[George16887]

The angle of view (diagonal) of 2 Canon lens:
1. EF-S 17-85mm f/4-5.6 IS USM: 78°30' - 18°25'
2. EF 24-105mm f/4L IS USM: 84° - 23°20'

Question 1
At a glance, it seems that lens #1 (17-85mm) has a wider angle than #2 (24-105mm). When we look at the actual angle of view, #2 has a much wider angle (84°) than #1 (78°30' )! Can anyone tell me if my finding is correct? If so, we should look at the angle of view but not the focal length of the lens!

Question 2
If I want to buy a Canon 350D w/ a wide angle zoom lens:
lens #1 will be about 27-136mm (x 1.6) and lens #2 will be about 38-168mm (x 1.6), will the wide angle of view change into narrower as well? If so, will lens #2 still have a wider angle of view than #1?

Question 3
What is the main difference between a lens w/ "L" and without L?

Tks very much in advance.

[Philippe]

Question 1
17-85是APS專用鏡,有1.6焦距增長,等效是27.2mm,所以視角比較窄.

Question 2
17-85較wide

有L貴好多,不過光學質素好D.

[George16887]

Thanks Philippe,
What is APS 專用鏡?

[Philippe]

即係例如350D, 20D等感光完件是APS size,只有FF大約40%的面積.有焦距增長1.6.
17-85只可用在這類機上,用在大感光完件的機上即使可以接上都會有黑角見到.