Have a read here. If used at around f5.6 it's optimum aperture you should get excellent sharpness. Try focus stacking at this aperture and then use unsharp mask in photoshop. Have never had any issues with sharpness on this lens.

A fine shot and nice focusing.

shield your eye's.

Agree with Smegy, all the shot's are moving away from you, would be better with some coming toward you.

Beautiful last three shot's, very imaginative.

Have used Photomatrix pro, good free but puts watermark on some shots.

Again focus stacked. 12 esposures.

Welcome Blaze, good to have you on board.

Firstly you need one of these, your camera attaches to this via the tripod mount. With this set on the tripod, your ready to go. Now this is the technique I have used, if it is wrong then someone correct me. Set the camera to manual mode, and manual focusing. Then focus on the nearest point to the camera, the edge of thebut subject closest to the camera. Take a sample shot and then adjust the shutter speed and aperture, I used an aperture of F8 and then set the shutter speed for best exposure. I set F8 because that is usually the best aperture for most lenses. Set the self timer or use the cable/remote release for the shot. Now take the first shot, nlinkow rotate the control dial on the focusing rail so the camera moves forward thus changing the plane of focus, or moving the plane of focus forward. for the shot in this thread I took six shot's. But you can take upto a dozen or so.
I took the shots as jpeg's at maximum quality.
You then need to download a freeware program called "CombineZM" When installed, open and goto file. select all the files you shot and click open. when imported goto the macro tab and click "do macro" it takes a while to process, when its done, save the file to your pictures.