[ray818]

我己有支A16, 想買支L鏡,筆直一萬樓下,邊支正D?

[littlelamb]

If you consider L lens, you may also consider using FF later on. Then why not consider 24-105 F4 L as well? The range is wider and the quality is about the same as 24-70 F.2.8L. You are now using A16 (17-50) and 400D (1.6x), then I will not suggest you to use 17-40 F4L. Although the quality is better than A16, the focus range is overlapped and even smaller.

[Legacy-RS]

有A16不如買支24-105 L f/4
又或者放左支A16
買10-22+24-105

[BomBoy-W]

如果係我，我會買支 ２４﹣７０ f2.8
然後賣 Ａ１６，入返支 １０﹣２２ 影景用

[M@TT]

definetly 24-70.
In terms of Aperture