Archived posting to the Leica Users Group, 1999/03/28
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Lucien: I will see if I can find the source of my info. As for Rom being used to tell the camera the true aperture of the lens, the caamera does this anyways since it meters through the lens. It may just be a poor translation that you have read, which should have read that it transmits the effective taking aperture. I checked my R8 manual and all it says is that the ROM lenses allow electronical exposure compensation. I will see if I can find where I got the idea that the ROM transmitted the aperture value at time of release to the camera so that it can compensate for any mechanical errors. This may be what Leica means by electronical, electro and mechanical. This system is needed on motor driven cameras to ensure the aperture stops down fast enough and if it doesn't, to correct the exposure. I think the EOS RT, just leaves the aperture closed when firing at a high framing rate in order to avoid these mechanical errors. Regards, Robert At 11:50 PM 3/28/99 +0100, you wrote: > > >Robert G. Stevens wrote: > >> The advantage of ROM over non ROM lenses when used on the R8 is that the >> lens sends info to the camera regarding how far it has stopped down prior >> to the shutter firing. For example, when the R8 motor arrives and you are >> shooting at say F16, the camera will adjust the exposure accordingly if the >> aperture say only got closed to say f12.5 when using a high framing rate. > >Robert, > >Are you sure ? >It is the first time that I read something like that. > >In the 7/98 issue of Leica Fotographie >on pages 30 and 31, there is paper >about the purposes of the electric contacts found >on the ROM Leica lenses and inside the R8. > >They say that small lenses with ROM permit >shorter time parallax or that the effective aperture >(mesured at the factory and stored into ROM) is taken to account. >At the end of manufacture, or when retrofitting of older lenses, >every Leica-R lens is individually measured and programmed in >order to make sure that the potential accuracy of the exposure >metering is maintained. > >Lucien > > > > > > >