Northern cardinals don't usually have much chance to eat suet at our feeders, since the suet feeders are usually oriented upright -- designed for birds that can cling to them, like chickadees, nuthatches and woodpeckers. Cardinals aren't clingers, and they prefer flat, stable feeders. But recently on a whim we oriented a cage-style suet feeder horizontally, and this male cardinal took advantage of the opportunity.
Luckily, I was sitting right by the window with my camera at hand when this bird flew in, and I was able to get some really good close-ups. Cardinals are quite skittish and are quick to fly off if they sense movement (such as someone reaching for a camera). As a result I don't have many good cardinal photos. But these photos are hardly cropped at all, and if you click on them (or right-click to open the image in a new tab) they are really big -- big enough to see that the cardinal's eye is brown and that it has some of the suet mixture it its beak.
We recently had the pleasure of seeing a cardinal courtship ritual: the male offering the female a sunflower seed from our hopper-style feeder that usually attracts them. However, "Mrs." was not on hand for the visit to the suet feeder.