Google| Subject | Re: ISO value names are becoming ridiculous |
| From | Savageduck |
| Date | 01/09/2016 15:50 (01/09/2016 06:50) |
| Message-ID | <0001HW.1C4155C20B28C3BE153DB23CF@news.giganews.com> |
| Client | |
| Newsgroups | rec.photo.digital |
| Follows | Sandman |
| Followups | Whisky-dave (1d, 22h & 54m) |
On Jan 9, 2016, Sandman wrote (in article<sandman-6fa741d6993cb0551719b4a6ebf436b1@individual.net>):
<Yeah I snipped a bunch of stuff. What I had to say is related to the cite below.>
SandmanAll the other parts of this discussion aside, the cite above is how I have always understood DIN/ASA/ISO film senstivety and exposure values. There was a reason that Tri-X was considered “fast†in the good old days. We were also hampered by the mechanical limitions of the cameras of the day. Both of my 60’s and 70’s vintage Pentax SLRs were limited to 1/1000s shutter speed. One of the reasons I loved my Yashica Electro 35 was that astonishing 1/2000 capability. Sometimes we don’t appreciate just how much has changed when it comes to the capability of today’s equipment when it comes to sensor sensitivity nd high shutter speed.
<http://camerapedia.wikia.com/wiki/Film_speed> "With an arithmetic scale, the exposure decreases in direct proportion to an increased speed - so a doubling in film speed requires half the exposure. For example if an exposure of 1/250s at f.8 is required for a 100 ISO film, a 200 ISO film would require either 1/500s at f.8, (or 1/250s at f.11) and 400 ISO film would need 1/1000s at f.8 for the same scene.
A logarithmic scale increases a fixed amount for a doubling of speed - 24 DIN is twice as fast as 21 DIN, and 27 DIN is four times as fast as 21."
Now we have to transpose that theory to the digital universe with sensors, and without arguing as to how it is implemented and all that, it is still easiest to think of ISO for sensors as an analogy for film emulsion sensitivity. With all that in mind we can apply all the advantages of digital to solve many of the exposure issues caused by the limitations of film.
--
Regards, Savageduck
01/06/2016-
