Walk through this. You get a cut and clean it appropriately, then cover it with triple antibiotic ointment. After a day or so, the wound and the surrounding skin get painful and red. Thinking your cut is infected you put more triple antibiotic ointment on it, which makes dermatitis worse.
The high quality, medium telephoto macro lens, has been developed for photographers who demand the highest level of optical quality. The new Hybrid IS system features up to 4-stop correction, compensating for the effects of camera shake, during normal shooting.
A 90D lens provides a wide field of view but less magnification in comparison to a +60D, which provides a narrower field of view but x1.15 magnification. It is this magnification and depth of field that makes the +60D lens a excellent choice for examining the optic disc ( and macular examination).