Google| Subject | Re: ISO value names are becoming ridiculous |
| From | Sandman |
| Date | 01/06/2016 16:26 (01/06/2016 16:26) |
| Message-ID | <sandman-d4af97bf4006feb4cf3f1371db88decc@individual.net> |
| Client | |
| Newsgroups | rec.photo.digital |
| Follows | Peter Irwin |
| Followups | Peter Irwin (44m) > Sandman |
In article <n6j6t6$hgt$1@dont-email.me>, Peter Irwin wrote:
SandmanPeter Irwin
So with the D5, it can boost its ISO to ISO 3,280,000, and suddenly how ISO is named is becoming just stupid. We should use EV steps instead:
It would be better to use Sv steps.
Ev is from the EVS system it means exposure value, and is the sum of Av (aperture value) and Tv (Time Value).
F/stop f/1 f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 Av 0 1 2 3 4 5 6 7 8
Speed 1 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 Tv 0 1 2 3 4 5 6 7 8 9
Hence a exposure of 1/125 at f/16 has a Av of 8, a Tv of 7 and an exposure value of 15 (8+7).Exactly. That's the EV of the exposed image. After exposure, the camera can apply image amplification, called "ISO", so instead of taking EV15 and applying "ISO 400", we would take the EV15 image and apply "ISO EV+2", meaning that the resulting bitmap has a brightness that is equivalent to EV17, so it makes perfect sense.
The user rarely, if ever, have any idea of the EV in the camera. I.e. they don't know that 1/125 f16 = EV15, and they don't care, nor do they need to. But if the scene is too dark, applying X number of stops of "brightening" in the form of ISO makes sense, rather than knowing whether ISO 12,800 or ISO 51,200 is the correct choice. People have managed, but when more and more cameras come with settings that says "ISO 3,200,000" most people will just not know what it means and how it relates to the other values.
This system has been in use since the 1950s. There was an expanded system proposed in the 1960s called APEX which also had light values (Lv) and film speed values (Sv) such that Sv + Lv = Av + Tv = Ev.Absolutely, and it made perfect sense, only it had a value of 0 at ISO 3, far below any used film and sensors used today. So it just makes more sense to reset it to ISO 100, otherwise it's the exact same thing.
Current: ISO 100 ISO 200 ISO 400 "my" proposal: ISO EV 0 ISO EV+1 ISO EV+2 APEX: 5 6 7
-- Sandman
01/06/2016-
