Canon 50D with M42 lens adapted help

So long story short I bought a 55mm 1.8 Super Takumar here. It came with Fotodiox adapter ring with AF confirm chip. Now looking around on the net tells me the camera should show 00 in the aperture field and then it's in stop down metering mode and I can stop the lens down manually and it will meter based on that. My issue is that the camera still displays aperture numbers and it allows me to scroll through them. With that said I can set the camera to whatever aperture the lens is actually manually set for. Set up Ex compensation and off I go but i'm just wondering why it's not showing the 00 when it's a manual lens how the hell could the lens be communicating with the camera? I'm just confused here as I figure if it showed 00 and stop down metering worked as intended I'd not need to set up Ex comp much.

The body talks to the AF chip, which is apparently already programmed to have an f/stop value, which it reports to the body irregardless of the actual f/stop on the lens.

Ah ok that makes sense. Like I said it's more of a WTF?! then anything. I just set the aperture on the camera to be what it is on the lens's aperture ring so it will meter accurately and then set Ex comp based on the histogram to make sure I'm getting good exposure and DR and go from there. I will admit I am amazed at the bokeh of this lens so smooth and creamy. stomps all my other lenses into the ground. They sure don't build em like they used to.

Beware, I have tested and found that stopped-down metering is NOT necessarily ACCURATE with Canon dSLRs when used with manual lenses, even with adapters that have the chip!

In practice, even metering with lens wide open, with chip programmed to the same FL and same max aperture, may NOT result in best metering accuracy:

https://photography-on-the.net …p?p=14450413&po​stcount=12

Moral: TEST your setup, trust no one else's result to be identical to yours, unless you confirm the result with your own camera and lens! As the link documents, I have tested a number of lenses on the same camera and adapter, five tests -- each one behaves a bit differently with regard to metering accuracy.

Some -- but not all -- cameras that meter wide open can also meter stopped down. I have a Topcon Super D (a.k.a 'RE Super'), the world's first TTL SLR back in 1963-4, which can meter accurately with the lens stopped down, for example. Some cameras, like the Pentax Spotmatic, were designed to meter stopped down to shooting aperture, and always do so.

[edit: fixed broken link to prior post]

Put another way - the lens is not talking to the camera. The chip just tells the camera: hey, there is a lens here and it is f/1.4 (whatever the chip was programmed to say.) It will always say 1.4. You adjust aperture with the ring on the lens. I use manual mode and my knowledge of Sunny f/16 most of the time. You can use A/V mode if you like. If you want to use LiveView you will have to use A/V mode. Metering will not be accurate or even linear with older lenses. Always do a test shot and review before shooting too many at any one aperture. Gene

gasrocks wrote in post #16104969
You can use A/V mode if you like....Metering will be accurate or even linear with older lenses. Always do a test shot and review before shooting too many at any one aperture.

Metering will NOT necessarily be accurate!

I just tested an OM lens on chipped adapter. Lens is Olympus 50mm f/1.8, chip tells the camera (40D) the lens is f/1.8, so that is the aperture displayed on the camera regardless of aperture set on the lens. Incident light meter said IS400 1/1600 f/1.8. Camera spot meter with lens at f/1.8 actual also said ISO400 1/1600. But as you stop down the lens -1EV in Av mode, the shutter speed does not step by +1EV increments. In this series, the Lightroom post processing settings applied for all RAW shots was identical (5000k, 0EV Exposure, Brightness 50, Contrast 26)

oops - typo - should read - will NOT be accurate.