[ALREADY DONE...Maybe Not] Fast way to trade ISO for Shutter Speed - Manual Mode

[PhotoCat]

Hello ML team:

Can the following adjustments be made more convenient?

1) Shooting in M mode and fixing aperture to f2.2 (selectable)
2) Need to keep shutter speed at or over e.g. 1/320S (selectable)
3) Use ISO to obtain proper exposure.

Right now doing it manually:

In M mode, when ambient is bright, I keep f at 2.2, ISO to 100 and set shutter to a value
to obtain proper exposure. (this value is usually faster than 1/320 for bright ambient)

When ambient level has come down, ISO 100 cannot sustain a shutter speed 1/320 or faster.
Then I will have to up the ISO to 160 or 320 or 640 to compensate, keeping the shutter speed to
at least 1/320.

Is it possible for ML to give me a single dial to achieve this shutter speed/ISO  trade off?

e.g. as you rotate the dial, the settings will change e.g. as follows (from left to right, from bright to dark)

f stays at a fixed value e.g. 2.2
ISO            ...100    100     100... 100    160     160    320    320     640    640...
Shutter ...1/2000 1/1000 1/500... 1/320 1/400 1/320  1/400 1/320 1/400 1/320...


Note I am not asking for auto exposure. I will use the built-in meter and histogram to determine proper
exposure. I just need an convenient way to trade ISO for shutter speed.

This would be very handy when shooting outdoor portraits when the sun comes in and out of the cloud
frequently. BTW, ISO 160, 320 & 640 were selected because of better noise performance in jpg.

Thanks!

[dmilligan]

ML Menu > Expo > Expo Lock

[PhotoCat]

Tks dmilligan for the info but I am not sure I fully understand how the expo lock works.

I cannot lock exposures because I need to keep compensating for ambient fluctuations manually.
What I need is a convenient way of changing ISO and shutter speed at the same time to adjust overall exposure.

[dmilligan]

Expo Lock Submenu:

Tv -> Off
Av -> Off
ISO -> Tv, Av


Now when you adjust Tv, nothing else will change. When you adjust ISO, Tv will compensate. So if you want to change exposure adjust Tv, when you want to "trade" Tv for ISO, adjust ISO.

[PhotoCat]

Thanks dmilligan for the teaching! That's vy interesting and now I know how this ML exposure lock works!
Although it is not the same thing I had asked for, it is very cool and I think I may be able to work with it.
Will test out this method in comparison to full M mode with Av, Tv & ISO
adjusted independently. 

[PhotoCat]

Oh... My apology... I wouldn't say it is already done...  The expo lock method is
very different from my proposal of a single dial to roll through different exposures:

Let me make the table more clear.
As you turn the dial clockwise for example, the camera setting will change according
to the following table from left to right:  (note the exposure is increasing from left to right)


f fixed at e.g. 2.2
ISO       100   100 100 100 100 100 125 160 200 250 320 400 500 640 800
Shutter  1000 800 640 500 400 320 320 320 320 320 320 320 320 320 320

With a fixed F-stop, the goal is to keep shutter speed at or faster than 1/320S (or another chosen value)
under all lighting levels.

One dial operation would be the ultimate solution for my feature request.

UI would be like:

set f stop and set min shutter speed in M mode then turn on this new feature on ML.
Roll the dial and the setting will be changed from left to right according to the table. (from low exposure to high exposure)
Then I have to select the best exposure by reading the meter or histogram. It is still manual exposure but I only need to
play with 1 dial instead of 2 dials to change exposures. The manual operation will be much faster.  Hope it is more clear now. Thanks for helping out!

[Audionut]

I don't really understand the usefulness.  You have a crux point where you shift from changing shutter to changing ISO, so you still only have to play with one dial.

[dmilligan]

With a fixed F-stop, the goal is to keep shutter speed at or faster than 1/320S (or another chosen value)
under all lighting levels.

AutoETTR in M mode with slowest shutter = 1/320 does exactly this.

You could also play with the autoexpo module, I've never used it, but I think it lets you build a sort of custom P mode, where you define which exposure parameters to change as overall exposure changes.

[PhotoCat]

I don't really understand the usefulness.  You have a crux point where you shift from changing shutter to changing ISO, so you still only have to play with one dial.

The complication occurs when the correct ambient exposure is around f2.2, ISO100, 1/400 when u r under a shade. Suddenly the sun goes into the cloud
then u will have to up the ISO to say 320 as well as lower the shutter to 1/320 to compensate. A 2-dial operation. 
(U don't want to keep the shutter at 1/400 and up the iso to 400
because you want to maintain a low ISO with the best noise performance.)
Then all of a sudden, the sun comes out of the cloud again and you will have to lower the ISO back to 100 and up the shutter back to 1/400 to compensate.
Another 2-dial operation.
On a partially cloudy day, this happened to me more than often and I had to constantly play with 2-dials when the sun goes in and out of the cloud.
After a while, you get tired of it and wish that ML could do something to help      Thanks for your attention Audionut!

[PhotoCat]

PhotCat:
With a fixed F-stop, the goal is to keep shutter speed at or faster than 1/320S (or another chosen value)
under all lighting levels.

dmilligan:
AutoETTR in M mode with slowest shutter = 1/320 does exactly this.

You could also play with the autoexpo module, I've never used it, but I think it lets you build a sort of custom P mode, where you define which exposure parameters to change as overall exposure changes.

Thanks dmilligan once again. Let me try autoETTR in M mode. I hv played with that b4 but it didn't seem to change ISO automatically but I will try it again.
I have also played with autoexpo module but it is auto only so it is hard to do spot metering on the face then recompose unless there is a button to lock
exposure. Even then it would not be convenient because I fine tune exposure almost from shot to shot based on false color reading on the face.
So I really need manual exposure.

[PhotoCat]

mm... autoETTR seems to be doing something very close... changing ISO and shutter speed but it has to go into live view
to do its things for a few seconds which takes time.  Full viewfinder shooting is what I need.  Also autoETTR will naturally overexpo jpegs and I will need
extra time to post-process raw files to darken the images to its normal range. I think manual exposure with spot metering works best for me for portrait shooting. Tks!

On the other hand, Autoexpo module is actually quite close to what I need as I can program the ISO and Shutter according to the metered level but unfortunately it is fully auto. Works well for landscape or still subjects perhaps depending on the metering used. For portraits, one really needs spot metering on the face.

It would be nice to be able
to turn off the "auto" part of the Autoexpo module but keep the "table-lookup" part.  Just give us a manual dial to sweep from left to right of the lookup table (curve).
Then we will spot meter ourselves manually.
That should do it.  I have a 5D2 BTW.

Thanks!

[Audionut]

I haven't played with autoexpo for a while, but try working with its Exposure Compensation settings.

[PhotoCat]

played with autoexpo again and indeed I can setup the curves to do exactly what I want but
the problem is that the auto feature cannot be turned off.  Tried expo comp as u had suggested but
it is not obvious how it can disable auto exposure.   Note that I am a spot-metering kind of a guy
and I want the face to be correctly exposed.

Another thing abt autoexpo is that ISO and shutter jump at 1-stop increment. Would prefer a jump to be 1/3 of a stop,
so that I can pick low noise ISO for jpgs such as 160, 320 & 640.
Tks!

[Audionut]

Since you're spot metering, and consistently putting skin tones at +2, the autoexpo module should work exactly as you need.

Those ISOs you describe have 0.1 EV less noise then full stop ISOs.  In other words, not worth it.  At some future stage, ML will enable ISOs that have greater then 0.3 EV (1/3rd stop) better noise.  http://www.magiclantern.fm/forum/index.php?topic=10111.0

[PhotoCat]

Oh, I spot meter white wall at +2 but for skin tone it is from 0-0.6 depending on the person   
The autoexpo module doesn't allow me to spot-meter and recompose. Manual exposure is much preferred.

Wow, u guys are amazing! ML enhanced dynamic range! Hats off to the ML team!

[Audionut]

Use exposure lock from the Canon menu.