Do we really need to worry about dust in the lens...?

Lensrentals to me seem to help add a bit of practicality to the theoretical talk that often comes with camera ownership and this article does it again.

http://petapixel.com/2015/06/10/we-f...r-sealed-lens/

And their conclusion:

Quote:

---

We took dozens of images with the lens before taking the fly out. We shot stopped down, we shot at all parts of the zoom range. We focused close, we focused far. And in no image could we find the slightest hint that there was a fly in the lens. And you guys worry about a dust particle or two!

---

Nice but this is somewhat a naive experiment. Anything inside or on the lens including the fly, is out of focus and will not show in the images, dust will be out of focus too and of course individual dust particles will never show. But if you get heavy dust inside your lens over the years in extreme cases it will reduce the contrast of the image.

Dust inside or on the element will cause flair when there is a strong light source in the frame other then that its pretty harmless.