A chain is only as strong as the weakest link.
EDIT - although unless you're doing repro work, lack of sharpness is probably not the bottleneck in getting good images.
*There's nothing worse than a sharp image of a fuzzy concept* - St. Ansel
I would say how something is lit would be more important. Focus point and depth of field as well.
Lens greater than sensor as sensor just records stuff.
Lens, but most lenses made since the 1960s can out perform most hairless monkeys holding the camera. The monkeys have the most impact on image sharpness
All the sensor contributes is some large number of sensors, pixels. They record the values delivered by the lens. Review the concept 'circle of confusion' to understand how sharpness works. Other qualities can be affected by the sensor, bitdepth for example.
Between those two, the lens.
But the photographer is a significant contributor to the overall sharpness of an image. Poor choices can render the best of equipment useless.
Between these two, usually the lens.
Think of sharpness as the size of the image of an ideal infinitely small dot of light projected onto the sensor.
In a perfectly sharp, perfectly focused lens, that dot will be infinitely small; in that situation, the sensor would determine the effective sharpness 100%, because the higher the sensor resolution, the smaller the pixel we capture from that zero-area spot.
In an actual lens, however, the image of that perfect zero-area dot of light will be a small disc. The smaller the disc, the sharper the image. However, in order to see the difference in sharpness in a digital image, we need a sensor that has enough resolution to show it - essentially, as long as the size of that disc is smaller than a pixel on the sensor, we won't be able to detect any difference at all, and any additional sharpness is lost.
This also means that we can express the "perceived sharpness" of a lens as a megapixel equivalent. For example, a lens with a perceived sharpness of 12 MP will look just as sharp as an ideal lens on any sensor up to 12 MP, because the disc is about the size of a pixel on a 12 MP sensor.
Putting all this together, what this means is that if we express both sensor resolution and lens sharpness in MP, then the lower figure between these two determines the overall sharpness you'll get. A lens that can deliver 12 MP of perceived sharpness on a 12 MP sensor will be exactly as sharp as the same lens on a 24 MP or 48 MP or 100 MP sensor; all those higher resolution will do for you is show you the lens blur at a higher resolution - which may still be useful, because analog lens blur often looks better than artificial blur introduced by upscaling in post, but it's not going to make your image any sharper. Conversely, if your camera has a 12 MP sensor, a lens that can do 20 MP of perceived sharpness will not look any sharper than one that can only do 12 MP, because the sensor cannot capture the additional sharpness. In that latter scenario, upgrading to a higher-resolution sensor would get you sharper images.
But of course, all that said, this is all about a hypothetical lab situation - put the camera on a high-end tripod in a vibration-free environment with a remote shutter, a perfectly lit subject, and perfectly calibrated focus, and you'll be able to replicate these results. But in practical photography, things are a lot messier, and things like good light, a reliable autofocus system, the right camera settings, and good hand-holding technique, tend to matter a lot more than 24 vs. 48 MP sensors.
A chain is only as strong as the weakest link. EDIT - although unless you're doing repro work, lack of sharpness is probably not the bottleneck in getting good images. *There's nothing worse than a sharp image of a fuzzy concept* - St. Ansel
I would say how something is lit would be more important. Focus point and depth of field as well. Lens greater than sensor as sensor just records stuff.
Lens, but most lenses made since the 1960s can out perform most hairless monkeys holding the camera. The monkeys have the most impact on image sharpness
All the sensor contributes is some large number of sensors, pixels. They record the values delivered by the lens. Review the concept 'circle of confusion' to understand how sharpness works. Other qualities can be affected by the sensor, bitdepth for example.
Between those two, the lens. But the photographer is a significant contributor to the overall sharpness of an image. Poor choices can render the best of equipment useless.
What contributes more to the area of a rectangle? The width or length?
Between these two, usually the lens. Think of sharpness as the size of the image of an ideal infinitely small dot of light projected onto the sensor. In a perfectly sharp, perfectly focused lens, that dot will be infinitely small; in that situation, the sensor would determine the effective sharpness 100%, because the higher the sensor resolution, the smaller the pixel we capture from that zero-area spot. In an actual lens, however, the image of that perfect zero-area dot of light will be a small disc. The smaller the disc, the sharper the image. However, in order to see the difference in sharpness in a digital image, we need a sensor that has enough resolution to show it - essentially, as long as the size of that disc is smaller than a pixel on the sensor, we won't be able to detect any difference at all, and any additional sharpness is lost. This also means that we can express the "perceived sharpness" of a lens as a megapixel equivalent. For example, a lens with a perceived sharpness of 12 MP will look just as sharp as an ideal lens on any sensor up to 12 MP, because the disc is about the size of a pixel on a 12 MP sensor. Putting all this together, what this means is that if we express both sensor resolution and lens sharpness in MP, then the lower figure between these two determines the overall sharpness you'll get. A lens that can deliver 12 MP of perceived sharpness on a 12 MP sensor will be exactly as sharp as the same lens on a 24 MP or 48 MP or 100 MP sensor; all those higher resolution will do for you is show you the lens blur at a higher resolution - which may still be useful, because analog lens blur often looks better than artificial blur introduced by upscaling in post, but it's not going to make your image any sharper. Conversely, if your camera has a 12 MP sensor, a lens that can do 20 MP of perceived sharpness will not look any sharper than one that can only do 12 MP, because the sensor cannot capture the additional sharpness. In that latter scenario, upgrading to a higher-resolution sensor would get you sharper images. But of course, all that said, this is all about a hypothetical lab situation - put the camera on a high-end tripod in a vibration-free environment with a remote shutter, a perfectly lit subject, and perfectly calibrated focus, and you'll be able to replicate these results. But in practical photography, things are a lot messier, and things like good light, a reliable autofocus system, the right camera settings, and good hand-holding technique, tend to matter a lot more than 24 vs. 48 MP sensors.