I believe Gerry means that with the contrast and sharpness cranked up, he can see better whether or not the AF has done its job to his liking. I shoot raw, and crank up the sharpening when I am in using the back LCD to determine focus hits/misses. It works. But you are right, it has no effect of AF performance. It just allows you to better see the AF results.
Yep, I do the same thing Gerry S(7,1,1,0).
To everyone who's saying "Contrast doesn't affect AF":
He's not saying that it does. He's just saying that it optimizes the on-camera preview so that he can check at 100% magnification on the LCD TO SEE IF THE FOCUS IS PERFECT and if not then reshoot. The RAW file remains unaffected.
this is a good idea that i had not considered. It is especially nice as my eye sight is starting to fade with age.
do you need to shoot RAW + JPG or is the picture style applied to the small preview file used by the camera even if shooting RAW only?
Age is but one factor I shoot RAW only
No need to shoot RAW+JPEG. RAW-only is fine as the LCD preview uses the camera settings for display, even though the actual RAW file remains unaffected.
The software I use (Shotwell for database) will use the JPEG information to create a JPG file whether I like it or not, for detailed viewing on the PC. I use these JPEGs to decide which RAW files to work with, but that's just my workflow. I could just as easily bypass Shotwell when importing the photos and use Darktable as the database (very similar to LR) but I like the quick access Shotwell gives me to over 15000 photos I have, complete with tags.