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Re: [OM] u43 anamorphic lens

Subject: Re: [OM] u43 anamorphic lens
From: "C.H.Ling" <ch_photo@xxxxxxxxxxxxx>
Date: Mon, 17 Feb 2020 10:23:11 +0800

On 20/02/17 3:14, Moose wrote:

I'm not sure where the advantage lies. Although I shoot short videos of things where a still shot doesn't show the whole aspect of the subject, I know very little about digital video, so what I say is largely theoretical.

If I shoot Panny 4K video, I have 3840 horizontal pixels. My current TV is FHD, i.e. 1920 pixels wide. If I get a new, 4K TV, the horizontal pixels match. I don't understand how compressing the width, then uncompressing it for display, at the same resolution, can increase detail.

You are right, you will only gain better image details with anamorphic when your monitor's resolution is higher than your source's resolution. Anamorphic video format is very popular, the PAL DVD have resolution of 720x576 (i.e. 5:4) while the display aspect is 4:3 or 16:9.

In addition to the various problems/artifacts discussed in the Wikipedia entry, there is inevitable loss of detail resolution. Assuming a detail one pixel wide on the sensor with a standard lens, with a 2x optical compression, it either disappears, or becomes 2 pixels wide, when expanded.

Yes, that's a gross simplification, but the effect is real. With fisheye images, an app like Fisheye-Hemi can do a wonderful job of "un-fishing", but details, especially as you move to the corners, are poorer than a shot with a linear UWA lens. With a 20 MP sensor, for display on the web or in a printed book, that's not a practical problem, but very obvious pixel peeping.

Your theory about digital compression/expansion is right because the number of pixel you have is fixed by the sensor.

In analogue world a 2x anamorphic lens might capture 2x the vertical detail. It gives better output when decompressed with a 2x anamorphic lens.

Likewise, with video, those effects are simply not visible to the human eye viewing a moving picture. I remember when I was a projectionist being amazed at the poor detail in individual frames, and the amount of motion blur, in an apparently sharp movie.

I agree with you, on resolution aspect the visual requirement on video is much less than still photo. But on the film movie days, film makers usually need to shoot high ISO film, the grain and resolution of the media is very poor when compared to the current digital media. You need to use every mm of the media to increase the output quality.

In fact, cameras with hor. pixel counts higher than 3840 need to deal with this issue. Panny sticks with the 1 to 1 pixel method. Looks good on the 16 MP sensors, where the frame is only slightly narrower that a still shot. On the 20 MP GX9, the frame coverage gets noticeably smaller in video. If I were interested in shooting a lot of 4K video, I might be using the 16 MP GX85.

I assume cameras with even larger sensors must do some re-sampling to record 4K.

Yes, resampling is done on many cameras when shooting either 4k or 1080p. But still, they may not be able to use the whole sensor so some may be cropped and not all re-samplings are the same, some give poor video output. Checking the GX85, it gives very good 4K quality but just so so on 1080p. Sometimes the cropping data is not easy to find, it is very critical to video shooters.

Instead of resolution, I'm more on high frame rate. My FZ1000 gives very sharp 4K 30p but I much prefer 60fps 1080p. I'm happy with 1080p which save me editing time and HDD space.


Am I missing something?

Which Kay Moose

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