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Handling Different Exposure Times with Keyframes?

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#1 wade51
To all,

First I apologize if this has already been answered.  I just couldn't come up with the proper search strings.

I have an aurora sequence where I changed the time from 10 seconds to 8 seconds.  I thought I could just handle this difference by changing the exposure time in the 8 second exposure to match the 10 second exposure.  That is, I increased the Exposure time in Lightroom from 0.33 (10 second exposure) to 0.41 seconds (8 second exposure).  Unfortunately, this did not work as LRTimelapse adjusted the exposure of several frames leading up to the 8 second exposure.  As a result, the several images before the 8 second frames are too bright.  What is the best way to change the exposure times of the 88 frames that need a Lightroom Exposure time of 0.41?  Any help would be greatly appreciated.  In another sequence, I tweaked the aperture from f/2.0 to f/1.6.  Since this is a 2/3 stop difference, I changed the Exposure time in Lightroom from 0.33 to -0.33.  Of course, this didn't work as expected due to the earlier behavior.  I'm probably just making things too difficult since I'm just now learning how to use the software.

Thanks,

Wade
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#2 Gunther
This is exactly what the holy grail wizard does: applying all the compensations for changes on the cameras parameters like exposure, iso, aperture. It's a one click thing. Just go though the workflow, make sure to click on "Holy Grail Wizard" and you will see a mirrored orange curve that compensates for the changes in brightness, visible in the blue curve. Those compensations will happen on a background layer - this means you can still keyframe the exposure.
Make sure to check out my holy grail tutorial: https://lrtimelapse.com/tutorial/
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#3 wade51
(2017-03-17, 11:03)gwegner Wrote: This is exactly what the holy grail wizard does: applying all the compensations for changes on the cameras parameters like exposure, iso, aperture. It's a one click thing. Just go though the workflow, make sure to click on "Holy Grail Wizard" and you will see a mirrored orange curve that compensates for the changes in brightness, visible in the blue curve. Those compensations will happen on a background layer - this means you can still keyframe the exposure.
Make sure to check out my holy grail tutorial: https://lrtimelapse.com/tutorial/

Thanks for the quick response.  The "Holy Grail Wizard" doesn't see the difference in brightness between the frames so the Exposure 2012 line remains flat.  I can only assume it is having difficulty "sensing" the change in brightness due to the nighttime nature of the scene.  In addition, the ever-changing brightness of the aurora are going to give the algorithm a hard time too.  I don't want LRTimelapse to adjust the exposure based on the "flickering" behavior of the aurora.  Is there a way to force a certain exposure within LRTimelapse?  For example, select all the frames that need their Exposure 2012 adjusted in LRTimelapse and edit the column to 0.41.  Is this possible?  I believe this step will have to be done manually given the reasoning above.

Wade
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#4 Gunther
The Holy Grail Wizard will only "see" changes in the exif data (Exposure time, Aperture, ISO). Check that in appropriate the table colums. If those values are all equal, there's nothing to do for the Holy Grail Wizard.

Normally when I shoot the aurora I work in M-Mode with fixed camera settings (no holy grail). Then you can decide, if you would like to deflicker or not. When deflickering of course you don't smooth the natural changes of the aurora out, only possible aperture flicker - but mostly you won't have any, because you would most likely be shooting with aperture wide open anyway. At least I do.


Quote:Is there a way to force a certain exposure within LRTimelapse?  For example, select all the frames that need their Exposure 2012 adjusted in LRTimelapse and edit the column to 0.41.
I'm not sure if I understand, of course you can have the same exposure for the whole sequence, just set the exposure on the keyframes as you want, LRTimelapse will do the rest.
I'm not really sure if you read my instructions or watched my tutorials? I guess it would make things much easier for you...
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#5 wade51
I really appreciate all your help and suggestions.  I finally got it to work by manually editing the Exposure 2012 values where necessary.  I will have better technique in photographing the aurora next time.

Wade

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