Redfordl22
IMHO here are a few pointers for you:
* The SX40 sensor has a circle of confusion of about 6 microns (I think, please check);
* Based on this the hyperfocal distance at the widest aperture F2.7 and at the shortest focal length of 4.3 is going to be less than about 2m. Which should mean that you have a good depth of field from about 1m to infinity.
* My numbers account for aberrations, in other words, F8 is not the best way forward.
* Low ISO is a good strategy;
* lock off everything, ie manual focus mode and fixed WB etc.
Bottom line: try shooting at the widest you can on your camera and focus at the hyperfocal distance, ie you dont get the deepest dof by closing down apertures beyond the sweet spot, because of lens aberration. Try shooting at the widest and manually focus at the hyperfocal distance (llok on line for DOF calculators, or at Apps on your Android or iphone etc).
Cheers
Garry