We can confirm that the bayonet mount of the SX40 HS has remain unchanged from the previous model, the SX30IS and all SX models preceding it. This means that the Lensmate 58mm filter adapter fits perfectly.
Why use the larger 67mm filter adapter when it’s not necessary? It just takes up more space and uses more costly filters. The 58mm Lensmate filter adapter does not vignette at all at full wide (24mm) using a full depth polarizer.
When things are not as they appear…
Out of curiousity we obtained two of our competitors SX series 58mm filter adapters. The first one appears to be a copy of the Lensmate filter adapter, though if you look closely the knurling has a finer pitch. But the real giveaway is that it’s made of aluminum, which seems like a reasonable choice of materials but isn’t in this case. We used Delrin™ instead for a couple reasons. One is that Delrin’s self lubricating properties means that it virtually eliminates wear on the plastic resin of the cameras’ lens barrel. But more importantly the material’s flexibility is necessary for the locking mechanism to work. Apparently whoever reverse-engineered our part didn’t understand the fundamental principle of its operation – our sample aluminum Asian knockoff turns about half way towards the lock position then starts to grind plastic – I didn’t even attempt to turn it fully to the stop. I would imagine that multiple installation/removal cycles could remove enough material to compromise the hood lock function.
Now where did I put that screwdriver?
Sample two is also a metal 58mm adapter, though it’s of a different design. It fits loosely so it probably won’t damage the camera. However, it requires tightening 2 very small slot head screws to keep it from falling off. I suppose if you wanted to permanently mount it on the camera this might make sense. Otherwise don’t forget to bring the jewelers screwdriver and magnifiers in your bag for filter changes. Included in this package was an uncoated glass UV filter – a throwaway in our opinion and a petal-style plastic lens hood which threads into the filter. Unfortunately the hood vignettes terribly, and in this configuration is not adjustable so the petals end up randomly positioned.
