Je crois que j'ai retrouvé:
Copier/coller du forum:
For those who wanted a 40-50mm focal length Q....
This is a 1.5x conversion lens, with a huge front element so no loss of light. It nearly covers the entire frame with just a touch of softness and moderate vignetting into the corners.
Where things get interesting is when you pull up the 35mm frame lines, which are basically a 1.25x crop of the sensor. 28mm x1.5 = 42mm, which then with the 1.25x crop takes care of the extreme corners gives a FoV of 52mm.
So essentially we've got a 42mm/f1.7 lens, on a 1.25x APS-H 15meg sensor, and I think I paid $9 for this conversion lens, so not a bad deal!
Also if we go to the 50mm frame lines, which are a 1.8x crop, we get a 8meg 75mm equiv FoV, which again is kind of cool for a $9 conversion lens.
Will I actually use it that much ? Probably not but its a bit interesting and does add some versatility for the cost of lunch.
Might need to see if I can borrow the 1.4x Fuji TCL for the X100 and see how that one works as well, given its just 6oz....
Apple iPhone 5s
iPhone 5s back camera 4.15mm f/2.2