Originally Posted by asdf 
BTW, I was around a meter away and the images were cropped without scaling. The white balance was set to the flash preset. I don't have studio lights and at first I didn't want to introduce noise due to long exposure, so I used flash.
With K200D, at 1m camera-to-subject distance, 50mm setting and f/5.6 depth of field is only -4.12cm/+4.49cm (in front of/behind the subject). So you have total DOF of only about 9.5cm, and very minor shift in focal length may affect the image.
In contrast, with identical settings at 5m camera-to-subject distance DOF will increase to -91.5cm/+144.3cm, giving you over 2m of total DOF!
WB on flash and flash use for this type of tests works the best. Tripod may be of great help as well.