Yi Technology -- Yi-M1

[VidThreeNorth]

Yi-M1 4K Portrait Video Profile:

I thought that I had finished my analysis of the Yi-M1 video modes but over the years I have learned that it often pays to take do a bit more than what should be enough. In this case there was a pay-off.

All the tests I have reported above were using recordings at 1080P (30 fps, and with digital stabilizing "ON"). I did this because I assumed that this would be my general setting for future video recording with this body. But after I completed the test sets I made a second "control pair" with the Panasonic G85. That means I recorded using the two cameras at the same time. I did this because a lot of time had passed since the original control pair and the lighting had changed a bit. I did not think it had changed enough to make a difference to my findings, but the point of doing the second control pair is to make sure that this is true.

However, just to make it a more valuable test, I changed the settings of both cameras. On the G85 I decreased the exposure by 1 stop, and on the Yi-M1 I decided to set it to "Portrait" and EV - +0.0 again, but at UHD ("4K"). I expected the results to be essentially the same as the 1080P recording.


"P4250011.MP4"
- 4K, Portrait EV = +0.0

File: "YiM1-P4250011-4K-Portrait-ev0_0-14h42m19s888.png"

"Black" sample: Luma = 52.1
"Black + 1" sample: Luma = 92.6
"Black + 2" sample: Luma = 151.3
"White - 2" sample: Luma = 194.4
"White - 1" sample: Luma = 223.0
"White" sample: Luma = 238.0

Contrast: ("Black + 1" - "White - 1")
223.0 - 92.6 = 130.4

In general, the contrast I calculated is significantly less than any of the Yi-M1's 1080P settings and close to the G85's "Standard" profile. Is there any reason for this in my test procedure? Possibly. When I switched from 1080P and Electronic Stabilizing ON to 4K (there is no stabilizing option for 4K) the crop changed, and so I zoomed out. When I did this, I actually matched the effective crop of the G85 almost perfectly. The only difference is that the Yi-M1 was pointed downward a bit. But the proportion of the background is closer than it was when I was recording 1080P. The question becomes whether there is any "dynamic range optimizing" going on. The Yi-M1 does not mention this, however, it is not an unusual function. One advantage of this function is that during video recording, the main subject is less likely to change exposure. It would be nice if this were mentioned in the instruction manual, but the Yi-M1 manual is sparse in general.

There are a couple of tentative conclusions I can make. First, just from this much testing, it seems like the best video recording for my personal general use might be "4K - Portrait". If there is "dynamic range optimizing" going on, then the "4K" might actually not make any real difference to the dynamic range, but until I do further testing, I will assume that the "4K" is making a difference. And the second conclusion is the obvious "I should do more testing someday."

Having said this, I have some mixed feelings. First, aside from the high contrast and lack of dynamic range, I actually like the "Standard" colour rendition of the Yi-M1. The main difference of the "Portrait" profile is that saturation is reduced. So if I record in "Portrait" from now on, I will have to increase the saturation in post. In the long run, it should not be a problem, but when I am evaluating what I have recorded, I generally just see my clips in VLC which does not have that kind of tuning ability. That is going to make it a bit harder for me to evaluate what I have. On the other hand, it won't be any worse than recording on the G85 in "CineLikeD" which is even "worse".

Second, it means that really, I am probably going to stick to "4K" video recording on the Yi-M1, with all the drawbacks of storage usage, and the fact that my "main" computer cannot be used to preview "4K" video -- I can only view it on my "editing" computer, which I usually leave "Off", or in "Sleep" mode.

Even with the better dynamic range of "4K Portrait" profile, the Yi-M1 is still really not going to be a great "sunny day" camcorder. It will still be best for overcast days, but I might not have to re-tool the gamma quite as much.

About The Sample Frame:

I chopped up the 4K sample frame into four parts. For this report only parts "A" and "B" (the top half of the overall frame) are used, but I have uploaded the rest in case you want to compare the colours against the Full HD frame.

You might notice that these pieces are 1920 * 1089. The actual format of the Yi-M1's UHD files is 3840 * 2178. The file defines the target format as 3840 * 2160 and the displaying device does the re-scaling. It is actually fairly common.

 

[VidThreeNorth]

Yongnuo M43 42.5mm, F1.7, Version 1 Lens

This is going to be a very short post. I recently bought this lens (new), hoping that I could use it on all my Micro 4/3 camera bodies. Unfortunately, so far, the Yi-M1 has turned out to be the only body I own that it does not work on. Nothing works. It does not focus and the aperture does not adjust. There is a new Version 2 of this lens, but I have no idea if it works. We will just have to wait for someone else to try it.

About why it does not work: When you mount a fully working Micro 4/3 lens on most bodies, it has to be pressed so that the flange on the lens touches the flange on the body before it can be twisted into place. The reason for this is because the electrical contacts in the body push against the contact plate on the lens, in order to ensure that they touch the electrical pads. When I mount the Yongnuo lens, it seems to drop into the lens cavity, only being stopped by the release pin. In other words, it appears that the electrical contacts are not close enough to the body to ensure that the pins in the body are actually making contact. There might be other problems or not, but that much would be the first thing to fix. But I will not actually try to fix it myself. It is working on my Panasonic bodies, so I am going to simply use it on that body.

Since I do not intend to attempt any kind of fix, it is unlikely that I will post anything more about this combination in the future.

 

[VidThreeNorth]

Lens: Panasonic H-FS014042 14-42 F3.5-5.6

"P3260013.JPG" (Source picture not posted)
Yi-M1 "Portrait" mode JPEG
Size 5,042,326 Bytes
Created March 26, 2021, 13:48:58

Win 8.1, Partial Properties
Program name ASDK-00142
Dimensions 5184x 3888
Bit depth 24
Resolution unit 2
Color representation Uncalibrated (Adobe RGB)
F-stop f/5.6
Exposure time 1/80 sec
ISO speed ISO-640
Exposure bias 0 step
Focal length 42 mm
Max aperture 4.98
Metering mode Center Weighted Average
35mm focal length 84
White balance Auto
EXIF 0230

- the following files based on the camera JPG using Coral Paintshop Pro X9

"P3260013a-rsz1920-C1.JPG"
- resized to 1920, no other adjustments

"P3260013b-Crop1920-C1.JPG"
- detail crop, no other adjustments
- Crop start 1150 x 1300


This picture was a result of casual curiosity resulting from my previous test picture of the strawberries using the Yongnuo 42.5mm lens on the Panasonic G85. On the spur of the moment I decided to see how it would turn out using my Panasonic H-FS014042 14-42 F3.5 - 5.6 kit zoom. This is the original series zoom and not the slightly better second series zoom.

The picture was taken on my Yi-M1, because this was the body that the Yongnuo was supposed to work on -- this is why I bought it. So you can think of this as the picture taking capability that it was supposed to "beat". Or more correctly, it is one of my lenses it needed to "beat" to be useful. Since the Yongnuo does not work on this camera, it is fair that I have taken this on the 20MP Yi-M1 while the only test picture I have posted for the Yongnuo was take on the 16MP Panasonic G85. That is to say, that for me, the only reason it cannot take a 20MP picture is because it failed to work on this camera.

In theory, if the pictures had been taken on the same 20MP body, then the level of detail would have had that starting point, but the result is that the Yongnuo simply could not do it.Beyond that, although it is hard to tell with such dis-similar pictures, the Panasonic does look a bit sharper. Anyway, eventually, when I get the time, I will eventually get around to doing more "scientifically valid" testing. But for now, this answers some of my curiosity.