The specs for a Sony AX53 state that it has 16-MP for photos, but only 8-MP for 4K video. Of course, that's all that's needed for 4K, unless it has a full-sensor readout. Also, on the side of the camcorder, it says, "16 Megapixels". I'm assuming that it only has 8 Megapixels and that the extra ones for the photo mode are extrapolated. Am I wrong?

The sensor has 16 megapixels. Photo resolution can be changed in the settings, up to 5,440 x 3,056 (16,624,640) pixels.

There are only two possibilities to reduce the 16mp sensor to 8:
1. crop
2. down sample

But knowing what method it uses won’t change anything

There's one more:
3. Pixel Binning

But I agree that knowing the method does not change anything. It is what it is.

Thanks Mark, Pete and Doug for your replies. I just watched a good online review of the AX53 and it said that it has an effective 30X zoom for 4K (which is also on a label on the camcorder). This tells me that 4K is produced with an 8-MP sensor crop. This would produce the equivalent of 786mm of focal-length.

Going back a dozen years, I had a Sony HDV camcorder, the HC9, which seems about the same size and configuration as the AX53. With good success, I used two telextenders, a small Raynox 2.2X and a larger Sony 1.7X. I have step-up and step-down rings that will allow me to mount these on the 55mm filter threads of the AX53.

With the 2.2X telex, it would deliver the equivalent of 1729mm for 4K and 1152mm for photos. Of course, there is vignetting in at least the lower half of the zoom range, but on the many cameras on which I've employed these telexes, the auto focus and image quality were very good. With the BOSS image stabilization, full-zoom images might be steady, even at those focal-lengths. My little Sony XYST1M stereo hotshoe mike will go well, with the AX53.

I have used a Sony AX53 for several days now and based on previous experiences with other Sony camcorders and on what I've observed from my new one, I have come to a speculation about how many pixels its sensor actually has. I will welcome responses that might point out how I am incorrect.

What I think is that the AX53 has only 8.2 active Megapixels on its sensor and that the 16.2-MP photos it produces are from extrapolated pixels, generated as a type of digital zoom. I had a similar-sized Sony HDV camcorder a dozen years ago, the HC9. It had only 3 Megapixels on its sensor, but recorded 6-MP photos. Those were definitely extrapolated from the 3-MP sensor.

Also, if the AX53 did have a 16.2 MP sensor, why doesn't it have an extended zoom effect, when an 8.2-MP sensor-crop is used for 4K? Only if it used a full-sensor readout for 4K, would that not be the case. Even cameras that use a full-sensor readout for 4K, don't use the entire sensor, giving a small extra zoom-effect. Pixel-binning or digital reduction in 4K sampling could cancel any increased zoom-effect, but I don't see evidence of that in the many other consumer cameras and camcorders I've investigated. An 8.2-MP 4K sensor-crop seems to me to be a simpler method and that must be why it's used in so many consumer models.

And today I went out and shot a few dozen photos with the AX53, in each of the 16.2-MP and 8.2-MP modes. I could see at least a small superiority in the 8.2-MP shots, which was also evident when I compared the 6-MP and 3-MP photos in my older HC9. If I'm wrong about this, what is the method for producing the 8.2-MP for 4K video, in the AX53?