Black colourway reading blue and red at different stages of being zoomed in and out.

Hello, 

I am working on a print file of a design, in a charcoal / black colourway. CMYK/8Bit Tiff file. 

But these 2 screen shots are of the same file, one zoomed in at 61.35% and the other at 64.53% - do you know why photoshop you read the colour so differently like that? 

It reads really blue when zoomed out past 64% then more red when zoomed in. 

Just curious as it's miss leading when working on colourmatching! 

Thanks