New issue 673 in Magic Lantern: Bulb Ramping

[Bitbucket]

--- you can reply above this line ---

New issue 673: Bulb Ramping
https://bitbucket.org/hudson/magic-lantern/issue/673/bulb-ramping

frame_michael on Wed, 14 Sep 2011 10:27:43 +0200:

Description:
Hi ML Team,
first off its absolutely great what you guys are doing -
it at least tripples the price my T2I is worth.

I do have a suggestion for a further enhancement.
You do have a built in intervalometer which works great.
But if you are doing timelapse from day to night the problem is
as you know - that the aperture is changing dramatically.
So it would be great to have something like the bulp ramper which changes specific values over a period of time.

See:
http://www.thewhippersnapper.com/LittleBramper/Site/Home.html

which is a great but i know you guys could do an even better version inside the firmware!

thanks - Michael

--

This is an issue notification from bitbucket.org. You are receiving
this either because you are the owner of the issue, or you are
following the issue.

[Malcolm Debono]

Check here:

https://groups.google.com/forum/#!topic/ml-devel/NLC0WDo_ViQ

It's already implemented, but either no one has yet figured out how it works or it still isn't functional.

[Alex]

I don't understand why you can't make it work. I've tested it right
now (with the current bleeding edge) on 60D:

- I've started the camera in bulb mode
- I've enabled bulb ramping (default setting)
- I've set bulb timer to 1 second
- I've set aperture to f22 to get correct exposure at 1 second (this
step is important!)
- I've set intervalometer on, 10s, wait
- I've closed ML menu and it worked from the first try.

> --
> http://magiclantern.wikia.com/
>
> To post to this group, send email to ml-d...@googlegroups.com
> To unsubscribe from this group, send email to
> ml-devel+u...@googlegroups.com
> For more options, visit this group at
> http://groups.google.com/group/ml-devel?hl=en

[scrax]

I have problem too using bulb ramping,

- I've started the camera in bulb mode
- I've enabled bulb ramping (default setting)
- I've set bulb timer to 1 second

- I've set aperture to f22 to get correct exposure at 30 second (this

step is important!)
- I've set intervalometer on, 10s, wait

- I've closed ML menu and it takes 3 pic, the first and the last are 30s the second pic is 20s.

after that i get a calibration error. The pic are exposed correctly 

[Alex]

> I've set aperture to f22 to get correct exposure at 30 second

Why 30 seconds?

My first 3 exposures are (as shown in exif) 2s, 0.5s, 1s. If I set the
bulb timer to 2, I get 4s, 1s, 2s. If the middle image is properly
exposed, calibration is OK.

Can you catch a screenshot of the fine print? I know it has a redraw
bug and disappears quickly. When I've tested the pre-bulbramping
version, I've set the review time at 8 seconds to be able to read it.

[scrax]

30s because don't matter what I have set in bulb time (1sec like you), it always takes a 30s pic, then a 20s pic and then a 30s pic again.

If a take a pic with the bulb time set to 1s it works, only with bulb ramping function there is that strange 30s thing.

I don't get what is the "fine print", for screenshot you need one of the error message after the 3 caibration pic?

[Alex]

OK, I'll check tonight. If you want to try an untested possible fix
(which should at least display the fine print always), you may
download it from my dropbox.

[scrax]

I can't set less than 16min in bulb timer with that new autoexec, but now I know what is the fine display. Now i need to go if I have time will try later with the 12/9/11 experimental build to take a pic of it.

[Alex]

Now it seems to work. There is a slight difference in bulb mode
handling between 60D and rebels.

There's a bug which triggers ERR70 in LiveView with bulb mode on 550D
only (as far as I could tell). I'm not sure what causes it, but the
shutter already has a different sound, so it may be related (my
shutter count is over 100.000).

Can you tell me if you get any ERR70 in LiveView, photo mode?

[heartbeat]

is it possible to get this too in silent mode? shutter counts!

>  autoexec.bin
> 626KAnzeigenHerunterladen

[Alex]

No.

[heartbeat]

is this a technical problem or what the problem or coding

[Alex]

Try it yourself on auto exposure.

[unity2k]

Bulb ramping on my T2i/550d seems to working fine for me. I'll try to
setup a day to night shoot to see what kind of timelapse I get.

On Sep 14, 12:38 pm, Alex <broscutama...@gmail.com> wrote:
> Now it seems to work. There is a slight difference in bulb mode
> handling between 60D and rebels.
>

>  autoexec.bin
> 626KViewDownload

>
> There's a bug which triggers ERR70 in LiveView with bulb mode on 550D
> only (as far as I could tell). I'm not sure what causes it, but the
> shutter already has a different sound, so it may be related (my
> shutter count is over 100.000).
>
> Can you tell me if you get any ERR70 in LiveView, photo mode?
>
>
>
> On Wed, Sep 14, 2011 at 4:21 PM, scrax <scri...@gmail.com> wrote:
> > I can't set less than 16min in bulb timer with that new autoexec, but now I
> > know what is the fine display. Now i need to go if I have time will try
> > later with the 12/9/11 experimental build to take a pic of it.
>
> > --
> >http://magiclantern.wikia.com/
>
> > To post to this group, send email to ml-d...@googlegroups.com
> > To unsubscribe from this group, send email to
> > ml-devel+u...@googlegroups.com
> > For more options, visit this group at

> >http://groups.google.com/group/ml-devel?hl=en- Hide quoted text -
>
> - Show quoted text -

[scrax]

Now it work also on 600D, I've made just a quick test to see if the 3 pic are ok, and a couple of shot with different ambient light to check if the exposure changes.

[daniel thissen]

work fine for me. 60d.

2011/9/14 unity2k <quantu...@gmail.com>

[unity2k]

Alex, Had bulb ramping working when I tried it on just a few shots
during the day. Trying it again towards sunset with the idea of it
running into the night, I set my 550 to M - Bulb, ISO Auto, and tried
f/22 - too dark, couldn't calculate.

Next try, bulb, f5.6 ISO 800 and a test with Auto: message was:
Calibration Error / Incorrect Threshold / Check for Correct Exposure.
In ML I had Intravalometer set at take pic every 20 seconds and Auto
Bulb Ramp Percentile = 90 and another test at 80. Same error message
as above

Bulb f10 no go

Tried changing M mode from bulb to 15 seconds - got an Error 70

Bulb f2.8, ISO Auto and 3200 - All three eval shots are same exposure
and shot duration (which also happened on earlier tests - but not the
daylight test earlier in the day) Errored out with: Calibration Error
etc.

Sorry, but no spectacular transition from great Arizona sunset to
night on this try.

On Sep 14, 8:32 pm, daniel thissen <thissendan...@gmail.com> wrote:
> work fine for me. 60d.
>

> 2011/9/14 unity2k <quantumsp...@gmail.com>

>
>
>
> > Bulb ramping on my T2i/550d seems to working fine for me. I'll try to
> > setup a day to night shoot to see what kind of timelapse I get.
>
> > On Sep 14, 12:38 pm, Alex <broscutama...@gmail.com> wrote:
> > > Now it seems to work. There is a slight difference in bulb mode
> > > handling between 60D and rebels.
>
> > >  autoexec.bin
> > > 626KViewDownload
>
> > > There's a bug which triggers ERR70 in LiveView with bulb mode on 550D
> > > only (as far as I could tell). I'm not sure what causes it, but the
> > > shutter already has a different sound, so it may be related (my
> > > shutter count is over 100.000).
>
> > > Can you tell me if you get any ERR70 in LiveView, photo mode?
>
> > > On Wed, Sep 14, 2011 at 4:21 PM, scrax <scri...@gmail.com> wrote:
> > > > I can't set less than 16min in bulb timer with that new autoexec, but
> > now I
> > > > know what is the fine display. Now i need to go if I have time will try
> > > > later with the 12/9/11 experimental build to take a pic of it.
>
> > > > --
> > > >http://magiclantern.wikia.com/
>
> > > > To post to this group, send email to ml-d...@googlegroups.com
> > > > To unsubscribe from this group, send email to
> > > > ml-devel+u...@googlegroups.com
> > > > For more options, visit this group at

> > > >http://groups.google.com/group/ml-devel?hl=en-Hide quoted text -

[Alex]

F22 was just an example; just make sure the image is properly exposed
(but since you can only select 1 second from bulb timer, you have to
stop down the lens in daylight).

Don't set ISO auto; it will result in all shots having the same
exposure, so it won't be able to calculate. What ML does here is to
see the relationship between 1 EV and the brightness level in
percentage. This varies according to picture style, your preference
for exposure... etc. Set it on fully manual, so that image is exposed
well at 1 second, and let it run.

You can do the calibration at some aperture value and then change it
while the intervalometer is running.

[unity2k]

I have read every bit of this thread, I have read the manual, and I
cannot get bulb ramping to work in some predictable way on my 550d.

Would someone who is getting consistent results in various lighting
situations please take the time to draw up some step by step
instructions and explain what they are doing to get rid of the
messages that tell of wrong exposure or calibration error?

I have started the camera in M mode set to Bulb
ISO 400
I have tried f2.8 to f22
I have set the bulb timer at 1 and 2 seconds
I have set intervalometer at 5 sec to 10 sec
I have tried percentiles of 20% to 95%

Obviously I am doing something wrong, but I cannot isolate where my
error lies. Please post clear and fully detailed instructions starting
with 'Turn on your camera'. Also include how do we ensure we have
correct exposure, my exposure preview button on the front of the
camera triggers the bulb timer to start shooting.

> >> > > >http://groups.google.com/group/ml-devel?hl=en-Hidequoted text -

>
> >> > > - Show quoted text -
>
> >> > --
> >> >http://magiclantern.wikia.com/
>
> >> > To post to this group, send email to ml-d...@googlegroups.com
> >> > To unsubscribe from this group, send email to
> >> > ml-devel+u...@googlegroups.com
> >> > For more options, visit this group at
> >> >http://groups.google.com/group/ml-devel?hl=en-Hide quoted text -
>
> >> - Show quoted text -
>
> > --
> >http://magiclantern.wikia.com/
>
> > To post to this group, send email to ml-d...@googlegroups.com
> > To unsubscribe from this group, send email to ml-devel+u...@googlegroups.com

> > For more options, visit this group athttp://groups.google.com/group/ml-devel?hl=en- Hide quoted text -

[Alex]

For successful calibration, you need to:

1) Expose your image properly for your selected bulb timer value (1s,
2s etc). This is VERY important. Don't underexpose and don't
overexpose. Use the histograms, the zebras... etc (you have them in
Play mode too). Don't use DOF preview, you won't be able to do any
preview for 1-second exposures or longer.

I assume everyone knows how to adjust ISO, shutter and aperture to get
a correct exposure.

2) Make sure ML can measure properly the brightness. Enable image
review and make sure the image in playback mode is full-screen.

3) When the calibration error appears, there is also some fine print.
Read it and make sure brightness level is not 0 or 100. Also make sure
bracketing works properly (e.g. 1s, 0.5s, 2s). Exif will only display
1s for shorter exposures, but you can listen to the shutter or check
the overall brightness.

If I don't know what results you are getting, I can't help you, sorry.
Post some images or videos showing what you are trying to do and what
happens instead.

Next, the percentile is what to meter for (highlights, shadows,
midtones). If you have a tricky white object which is very easy to
overexpose, measure for highlights. If you don't, probably the best
thing is to measure for midtones. Keep in mind that highlights are
easily overexposed on digital cameras.

Then, the algorithm behind bulb ramping is a very simple one (at each
step do half of the exposure correction). If you want a mathematical
proof of why this works, and why I don't do full corection, just ask.
You will only have to learn a bit of control systems theory, PID
controllers, stability, robustness and such (the algorithm behind bulb
ramping is actually a P controller, the process is also considered a
simple gain K without dynamics, and in the first 3 pictures it does
system identification... it computes K).

There is no fixed recipe for bulb ramping, you can setup it in a lot
of ways (depending on what you need to achieve... the compromise is
basically less flicker vs. better highlights) and you need to
experiment. Default setting should be a good starting point (every
time I start the bulb ramping with the defaults, it works very well),
but you **MUST** expose properly.

[unity2k]

Alex,

Your description and the User Guide description is too technical for
the average user (though probably great for programmers). After much
experimentation, and your help, I finally got this dialed in and
working perfectly every time.

Question: Can the bounce turning the screen on when starting a
calibration prior to taking an Intervalometer shot be suppressed to
save on battery and kill the light that flashes from the monitor? This
would be really important for someone filming in remote dark areas
where any artificial light is undesirable.

I wrote the following instructions for User Guide that I believe is
easier for the 'average' person to follow. It is my first draft, but
if you use it, I'll edit it online when I can refine it:

BulbRamping allows the capture of a timelapse that gradually changes
exposure over the duration of the shoot compensating for the
transition from day to night.

First, you must establish what properly exposed image settings would
be for the shot. You do not need to take a photo to do this, you can
see on your Canon display menu if your image will be properly exposed.

Set your camera to AV or TV mode.
Select Manual Focus on your lens.
Turn image review in the Canon menu to: Off
Choose a fixed ISO, this cannot be set to Auto. In bright daylight
situations, you may want to set ISO to 100 – you will likely also
require the use of an ND8 or darker, filter.
Consider the subject matter you are photographing and your depth of
field requirements, this will help determine the aperture settings. Do
not set this yet.
The objective is to find an exposure time of 1 second or greater, this
is a requirement of using BulbRamping.
If the camera is set to TV mode; changing the exposure time will set
the aperture – note the exposure time as you must set this in the ML
Bulb Timer menu. Also note the aperture, this must be set while in
Manual mode.
If the camera is set to AV mode; changing the aperture will determine
the exposure time – again, note the exposure time as you must set this
in the Bulb Timer menu. Note the aperture, this must be set while in
Manual mode..

Turn the mode dial to M (Manual Exposure).
Set exposure to BULB
Set your aperture to the f-stop that was used to establish proper
exposure

Start ML and move to the Shoot menu and set the following:

Take a pic every: Choose the time between shots.
Intervalometer: On, Wait.
Auto BulbRamping: Leave on default setting.
Bulb Timer: Set this to the exposure time you calculated in the steps
above.
Press the Trashcan button to exit ML

ML will now automatically take a series of images to establish a
calibration point. If you set up a proper exposure in the steps above,
ML will calculate the settings and begin your bulb ramped timelapse.

If you receive the Error Message: Calibration Error / Incorrect
Threshold / Check for Correct Exposure, you have not set a proper
exposure. Try stepping the aperture up or down a stop or two. Return
to the ML / Shoot menu and start the Intervalometer again which will
attempt another calibration.

Once your camera is shooting the timelapse, press DISP to turn the
display off, saving battery life.

> >> >> > > >http://groups.google.com/group/ml-devel?hl=en-Hidequotedtext -

>
> >> >> > > - Show quoted text -
>
> >> >> > --
> >> >> >http://magiclantern.wikia.com/
>
> >> >> > To post to this group, send email to ml-d...@googlegroups.com
> >> >> > To unsubscribe from this group, send email to
> >> >> > ml-devel+u...@googlegroups.com
> >> >> > For more options, visit this group at
> >> >> >http://groups.google.com/group/ml-devel?hl=en-Hidequoted text -
>
> >> >> - Show quoted text -
>
> >> > --
> >> >http://magiclantern.wikia.com/
>
> >> > To post to this group, send email to ml-d...@googlegroups.com
> >> > To unsubscribe from this group, send email to ml-devel+u...@googlegroups.com
> >> > For more options, visit this group athttp://groups.google.com/group/ml-devel?hl=en-Hide quoted text -
>

[unity2k]

On todays build, September 18, the Bulb Timer menu. Let's say I set
Bulb Timer at 2 sec., I shoot a short timelapse, when I return to ML
the Bulb Timer menu item will have incremented up 1 sec and has (OFF)
next to it. I do not see any impact on performance, I change it back
for the next test and everything is fine - just a quirk in the menu
and very minor.

Also, in the Bulb Ramping instructions I wrote above, sorry the
bullets (formatting) is missing, I would add that; During calibration,
ML may choose an optimal ISO setting different from what the user
selected.

> > >> >> > > > later with the 12/9/11 experimental build to take a pic of it.- Hide quoted text -
>
> - Show quoted text -...
>
> read more »