Archived posting to the Leica Users Group, 1999/02/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> >Thus, when quoting the sensitivity of a TTL light meter in a camera >specs are usually given as: > >EV 1 @ 100ASA and F1.4 > >By the way, this would be equivalent to > >EV 0 @ 100ASA and F1.0. > >Hope this clarifies the point I was trying to make. > > >Mark Hammons > Right. I think you are still missing my point. I am not misunderstanding the use of EV, film speed and aperture, I am trying to suggest a better way. What I am saying is that the EV method is less useful than simple shutter speed and ASA. For both the cases quoted above, the identical information can be given more simply and directly as two pieces of data: 1 second for 100 ASA. That is directly related to the ONLY things that you can set on an M5 or 6: ASA and shutter speed. EV is not indicated on M5 and M6s. As you point out, <<If you are in EV 1 light and you have a camera with built in meter that is just barely reading the light with an F1.4 lens on the camera, will the camera be able to meter the light if you put an F4 lens on the camera? The answer is no. The EV 1 light will be cut down by another 3 f stops and will be below the minimum sensitivity of the camera's meter.>> Now, replace EV with a shutter speed and it becomes independent of the lens aperture. You point out that just because you can measure at EV1 with an open f1.4 lens it doesn't mean that you can measure at EV1 with an open f4 lens. But if you can measure at 1 sec with an f1.4 lens, you can measure at 1 sec with any lens at any aperture. That is why I believe that shutter speed and film speed are better indicators for stopped-down TTL metering systems. Does anyone out there see what I am attempting to say? Regards, Malcolm