What Does Sony APS-C Lens Mean?

[Alain]

APS-C is the sensor size, right? When Sony says they designed a lens for APS-C, what does it mean exactly? Is there something technically different than FF lenses, or is it just a marketing thing with a different performance and price point?

 

[Uncle Kevriano]

Yes there's a huge difference, so if you put an APSC lens on a Full Frame camera it only uses a tiny part of the sensor, in the middle, which is probably ok on the RIV, but not ideal. Conversely, using a FF lens on APSC is fine and often better as you use the best part of the glass, the centre. When I switched to digital my old Minolta 35mm lenses were great on the APSC crop sensor that the first digital cameras had.

 

[Alain]

Yes there's a huge difference, so if you put an APSC lens on a Full Frame camera it only uses a tiny part of the sensor, in the middle, which is probably ok on the RIV, but not ideal. Conversely, using a FF lens on APSC is fine and often better as you use the best part of the glass, the centre. When I switched to digital my old Minolta 35mm lenses were great on the APSC crop sensor that the first digital cameras had.

so, basically, less glass for the same focal and aperture, right?

 

[Uncle Kevriano]

so, basically, less glass for the same focal and aperture, right?

Sort of, yes. Basically the rear element of a lens is the same size as the sensor it's designed for, so an APSC lens rear element will be about 2/3 the size of a Full Frame lens, which is why it only hits the centre of the sensor on FF. Front elements are generally the same.

 

[Paul stuart]

so, basically, less glass for the same focal and aperture, right?

sort of true ,but at some point physics takes a hold ,and front elements have to be a certain size to gather the light ,i know being a m43 shooters which is half the size sensor of your apsc sensor ,and that a 600mm lens will still be as big and heavy as your full frame 600mm lens ,which is basically a 95mm front element for f6.3 for example so regardless of the projected light needed on the other end the lens to the sensor. Which on m43 is 4 times smaller and aps-c which is 2x smaller than a 35mm sized sensor ,but on the other end of the scale things can be a lot smaller/lighter travel zooms for example etc where front front optics do not need to reach a criteria on crop sensors .On this note you still pay a premium for compact and small on crop sensor lenses ,and you can throw equivalence in to equation also so ff is 1 stop different to apsc ,so a 50mm f1,4 lens on ff to match it on apsc you need a 35mm f1.0 ,for field of view .dof and light gathering due to the crop sensor .