<100 minimum ISO

Started by sharper9, September 17, 2014, 01:02:41 PM

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sharper9

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.

dmilligan

please search before posting

sharper9

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?

Stedda

Typing ISO in search came up with 30+ hits, several feature requests, and the reasons they're not implemented...
5D Mark III -- 7D   SOLD -- EOS M 22mm 18-55mm STM -- Fuji X-T1 18-55 F2.8-F4 & 35 F1.4
Canon Glass   100L F2.8 IS -- 70-200L F4 -- 135L F2 -- 85 F1.8 -- 17-40L --  40 F2.8 -- 35 F2 IS  Sigma Glass  120-300 F2.8 OS -- 50 F1.4 -- 85 F1.4  Tamron Glass   24-70 2.8 VC   600EX-RT X3

PaulB

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.

dmilligan

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). 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

PaulB

That would explain what I saw. Thanks for the clarification.

babarasghar

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