tirediron said:
Shoot in RAW+JPG. That gives you the best of both worlds; an image you can post right out of the camera if you're happy with, plus all the benefits of the raw file to work with if and when you want to tackle the post-processing. Nothing worse than having a great image in .jpg only that just needs that little extra you can't get out of a lossy file format.
One thing about Canon in RAW+JPG mode: it has a GORGEOUS option, for Sepia under Color Toning; it has an option for YELLOW filter under Filter Effects; and it has options for the Image Sharpening, and the tone curve (degree of contrast applied to the image data), plus Image Compression, and Image Size. All in all,
Canon has a fantastic, lovely RAW + JPEG set-up for B&W images. Sepia-toned, yellow-filtered, Moderately High Tone Curve or Auto, High sharpening, and Medium-sized, Fine-compression images from a Canon d-slr will look amazing!
This RAW+JPG mode gives the gorgeous B&W JOPEG images, and it delivers FULL-COLOR .CR2 files, so you can make a color JPEG as well, and have ALL the color data in the .CR2, but get ready-to-show, beautiful B&W images. Medium-sied is perfect from the 18-MP or 24_MP Canon captures: down-sizing from full-rez to medium-sized is still a BIG image, and it suppresses noise, a lot!
Of course, you could also shoot RAW+JPG, and do it in color as well.
Make sure to have a fresh,m spare set of AA batteries for the flash! Keep in mind: the higher the ISO set on the camera, the LESS flash power is used on each shot, and also, the higher the ISO, the brighter the backgrounds can appear at a given flash shutter speed. If the shutter is set to 1/160 second for flash shots, the backdrop will tend to be very DARK in a big hall;, or in the evening, or in a not-so-bright room. You might think about slowing the shutter speed down to 1/40 second,and moving to ISO of 400, or 500, to make background areas "lighten up" in comparison to the flash-lighted foregrounds.
Do some practrice shots the day before the event, and look at them on-computer.