Take a look at this picture. The slide behind Steve Jobs says:
300 [pixels per inch] is limit of human retina.
My question: why is there no indefinite article before limit and why is there no definite article before human retina?
The indefinite article before limit seems to be needed because the human retina has many limits, and the definite article before human retina seems to be needed because we are talking about a specific part of the human eye. This question is very similiar the one I posted earlier, but this time OED is silent on limit (either that or I'm just stupid, and I won't be surprised if it's the latter).
Also, it very well may be ellipsis and I'm overthinking.
What do you think?