topic Re: Canon M50. Fake 1080p in EOS DSLR & Mirrorless Cameras

Canon M50. 1080p video quality issue

AGscience — Sat, 29 May 2021 20:39:16 GMT

Hi,

It seems, Canon M50 is not recording in 1080p. In fact, it records video in 720p and then upscales it to 1080p. That is how we get blurry 1080p.

I took a video in 720p, 1080p and 4K.

This is the snapshot from 720p video (snapshot upscaled to 1080p in photoshop for comparison with 1080p).

This is the snapshot from 1080p video:

720p and 1080p look exactly the same.

The next is the snapshot from 4K video downscaled to 720p (then upscaled to 1080p to compare with 1080p).

I know that this technique is called an oversampling and we can expect much better quality than for original 720p. But...

I then upscale this snapshot from 720p to 1080p (720p is the 44% of loss in the number of pixels from 1080p) and see a flattering difference.

This is how 1080p video on this camera should look:

Closer comparison (open the image to see at larger scale):

I included 4K -> 480p -> 1080p for comparison. And we see that the actual 1080p has an image quality on the level of 480p upscaled. And the 1080p video is no better than 720p video.

Is this a firmware issue?

Re: Canon M50. Fake 1080p

AGscience — Sat, 29 May 2021 01:52:16 GMT

It is for 15-45mm kit lens, PAL video system.

Will make test for 40mm/2.8 with EF->EF-M adaptor.

Re: Canon M50. Fake 1080p

rs-eos — Sat, 29 May 2021 02:38:53 GMT

Most consumer equipment will not provide oversampled HD. And video in consumer gear is often highly compressed along with having lots of color information thrown out.

To get very good HD, you'll want to at least capture 4K (oversampled HD).

Also, I'm not sure if it's the case with the M50, but some video equipment would capture at 1440 x 1080 and then stretch the image to fill 1920 x 1080.

In consumer equipment (especially video equipment), there are numerous compromises being made to cut cost, required storage of the media, heat, etc.

I'll have more time tomorrow to look at the specs of the M50 to provide more details.

Re: Canon M50. Fake 1080p

AGscience — Sat, 29 May 2021 02:44:15 GMT

Canon 40mm/f2.8 (4f,1/640, 320 ISO) with EF->EF-M adapter.

Looks like 1080p video has the image quality somewhere between 360p and 480p.

720p and 1080p looks the same to me.

The prime lens didn't change the conclusion.

There is something wrong at the level of firmware.

I can believe that 360p downsampled from 4K can look similar to 720p captured.

But why 360p looks almost the same as 1080p???

Amount of pixels for 360p is only 10% of 1080p. 10 times difference, the same quality...

Re: Canon M50. Fake 1080p

Waddizzle — Sat, 29 May 2021 18:35:04 GMT

Whatever it is that you are seeing on your computer is not coming through on the forum images. It never will, either.

Re: Canon M50. Fake 1080p

AGscience — Mon, 31 May 2021 14:48:46 GMT

I guess i found the reason for the low quality 1080p.

It is the shutter speed.

Here is the zoomed part of the snapshot from 1080p video filmed at 1/25 shutter speed using 15-45mm kit lens:

Here is the zoomed part of the snapshot from 1080p video filmed at 1/640 shutter speed (as in previous example):

Looks like the shutter speed setting significantly degrades the video quality. It is not seen by the naked eye since you need to zoom the video.

I tested other speeds and it seems all speeds higher than 1/30! lead to the degradation in video quality.

So it seems the optimum is to shoot 1080p at 1/30, not faster.

In this case, the exposition can be controlled using ND filter.

Quality degradation is significant even at 1/100:

Re: Canon M50. Fake 1080p

rs-eos — Mon, 31 May 2021 10:41:51 GMT

The last three images you posted all look the same in terms of quality. All are pixelated. The first though looks a tad bit overexposed.

For video, you generally want to use a 180-degree "shutter angle". For cameras, the shutter would be one over double the framerate. So if you're capturing in 30 fps, shutter would be 1/60 second. Of course you can change the shutter for specific looks, but the 180-degree setting will give the most natural motion blur for moving subjects.

Having said that, if you set the shutter to a high value, the aperture will be stopped down and/or ISO (gain) increased. On lenses that are stopped down alot (near their maximum), diffraction can cause image quality to degrade. And higher ISO also causes image quality to degrade.

Thus, it's not the shutter speed that is leading to the lower quality footage.