Hello all,
Sorry if this topic has been covered before but just curiosity on my part. Was having a look at the rear mounts of some of my lenses and noticed some have different numbers of electrical contacts on them. My three non-IS lenses have 7 contacts in total, one group of 5 and one group of two which is slightly more recessed into the mount (and of these one of the two contacts is considerably wider than the other). However, my 70-200 F4 IS has 10 contacts, one group of 8 and the other 2 recessed further same as above. Now initially I assumed that the extra contacts were to do with the IS mechanism but having looked at the corresponding contact pins on my 7D body I see that there are no pins on the body to make contact with the additional 3 pins of the lens (ie, the body only has a total of 8 pins and two of those pins contact the single wider contact on the lens)- therefore it cannot be to do with the IS mechanism and the crop sensor body does not support whatever function the extra contacts are for... Do the full frame bodies have more contact pins and if so what additional functions are they for?
Hopefully I have explained myself well enough!
Thanks for your input!
Sorry if this topic has been covered before but just curiosity on my part. Was having a look at the rear mounts of some of my lenses and noticed some have different numbers of electrical contacts on them. My three non-IS lenses have 7 contacts in total, one group of 5 and one group of two which is slightly more recessed into the mount (and of these one of the two contacts is considerably wider than the other). However, my 70-200 F4 IS has 10 contacts, one group of 8 and the other 2 recessed further same as above. Now initially I assumed that the extra contacts were to do with the IS mechanism but having looked at the corresponding contact pins on my 7D body I see that there are no pins on the body to make contact with the additional 3 pins of the lens (ie, the body only has a total of 8 pins and two of those pins contact the single wider contact on the lens)- therefore it cannot be to do with the IS mechanism and the crop sensor body does not support whatever function the extra contacts are for... Do the full frame bodies have more contact pins and if so what additional functions are they for?
Hopefully I have explained myself well enough!
Thanks for your input!
)
With the TC pins taped and a 100-400 mounted, the camera will try to AF. Whether or not it actually succeeds in locking focus depends on the subject (lots of light and a high-contrast subject works ok, although noticeably slower than native), low light/low contrast and AF will fail.
