p.2 #1 · Why do crop lenses usually start at 18mm?
The gem of "standard" zoom lenses for Canon APS-C was the EF-S 15-85mm f/3.5-5.6 IS USM (2009), equivalent to 24-135mm, a very powerful focal length range that satisfied all the check boxes for single walk-around lens. For those more interested in the longer focals, the EF-S 18-135mm f/3.5-5.6 IS also launched in 2009, equivalent to 28 - 215 mm, was an interesting alternative. These were not the $100 cheap kit lenses, their price at launch was quite high for EF-S, $800 for the 15-85 and $500 for the 18-135. These became my main lenses until I retired my APS-C cameras in 2011, replaced by full frame. My son is still using the 18-135 on an SL-2 today.
p.2 #2 · Why do crop lenses usually start at 18mm?
Indeed, both the EF-S 15-85 and 18-135 are excellent. I used them intensively on the 750D. Even on the 32 megapixels of the M6ii they hold up very well optically but the kit is a bit front heavy.
