Originally posted by Wheatfield Image quality is definitely not subjective. Every aspect of image quality is measurable and definable.
True. Well, most of it anyhow - bokeh and rendering are commonly used "metrics" in describing IQ that are hard to measure. But true, lots of stuff *is* nicely definable.
Still, the subjective part is in deciding how to compare two lenses where one is sharper in the center but the other sharper in the corners, or one is sharper at f/4 but the other at f/8, or one is sharper at 100mm but the other sharper at 200mm, or one is sharper overall but the other has more PF, or where one has less distortion but the other less vignetting, etc. The individual components of IQ may be (mostly) measurable, but that doesn't always make it possible to objectively declare one lens a winner over another - it will often depend on how each individual photographer weights those various components.
Anyhow, you're right. I was needlessly imprecise, so thanks for the clarification.
Quote: As far as the price of good optics being subjective, again, no it isn't. Good glass will cost more than poor quality or average quality glass.
I didn't say the *price* was subjective. I said the *worth* of the IQ differences was. That is, would any given photographer find a 15% increase in MTF numbers at a given aperture worth $500 to them? I say that is "subjective", you say it is "discretionary", but I'm not sure I understand the distinction being made. Either way it boils down to this: different people will legitimately have different answers to questions like that.
Anyhow, my point being, when it comes to asking about lenses, it's a lot easier to have objective discussions about which lens is wider or longer than which, or which has a larger maximum than which - and to precisely quantify the *extent* to which one is wider/longer/faster than another - than it is to have equally objective discussions of which lens is "better" than which, or just what a 15% advantage in MTF really means in practice.
Quote: To the OP, your kit lens will serve you quite well, but when it stops serving you well, you would be better off to spend your money on one or two very good lenses than a slew of mediocre lenses.
Definitely agreed.