Originally posted by newarts I think a piece of thin copper wire pulled from a lamp cord would work well as a substitute for the aluminum foil.
I wouldn't try using copper wire. It is harder than the aluminum foil and may damage the lens mount when you press it back into place. The foil is easily cut forming the 'chad' within the contact hole on the lens mount.
I personally don't have a strictly manual lens to test. So my 'A' lens are always at full open until the lever is pressed. With the green button programming set to stop the lens down, I can see that the lens stops to its manual setting.
But if you have a strictly manual lens, you should be able to use either Av or M mode, set the aperature wide open during metering, then use the e-dial to adjust to the desired f/stop, lock exposure and finally set the lens' aperture to match what the camera says.
Regardless - fooling the camera into thinking all lens are using an automatic aperture harms nothing and allows you to see what the camera thinks is the aperture.