Is there a megapixel amount that would make a zoom lens irrelevant?

You would be able to create the same field of view by cropping, but there is more than just getting closer that makes a telephoto focal length useful. You can use a telephoto to create a really great background blur for example. That cannot be created by cropping the photo later on.

Cropping versus Zoom

Mmm first of all how big is the sensor we are talking about if you talk about putting 100Mp on a 1/1.8" sensor. Not only am not sure how the hell you are going to do that but also the pixels would be so small it would be WORTHLESS. You would get allot of noisy images that exist out of more noise then actual usable image data.

So for your idea to work it would require a HUGE sensor. Meaning also a HUGE lens.. probably as big as the HUGE camera's that we're the start of photography. Obviously IF you get a 100Mpixel image made from a sensor with big pixels.. [important] then sure you could use a wide lens and crop bits.

But as you noticed we are talking about sensor Size. Very Important part of the equation. Just putting more pixels on a small sensor makes things worse. And even a hasselblad medium sensor if you put 100Mpixels on it would definitely feel the pain, raise noise raise noise!

For normal use the reality stays that you want to get as many pixels right so you don't have to crop. IF you can get the perfect framed picture then you can enjoy ALL those pixels for instance for print.

If you gotta crop try not to crop to much... as in while making the pictures try to get the best result. If you have to crop half an image away you throw away allot of pixels.

There are those that say don't crop, I disagree, but I do add don't crop to much. It is better to get a well framed picture right. But sure if you got some half decent images...and with a crop you can make them slightly better I would say go for it. Just understand that maybe next time you should have taken two steps closer!

Yeah if you gotta crop you we're to far away! And really if you know what kind of picture you desire to get.. use the right lens and move around. What is the difference between a snapshooter and a photographer. A snapshooter makes a picture within 20 seconds, a photographer judges the situation walks around lowers his sight and tries to find the perfect angle and then make the picture.

What is the difference, the snapshooter has many meh images, the photographer has a few pearls.

And that "Light field" stuff.. yeah really.. what we have to deal is today is what is on the market.

While you can crop a larger photo which mimics zoom to some degree, there are a lot more things going on a lens than it's focal length. For one, a good lens will have an adjustable aperture to control depth-of-field. And the physical length of the lens also contributes to DoF. You would lose that characteristic if you cropped a photo as it would take on the characteristic of the lens used - DoF wise.

DoF makes a difference in the creative aspect of photos, and there is no sensor that will capture that effect, no matter the megapixel count.

Even with expensive DSLRs and $2,000 zoom telephoto lenses, above 25 to 30 MegaPixels, these lenses will begin to show their limitations.

So for the most point, a 100 MegaPixel sensor would be crippled by even today's consumer and commercial lenses.

So in theory, notwithstanding other factors such as the mentioned depth of field, some degree of zoom would be capable in a large enough sensor.

By the way, digital zoom is worthless. If your camera has that feature, turn it off. DSLRs do not have digital zoom features for good reason - they don't produce good photographs.

I still buy and use film. During the old film days when digital cameras weren't even conceptualized, I already found zoom lenses irrelevant.

You are saying that if someone were to make the picture large enough, using a long focal length lens will be useless since we could just crop the picture. My problem with that is simple. Photography is an art. Artists like to see what they want. The Mona Lisa wasn't painted with her dog on her lap that was cut out of the painting later. Artists paint their vision on canvass at once. It's the same with photographers. They don't go using zoom lenses, shoot and hope for the best. They walk around back and forth, left and right, anywhere to get the right angle and more importantly, the right frame at once. They have to get it right in-camera to maximize the strength of the camera with their talents. As megapixel count rises all the world will see is just a rise in bigger pictures not necessarily a decline of the use of longer lenses.