Inspired by the DA40 lens hood, I will convert all of my lens hoods to this kind:
It consists of one or more step-down adapter rings. The one in the photo is a 49-37 plus a 37-30.5. A nice thing about 30.5 size is that the lens cap costs nothing:
Sigma 135-400mm: 77-62 + 62-55 + 55-37. Compare the 37mm cap with the original 77mm cap:
Tamron 90mm macro: 55-37 + 37-30.5. Next to the lens is the original lens hood:
Of course this kind of lens hood can't be use with the newer DA zoom lenses (problem with vignetting). But those zoom lenses normally come with dedicated petal-shape hood anyway.
It is great for most full-frame lenses, especially primes. You can reduce the size of the opening until vignetting, then back up one size. I think it provides better protection than any other kind of lens hood.
Prices are very reasonable, as long as you can wait for shipping from China.
Last edited by SOldBear; 09-19-2009 at 12:09 AM.