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LRTimelapse Holy Grail Recognition with Variable ND

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#1 CSSmedia
Gunther,

I recently experimented capturing a day-to-night time-lapse manually adjusting the exposure using a variable ND filter.

I was hoping that the LRtimelapse software would automatically detect the spike changes in exposure, but it seems that it relies on seeing changes to the shutter/aperture/ISO for it to add the holy grail keyframes.

Can I ask, what would be your recommendation on LRtimelapse workflow for shooting in this way?

My trial method was to create two regular keyframes next to each other for each of the steps in exposure, then to match them by eye in Lightroom before heading back to LRtimelapse to complete the auto-transition for the rest of the frames.

Unfortunately, this seems to have created bad flicker, especially in the sky, which the deflicker option does not fix.

Here is the final sequence: https://www.facebook.com/CSSmedia/videos...955295008/

Anything you can suggest?
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#2 Gunther
If you use different ND filters like you did (a technique that I do not recommend) your best option would be to "tag" an appropriate aperture for the different segments, since the Holy Grail Wizard in LRTimelapse cannot know about the changes of the ND filters, since they are not in Exif data. So use the Metadata/Lens Tagger feature on the subsequences shot with different ND filters to tag appropriate Aperture Values for the different filters.
Next time rather use a constant filter and ramp the aperture instead.
Of course you can use the regular keyframes (4*) where you changed the filters and try to match the exposures in Lightroom manually too. This should work, maybe you did something wrong in the process.
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#3 CSSmedia
I did not change the filter, it was a variable ND, so same filter, but rotated to different strengths during the day-to-night transition.

The reason I chose to use this technique was to keep constant shutter speed, aperture value & ISO. Changing these values has an effect on the look of the images, where changing ND simply alters the amount of light entering the lens - which is ultimately what we want to do to adjust the exposure accordingly.

Like I mentioned, I know now that LRtimelapse detects the that the HG method was used through the metadata. I originally thought it did this through analysing the exposure graph and seeing large step differences.

Is there not a way to add the HG keyframes manually?
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#4 Gunther
This will not work. If a variable ND was a useful tool for time lapse shooting, everyone would be using it...
My recommendation: don't use it. It will give you nasty shadings as you rotate it and you will never get a really smooth sequence with that technique.
Rather use qDslrDashboard to ramp Exposure, ISO and Aperture. This is the way to go for good results!

PS: You can try to do the matching manually, but use 4* keyframes for this: set one to the frame before each change and one after each change. Then try to match with the exposre slider in LR. But as I said, it won't be really good...
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#5 CSSmedia
I appreciate the advice Gunther.

Maybe the shadings you mentioned are a problem with lower-cost variable ND filters? In my very short experience shooting with the variable ND I purchased, there are no issues with un-natural shadows or colour shift.

I am not a fan of look when shutter speed is changed greatly during a day-to-night transition. This is exactly the reason why I experimented with the variable ND technique - to keep consistent camera settings.

Unfortunately I am shooting with a Sony A7RII, so it seems the qDSLRdashboard is not an option.

The post workflow technique you mentioned of trying to match the exposure of the 4* keyframe before/after the exposure change is exactly the method I used.

I am going to try a reprocess of the sequence using another method to see if it produces better results.
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#6 Gunther
A ND fader is always a pair of Polarization-Filters. If you turn them to very dark positions they will cause nasty shadings no matter what money you spent on the filter, this is physics...

qDslrDashboard works with the Sony, no problem, check out the tips on dslrdashboard.info - you have to install the latest version of the Sony WiFi app onto the camera for it to work.
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#7 CSSmedia
Yes, I know this. There is a 'safe window' where the variable ND can be operated without the partial darkness appearing.

I will do some research into qDSLRdashboard - thanks for correcting me.

It was only an experiment to use the variable ND filter in the first place. Apart from the flicker, I am pretty happy with the results.

This was also the first time using a pan & tilt head, so it was positive in this sense too!
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#8 lerroy
(2016-04-26, 15:26)CSSmedia Wrote: Yes, I know this. There is a 'safe window' where the variable ND can be operated without the partial darkness appearing.

I will do some research into qDSLRdashboard - thanks for correcting me.

It was only an experiment to use the variable ND filter in the first place. Apart from the flicker, I am pretty happy with the results.

This was also the first time using a pan & tilt head, so it was positive in this sense too!

Sorry I know this is an old thread but ill jump on it Smile

I did some testing on a Vari ND filter and although and as Gunther mentions there was slight irregular darkness, similar to a CP on super wide I was fairly happy. (widest 24mm on ff)

I've been using Qdslr and now Timelapse+ View for holy grail in conjunction with Lrtimelapse and I'm pretty happy with results, one area I would like to improve is the day section.

Normally I would use ND filters for day time lapses to slow the shutter down and get the blur effect on movements, rather than trees moving erratically at fast shutter speeds for example. With the view I can ramp the aperture now, I find results not great and I introduce flicker at smaller aperture numbers so normally shoot wide open.

With night exposures though where I want all the light I can get, if i leave the filter on there are no stars, if i remove the filter I get a huge jump in exposure which is hard to fix in post.

So back to the post I had and idea to use a stepper motor on a focus ramper arrangement and get it to slowly adjust the vari ND filter from say 4 stop for day exp then 0 stop for the night.

Thoughts ?

Do you have any results from you Vari ND shooting to show us ?
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#9 CSSmedia
(2017-04-18, 04:32)lerroy Wrote:
(2016-04-26, 15:26)CSSmedia Wrote: Yes, I know this. There is a 'safe window' where the variable ND can be operated without the partial darkness appearing.

I will do some research into qDSLRdashboard - thanks for correcting me.

It was only an experiment to use the variable ND filter in the first place. Apart from the flicker, I am pretty happy with the results.

This was also the first time using a pan & tilt head, so it was positive in this sense too!

Sorry I know this is an old thread but ill jump on it Smile

I did some testing on a Vari ND filter and although and as Gunther mentions there was slight irregular darkness, similar to a CP on super wide I was fairly happy. (widest 24mm on ff)

I've been using Qdslr and now Timelapse+ View for holy grail in conjunction with Lrtimelapse and I'm pretty happy with results, one area I would like to improve is the day section.

Normally I would use ND filters for day time lapses to slow the shutter down and get the blur effect on movements, rather than trees moving erratically at fast shutter speeds for example. With the view I can ramp the aperture now, I find results not great and I introduce flicker at smaller aperture numbers so normally shoot wide open.

With night exposures though where I want all the light I can get, if i leave the filter on there are no stars, if i remove the filter I get a huge jump in exposure which is hard to fix in post.

So back to the post I had and idea to use a stepper motor on a focus ramper arrangement and get it to slowly adjust the vari ND filter from say 4 stop for day exp then 0 stop for the night.

Thoughts ?

Do you have any results from you Vari ND shooting to show us ?

Don't worry about it!

Personally, I have stopped adjusting the variable ND during a capture. The main problem I had was with colour shifts for the images before/after the change in ND. It was very difficult to compensate for during the compositing stage, mainly because the colour shifts were not consistent - even when adjusting the ND the same amount for each shot.

Now I make exposure adjustments in this order; ISO > Aperture > Shutter Speed

Like you, I prefer to prioritise the shutter speed in order to keep a consistent motion blur 'look' for the sequence duration.

Not sure if this helps at all, but that's where I'm at right now.
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#10 Gunther
I totally agree to @cssmedia.

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