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Alt lenses and aperture reading on Rx

Hello all,

I just got a beautiful condition Rx body :), and the only lens I have for it is a new looking Panagor 24mm f2.5. Not much info about this lens on the web, but apparently it is made by Kiron.

Anyway, when mounted on the Rx, in Av mode, at widest aperture the Rx shows 2.4. With the lens set at 5.6, the Rx shows 4.5; at f8, Rx shows 6.5. Is this because I'm using a non mm or ae lens? Will this mean that all my exposures will need to be compensated so they are not overexposed?

I do have the complete manual, and on page 188 for "shutter speed and aperture indicators," it notes on the bottom of the table that the camera will show "approximate values" if the between the standard apertures, but I'm not sure this applies to my lens...I guess the Rx is showing approximate values because it is not receiving the aperture information electronically from the lens?

Answer in Rx manual...

Upon further reading, the Rx manual states: "If the exposure mode is "Av" or "P", the shutter speed coupled with the aperture is shown in 1/2 steps. If "Tv" or "M," the set value is displayed."

At least on the Panagor lens on my Rx, the apertures display correctly in the viewfinder if you move the aperture ring between the click stops. As stated somewhere else, it probably makes no difference as the camera will compensate automatically with the shutter speed.



Well-Known Member
There's likely to be a problem with the pin that sticks out of the back of the lens and tells the camera what aperture is set. It won't cause exposure problems as the meter sensor relies on the amount of light hitting it.