how measure light / aperture with adapter attached?

Hi

i recently purchased an adaptall to mount my tamron screw mount telephoto lense to my pentax k1000 bayonet mount camera. it works fine. but i have one problem...

how on earth do u figure out what aperture you need / how much light there is?

once the lens and adaptall are mounted the light meter will move up and down however it DOES NOT vary according to the aperture as set on the lense!

how do i work out what aperture is required?

the note that came with the adaptall reads:

"the automatic diaphragm of the lens will not function, so meter reading must be made with the lens aperture stopped down."

what does this mean?

can anyone please help me? i am in desperate need for quick help as am leaving on an overseas holiday in 6 weeks and i want to take some good photography!

thank you for any advice you can give me!

cheers

OzSheppy

Hi,
I have replied to this under Troubleshooter. By the way, it is not a good idea to post the same question in 2 places. It just causes confusion.


Regards
Kim