Do I need a high resolution lens for 4k?

Hi,

I understand that 4k is 8.3 megapixels. When shooting a 4k video, does the resolution of a lens matters? OR is it okay as long as the lens can resolve 8.3 megapixels? I'm strictly talking about resolution, not contrast or characteristics.

Moon0326 said:

Hi,

I understand that 4k is 8.3 megapixels. When shooting a 4k video, does the resolution of a lens matters? OR is it okay as long as the lens can resolve 8.3 megapixels? I'm strictly talking about resolution, not contrast or characteristics.

Click to expand...

If, as your inquiry states, the issue is specifically resolution, then the answer is YES it is OK / theoretically sufficient to use a lens with such resolution when capturing 4K with the caveats that 1). some oversampling cameras begin with many more than 8.3 Mpixel captures, then downsample / bin, and 2). also recognizing that ALL lenses have better central resolution than they provide at their edges. With typical widescreen playback, edges and corners are potentially much softer than centers, so choosing a lens with central resolution barely meeting the sensor resolution ignores the inevitable real-world behavior of actual lenses beyond their central sweet spot.

Given these caveats, one needs to look at the sensor and sampling specs and also the lens resolution (and MTF) fall-off, and also consider intended usage. Panoramic landscapes may, for example, stress the optics a lot more than, let's say, rock videos. A camera which captures 4K video initially on a 16 megapixel sensor before binning needs a lens with a lot better spatial resolution than your proposed 8.3 megapixel 'matched' lens.

Hope this helps!

Larry

Hi Larry,

Thank you so much for the detailed information. Since I have absolutely 0 knowledge in video area, it's been hard understanding what other people wrote over the internet. Many people did not even understand what I was asking. Your post makes sense.

Have a great weekend!

Moon

Moon0326 said:

Hi Larry,

Thank you so much for the detailed information. Since I have absolutely 0 knowledge in video area, it's been hard understanding what other people wrote over the internet. Many people did not even understand what I was asking. Your post makes sense.

Have a great weekend!

Moon

Click to expand...

Glad to help, Moon !

Larry

Moon0326 said:

Hi,

I understand that 4k is 8.3 megapixels. When shooting a 4k video, does the resolution of a lens matters?

Click to expand...

Many 4k cameras record video using the center crop of the sensor. The lens must be then as sharp in video as in photos.

Better lens still makes a difference even in full sensor readout 1080P. The contrast and color performance shows also in subjective resolution. Better lens looks better in fullhd.

Some expensive cinema lenses has a soft look with reduced sharpness. When shooting movies with 24P some prefer softer "cinematic" image.

When using lenses with smallest apertures the diffraction softens 4k image very visible.

No. There are a lot of smartphones with tiny lenses which make excellent 4K videos.

Yes the lens resolution/sharpness does matter to an extent. Slightly soft lenses aren't necessarily a bad thing, as you don't always want to see all the pores on peoples faces.

Bear in mind that many cheaper 4K cameras use very compressed codecs at comparatively low bit-rates which affects the captured detail and sharpness. Your lenses will long outlive your camera, so buy the best lenses you can afford.

I would say its the old story. The optics tell it all, or crap in, crap out! old saying!

People often ignore the lenses. Go for good lenses and you will realise how much better your shots are.

If you are shooting old women, then you may not like the extra details in their skin ie wrinkles etc. So a softer lens may be better in that scenario.