Yi 4K and FOV narrow in 4K mode: any help?

[Mighty777]

Hi everyone,

any idea how to modify the FOV while working in 4K?

I have another 4K camera (a ThiEYE TM5E with external microphone port), and latest firmware allows to modify FOV also in 4K, thus getting a 90° picture which suffers less of the "bubble" effect. Of course, such narrow FOV might be less ideal when using the cam for action such as on a mountain bike, but when using to record people or anything else like on a travel footage, being able to go from the 150 to the 90° FOV is great.

I would love to be able to make it also with the Yi 4K (which I believe is a better camera, especially with the custom bitrate set to 100 or 120Mbit), but FOV is set only to wide when in 4K mode, and have not heard any news about upcoming firmware going to fix this.

Can we do something with scripts?

 

[HeWhoMustNotBeNamed]

Hi everyone,

any idea how to modify the FOV while working in 4K?

I have another 4K camera (a ThiEYE TM5E with external microphone port), and latest firmware allows to modify FOV also in 4K, thus getting a 90° picture which suffers less of the "bubble" effect. Of course, such narrow FOV might be less ideal when using the cam for action such as on a mountain bike, but when using to record people or anything else like on a travel footage, being able to go from the 150 to the 90° FOV is great.

I would love to be able to make it also with the Yi 4K (which I believe is a better camera, especially with the custom bitrate set to 100 or 120Mbit), but FOV is set only to wide when in 4K mode, and have not heard any news about upcoming firmware going to fix this.

Can we do something with scripts?

Both cameras use 12MP sensors so there is no way to zoom in and still achieve 4k resolution without upscaling. This means narrow mode at a lower resolution will be the same or better image quality.

You can swap the lens for 4.35mm but that is more or less permanent.

 

[Mighty777]

Both cameras use 12MP sensors so there is no way to zoom in and still achieve 4k resolution without upscaling. This means narrow mode at a lower resolution will be the same or better image quality.

You can swap the lens for 4.35mm but that is more or less permanent.

I believe you are wrong, and I try to explain: 4K resolution, means approximately 8Mpx (actually...8.3). Thus, a 12Mpx sensor in theory is more than enough to "crop" to deliver a final 8Mpy image. Hence, unless the "zooming" performed by the camera when you reduce the FOV from 170° to 120° or 90° (I do not remember the right values...) is crap, I see not many problems (at least, not in zooming to go from a 170° to a 120° FOV). Problems in these small camera is perhaps the lens....indeed, when I compare the quality of the footage of my Sony FDR-AX100 to the one of the Yi, even when both are set to 100Mbit, there is a huge difference....but that is ok, the two cameras serve different purposes at the end....

 

[HeWhoMustNotBeNamed]

remember sensor is 4:3 so it is cropped down to 16:9 first.

but even after cropping to 16:9 you're right, there are a few hundred pixels unaccounted for in both dimensions.

hm. wonder what actually is going on. in both cameras.

very curious about this zoom feature on the thieye now. have to know how it works! it's bugging me






PS... feel free to send me the Sony for testing

 

[Mighty777]

....I checked....and you are right...there is not enough pixel to do the "crop"....so either one replaces the lens, or the sensor (unrealistic!), or shoot in a smaller mode if you want to get the medium or narrow FOV :-(

and this is valid for both the 4K and the 4K+ as there is no difference in terms of sensor: both use the Sony IMX377, which produces an image which is 4032 x 3024px in size (12.2 MP), and have a lens with a 155° FOV.

as in 4K a 3840x2160px image is needed, and this is what you get when using wide setting (I actually wonder what you get when going ultrawide....in theory you should use the ~200more pixel orizontally, thus taking the whole horizontal area given by the 4032px and then rescaling to 3840....in any case....);

when going for medium fov, you crop the more central part of the sensor, which ultimately produce an image which is "slightly" with less horizontal resolution, thus not real 4K (i.e not real 3840x2160p). for example, when you take picture in medium, the real output is 3008px large....thus something in between the 2.7K (which is 2704px large) and the 4k (which is 3840px large).

Probably the ThiEye, with the "Medium" or "Narrow" mode in 4k, does some "upscale" of the footage which is internally recorded at a slightly lower resolution than 4K when going for "Medium" or "Narrow" FOV....but quality after all is not dramatically worse, and in my view still better than when shooting in 2.7K.

I just wonder why, in the new Xiaomi Yi 4k+ at least, Xiaomi did not decide to go for a different Sony sensor, considering there are better sensor with a 16Mpx resolution which could have fit the purpose.....let us hope they soon release a new version of the 4K+ with maybse sensors such as IMX400 or IMX398....