A New Constant f/4 Aperture RF-S Zoom Coming

Well, a 15-70 f/4 would be a great addition to the lineup. Kind of a jack of many trades type of lens, an APS-C version of something like the well-liked 24-105 f/4L. In fact, in terms of field of view equivalent, it would be a 24-113 mm lens. I'd buy the lens on its own merit for any APS-C R body really.
 
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Well, a 15-70 f/4 would be a great addition to the lineup. Kind of a jack of many trades type of lens, an APS-C version of something like the well-liked 24-105 f/4L. In fact, in terms of field of view equivalent, it would be a 24-113 mm lens. I'd buy the lens on its own merit for any APS-C R body really.
Should be a perfect kit lense for the R7 mkII if it's sharp enough.
 
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Distortion and vignetting on the 15-85 it's well corrected by digital correction, an RF version should be a lot smaller, like all angular APS-C lenses are because of the flange distance reduction.

Should be a big upgrade over RF-S 14-30 or 18-150 as a kit lense.
 
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F/6.3 equivalent is nice for a kit lens, but come on already, Canon.
It's not f/6.3. It's a 15-70 f/4 lens with the DOF of a 15-70 f/4 lens, regardless of the size of sensor. The only reason the DOF changes is when people move forward or back or change the focal length to maintain the same FOV. I'm rather interested in this lens but I already own the 18-50 Sigma and I highly value small size and especially light weight.
 
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It's not f/6.3. It's a 15-70 f/4 lens with the DOF of a 15-70 f/4 lens, regardless of the size of sensor. The only reason the DOF changes is when people move forward or back or change the focal length to maintain the same FOV. I'm rather interested in this lens but I already own the 18-50 Sigma and I highly value small size and especially light weight.
He said "f/6.3 equivalent", which is (approximately) correct. It will take similar photos to a hypothetical 24-112mm f/6.4 full frame (same position, same DOF, same FOV, same shutter speed, same image quality with the full frame aperture and ISO 1.6x higher than APS-C). However, the hypothetical 24-112mm f/6.4 will take photos with higher IQ if the exposure permits base ISO, compared to the 15-70 f/4.

I would not buy a f/6.4 FF mid zoom, nor I would not buy a f/4 APS-C mid zoom. I consider FF f/4 to be acceptable compromise of versatility, IQ, and size/weight for wide and mid zooms, and f/2.8 to be acceptable on APS-C (I have the Sigma 10-18 and 18-50 f/2.8 lenses). I would LOVE a 15-70 f/2.8 RF-S lens. But f/4 on APS-C is a stop slower than I want.
 
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