But it looks like as if many manufacturers build their top lenses as fast lenses.
I want to spend money on a really good lens, but it doesn't have necessarily be fast (and, that comes with being fast - big and heavy).
So there should be lenses, that are excellent, but not super expensive and super heavy, as they do not strive for maximum speed.
Or are there?
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That's a good point. To some extent we do have such options with Canon lenses. Don't know about Pentax and Nikon though. For example we have the choice of the 70-200 f2.8 zoom or the 70-200 f4 zoom. Both lenses are about equally excellent, but the latter is significantly cheaper and lighter.
We have the choice of the 50/1.4 and 50/1.8, the latter being cheaper and lighter but both lenses probably just as sharp when stopped down to f5.6 and lower. My copy of the 50/1.8 appears very slightly sharper than my copy of the 50/1.4, probably due to QC variation.
We've also got the choice of the 85/1.2 and 85/1.8, the latter being cheaper and lighter but both probably about equally good at f8.
I think it would be true to say that most (at least reasonably good) lenses would be equal at f11, or as close as matters.
The problem of designing a lens purely for lightness, low cost and good performance at relatively narrow apertures is that such a lens would tend to be specialised. It wouldn't be useful for applications where a shallow DoF is sought, or for low light situations. Such a lens would therefore probably not sell well and that would add to its cost and defeat the purpose.
