It’s not “cheap plastic” - it’s no less precisely made, and it has some advantages. Won’t dent if dropped, won’t show silver marks if scratched, is more stable thermally, doesn’t corrode - and presumably tolerates getting wet better than metal. If lubricant dries out, you won’t get metal-metal wear. The internal moving surfaces of many older lenses were already plastic. Also it’s lighter (matters when travelling, hiking etc). Why exactly are you worried - is it just the perceived “feel” or a specific engineering issue?
All you talked has nothing to do with the reason Canon uses more plastic to make RF lens.
No.
The only reason is, it's cheaper.
Plastic is always cheap option to metal when it comes to material selection of industrial product design unless for optical transparency or electric insulation.
Have you ever compared the price, weight, toughness and stiffness of a carbon fibre reinforced plastic tripod with an aluminium alloy one?
Someone say plastic is light. No, it's heavier than metal if measured with same strength since plastic has to be thicker.
But polycarbonate is less than half the density of aluminium, which in turn is a third of the density of steel. Metal hasn't a huge advantage over polycarbonate for bending strength and stiffness, especially if the polycarbonate is reinforced with fibres.
The reduced weight of the lens is from less glass elements design, not the plastic barrel. If a plastic lens is really light ( oops as plastic
), it means compromising.
All engineering is compromising between cost, weight, strength, stiffness, precision, stability, durability and constructibility.
The only good reason to use more plastic is to keep this industry alive. We need to keep buying/upgrading the camera and lens to like how we do to our smartphones.
Nothing lasts forever.
