If you’ve ever been bothered by your camera changing the shape of a piece, you may be experiencing barrel distortion. Barrel distortion is caused by the shape of the camera lens, which compresses light waves in order to focus them on the image capturing plane.
Below, I intentionally held the camera very close to the subject. The result? Finials on the outer two pieces appear to bend away from the center (vertical lines added to illustrate):
To correct this problem, increase the focal length: move your camera farther away from the subject and zoom in. This causes the light to bend less radically, and “straightens” the distortion.
There will almost always be some degree of distortion in your photos, it is lessened, and your images appear closer to their actual form.
There are other factors that effect this distortion, but this simple tip can improve photographs of your art.