auto iso not working correctly with large shutter time values

[GoogleCodeExporter]

What steps will reproduce the problem?
1. camera in Av mode, lens aperture as wide as it will go (ie: f1.8)
2. auto iso enable: 'Yes', max iso: 400, min iso: 100, Min Tv: 30"
3. point camera at bright light, iso should be 100, but is set to 400!

only seems to be an issue with large 'Min Tv' values 

What is the expected output? What do you see instead?

 iso should be lowest possible, actually uses highest.

What version of the product are you using?

 latest 'stable' version

Please provide any additional information below.

 I tested this on two cameras, both showed same behaviour

Original issue reported on code.google.com by purest...@gmail.com on 11 Aug 2012 at 7:09

[GoogleCodeExporter]

In Tv mode AutoISO raises ISO when the camera sets an exposure longer than 
MaxTv; with those parameters, I would expect a constant ISO at 100, because the 
camera cannot set an exposure longer than the limit, and thus AutoISO never 
kicks in. And this is exactly what happened in my tests.

For AutoISO to work in those conditions, you should set a MaxTv value shorter 
than the camera's limit (25 seconds, for example).

Original comment by eduardo....@gmail.com on 12 Aug 2012 at 10:06

[GoogleCodeExporter]

Did you point the camera at a bright light source during your test?

I would also expect a constant ISO 100, indeed this is what I want to happen, 
but this in not the behavior i am seeing when "min Tv" is set high (25sec or 
30sec), and the camera is in bright conditions. (if it is not bright then it 
works as it should)

I have tested this on two cameras, both show the same behavior.

please re-test this as it is a real bug, not my imagination.

camera setting:
camera in Av Mode. lens aperture at f3.5

AutoISO
Enable    Yes
Min ISO   100
Max ISO   400
Min Tv    25"
Max Av    f/5.0

indoors seems fine (constant ISO 100), but with bright light (point camera 
directly into a light/at the sun) it go's back to ISO 400!

Original comment by purest...@gmail.com on 12 Aug 2012 at 1:43

[GoogleCodeExporter]

Retested and reproduced!

In the context of long exposures, I assumed that a "bright light" was a lamp or 
something similar, I was not expecting the sun to enter the game. But yes, when 
the camera sets a very short shutter speed (1/1000 - 1/4000, for example), 
400plus wrongly raises the ISO.

I'll try to fix this as soon as possible.

Original comment by eduardo....@gmail.com on 12 Aug 2012 at 5:35

• Changed state: Accepted

[GoogleCodeExporter]

This issue was closed by revision r1424.

Original comment by eduardo....@gmail.com on 12 Aug 2012 at 9:59

• Changed state: Fixed