[DONE] Remove Canon's AutoISO400 limit in flash mode

[1ab]

Hi,

not sure whether it is possible to fix this from within MagicLantern, but as this seems to affect all Canon SLRs on which I managed to get a grip, and some of them I guess would not receive further updates from Canon any more, it would be great if it could be made possible...

Setting AutoISO to ON
and setting the AutoISO Limit to ISO6400
is great!

But it works only as long as it's without flash.
As soon as you add a flash (either builtin or EX-430/580 and probably also others)
=> The camera would limit the AutoISO to 400 and never choose a higher ISO despite the camera's AutoISO Limit is set to ISO6400
Originally seen on 550D but also checked 5DmkII, 650D

I would like to be able to use an actually working higher ISO limit than 400 together with a flash very much for the purposes of stagelight situations, where the light is mostly unpredictable. On a ballroom dancefloor with effect lighting, I now try to manually switch from ISO800 through ISO3200 in order to keep the room's original brightness in the picture according to the changing light situation, but I would rather like AutoISO to do that job for me. The flash is obviously in ETTL mode, and I set it to ETTL-1 or sometimes even ETTL-1 2/3, in order to bighten up the faces not too much.

Not even sure whether the way Canon implemented it with this strange flash-ISO400 limit, has any actual purpose, or whether one would need to consider it a Canon bug??

If this feature could be implemented, should there be two different AutoISO limits? (One for without-flash, and one for with-flash?) Or should flashing make use of the normal AutoISO limit? The latter would be good enough for me, but not sure whether others might need it differently...

Regards,
Roland

[StefanKeller.AC]

Hi, I am new here with my 7D  thanks a lot so far...

this Limit is well documented in the 7D manual, p.65
but there is one exception,
"Using the camera in P or full auto and attaching an ext. speedlite and bounce flash is used
will give an Auto-ISO Range from 400 - 1600"
Why Canon, why?

It would be fantastic if ML could do something...

[a1ex]

Yea... the only trouble is that most ML developers are not really interested in using the camera in auto

[StefanKeller.AC]

 
but maybe you will get more supporters like me, making the camera better usable at event-photo-shootings... 
Quickzoom e.g. is a great Thing for me as photographer

[a1ex]

If there was a way to auto-expose to the right outside LiveView, I would look into it (because that's how I expose my pics).

There are some experimental auto ISO implementations buried in the source code; they work in LiveView, but they are too slow for real use.

To change Canon's algorithm is very hard or impossible. What I can do is to rewrite it from scratch. But not with flash.

[nanomad]

The ISO 400 decision is actually a smart one. It allows a fast flash recycle time without introducing significant noise in the picture 

[ilguercio]

The ISO 400 decision is actually a smart one. It allows a fast flash recycle time without introducing significant noise in the picture 

I have to agree.

[StefanKeller.AC]

I frequently use (very) high ISO-values with a little fillflash e.g. for faces in the foreground,
... but I think this is not the right thread to discuss "auto" and "high ISO" 
I would be very glad to use it, as Nikonians can...

An own Implementation seems to be very difficult, would it be reliable?
and only in liveview is not enough...

CHDK can manipulate the auto-ISO behavior, ( ISO-limits, shutter limits, IS-factor, ...)
would something like this be possible in ML?

Or could there be a trick, to let the firmware calculate ISO and then using flash??
the algorithms are in the cam 

[ilguercio]

You're making it easy without knowing what's the work behind all this. It's not like you just tell the camera to do stuff and it does...
If you use high iso then what's the point in using auto ISO?

[StefanKeller.AC]

I did not say its easy, I asked if these parts of firmware are manipulable/accessible
(I worked as software developer a lot of years...)

[a1ex]

This area is not yet understood, so I don't know how to alter flash behavior or ISO limits, other than changing parameters that are already in Canon menu.

CHDK does not run on dslrs, the architecture is quite different.

If you know where to look, just look inside and tell us.

[StefanKeller.AC]

of course CHDK is different, therefore I ask you 

one trick done by ML could be:

in Av,Tv, or M:

disable flash firing
let camera calculate ISO
read out and switch to this ISO
enable flash firing
let camera fire

but even if possible there may be a delay...

[nanomad]

Trouble is, if the subject is close to the flash you would probably end up with a overexposed picture

[StefanKeller.AC]

not more than setting the same exposure-values manually, dooing so this has never been a Problem in my pictures
But running arround at an event end repeating to change the ISO is a work which should be done by a computer 

[1ab]

If it would be easy to implement, I would like to try an implementation of my own, because I would just like it much. :-)
Conceptually agreeing that this is a kind of automation that should be done by a computer while I walk around, and also acknowledging that there may be a certain risk that when flashing at high ISO, in some cases the lowest possible flash level (as selected by ETTL? or even as set manually?) might still be too much light into the scene and result in overexposure.

My trouble while poking around is (and maybe that matches what the actual ML developers previously said?) that when I try to register any PROP_HANDLER on PROP_AUTO_ISO_RANGE, PROP_ISO_AUTO and PROP_ISO (hoping to possibly be able to make my adjustments from there?), my code is called fine, and the camera tells my code what ISO value has been selected by AutoISO -- but only as long as there is no flash. :-( So if anyone manages to find a way ...I guess that would have to be much trickier...

[a1ex]

Might work with latest nightly, but I don't use a flash.

[StefanKeller.AC]

thanks!, but I can't test it on my 7D ... 

[discocalculi]

I can confirm that ML Auto ISO limit can surpass iso 400 and even up to 6400.

I choose 1/1000 shutter for Av mode and was able to get pretty high iso with the Canon Speedlite 580EX II. I had to activate the High speed function on the flash, of course.

With Canon it will never go beyond 1/200, iso 400 unless one does it manually, where it is fully operationable of course.

Using built in flash, I noticed a tendency to overexpose, but that's because setting a value above 1/200 seems not possible...

[1ab]

Just found the ML Auto ISO in a current build, and it looks very promising - can select all ISOs even with flash (550D). On the config options for this feature I would like to suggest an additional option that in Av the t limit is selected as 1/f, configurable with plus/minus a few stops.

But anyway, it's great that you made it work. Much appreciated, and can't wait to give it an actual test in real-world circumstances.

PS: I did not find much of FAQ about donating. Only possible via PayPal and not via old-fasioned bank transfer?

[nanomad]

Yes, it's paypal only

[StefanKeller.AC]

great, it works on my 7D  (with the "bitrate Monster branch")
can I change the behavior for the minimum shutter speed?, menu isnt accessible there
(and OT: how can I disable Audio for movie there?)

[StefanKeller.AC]

ok, I have it:

defaults are:
auto.iso.tv.av = 3
auto.iso.av.tv = 3

.choices = (const char *[]) {"f/1.0", "f/1.4", "f/2.0", "f/2.8", "f/4.0", "f/5.6", "f/8", "f/11", "f/16", "f/22"},
.choices = (const char *[]) {"1/15", "1/30", "1/60", "1/125", "1/250", "1/500", "1/1000", "1/2000", "1/4000"},

Its like X-Mas !!!!!   

[StefanKeller.AC]

I dont know what the current nightly Version does, but with the 7D Bitratemonster are 2-3 issues:

1. focal length is not taken into calculation
2. when camera shuts down, the last ISO is chosen after powering up again (7d doesn't yet load ML at startup)
  (not easy to fix...)
3. smaller steps for the setting would be fine, because e.g. choosing 1/125 often 1/200 is taken

thanks a lot so far!

[a1ex]

1. impossible
2. may be possible to fix
3. the selected values are not hard limits, Canon code is the one choosing the exact value. It may be possible to allow intermediate ISOs, but they are pretty much pointless in photo mode (and the math for 1/3 EV approximations is not easy).

[1%]

Why no ML Auto ISO for P and M modes?