A handy tip that has helped me.
I was in an airplane accident where I lost 4 fingers on my right hand. I have just a little less than half of my index finger and still have my thumb.
I found it very difficult to press the shutter button with my handicap. I was at the local electronics store one day and noticed some small self adhiesive rubber buttons about 3/8 of an inch in diameter and about 1/16 of an inch thick. I simply place one on the shutter button and it maakes it so much easier to push.
I hope this will help others even with normal fingers, www.friendsoftony.com