Because: size and weight. It looks to be too big and too heavy for my idea of its best use role. The existing lenses in this segment are the 24-105 f4.0, the 24-70 f/2.8 and the 28-70 f/2.0, all very good performing lenses. The first two are also fairly compact and light, while the 3rd isn't, but has a truly rare, for any zoom, really wide SKU code: 41044. Versatile 24-105mm Zoom Range. Constant f/4 Aperture. Fast, Accurate Nano USM Auto Focus. Built-in Image Stabilisation. 18 Elements in 14 Groups. Canon L Series Quality Optics. Designed for Canon RF Mirrorless Cameras. Canon RF 24-105mm F4-7.1 IS STM: Image Circle: 35mm (RF-mount) Type: Standard Zoom: Focal Length: 24 - 70mm: APS Equivalent: 38 - 168mm: Weight: 395g / 0.87 lbs. Notes: For Canon RF-mount The two shots with the baby and the little girl were shot with FF bodies. The 24-105 may work on portraits ( due to being up close) but there have been mixed reviews about using EF lenses on crop bodies. As someone said the 85mm range would be best for portraits on a crop. Kent. Well, optics only get worse if you try too hard to get all the goodies. Compare the 28-70/2 with the 24-70/2.8. Going for quality increases the weight significantly, and they had to shorten the An 18-55mm f/2.8-4 on Canon APS-C is equivalent to 29-90mm f/4.5-6.3. The RF lens is 24-50mm f/4.5-6.3, so by the time you've increased the ISO on the full-frame camera for equivalence both lenses are exactly the same speed, but the Fuji lens is bigger, 10° less wideangle, 1½x the weight and here it's been reduced in price to nearly twice the Canon RF 24-70 f/2.8 vs RF 28-70 f/2 (AKA: The Beast) If you are into photography and gear, and especially if you are a big Canon fan (like me). You may have been loosing your mind ever so slightly over Canon’s announcement of their new, professional mirrorless camera bodies. The Canon RF 24-70mm F2.8 L IS USM is the lens that pros and serious shutterbugs will want for their full-frame camera. Weight: 2 lb Filter Thread: 82 mm the RF 24-105mm F4-7.1 is a better The Canon RF 24-105mm f4 L IS USM has some incredible image stabilization that I truly can't fault at all. It's a great lens in many ways. Weight. Φ3.29 x 4.22 in., approx. 1.54 lbs. / Φ83.5 Even if the 2,8/24-105 becomes quite a brick, it will, I'll save weight. Switching lenses on narrow mountain paths is fastidious AND risky (for the lenses). As to the RF 24-105 F.4 L, I own it, but I'm not so enthusiastic about it, when compared to my M lenses. I'd like the new (CR 1 !) 24-105 to be optically in the RF 28-70 F.2 league DyQQWMd.