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Canon S110 Time Lapse Advice/Recommendations

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Offline MarkB

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #40 on: 17 / March / 2016, 22:05:02 »
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Quote from: c_joerg on 14 / March / 2016, 05:10:08
It looks good. You got more and more experience.


Thanks.


Quote from: c_joerg on 14 / March / 2016, 05:10:08
There is one suggestion about the parameter from my side. I never set the overexposure higher than 1%. Underexposure is always off. From my side, parts of your video looking too much overexposed. I know, by setting this value down, the whole scene gets darker. But when you work in RAW, you can really good correct these parts in Lightroom, but you can’t correct overexposure parts.


Which rawopint.lua menu item are you referring to when you say you never set overexposure higher than 1%,  and what value are you entering?


I agree there is too much overexposure in especially in the sky.  That is what I would like to fix next.  I am using the setting from when I shot some sunsets and tweak them to also deal with sunrise.  Not sure if this is possible and there will be a compromise somewhere.  When I get a chance I will pick up some larger SD cards and start experimenting with shooting a sequence in RAW.   I am well aware that with RAW files you can be more aggressive with highlight and shadow recover before it starts to fall apart than with jpeg's.  Right now I am thinking that if I can get the jpeg's close to what I am looking for, then when I switch to RAW's I will have that much more ability to tweak the images to my liking.
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Offline reyalp

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #41 on: 18 / March / 2016, 00:35:30 »
Quote from: MarkB on 17 / March / 2016, 22:05:02
Which rawopint.lua menu item are you referring to when you say you never set overexposure higher than 1%,  and what value are you entering?
The setting is Overexp thresh x/100k. 1% would be 1000.

However, setting this low involves some trade-offs. If there is something very bright in the scene, the rest can be very under exposed, down to your meter and under exposure limits.
If you are using raw and can do a lot of adjustment in post processing, you may be able to recover the undere exposed areas. If you are doing minimal processing on jpeg, you may be better off allowing some of the scene to be blown out (though probably less than the sky in your last run)

If you use a very low thresh, you need to make sure the "Histogram step" is small enough to give you useful precision.
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Offline c_joerg

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #42 on: 18 / March / 2016, 03:06:58 »
Quote from: MarkB on 17 / March / 2016, 22:05:02
I am well aware that with RAW files you can be more aggressive with highlight and shadow recover before it starts to fall apart than with jpeg's. RAW's I will have that much more ability to tweak the images to my liking.

That’s my typical developing of RAW’s against the sun. Highlight’s down and shadow’s up.

Quote from: MarkB on 17 / March / 2016, 22:05:02
Not sure if this is possible and there will be a compromise somewhere.

Yes of course. The suggestion of 1% overexposure and no underexposure control is my compromise.
That’s the reason why the dynamic range of a camera gets more and more important for me…

Quote from: reyalp on 18 / March / 2016, 00:35:30
If you use a very low thresh, you need to make sure the "Histogram step" is small enough to give you useful precision.

Well, that’s what I forgot most time… ;)
It might be helpful, when the script calculates an optimal step size (same as meter step) and you have just an parameter like low/medium/high precision.
« Last Edit: 18 / March / 2016, 03:09:08 by c_joerg »
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Offline MarkB

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #43 on: 18 / March / 2016, 15:53:45 »
Quote from: reyalp on 18 / March / 2016, 00:35:30

The setting is Overexp thresh x/100k. 1% would be 1000.

However, setting this low involves some trade-offs. If there is something very bright in the scene, the rest can be very under exposed, down to your meter and under exposure limits.
If you are using raw and can do a lot of adjustment in post processing, you may be able to recover the undere exposed areas. If you are doing minimal processing on jpeg, you may be better off allowing some of the scene to be blown out (though probably less than the sky in your last run)

If you use a very low thresh, you need to make sure the "Histogram step" is small enough to give you useful precision.



I am happy to let very bright objects, the sun, streetlights at night etc over expose, since those object would appear bright anyway. But in my last two runs, the sky was a bit brighter than what I really wanted.  I had  Overexp thresh x/100k  at 3000 (3%?) for every run I have done.  Would dropping it to 2.5% 2% or 1.5%  make much difference?  I am not looking to keep the sun well exposed at the cost of the foreground, but a little less exposure so I have something to recover.


All my runs have had a Histogram step of 15  If I start lowering the Overexp thresh x/100k  should set the Histogram step to 23 or 27?




Quote from: c_joerg on 18 / March / 2016, 03:06:58


Yes of course. The suggestion of 1% overexposure and no underexposure control is my compromise.
That’s the reason why the dynamic range of a camera gets more and more important for me…


I wonder if a 1.5-2.5% overexposure and some underexposure control is what I am looking for?




With the last run I did,   s110Test15  I posted a couple days ago,  I noticed during the run the shutter speeds started to get faster at ISO320 and as the ISO got lower the shutter speeds were increasing, unlike a previous run where the shutter stayed at .5sec until ISO 160  sped up a bit, then did a lot as ISO80.   In this last run I set ISO adj TV Sec/1000 to 125  (⅛ sec).  Would this have caused the shutter speeds to change quicker or was it some other parameter I set?  Would setting it to 1/15 or 1/30 have the shutter speeds move up faster relative to the ISO changes?
 
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Offline reyalp

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #44 on: 18 / March / 2016, 17:26:21 »
Quote from: MarkB on 18 / March / 2016, 15:53:45
I am happy to let very bright objects, the sun, streetlights at night etc over expose, since those object would appear bright anyway. But in my last two runs, the sky was a bit brighter than what I really wanted.
Yes, I agree.
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  I had  Overexp thresh x/100k  at 3000 (3%?) for every run I have done.
Yes. The x/100k is meant to indicate parts per hundred thousand. It's hard to make these settings clear in the menu, but they are describe in some details on the wiki page http://chdk.wikia.com/wiki/Lua/Scripts:_Raw_Meter_Intervalometer (the same content is in the readme.txt)
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  Would dropping it to 2.5% 2% or 1.5%  make much difference?
I would guess 1.5 would make a pretty big difference.

My earlier suggestion of increasing the ev range treated as over exposure (Overexp Ev Range) would also make some difference. In your video, it looks to me like more than 3% of the sky is "blown out". This may be partly due to histogram working on all color channels, but the only one of them hitting the over exposure limits.

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All my runs have had a Histogram step of 15  If I start lowering the Overexp thresh x/100k  should set the Histogram step to 23 or 27?
You would use lower step values for lower thresholds. The histogram samples every step-th pixel in X and Y,  so <sensor resolution>/<step squared> gives you the total number of pixels sampled.

The histogram needs to sample enough pixels to see smooth variation around your thresh value. As an extreme example: If you set thresh 1, and only sampled 100K pixels, the script would jump from no over exposure, to fully over exposed as soon as one sample was overexposed. This would lead to severe oscillation. If you sampled 1M pixels, then it would ramp up over 10 values.

For a 12MP sensor, a step of 15 gives you about 800k samples. For a thresh of 1% that gives you 80 values, which is probably plenty. I would consider decreasing step if you set thresh below 1%. Smaller steps take more processing time, so can affect the maximum shooting rate. You can see this in the histo_time column in the log. As mentioned on the wiki, a digic 4 cam like D10 takes about 60ms with a step of 11.


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In this last run I set ISO adj TV Sec/1000 to 125  (⅛ sec).  Would this have caused the shutter speeds to change quicker or was it some other parameter I set?
This option controls the shutter speed at above which ISO starts to be used. If you think about a sunset, exposure control will be entirely through shutter until it gets dark enough to hit this value. Once the value is hit, the shutter and ISO changes are mixed until one or both of their limits is reached.
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Offline MarkB

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #45 on: 19 / March / 2016, 19:07:04 »
Did another sunrise this morning


This one was a bit different,  there are two points where the exposure really jumps  and I notice a bit of oscillation/flickering in the sky.  I am assuming I went too far with my overexposure protection or if trying to protect the highlights I should have relaxed the underexposure setting I set for the sunset  runs.    The  main settings I was playing around with this time were ISO adj sec/1000, overexp thresh x/100k  ands overexp Ev range




The Setting I changed from default include
Interva; 25  2.5sec
Max Ev Change  ⅓
Bv Ev shift % 15
Bv EV shift base Bv 10
Max Tv sec/1000 500  1/2sec
Min Tv sec/100k 10  1/1000
Target ISO 80
ISO adj Tv Sec/1000  66  1/15sec
Over meter high thresh Ev 1
Meter high limit Ev 1 ¾
Meter low thresh -Ev 3 ¾
Meter low limit -Ev 6
Overexp thresh x/100k 2000 2%
Overexp Ev range ¾




So the oscillation/flicker in the sky is the most disturbing mistake in this run, since I wasn't getting that at all with rawopint.lua up until this point.  Then the obvious jumps in exposure.  I am wondering if it was ISO adj Tv sec/1000 is the cause of the exposure jumps and I should drop this back a bit.

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Offline reyalp

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #46 on: 19 / March / 2016, 21:58:06 »
Quote from: MarkB on 19 / March / 2016, 19:07:04
This one was a bit different,  there are two points where the exposure really jumps  and I notice a bit of oscillation/flickering in the sky.
Assuming you mean the jumps around 17 and 24 seconds, this is really strange. It doesn't look like exposure to me. It looks more like a big change in white balance, but white balance really shouldn't change.

It would be helpful to know which frames this happened on. I'd guess around 510 and 720, but nothing big happens to the exposure or meter at this point. It's kinda close to where the shutter speed starts to change (650) and where the ISO starts to change (799) but I don't it quite lines up.

The oscillation is something I've seen before in this kind of scene, but don't fully understand. It's very visible in the sky, but not really in other parts of the scene. It doesn't show up much in the meter, and the script isn't making large changes to exposure. I think the kind of gradient you see in the sky makes it more apparent, but that isn't the whole story. Maybe there's something related to the alternating changes in ISO and shutter that affect the jpeg colors. Unfortunately, I don't have a solution. Increasing the precision of the meter / exposure calculations might help, but it would take some work.

I've attached the usual exposure plot and one focusing on meter exposure change, starting at frame 800. In the second plot, you can see the script is requesting either 0, -1 or -2 change in exposure from 800-1300. After that, it's mostly alternating between 0 and -1.

In the log you can see a repeating pattern every ~7 frames, where it requests -1 for 3-4 frames,  -2, then 0 one or two times. This is pretty much what you'd expect in a scene that is changing at a rate that just a bit more than 1/96th of a stop per frame. It's not really flapping.

Around 1300, it settles down to requesting either -1 or 0. The ISO change also ends around here (frame 1245)
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Offline MarkB

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #47 on: 20 / March / 2016, 03:09:10 »
Quote from: reyalp on 19 / March / 2016, 21:58:06

Assuming you mean the jumps around 17 and 24 seconds, this is really strange. It doesn't look like exposure to me. It looks more like a big change in white balance, but white balance really shouldn't change.

It would be helpful to know which frames this happened on. I'd guess around 510 and 720, but nothing big happens to the exposure or meter at this point. It's kinda close to where the shutter speed starts to change (650) and where the ISO starts to change (799) but I don't it quite lines up.




It is indeed a white balance issue and a weird one at that.  I so do some post in Lightroom to the jpegs before outputting them to create the video sequence in Photoshop.  What I normally do is take a photo in the middle of the sequence and do all my adjustments to it then sync it with the rest of the images in the run.  Well for some odd reason the effected images about 250 of them had the white balance I set for the rest of the images  reversed.  As in I set WB to +25 for the sequence and the affected images had a WB of  -25.  I tried resetting everything back to import and redoing my post and again the 250 images when I synced them to the rest of the images  would reverse the WB value.  I could go in and individually change them but if I tried the sync function it was reversed.  Weird, I will put it down to some form of corruption either on import or with the catalogue.  It would be interesting to see if it ever happens again.


I made a video of the images with no post.




So with this no colour temperature anomilies but still the oscillation in the sky.


Quote


The oscillation is something I've seen before in this kind of scene, but don't fully understand. It's very visible in the sky, but not really in other parts of the scene. It doesn't show up much in the meter, and the script isn't making large changes to exposure. I think the kind of gradient you see in the sky makes it more apparent, but that isn't the whole story. Maybe there's something related to the alternating changes in ISO and shutter that affect the jpeg colors. Unfortunately, I don't have a solution. Increasing the precision of the meter / exposure calculations might help, but it would take some work.



Test15  looked good to me with no oscillation, just too much over exposure in the sky in the daylight.  With Test16, I changed 4 things so maybe I was being too ambitious and will take it slower.  I dropped the Bv Ev shift base Bv to 10 to brighten up the overall image, I changed the ISO adj Tv sec/1000 to a faster shutter speed in the hopes of getting the shutter speeds to increase quicker than the ISO, dropped the Overexp thresh x/100k to 2%  and increased Overexp Ev range from ½ to ¾.  I think in the next test I will reset everything back to what I had in Test15 except for the Overexp EV range and see how that turns out. 


Also picked up a 64GB card this weekend so the next test will be shot in RAW and that might allow me some highlight and shadow recovery that I can't get now.

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Offline reyalp

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #48 on: 20 / March / 2016, 17:38:14 »
Quote from: MarkB on 20 / March / 2016, 03:09:10
So with this no colour temperature anomilies but still the oscillation in the sky.
The oscillations seem greatly reduced to me, much more in line with what I would expect from what's happening in the meter and exposure values.

In the original test 16, from ~25 to 55 seconds, the different tones in the sky are really pulsing. In the NP version there's a little flicker, but not nearly as bad. I'd certainly like to make the script smoother of course, but at this level a de-flicker stage in post might be enough.

The original shows quite a bit of banding that isn't present in the NP, which I suspect is related. Only looking at the original it's hard to tell if there are really bands in the sky or this is a processing artifact, but from NP versions, it looks like it's an artifact. IMO, the post processing ran out of precision on the sky, which really amplifies the oscillation because a tiny change in value moves the bands by a bit amount. Working in raw should help avoid this kind of effect.

Attached screenshots at 42 seconds from each video show the banding.

edit:
Some of the apparent over-exposure in your earlier test15 might have been clipping in post processing as well. My earlier posts were based on the assumption that it was essentially straight out of the camera jpeg.

If you do use jpeg, it's possible you could avoid some of this clipping by keeping the overall exposure lower, but this would result in more noise. Getting the camera jpeg as closer to what you want for the final product might also help. Aside from white balance, you can use the Canon "my colors" stuff to make to adjust saturation, contrast etc a bit.
« Last Edit: 20 / March / 2016, 17:45:57 by reyalp »
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Offline MarkB

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Re: Canon S110 Time Lapse Advice/Recommendations
« Reply #49 on: 23 / March / 2016, 23:58:01 »


Well finally did a run while recording in RAW,  native CR2's




I have to say I am quite happy with this one. 


Doing an auto white balance in Lightroom does a much better job with the colour temperature  when working with RAW's. No more crazy blues.


The noise in the sky is one complaint I have.  I only did a minimal  amount of post before exporting  the images as 1080x1920 jpegs, so I might be able to tame the noise  a bit in Lightroom.  I was wondering if I could get away with  a Max ISO of ISO 500 or ISO 640 before I get the issues I did  with the runs I did when the Max ISO was 1600


After the sun was over the horizon there was a bit of highlight clipping in the clouds. I am happy to let the sun or other light sources in the scene over expose though. If possible I would like to be able to protect this.  What setting should I play with next, reduce Overexp thresh x/100k or Overexp Ev range?  Would Meter high thresh EV change much?  How about Bv Ev shift base Bv? 


Anyone who has suggestion on how to improve it, or changes to suggest, I am happy to experiment further with this script.


The setting I changes from default in rawopint.lua for this run  are:
Interval sec/10  25   2.5sec
Max Ev change ⅓
Ev shift ¼
Bv Ev shift %  15
Bv Ev shift base BV 11
Max Tv sec/1000 500   ½ sec
Min Tv sec/100k 10   1/1000 sec
Target ISO 80
ISO adj Tv sec/1000 125  ⅛sec
Max ISO 400
Meter high thresh Ev 1
Meter high limit Ev 1 ¾
Meter low thresh -Ev 3 ¼
Meter low limit -Ev 6
Overexp thresh x/100k 3000  3%
Ovberexp Ev range ¾







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