Signal Transmission and Function of the FD Lenses
The FD series lenses can be used for full-aperture metering when mounted on any of Canon SLR models after the Canon F-1, EF, and FTb cameras, and also for stopped-down metering when mounted on the earlier pre-FD era's FT QL and other Canon SLR cameras.
Earlier section mentioned and illustrated Body and lens coupling was based on a newer FDn lens and here is an illustration which used an original older version of an FD lens to demonstrate. 1. Automatic/Manual Aperture Lever This is the conventional stopped-down coupling lever which automatically resets to full aperture opening position after shutter release. This lever also couples with stopped-down functioning/self-timer lever on the camera body. By turning stopped-down functioning lever, stopped-down metering is also possible.
NOTE:- Info on the NEWER autofocus version
2. Full-Aperture Signal Pin. It is used to compensate for the metering error at full-aperture f/stop when using a large aperture lens. In order to correct this error, the full-aperture signal pin plays a role to adjust the matching needle position.
3. Aperture Signal Lever. This lever is a coupling lever that plays three important functions in full aperture metering:
a) First function is the aperture transmission signal in full-aperture metering. It is coupled with the preset aperture ring to move on a synchronized oneto-one ratio and transmits the preset f/stop position to the exposure meter of the camera body. At this time, of course, light metering is full-aperture method. As soon as the shutter is released, the aperture closes down to the preset f/stop by this lever and the proper exposure is obtained.
b) Second function transmits the automatic setting of the full aperture opening f/stop to the exposure meter. Even if a lens with a different lens speed is used, the aperture signal lever is in the same position at full aperture opening f/stop. When a lens is mounted on the camera body, the full aperture opening f/stop is transmitted to the exposure meter and the aperture needle is set at a fixed position.
c) Third function is the inner setting of the preset f/stop for the automatic exposure EF camera and Servo EE photography with F-1. When the preset aperture ring is set at the 'A' mark, located outside the scale, this lever is automatically disconnected from the preset aperture ring and can be freely moved. This function is made possible in EE photography with the EF and Servo EE Finder attached to the F-1. But all these FD lenses can also be used and compatible with all FD mount automatic Canon SLR bodies that introduced in later years (In fact, other than the New F-1 in 1982, virtually all Canon bodies that followed will require batteries to power its functions (other than aperture priority AE bodies such as Canon AV-1 in 1979, the AL-1 Quick Focus camera of 1982 and Canon T-60 of 1990), these automatic bodies made by Canon feature shutter priority automation that would require a FD lens be locked at the "A" Mark.
In other words, for other older Canon bodies, this lever is turned to the proper position for closing down the aperture upon information received from the EF and Servo EE Finder. Thus the proper exposure can be obtained and unmanned EE photography is possible. During those days, lenses other than Canon FD lens do not have these features. Therefore, it is impossible to use them for EE (AE) photography. The tremendous success of the shutter priority AE based Canon AE-1 in 1975 firmly put Canon on the driver seat as being the forerunner of camera automation. I remembered Minolta was the first Japanese camera maunufacturer to react and it fact, won introduced the world's first multimode AE body slightly ahead of the equally popular Canon A-1 with their XD-7 (Or XD-11 in US) model that also combine Program AE other than the popular automatic aperture and shutter priority exposure control.
4. EE Lock Pin. A safety lock pin to prevent accidental movement of the aperture ring over to the 'A' mark. When this pin is pressed, the lock is released and the aperture ring can be turned. The lock pin for earlier FD lenses is located at a separate ring just above the chrome mounting ring. The newer FD lenses has it at the same aperture ring.
5. EE Switch Pin. When the preset aperture ring is set at the 'A' mark for EE use, the lens can be attached only to the cameras designed for EE photography. If the lens is attached to the older bodies such as the FTb or TX, it cannot be set at the 'A' mark.
See A variation.
6. Spare Signal Pin.
Canon indicates it is a reserved pin for developing System Accessory but I am not so sure which types of accessories would require this pin to work. May be someone out there could shed some light on this feature.
Manually Operated Aperture
When the automatic/manual aperture lever is turned all the way, it is clamped and stops. By mounting a lens in this condition, manually operated aperture can be used. This function is used when any non-automatic accessory such as bellow or extension set is used between the camera body and the lens.
Note: However, in ordinary photography using an Canon F-1, FTb, or TX, manual aperture may be used by locking the stopped-down metering lever. Below: Shown below are how older bodies handle their respective viewfinder display in manual aperture control. For newer Canon bodies has their respective sites in PIM, click here for the various A-series or the T-series models.
FD Fisheye 7.5mm f5.6 S.S.C. | FD Fisheye 15mm f2.8 S.S.C. | FD 17mm f4.0 S.S.C. | FD 20mm f2.8 S.S.C. | FD 24mm f1.4 S.S.C. ASPHERICAL | FD 24mm f2.8 S.S.C. | FD 28mm f2.0 S.S.C. | FD 28mm f2.8 S.C. | FD 35mm f2.0 S.S.C. | FD 35mm f3.5 S.C. | FD TS 35mm f2.8 S.S.C. | FD 55mm f1.2 S.S.C. ASPHERICAL | FD 50mm f1.2 S.S.C. | FD 50mm f1.4 S.S.C. | FD 50mm f1.8 S.C. | FD Macro 50mm f3.5 S.S.C. | FD 85mm f1.2 S.S.C. ASPHERICAL | FD 85mm f1.8 S.S.C. | FD 100mm f2.8 S.S.C. | FD Macro 100mm f4.0 S.C. | FD 135mm f2.5 S.C. | FD 135mm f3.5 S.C. | FD 200mm f4.0 S.S.C. | FD 200mm f2.8 S.S.C. | FD 300mm f2.8 S.S.C. FLUORITE | FD 300mm f5.6 S.C. | FL 300mm f5.6 S.S.C. FLUORITE | FD 400mm f4.5 S.S.C. | FL 400mm f5.6 | FD 500mm f5.6 S.S.C. FLUORITE | FD 600mm f4.5 S.S.C. | FL 600mm f5.6 | FD 880mm f5.6 S.S.C. | FL 880mm f8.0 | FL 1200mm f11 S.S.C. | FD Zoom 35-70mm f2.8-3.5 S.S.C. | FD Zoom 100-200mm f5.6 S.C. | FD Zoom 85-300mm f4.5 S.S.C.
Canon FDn lenses
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