Full Frame
The full 35mm photo sensor
This is a large photosensor that is (more or less) the same size of the traditional 35mm film.
Digital cameras rely on image sensors instead of photographic film to capture images. For analog photography, the 35mm film had established it over many years. The size of the film also determined the parameters of the lenses as they needed to be designed in a way to illuminate the full size of the film. Once digital cameras started appearing, the film was replaced by an image sensor that could convert the light intensity to an electrical signal.
At this point it was actually a coincidence that it was still possible to manufacture image sensors the size of 35mm film, roughly 36mm by 24mm. The beauty of this was that, new digital cameras could continue to use all the lenses developed for 35mm film directly.
Basically the image sensor is larger. This could be used to have:
- more pixels in total, which increases the resolution
- larger pixels which increases the sensitivity to light (i.e. ISO)
These are both good things. Still a full frame sensor is a bit more than 2x the size of a APS-C sensor, so the increase is limited to this number.
In electronics, the size of the chip (in this case the sensor) determines the cost, so a 2x larger sensor costs 2x more as well. But there is more, since larger chips have a higher chance of having some defects, you get a lower percentage of fully functional sensors when you manufacture larger sensors which increases the cost (for 1000 functioning sensors, you have to manufacture comparatively more as you have more defective sensors). This is why the full frame sensor is actually more than 2x more costly.
While the resolution is what it is, over time, electronics industry manages to improve the electrical properties of sensors, so newer sensors can be made more sensitive even if they have the same size. This is true both for APS-C and full frame sensors.
Further Reading
Full frame equipment on this wiki
Cameras
Canon EOS RP, Nikon D850, Nikon D750, Nikon D610, Nikon D700
Lenses
These pages are for Amateur Photographers and not really for seasoned photographers and professionals. I have no affiliation or commercial interest with any brand/make. I write from my own experience. I ended up using mainly Nikon, so I am more familiar with this brand than others. See price for notes on pricing as well as photography related links.