Open Aperture Metering

The Pen FT was introduced in 1966 and provided full aperture metering, although with a bit of a creative twist. While this was a couple of years after the Pentax brought out Spotmatic, the Spotmatic still used stop down metering (with a different creative twist).

Did anyone predate Olympus with TTL, full aperture metering?

Good question, but here is an off the wall answer.

The Bolex 35EE zoom lens coupled with the SLR Bolex REX (uses a prism for SLR function) had a cable (not attached in the picture) that connected the pistol to the meter. When the trigger was pressed, the cable activated the meter. This meant, one could focus with the lens wide open before the shot. The camera then automatically stopped down and metered when you pulled the trigger to shoot.

So the lens would still be wide open for a moment as exposures began, making the first few frames over exposed...a 'look' duplicated by some of the best 'fake move film' digital effects...

Topcon RE Super?

If you are talking about SLR cameras then Topcon's RE Super had full aperture TTL metering in 1963. Konica had full aperture metering on the Auto Reflex of 1965 but it was not TTL metering. Konica first had that with the Autoreflex T in 1968. The Minolta SRT 101 had full aperture TTL metering in 1966. The Canon FT QL had stop-down TTL metering in 1966. Canon's full aperture TTL metering cameras came in 1971. They were the F-1 and the FTb.The Nikkormat FT of 1965 had manual aperture indexing but it also had full aperture TTL metering. Mamiya's TL and DTL camers had stop down TTL metering. In 1974 it introduced the SX line. These cameras had full aperture TTL metering using a modified M42 mount. The Olympus FTL of 1971 has full aperture TTL metering using a modified M42 mount. It bridged the short gap between the Pen series half frame SLRs and the OM series.

dynachrome said:

If you are talking about SLR cameras then Topcon's RE Super had full aperture TTL metering in 1963. Konica had full aperture metering on the Auto Reflex of 1965 but it was not TTL metering. Konica first had that with the Autoreflex T in 1968. The Minolta SRT 101 had full aperture TTL metering in 1966. The Canon FT QL had stop-down TTL metering in 1966. Canon's full aperture TTL metering cameras came in 1971. They were the F-1 and the FTb.The Nikkormat FT of 1965 had manual aperture indexing but it also had full aperture TTL metering. Mamiya's TL and DTL camers had stop down TTL metering. In 1974 it introduced the SX line. These cameras had full aperture TTL metering using a modified M42 mount. The Olympus FTL of 1971 has full aperture TTL metering using a modified M42 mount. It bridged the short gap between the Pen series half frame SLRs and the OM series.

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I believe the Nikon F Photomic T was famous for being the first, with the Nikkormat FT also getting this feature - both in 1965. Also, I believe the F had full aperture coupled non-TTL metering with the external selenium Nikon Meter very early, and in 1962 the full aperture non-TTL metering Photomic finder (with meter display in the viewfinder). Bear in mind that the F was a 6 years old camera in 1965, so it was as if today suddenly the original Nikon Z6 got a special accessory and became way more modern than the newest-best Canon. Nikon's motto at the time was that they eliminated deprecation or something. It seems to me that they have reinvented it since

thuggins said:

The Pen FT was introduced in 1966 and provided full aperture metering, although with a bit of a creative twist. While this was a couple of years after the Pentax brought out Spotmatic, the Spotmatic still used stop down metering (with a different creative twist).

Did anyone predate Olympus with TTL, full aperture metering?

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If the Olympus Pen was the first with full aperture metering then the newer Olympus OM-2 meters stopped down in automatic mode. It meters at full aperture in manual though and in auto mode but in auto mode the meter is only for displaying. Actual exposure is done stopped down.

The Mec 16SB was the first camera with full-aperture TTL metering -- in 1961. Just because it was a 16mm "subminiature" camera doesn't mean it doesn't count. After that it was the Topcon RE Super in 1963, as mentioned, for 35mm. Then everyone soon had it, but many (particularly those with screw-mounts) got stuck in the "stop-down metering" ditch. Those with bayonet mounts -- Minolta, Nikon, Canon, etc. -- were able to figure out easy ways to tell the meter what f-stop was set on the lens. It took Pentax, Yashica, Mamiya, etc. years to get out of the ditch.

thuggins said:

The Pen FT was introduced in 1966 and provided full aperture metering, although with a bit of a creative twist. While this was a couple of years after the Pentax brought out Spotmatic, the Spotmatic still used stop down metering (with a different creative twist).

Did anyone predate Olympus with TTL, full aperture metering?

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The Topcon RE (in Japan) sold by Charles Beseler Co. in US as Beseler Topcon Super D, was launched in 1963 as the world's first TTL metering SLR on the market, beating Pentax to the commercial market. The Topcon Super D (followed by the Topcon D-1 and Topcon Auto 100) had wide-open aperture metering using ANY finder...prism, waist level, or chimney, because its photosensor was on the back surface of a patterned semisilvered reflex mirror.

xkaes said:

The Mec 16SB was the first camera with full-aperture TTL metering -- in 1961. Just because it was a 16mm "subminiature" camera doesn't mean it doesn't count. After that it was the Topcon RE Super in 1963, as mentioned, for 35mm. Then everyone soon had it, but many (particularly those with screw-mounts) got stuck in the "stop-down metering" ditch. Those with bayonet mounts -- Minolta, Nikon, Canon, etc. -- were able to figure out easy ways to tell the meter what f-stop was set on the lens. It took Pentax, Yashica, Mamiya, etc. years to get out of the ditch.

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The documentation provided for the MEC 16 SB is vaguely worded as to wheter or not the metering was 'wide open aperture' per the inquiry of OP.
One sets the shutter speed, then adjusts the Aperture dial to line up the exposure meter needle....this identical description applies to the stopped-down metering Pentax Spotmatic too! One would need to view the front of the lens while operating the Aperture dial to see if it was always open (except during actual shutter release) or not. However, judging from the Wikipedia description, " with diaphragm working on principle of "cat's pupil" it does not sound like an aperture design which stops down only at time of shutter opening.

edit: I found the original marketing brochure for the MEC 16 SB and it states that only light striking the film plane "WHILE THE PHOTOGRAPH IS TAKEN is measured" But while the photographer changes the Aperture dial prior to the exposure, so that metering is not literalluy 'at the time of exposure', it does seem to indicate the opening size is changed when the dial is rotated.

I'll just note that many cameras that provide full aperture metering do so with a catch. Some will let you know in their manual (example: Canon T90) but others will leave you to figure it out on your own.

Certain lenses will fool their metering system when not stopped down and require you to dial in exposure compensation. Certain teleconverters will do this as well. Sometimes the amount of compensation you have to dial in depends on the metering mode. It seems if you use lenses that extend more toward the mirror, have very fast apertures, are older, only partially compatible, or are third party, you increase your chances of this.