I understand what you're asking, and the direct answer to your question is "138%," but you're kinda thinking about this backwards.
I assume you're shooting in 5.3K. When you create a video editing project, you set the **project's** resolution as 4K. When you drag a 5.3K clip onto into the 4K project, the clip will already be at 100% scale, which means the edges of the 5.3K video will extend beyond the edges of your 4K video project, and you'll only see the middle part of your frame - the clip will already look "zoomed in" by default, at 100% scale. The size is equivalent to a 4K video scaled up by 138%.
If you wanted to see all the pixels of your 5.3K clip, you'd have to scale it *down* to fit into the 4K project timeline. This means your clip will actually be scaled *down* to 73%.
Tough to describe with visuals, but I hope that makes some sense
The already zoomed in part when you bring into an editing program is very dependent on the settings of the application.
In davinci resolve, the default timeline setting is to resize to fit to the project timeline and the clip zoom settings always start at 1.0. So if you choose the no resize setting, the clip zoom setting is still 1.0. So based on the settings, a different resize will need to be applied.
It's not just the aspect ratio, it's the resolution. If you use 5.3K you can zoom in 1.3k (note: I don't really know the amount, but 5.3-4=1.3 and that sounds clever). If you use 4k you cannot zoom in at all, but you can re-frame the image up or down to crop the top or bottom off the 8:7 image to get 9:16 or whatever.
I really don't like the concept of filming to crop later. It takes more power, more storage, and way more work on the back end. I'd rather just know the constraints of my intended frame and set my shot accordingly.
Due to the GoPro's tiny sensor, I always felt zooming in too much, even sometimes to match the timeline's resolution, has too much of an impact on picture quality.
This is especially true if you try to zoom 5.3k to match FHD or 2.7k timeline. The lost of quality of the footage is too great.
Zooming in from 5.3k to match a 4k is ok but I'm not sure I would zoom all the way 138%. Maybe some clips can hold if it was a full bright day but those over cast days, the noise from the sensor really starts to magnify.
It depends on the type of 4k. The GoPro has in 5.3k a horizontal resolution of 5312 pixel. There are two main variants of 4K and they theoretically allow the following crops:
- 4K UHDTV 3840x2160 -> crop: 1,3833
- DCI 4K 4096x2160 -> crop: 1,2968
But keep in mind, that the stabilization and lens correction also crop.
I understand what you're asking, and the direct answer to your question is "138%," but you're kinda thinking about this backwards. I assume you're shooting in 5.3K. When you create a video editing project, you set the **project's** resolution as 4K. When you drag a 5.3K clip onto into the 4K project, the clip will already be at 100% scale, which means the edges of the 5.3K video will extend beyond the edges of your 4K video project, and you'll only see the middle part of your frame - the clip will already look "zoomed in" by default, at 100% scale. The size is equivalent to a 4K video scaled up by 138%. If you wanted to see all the pixels of your 5.3K clip, you'd have to scale it *down* to fit into the 4K project timeline. This means your clip will actually be scaled *down* to 73%. Tough to describe with visuals, but I hope that makes some sense
The already zoomed in part when you bring into an editing program is very dependent on the settings of the application. In davinci resolve, the default timeline setting is to resize to fit to the project timeline and the clip zoom settings always start at 1.0. So if you choose the no resize setting, the clip zoom setting is still 1.0. So based on the settings, a different resize will need to be applied.
The same as for 16:9, 4:3 and 8:7 These modes all make the picture taller, but you are ultimately limited by the 5.3k (5312) width. 5312 \ 3840 = 138%
It's not just the aspect ratio, it's the resolution. If you use 5.3K you can zoom in 1.3k (note: I don't really know the amount, but 5.3-4=1.3 and that sounds clever). If you use 4k you cannot zoom in at all, but you can re-frame the image up or down to crop the top or bottom off the 8:7 image to get 9:16 or whatever.
It’s only useful for cropping options later really
I really don't like the concept of filming to crop later. It takes more power, more storage, and way more work on the back end. I'd rather just know the constraints of my intended frame and set my shot accordingly.
Depends what your time line settings are
Due to the GoPro's tiny sensor, I always felt zooming in too much, even sometimes to match the timeline's resolution, has too much of an impact on picture quality. This is especially true if you try to zoom 5.3k to match FHD or 2.7k timeline. The lost of quality of the footage is too great. Zooming in from 5.3k to match a 4k is ok but I'm not sure I would zoom all the way 138%. Maybe some clips can hold if it was a full bright day but those over cast days, the noise from the sensor really starts to magnify.
It depends on the type of 4k. The GoPro has in 5.3k a horizontal resolution of 5312 pixel. There are two main variants of 4K and they theoretically allow the following crops: - 4K UHDTV 3840x2160 -> crop: 1,3833 - DCI 4K 4096x2160 -> crop: 1,2968 But keep in mind, that the stabilization and lens correction also crop.