Spending some time observing these animals re-endorses their relationship to our species. This was during my October visit to Africa, and was on the road near Lower Sabi camp in the Kruger NP. 1DMk3 300 2.8 2x ISO 800 1/200 F5.6
Nice looking portrait image and getting the yawn adds impact. In a situation like this, also look at the background. It looks like if you had moved left or perhaps right you would have gotten the large vertical OOF streak out of the image and intersecting with the animal's jaw.
This is lovely Nevil. Could go a tad sharper and a tiny position change could have used the OOF baboon more for the image by a tad more separation. Welcome to BPN.
Good behavioural shot Nevil - pity he didnt show his large inscissors. I agree another round of USM will work, and the OOF object does distract a bit, especially as it is right in front of the mouth.