500mm Mirror Lens fixing the aperture

[YellowBay]

I'm stuck!!!
I recently got given a Centon ( I think it's Jessops own brand) 500mm lens. Common to mirrors, it's a fixed aperture of f8. My question is......

How do I get my 400d (Rebel Xti for the Americans) to beleive it! When it's on the camera, the aperture is showing up as F00.

It's on a T-Mount so there's no connection to the camera but even in manual I can't seem to do anything about it......

 

[Bifurcator]

F00-BAR

Doesn't the XTi have a manual mode?

 

[YellowBay]

Yes, but as I said, even in manual I can't set the aperture with this lens. I think it's something to do with the T-Mount

 

[Kegger]

It's not gonna matter what the camera thinks.

I use a lot of the old non-AI lens and even though my camera has no idea what to do it will still take the picture. The lens is at f/8, doesn't matter what the camera says. Just set the shutter and snap away.

 

[Marnault]

Since the lens doesn't communicate with the camera in anyway the apature will always show up as F00, which basically means it can't set the apature, not that the apature is 0 which would be impossible.

Assuming you are shooting in manual mode, all you need to to is adjust the shutter speed and iso for your exposure. The cameras light meter will still work properly.

As you probably know you wont be able to stop down the lens, so you are always shooting at F8.

 

[YellowBay]

Cheers guys.
Thanks for the info. I was just a bit worried at the impossible f0!