Canon Reflex Lens 500mm 1:8 FDn

I recently acquired one of these mirror lenses just for fun.

 

Out of curiosity I have been trying it on various FD bodies. I've never had a

fixed aperture lens before, so I've had to try and understand stopped-down

metering. It seems that each model has a different approach.

 

When I tried it on an AL-1, much to my surprise, the Quick Focus feature

actually worked. I had thought that f8 would have been too small. This is useful

because it's difficult to focus manually.

 

Apparently the AL-1 knows it has a fixed aperture lens attached and meters

accordingly. I can't see how it manages this. Does anyone have experience of the

AL-1 stopped down metering?

 

Thanks.

 

Henry

Henry, the "FD" designation on your 500mm lens indicates that it should have the signal devices needed to communicate with FD bodies. The camera knows that the maximum aperture is f/8. Because the aperture is fixed, none of these signal devices should move or change. Your AL-1 should meter correctly with this lens in its normal aperture preferred mode.

 

My understanding is that, with non-FD lenses, the AL-1 will meter properly only if you stop the lens down manually before taking the picture. There is no provision on the AL-1 to do this. Even though FD and FL lenses have the same aperture lever, you still need to close the aperture manually on an FL lens to get proper exposure. If you're using a non-FD lens that does not have the ability to close the aperture manually, I don't think you can get proper exposure on the AL-1.

 

In stop down mode, the AL-1's aperture priority AE simply selects the correct shutter speed at the time of exposure based on the scene's brightness. Because of its fixed aperture, there would be no difference between automatic and stopped down metering with the FD 500mm mirror lens on an AL-1.

Gordon, Thanks for the answer.

 

The lens has neither of the aperture levers, nor the maximum aperture pin. The only FD bit about it is the mount.

 

I guess the AL-1 must be designed to infer that the lens is fixed aperture if it gets no information from the normal levers and pins.

 

Henry

That's interesting, Henry. I don't own one of these lenses but there's a photo of the back of the lens on the MIR web site. The full aperture signal pin is longer on FD lenses with larger apertures. The pin on my FD lenses with a maximum aperture of f/5.6 is relatively short. I would surmise that an FD body reads the maximum aperture to be f8/ (i.e., defaults to f/8) in the absence of a pin.

> I recently acquired one of these mirror lenses just for fun.

 

Would love to see some shots

FD max aperture values stop at f/8, so "no pin" = f/8 !

I had one, the back of the lens sure looks poor compared to all the pins and levers that clutter the other lenses!

;-)

<p>In the past the FD 500 reflex had a good reputation. Unlike the other FD lenses this one has neither a diaphragm nor other connections between the lens and the camera body. So one might think it could be possible to skip thoughts about bad adapters, get a monkey wrench, unscrew the original bayonet mount and replace it with something more useful, like EF, Nikon, M42, whatever.<br>

Was this ever done by a crafted mechanic?</p>

<p>Not to long back I bought the canon reflex lens 500mm 1:8 lens. I was able to remove the back and by a converter off of ebay that had a slightly bigger diamoter then the whole that is left when you remove the FD bayonet. Then with a bit of sanding on the converter ring that I bought was able to press it into the whole.<br>

I was able to convert the lens with very little trouble to the Olympus 4/3 and I was able to focus to infinity because I made sure that the face of the converter was even with the back of the lens.<br>

However, this being said, because the lens is a fixed aperture I had no problems with an quadrature ring had it not been then I would have had to do God knows what to make the aperture usable, if I even could. Most likely I would have had to fix the aperture at an exceptionable point and just deal with the inalienability to change it.<br>

Hope this helps if you still needed the info.<br>

Thanks<br>

Tom</p>