nikon d90 - 50mm lens
hi digital photographers.
i am puzzled at this image i took at our studio, it has blue patch in the center of the frame.i am thinking its because of my lighting setup because if i turned off the backlight the blue patch disappears.another 50mm i attached also shows the same patch.but heres the thing, if used 18-135mm lens i get good image without the patch.
heres the image i took using 18-105mm lens @ same settings and lighting setup.
can anyone enlighten me where i am going wrong, in my lighting setup or the lens i am using.