cases and cause way less work in post.

The new version 2014 of my EBook Timelapse Shooting and Processing is available now,
covering all new Workflows with LRTimelapse 3! Available in English and German.

lrtimelapse.com - advanced Time Lapse Photography made easy!
gwegner.de - Fotografie, Zeitraffer, Video, Reisen.
facebook · Google+ · twitter · vimeo

01-20-2013 05:45 AM
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