espressogeek said:
The m8 didnt record aperture on any files I took when i had it.
The M8 doesn't either, and for the same reason: there's no coupling between the lens and the camera body to report the set aperture. This has never been necessary on a rangefinder camera, since it's always been possible to meter at the
working aperture.
On the other hand, SLRs (including DSLRs) that have full-aperture metering have always needed to provide a way for the lens to let the camera body "know" both the maximum aperture and the set aperture. This is necessary so that the metering system can determine the correct shutter speed without having to stop down the lens. Older SLRs provided this information via mechanical coupling levers; newer ones use electronic contacts.
(Yes, it's also possible to meter an SLR by stopping down the lens: some older SLRs, such as the Pentax Spotmatic and Canon FT, worked exactly this way. However, this type of metering made the SLR viewfinder grow dim, and eventually the marketplace voted overwhelmingly for the more complicated but friendlier full-aperture type of metering.)
So, all these years we RF users have been blissfully metering away without any need for the lens to tell the body what aperture it's set to -- which is one reason we've had these nice, simple lens mounts that make it so easy to mount Manufacturer A's lens on Manufacturer B's body and vice-versa. (All the different styles of coupling linkages made this a nearly impossible feat on SLRs.)
But now that many of us are used to digital cameras, we're accustomed to seeing the aperture data in the EXIF header -- and our digital RFs can't provide it, because there's no way for the lens to transmit the information to the camera. Oh, well, I still feel it's a small price.
Interestingly, although the M8 doesn't record the actual aperture in use, I'm told that it does estimate the working aperture by comparing the TTL-metered value with the non-TTL-measured value received from the external meter cell -- the little round dot above the RF window. Evidently Leica doesn't feel this estimate is accurate enough to include it in the EXIF data, but it's still doing the calculation.
Originally the purpose of this external reading was simply to control the brightness of the readout digits in the finder. But now Leica uses the data to estimate the working aperture and uses that estimate in calculating how much vignetting correction to provide.
At least, that's the explanation I've read on 'Reid Reviews.' Smug aside: When photos of the M8 first began to appear and people were speculating on the purpose of the "blue dot" (it looked blue in some of the early illustrations) I had speculated that it might be used to estimate working apertures. But Reid, who had a pre-production review camera and access to inside information, rather tersely dismissed such speculation, declaring that he had been assured by Leica that the external meter cell had absolutely no purpose other than to control the finder readouts!
