How do I tell it the lens is F8 ?

[jonsegar]

I have a Canon 400D. I know how to set aperture and speed in manual (with a canon lens attached).

I have borrowed a 500mm mirror lens, which does not communicate with the camera, so the aperture always shows up as F00.

How can I tell it that it is an F8, so I can get the metering to give me a reading ?

(and I have RTFM, but it does not seem to say)

jon

[donoreo]

Is this a Samyang? They are fixed at f/8 or f/6.3 (depending on the model). So you know the aperature, you just need to calculate the shutter speed.

I do not have time right now to look it up, (at work 5 time zones behind the UK here) but I will later it no one else posts.

[jonsegar]

donor,

It is an f8 Sanyang.

jon

[GeoffWessex]

How about setting the aperture to whatever gives you the "fastest" shutter speed? That will be the max aperture - f/8. It's not going to be a great lens, though, and certainly not for wildlife (unless the wildlife/s dead and you're using a tripod). With f/8 as the max aperture you're going to have to increase the ISO to 400 or 800..... and the Canon 400D is quite noisy at those sensor speeds. Hopefully the lens hasn't cost you a lot.