This is either a confusing explanation or incorrect.
You would multiply the focal length of the full frame glass by 1.5 (the crop factor of the lens) to find out the equivalent field of view it would offer on the C70. For example the EF 11-24 f/4 would be a 16.5-36 equivalent while the EF 16-35 2.8 iii would be equivalent to a 24-52.5.
I believe this comment was referring to the Canon 0.71 speed booster that is available for the C70. That accessory does in fact make a lens appear wider on the C70 body by condensing the full frame lens onto the super 35 body. There are a few major caveats though. The speedbooster is known to have horrible flaring, low contrast and a purple halation across the image when pointed at a light source (especially the sun). That being said. The equation for the speed booster is Lens Focal Length * 1.5x Crop Factor of the C70 * 0.71 Crop Factor of the Speed Booster. Effectively the same for as full frame but it does not make the lens wider than it already was on full frame cameras.
The extra stop of light would be nice however for applications such as architecture and landscape that wouldn’t be an optimal aperture. You’ll be sticking around f/5.6-f/8 for the most part in those situations.
Hope this helps!
Cameras: 2x R5, C70, 5D IV
Lenses: RF 28-70 f/2 L, RF 85 f/1.2 L, EF 11-24 f/4 L, EF 17 TSE L, EF 24 TSE L, EF 135 f/2 L, EF 70-200iii f/2.8 L, EF 100 Macro f/2.8 L
