Shutter Speed Limit

Started by kloned, September 27, 2012, 11:01:34 AM

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kloned

Is it possible to set a slowest possible shutter for 550D ?
This refers to 500D, 600D, 650D, 60D as well.

As I know, this feature is available in 5DmkIII.

I know, this request can be considered a duplicate to this one (http://www.magiclantern.fm/forum/index.php?topic=2152.0), but there was no answer about it's feasibility.

The desired settings are:
- Av mode
- Auto ISO
- non LiveView

The solution like Enhanced Exposure Lock in Manual Mode - is very close to what I need, but you have to pay too much attention to the exposure, and lose control of scene composition.

Sometimes is critical to take a picture of a dynamic scene with changing light environment: kids, pets, street photography..
And if the dynamic scene is the priority, you should be able to take a good catch even if you go too much in darkness. At least you have a chance to recover it in post, which is impossible when you have a mess with accurate exposure.


Here is a short debate about this feature: http://www.flickr.com/groups/canondslr/discuss/72157630944039096/

UPD: here I've also tried to explain a possible extension (generalization) of this feature.

Alia5


engardeknave

I was actually just going to post asking if it would be possible to do the opposite of this, i.e. setting the lower shutter limit in A mode. Right now what I find is that in A mode my MKII is way too quick to up the ISO for my purposes. So for example it's choosing 1/80 @ ISO 2000 but I'd prefer 1/40 at a lower ISO.

If possible, this may be a good alternative to Auto ISO ranges, which I've read is not going to happen.

kloned

I would go even further... why not to give the possibility to set ranges for all the components: shutter speed, DoF and ISO (here some meta-components may be added as well, such as exposure).

This feature results in more advanced, semiautomatic, configurable mode.

Let's suppose now that we have a fully configurable ranges, with optional "golden" (the most desired) values:

Sutter: [Min; Gold; Max]
DOF:    [Min; Gold; Max]
ISO:     [Min; Gold; Max]

The biggest problem is to set the dependency behavior between all of these components.

To illustrate it better I'll give a scenario of practical problem which could be resolved with this mode: dynamic scenes during a city event, in early evening.

Settings:

(from highest to lowest priority)
Shutter:        [60: 200 :1000]    the highest priority
Exposure:     [-1: 0; +1/3]
DOF:             [2.5: 5.6: 8]   
ISO:              [160: 1250]    lowest priority

Now, let's stress our hypothetical camera and go from brighter to darker environment and follow its components values change:

UPD: Values updates should be smooth, I'm just showing key-changes (in red)

Brightest ->
S=1000           DoF=8                 ISO=160      E=+1/3
S=1000           DoF=8                 ISO=160      E=0
S=200(gold)    DoF=8                 ISO=160      E=0
S=200(gold)    DoF=5.6(gold)    ISO=160      E=0
S=200(gold)    DoF=5.6(gold)    ISO=640      E=0
S=200(gold)    DoF=5.6(gold)    ISO=1250    E=0
S=200(gold)    DoF=2.8             ISO=1250    E=0
S=60               DoF=2.8             ISO=1250    E=0
S=60               DoF=2.8             ISO=1250    E=-1
-> Dark

If we've reached the minimum limit and to have the possibility to continue shooting during even more severe conditions we can consider automatic mode switching :

Shutter:        [10; max]     the highest priority
Exposure:     [-2; max]
ISO:              [min; 6400]
DOF        [1.4; max]    lowest priority

Now we have:

Dark ->
S=60        DoF=2.8        ISO=1250    E=-1
S=60        DoF=1.4        ISO=1250    E=-1
S=60        DoF=1.4        ISO=2500    E=-1
S=60        DoF=1.4        ISO=6400    E=-1
S=60        DoF=1.4        ISO=6400    E=-2
S=10        DoF=1.4        ISO=6400    E=-2
-> Trash :)

So here we can say that we've done all possible to catch the subject.


I hope somebody understand what I mean... if not, just keep considering "shutter speed limit" for a while :)

gerk.raisen

+1

I was trying how to explicate more or less the same final idea (when posted "Aperture Range Mode"
to manually restrict to a range of aperture values (ex. f5.6 to f8) was thinked like a first step to reach this)
but kloned did it sooner and better.

It's a pleasure to donate if this option can be added, or for the moment also just researched.

Thank you.

engardeknave

AutoISO ranges are not even possible without a rewrite supposedly, so all that's not going to happen.

kloned

AutoISO with maximum value limitation is already available in original Canon's firmware.
Not so flexible, but anyway, better than nothing...

engardeknave

Oh, maybe on another camera. I have the MKII.

Yeah, I didn't see the first two lines of the OP before.


kloned

QuoteI think I've got something working: https://bitbucket.org/hudson/magic-lantern/changeset/645f3e8eeb08
Great !

Realtime shutter speed monitoring and ISO adjusting seems to be quite feasible.

Apparently the shutter speed is (somehow) constant only within available ISO interval. When ML is up to be out of limits (lower or upper), it begins to adjust shutter speed accordingly, ignoring the predefining value.

Hope you'll manage to freeze the shutter's slowest value.
Optionally, sticking to fastest value could be also useful for somebody...

a1ex

If you want to freeze shutter speed, why not use the Tv mode?!

kloned

The omitted keyword in "to freeze ... shutter speed" is slowest :)

The idea is not to stick shutter speed to a specific value.
The shutter speed should remain in auto-adjusting mode (as in Av), but with reduced interval of its possible values.

We already have speed interval limitation in Canon's firmware. The problem is that we can't adjust its [Min; Max] bounds - for 550D they are: [30; 1/4000] sec.

The Max value doesn't bother us too much, usually it's not fast enough. However, there are some situations when we would want to limit Max value as well. For instance, when it's essential to keep obtaining a "motion blur" effect (car movement, wheels rotation, ...).

But the most desired here is to stop at a Min value, even if we risk to go too much in darkness. Our priority is to obtain the sharpest image possible of an object in motion, in various light conditions.

Let's say we want to take some challenging pictures of birds in fly with fixed aperture of 2.8 (for a great isolation). In a sunny day I would want the shutter speed to its maximum value (ISO160, 1/4000). But if it's already early evening, and light conditions become more and more complicated (ISO1250) ? With Canon's firmware we'll easily reach unusable shutter speeds for such a task.

Simple: it would be great to have the possibility to change available Canon's interval [30; 1/4000], into something like [1/100; 1/4000].

a1ex

So, rather than shifting the shutter to get a correct exposure, you say it's better to underexpose, right?

This requires changing the exposure compensation back and forth, not quite funny (because that's a setting which you want to change in normal usage).

Shizuka

Technically speaking, that's probably the right thing to do for the Canon CMOS sensors. None of the cameras benefit from ISO > 1600, and all that is being done is lopping off one stop of highlight dynamic range at each higher ISO stop.

kloned

Quote from: a1ex on October 27, 2012, 05:24:22 AM
So, rather than shifting the shutter to get a correct exposure, you say it's better to underexpose, right?

This requires changing the exposure compensation back and forth, not quite funny (because that's a setting which you want to change in normal usage).

Yep, this is exactly what I'm doing all the time in such situations.
When you're shooting in a constantly changing environment in handheld mode (street), you likely will lose a lot of precious moments or (most of the time) will obtain a good amount of unusable blurred pictures. This is because sometimes we just have no time to adjust something.

Briefly: no tripod, no time, difficult light (club), constantly changing dynamic environment.

In such conditions we want some sharpen silhouettes rather than a "correct exposed" skewed mess :)

If we push ISO interval up to 6400 (available feature from Canon), we also have the chance to obtain "static" images... but here are at least 2 moments: target objects will become too noisy, and brighter objects (often background) - overexposed.

The idea is to keep Av "as-is", with this little exception (in limiting slowest shutter speed).

kloned

A little update which could help a bit:

550D already has this feature implemented for Av mode. In C.Fn menu chose 3'd option "Exposure: Flash sync. speed in Av mode".
There are 3 options:
0. Auto ([1/4000; 30] sec)
1. [1/200; 1/60] sec
2. 1/200 sec (fixed)

This feature works well and second interval is quite usable. The only condition - external or built-in flash must be enabled.
However, ML can somehow control the flash (in ML menu Flash tweaks... -> Flash / No flash option).
I've already tried, and  it works ! The second shot without flash firing keeps shutter speed limited bounds !*

UPD: It works only with external flash attached, and not always reproducible...

Is it possible to disable the flash firing (with enabled flash) ?
For me it's not a big deal if built-in flash required to remain opened.

a1ex

Doesn't work for me with flash/noflash.

kloned

Yep, for me either. Seems that I've missed something.  :-[
I thought ML knows how to disable flash firing while keeping flash status "enabled".

Is there a way to fake "flash enabled" state, delivered to the stock firmware ?

he56ys5ysu7w4

C'mon. Pretty please with sugar on top. Me wantzz it.  :D

It's easy, see.

Set min = 1/200
If EV =< recommended {
ISO++;
Do not touch shutter;
}

:P
Amateur shooting family stills and video
Gear: Canon 600D/T3i -- Sigma 30/f1.4 EX DC HSM -- Canon EF-S 15-85/f3.5-5.6 IS USM -- Canon EF 50/1.8 II -- V3 LCD Viewfinder loupe -- Velbon RUP-L40
Editing with LR3 and FCPX

drfrogsplat

This sounds like the feature I'm after as well, but perhaps with a slightly different use case.

In Av mode, the default Canon firmware tries to set the shutter to 1/f, whether or not I'm using an IS lens, and (obviously) independent of the subject and its motion. So it tends to go unnecessarily low on wide angle lenses and unnecessarily high on telephoto lenses. The result is either blurry subjects or unnecessary noise (high auto ISO) if the light isn't great.

This situation is usually better in Tv mode (with auto ISO), but the camera often chooses a smaller than necessary aperture, so I still end up with noisier images thanks to high ISO. My only control is to limit the Max Auto ISO, which doesn't really help the issue.

Another technique is to use M-mode with auto ISO, so I can hold the aperture at the lowest value (or stopped down just enough to sharpen the image enough), but I lose Exposure Compensation and EV lock (on the 7D at least). So if there's a bright light or background, I can't do anything about it except switch to manual ISO or another mode for the shot. Different metering modes don't help either without EV-lock.

The ideal situation for me would be either Av with a minimum shutter speed, or Tv with a maximum aperture. Both of which are fairly simple algorithmically (though not sure if possible programmatically?) and would be pretty easy for a user to configure/understand I'd think.

Sometimes I don't actually want the lens to be wide open (some lenses have too low DoF or poor image quality wide open), so I might also want a minimum aperture, which is starting to look a bit more like the min/gold/max range posts above. e.g. with my 50mm f/1.8 I usually want a max aperture of f/2.5, but its much nicer at f/4 if there's enough light, and any higher indoors is going to mean really high ISO... but this is sounding like it might be a hassle to set up with so many parameters, and if it was too fiddly to set up or modify I'd end up just using M-mode most of the time anyway (I'd probably use Av mode with min shutter speed mentioned above, and just manually adjust the aperture to suit).

So perhaps this feature has a kind of 'basic mode', for dealing with the disconnect between the minimum shutter speed for avoiding camera-shake (Canon's method) and the minimum shutter speed for avoiding subject blur. Really easy to set/clear the limits. And then (if its even possible), a more advanced mode for allowing full customisation of Shutter/Aperture/ISO ideals & ranges?

jedivader

Quote from: kloned on October 08, 2012, 12:08:14 AM
... why not to give the possibility to set ranges for all the components: shutter speed, DoF and ISO (here some meta-components may be added as well, such as exposure).

This feature results in more advanced, semiautomatic, configurable mode.

Let's suppose now that we have a fully configurable ranges, with optional "golden" (the most desired) values:

Sutter: [Min; Gold; Max]
DOF:    [Min; Gold; Max]
ISO:     [Min; Gold; Max]

The biggest problem is to set the dependency behavior between all of these components.

To illustrate it better I'll give a scenario of practical problem which could be resolved with this mode: dynamic scenes during a city event, in early evening.

Settings:

(from highest to lowest priority)
Shutter:        [60: 200 :1000]    the highest priority
Exposure:     [-1: 0; +1/3]
DOF:             [2.5: 5.6: 8]   
ISO:              [160: 1250]    lowest priority

+1

This is the feature that I always though any advanced camera should have. It's what photography is all about (in its technical aspect).
This can make the Av and Tv modes incredibly flexible and customizable.

Aside from setting the min/gold/max values, the user should also be able to set the priority order - you might have different preferences in different situations.

Everything should be optional, of course, you don't want the user to be overwhelmed by a ton of settings if he/she doesn't need them.

The feature could start as a couple of simple settings for min/max values for Shutter speed and Aperture. That should be easy. Later it could evolve into this more complex system with gold values, exposure values, and priorities.


This is a must. A killer feature.
60D | EF 50 f/1.8 II | EF-S 18-55 f/3.5-5.6 IS

Mario81

Hi,
IMO if to develope a management with min,gold,max is a big problem could be enough add only a shutter speed limit (for A and P mode) and after, if is possible, change priority between shutter limit FORCED or NORMAL. Is a good idea?

Priority: Shutter limit = FORCED  (possible dark photo)

Brightest ->
S=4000(max)                               F=5.6(due shutter limit)       ISO=100                        E=0
S=4000(max)                               F=2.8                              ISO=100                        E=0
S=4000                                      F=1.4(max)                       ISO=100                        E=0
S=1000(due diaph.limit)                 F=1.4                             ISO=100                         E=0
S=500                                        F=1.4                              ISO=100                        E=0
S=200                                        F=1.4                             ISO=100                         E=0
S=100                                        F=1.4                             ISO=100                         E=0
S=60 (select  limit,example 1/60)     F=1.4                             ISO=100                         E=0   <--- Desired limit, currently not present!!!!
S=60                                           F=1.4                            ISO=200(Increase ISO)      E=0
S=60                                           F=1.4                            ISO=400                          E=0
S=60                                           F=1.4                            ISO=800(limit choosen)      E=0
S=60                                           F=1.4                            ISO=800                         E=-1
S=60                                           F=1.4                            ISO=800                         E=-2
-> Dark


Priority: Shutter limit = NORMAL (possible long time photo)


Brightest ->
S=4000(max)                               F=5.6(due shutter limit)       ISO=100                        E=0
S=4000(max)                               F=2.8                              ISO=100                        E=0
S=4000                                      F=1.4(max)                       ISO=100                        E=0
S=1000(due diaph.limit)                 F=1.4                             ISO=100                         E=0
S=500                                        F=1.4                              ISO=100                        E=0
S=200                                        F=1.4                             ISO=100                         E=0
S=100                                        F=1.4                             ISO=100                         E=0
S=60 (select  limit,example 1/60)     F=1.4                             ISO=100                         E=0   <--- Desired limit, currently not present!!!!
S=60                                           F=1.4                            ISO=200(Increase ISO)      E=0
S=60                                           F=1.4                            ISO=400                          E=0
S=60                                           F=1.4                            ISO=800(limit choosen)      E=0
S=30                                          F=1.4                            ISO=800                         E=0
S=10                                           F=1.4                            ISO=800                         E=0
S=5                                           F=1.4                            ISO=800                         E=0
-> Dark




Thank you

gerk.raisen

As I write before

+1 to a more flexible management with min,gold,max like kloned proposal.

Thanks.

Mario81

Performing an accurate test, i have noted that the canon firmware already have the shutter limit.

I used the camera in mode A  (600D) and I have seen that the behaviour is similar to 2nd table in my last post, but the shutter limit is variable depending of focal distance.

18:55 mm IS II

-ISO auto

-At 18mm the shutter limit is 1/30 - 1/40 ( swings ) for all auto ISO range
-At 55mm the shutter limit is 1/80 - 1/100 ( swings ) for all auto ISO range

So, is possible that the factor is about 0,5 :

Shutter limit (0,5 x 1/Focal Dist)

0,5 x 1/18 = 1/36
0,5 x 1/55 = 1/110

In ML, could be possible to change this Canon value (so shutter related to focal distance but with different factor)?
Or, could be possible to elude the focal distance for Canon FW to make fixed this value ?

Or ( IMO is best solution), to add a shutter limit like in previous post.

alband

+1 to kloned's suggestion of a "min,gold,max" thing. I'd been thinking of this myself a lot and didn't realise it was in a thread already :)

Would a min,gold,max solution even be possible? ML would need control over ISO, shutter and aperture individually. Does it have that? If it doesn't have individual control of them, would it be possible in program mode? ML could then change the ISO, and then use the program shift and exposure compensation to change Av and Tv.

The routine would be:

QuoteCheck ISO,AV,TV
If any are outside their limits, changed them to their limit and compensate with the other two settings.
ML would need to decide how much to compensate and how to share the compensation between the other settings.

Presumable ML can't actually limit the values that the Canon firmware chooses from, but can only change them. In which case, it would need to change them just before taking the picture? That could be difficult?

In the end, I learned to shoot in manual mode to solve this problem, but then you risk not getting the exposure right in time, which often happens.