Re: John_Nikon_F and Xmas...some PRE-AI "K" lenses were available with factory AI aperture rings...e.g. 135mm/2.8 Q.C and 85/1.8K, both of which I have...I think they are less available than their non-AI versions, so they'd be worth more I should think...

...and I would think that the market value of lenses converted with the "cut" notch at the rear of the aperture ring (I have one of those too) would likely be worth less than OEM...but its value to the owner/user is another matter of course....

In some cases it may be cost-effective to convert a lens...in other cases it may be cheaper to get the factory-AI version and sell the non-AI lens.