Canon A-1 SLR - 28mm lens' exposure seems off

[aj0]

Greetings. I'm new to this forum. Also new to film photography.

I picked up a Canon A-1 and got its 50mm kit lens. The lens works great. And, while I don't rely on it, the digital exposure meter still functions and is accurate relative to my Canon R5's meter. It's also pretty accurate relative to the light meter app on my phone (using the ambient light sensor on a sunny day).

Recently, I picked up a 28mm FD lens because I wanted a wider angle lens. I noticed, however, that the digital exposure meter is way off for it. On a sunny day, with a brightly-lit subject, the A-1's exposure meter recommends something less than f/2.8. (100 film speed, 1/125 shutter speed, following sunny 16 rule.) Maybe for a very bright subject it will recommend f/2.8 to f/3.5. I'm curious if this is the intended behavior for a 28mm lens on the A-1 or if the sensor is just busted. The camera was manufactured in the 1970s after all. (The sensor works fine for the 50mm lens, though.)

Any help in understanding would be appreciated. Thank you.

 

[RAZKY]

Greetings. I'm new to this forum. Also new to film photography.

I picked up a Canon A-1 and got its 50mm kit lens. The lens works great. And, while I don't rely on it, the digital exposure meter still functions and is accurate relative to my Canon R5's meter. It's also pretty accurate relative to the light meter app on my phone (using the ambient light sensor on a sunny day).

Recently, I picked up a 28mm FD lens because I wanted a wider angle lens. I noticed, however, that the digital exposure meter is way off for it. On a sunny day, with a brightly-lit subject, the A-1's exposure meter recommends something less than f/2.8. (100 film speed, 1/125 shutter speed, following sunny 16 rule.) Maybe for a very bright subject it will recommend f/2.8 to f/3.5. I'm curious if this is the intended behavior for a 28mm lens on the A-1 or if the sensor is just busted. The camera was manufactured in the 1970s after all. (The sensor works fine for the 50mm lens, though.)

Any help in understanding would be appreciated. Thank you.

Try metering the exact same evenly lighted area with both lenses. Put the camera on a tripod and don't move it when changing lenses. The indicated settings should be the same.

 

[webestang64]

Also possible the aperture in the 28mm lens is bad?

 

[aj0]

Try metering the exact same evenly lighted area with both lenses. Put the camera on a tripod and don't move it when changing lenses. The indicated settings should be the same.

Did this with a bright but diffusely lit backdrop. With 50mm, meter recommended f/8 (at 1/125s). 28 mm showed f/2.5 (at 1/125s).

Also possible the aperture in the 28mm lens is bad?

Whenever I activate the stop-down lever, the blades move when I adjust the aperture ring.

Might see if I can get another one for comparison.