Joey said:
Explanation please? What is a low pass filter in this context? What is it for and if it's necessary, why build a camera without one? Is it the same as an anti-aliasing filter (another term I don't understand...)
It is essentially a "low pass" filter that "smoothes" image data that could otherwise produce moire distortion patterns. In general this is not a negative thing, and you can produce extremely detailed photographs from such images. On the other hand, some cameras now come with sensors that do not have a the "low pass" (or "anti-alias") filters. Nikons D810 doesn't have one, nor to the Fujifilm X-trans sensor cameras. The idea is that they might produce slightly sharper images in some cases, with a slightly increased chance of moire/aliasing distortion with some subjects.
If none of this makes sense to you, frankly you can probably just ignore it.
drjlo said:
Is it just me who thinks 50 mp is not a good idea unless the sensor size is substantially larger than even full frame?
If things advance the way they have though the previous development of DSLR sensors, the higher MP sensor will have the same or better low light performance, dynamic range, noise performance, and cost. Unless something changes this time around, there is no disadvantage to the higher MP sensor.
(Some will tell you that they will need more computer storage, faster processors, and so forth — but in the grand scheme those things also advance at a rate that keeps their cost relatively stable or declining.)
In the best of circumstances — very careful photographer, excellent lenses, good aperture and focus decisions — there are image resolution advantage to higher MP. Even in cases where the image isn't going to be resolved with greater sharpness, a large print will require less interpolation to deal with potential pixelation. (This is an issue for those who make very large prints.) It is also possible that denser pixels can produce smoother gradients, and they also reduce the "grain size" of any noise.