The Myth Of 4K, Part II

Last time, I talked about correcting somebody’s misconception about 2k versus HD. I listened to their idea of shooting 2K with their new 4K camera instead of HD so they could “push in.” They didn’t want to shoot 4K and use a lot more storage.

I’ll admit, I was pretty pleased with myself as I explained the difference between HD and 2K. Instead of their being able to push in, 2K only meant that they could reposition the framing from side to side a bit. This is the case because 2K and HD have the same vertical resolution—1080 pixels, but HD is 16×9 and 2K is more like 17×9 (depending on the 2K version). So 2K is wider.

But I made a big mistake. A mistake of omission.

When I explained that 2K didn’t allow them to push in, I implied that if they shot 4K they could push in. That was an error. Pushing in isn’t the same as moving the image left or right.

Yes, when you bring a 4K clip onto an HD sequence, depending on how your software is set up, it will be scaled down—50 percent—to fit into the sequence. So you could push in quite a bit. Some have taken this ability to the extreme, shooting mediums and close-ups as “one shot.” Shoot wide, and push in as needed.

In many cases, it is assumed that there’s no trade-off: You have lots of pixels, let’s use them. But there’s a trade-off. Sharpness will be different. Take a look at these two images:

The screen stays sharp when the shot is composed for the final framing.
By pushing in, sharpness is diminished.

The top image was framed up for the close-up that I wanted for a final framing. Although it was scaled down from UHD to HD, I didn’t adjust scaling once it was on my timeline. The bottom image was framed wider, and I scaled up the image from 50 percent to 95 percent to get the final framing.

Obviously, these shots were created to illustrate the issue. I’m not trying to draw a line in the sand and say you can’t do this, particularly because I’m not sure where all this sand came from. But I’m saying that you should recognize there’s a cost to framing your shots in post.