Yellow Marking On Leaves

Hi All,

Just a quick question about the yellow markings. I'm at just on 7 weeks into bloom and is normal for leaves to yellow I was told, as the heading takes most of the food and some leaves die off.

I was also told this could be a nutrient problem (EC 1.7) so was hoping someone could look at the pictures below with some feedback.

Thanks all for your help.

ShadowAD