Macro photography is a type of photography in which the depth of field is very shallow. While the effect of sensor size to image depth of field is not much of a popular factor, for those who know, they attest to the principle that using a smaller format or smaller size sensor can give more depth of field to your macro image.
Depth of field is quite essential in macro photography as it deals with capturing images of very small objects and magnifying them into larger-than-life images. A larger depth of field makes the entire image sharp, while a shallower depth of field gives emphasis on the part of the image focused.
As for the effect of sensor size to image depth of field, sensor size or sensor format is directly proportional to depth of field as briefly mentioned before. A bigger sensor size means shallower or smaller depth of field and vice versa for a given aperture. Larger sensors require the use of longer focal length or for the photographer to get closer to the subject in order to fill the frame.
In doing macro photography one should simply be focused on simply filling up the frame with the subject. With this in mind and knowing the effect of sensor size to image depth of field, by using a smaller DX sensor, one would be able to fill the frame with the subject with a more in-depth magnification.
To sum it all up, change of sensor sizes or change of sensor formats can give more possibilities in playing with an image’s depth of field which is a principle that will work handy for photographers who play up with depth of field and macro photography.