I have R50 and I just got the sigma 18-50mm. I only have experience of rf 50mm f1.8 so I'm not sure if this behavior is normal. Rf 50mm kept focusing alltime and kept the picture clear on the screen but sigma goes instantly blurry when I release the shutter button. Is this normal? I usually get the focus back when I half press the shutter button. And sometimes it just won't find the focus. I get the red square instead of green. So far I've only tested it only inside. Will try outside soon. Is there something wrong with the lens? Or am I doing something wrong?
