Magic Lantern Forum

Using Magic Lantern => General Help Q&A => Duplicate Questions => Topic started by: sharper9 on September 17, 2014, 01:02:41 PM

Title: <100 minimum ISO
Post by: sharper9 on September 17, 2014, 01:02:41 PM
This may be stupid or there may be another easy solution to it...but is it possible to have ML to lower ISOs under 100?

This would allow for shooting at wide open apertures and getting shallow depth of field in bright conditions without using an ND filter.

If there is another obvious solution to achieving this that I'm not aware of, please let me know.
Title: Re: <100 minimum ISO
Post by: dmilligan on September 17, 2014, 01:26:42 PM
please search before posting
Title: Re: <100 minimum ISO
Post by: sharper9 on September 17, 2014, 01:30:37 PM
I searched but was only able to find posts referencing dual iso and shooting in low light situations. Could you please refer me to the thread you're referencing?
Title: Re: <100 minimum ISO
Post by: Stedda on September 17, 2014, 01:50:08 PM
Typing ISO in search came up with 30+ hits, several feature requests, and the reasons they're not implemented...
Title: Re: <100 minimum ISO
Post by: PaulB on September 17, 2014, 02:19:03 PM
I've seen photos online taken with Canon EOS cameras where they were listed as using ISO 50, but I have no idea how this was achieved. I assumed it was an EV adjustment, but I've not tried it.
Title: Re: <100 minimum ISO
Post by: dmilligan on September 17, 2014, 02:27:52 PM
Some high end cameras have an ISO 50, but it is digital, so technically it is still ISO 100 (because it has the same highlight clipping point as ISO 100).

It appears that Canon has left a small amount of overhead in the amplifier gains that we can take advantage of to get a slightly lower ISO (~0.5 stop) (read more here (http://www.magiclantern.fm/forum/index.php?topic=10111.0)). But something like ISO 25 or something low enough to avoid ND filters is never going to happen. The CMOS can only hold so many photoelectrons in a sensel before it overflows (full well capacity). ISO has no effect on this, it is a post CMOS amplifier gain: http://www.clarkvision.com/articles/iso/index.html
Title: Re: <100 minimum ISO
Post by: PaulB on September 17, 2014, 02:37:03 PM
That would explain what I saw. Thanks for the clarification.
Title: Re: &lt;100 minimum ISO
Post by: babarasghar on September 19, 2014, 06:30:13 PM
We see that on APSC cameras like 60D etc there is less noise at ISO 160, 320, 640 Etc as compared to other ISOs! Below them
N why is it like that? Why ISO 640 is less noisy than ISO 500 or ISO 1250 is cleaner than ISO 1000 or even ISO 800
Title: Re: <100 minimum ISO
Post by: Audionut on September 20, 2014, 02:12:26 AM
http://www.magiclantern.fm/forum/index.php?topic=9867.0
http://www.magiclantern.fm/forum/index.php?topic=10111.0