Question re: filter threads

[andythebrave]

My sincere apologies if this is a bit of a stupid question but why is it that some lenses have a filter thread considerably larger than the diameter of the front lens element?
For example the Olympus 11-22 for four thirds.
Thanks in advance.

 

[sk66]

So the filter ring is not seen in the wide angle FOV

 

[Erty]

And small filters in non-standard sizes are more expensive and can fit less lenses.

 

[andythebrave]

Ah, should have thought of that, thank you.