Mobius 2 Action/Dash Cam support thread

[russ331]

I had hoped this focus shift would not happen. This same problem that arrived after the mobius 1 C lens was introduced stopped me from buying 2 or 4 mobius for my rigs.

You know as well as anyone that this issue was confined to lens C. You could have bought the C2. What did you eventually buy? Or still browsing?

 

[richcam]

Did you get your bracket sorted to have the M1 and M2 running side by side? If so, have you looked at the M1 footage at the same moments as these screenshots?

Thanks for reminding me, yes the bracket is in place for the M1 and the power cable was delivered a few days ago so will test them both out either today or tomorrow and post the results on here.

EDITED to ask whether fitting a super-capacitor in place of the battery would reduce this issue? I have a SC fitted to the M1.

 

[TonyM]

Thanks for reminding me, yes the bracket is in place for the M1 and the power cable was delivered a few days ago so will test them both out either today or tomorrow and post the results on here.

EDITED to ask whether fitting a super-capacitor in place of the battery would reduce this issue? I have a SC fitted to the M1.

I noticed the focus shift when, like you, I was running the M2 with an internal battery and continuous power from an external battery pack. I have since fitted a SC to the M2 but have not left it running as it's now wired into a 12v socket adaptor.

I can pop outside now and plug the external battery in for the afternoon to see what happens....

 

[richcam]

OK then, I fitted the M1 and M2 side by side in my car and left them both recording all afternoon, have now copied some screenshots from both cameras for you to compare. The angle of the cameras isn't quite exact so will carry out a few minor adjustments tomorrow but I think this demonstrates that there is a focus shift on the M2 later in the day and I have to say that it's not been particularly hot today!

It does also show that there is considerable potential for improving the quality of the video footage of the M2 because the resolution was set to 'High' rather than 'Higher' or 'Highest' whilst the M1 was set to its maximum resolution.

NOTE: If you're trying to figure out which is which, the Mobius 2 has the date stamp shown in the bottom left of the screen starting with the year (US style) whilst the Mobius 1 starts with the day (UK style). You will need to view the images full-size to see the difference between the two.

 

[kamkar]

Did you run both with 1080/30 and WDR on ?

 

[richcam]

Did you run both with 1080/30 and WDR on ?

Video set to 1080/30 on both and WDR was OFF because I read somewhere on here that it's not so good for low light/night-time.

Actual bit rate and file sizes for a 3 minute 1920x1080 clip - H.264:

M1: Bit rate: 18,204 - File size: 415.6MB
M2: Bit rate: 25,292 - File size: 569.2MB

I've been having a few minor issues with playing the M2 video files on my old iMac using VLC, though have found that if I switch Deinterlace mode from 'Automatic' to 'OFF' it does play smoother, guess this is an excellent reason to upgrade my iMac to something newer

 

[TonyM]

You did well to snap the same Land Rover two days in a row!

 

[TonyM]

Admittedly I'm looking at your screenshots on my phone (zoomed in to full size) but the focus shift is much less evident than it was yesterday.

I ran mine side by side for 2 hours in a parked car today and saw no focus shift. Both cameras have supercapacitors fitted and were running at 1080p30 on the highest bitrate available. Outside temp 20degC. In car temp reached 42degC.

For a while I thought I did see the focus change, but then realised that the higher brightness on the M2 was affecting the image. I switched to WDR on (after the 2 hour test) and the M2 looked much sharper than without WDR.

 

[jokiin]

there's a bug with the WDR when used with 50Hz frequency setting that doesn't do it any favors, it has been reported already and they are working on a fix

 

[Dashmellow]

there's a bug with the WDR when used with 50Hz frequency setting that doesn't do it any favors, it has been reported already and they are working on a fix

Actually, according to the developer there is a problematic issue with the current algorithm for WDR regardless of frequency that is being reworked at this time. The WDR aspect works just fine; excellent actually, but image quality is suffering. This has to do with the the unique way WDR technology functions with this camera which is really more like what is familiar to still photographers as HDR. The camera is really shooting at 60 fps but out-putting as 30 fps. The frame rate is basically a double exposure with half exposed for the shadows and half exposed for the highlights and then blended into a very well balanced exposure.

Here's a good but very brief example of driving under an overpass on a bright day.

 

[jokiin]

yes I'm familiar with the other issues, the WDR with 50Hz problem is a separate issue, when set to 50Hz it still behaves like it does at 60Hz so even if you set it to 50Hz you wouldn't see the problem as your power is 60Hz, for those of us in 50Hz power areas the results when there is any artificial lighting about are very poor, something they've been made aware of and they're working on it

the type of WDR they are using has some distinct advantages but it also has a lot of challenges, expect it will take a lot of work to get it sorted

 

[Dashmellow]

yes I'm familiar with the other issues, the WDR with 50Hz problem is a separate issue, when set to 50Hz it still behaves like it does at 60Hz so even if you set it to 50Hz you wouldn't see the problem as your power is 60Hz, for those of us in 50Hz power areas the results when there is any artificial lighting about are very poor, something they've been made aware of and they're working on it

the type of WDR they are using has some distinct advantages but it also has a lot of challenges, expect it will take a lot of work to get it sorted

I see. Yeah, since 60Hz is the standard where I live I haven't tested that, so I wouldn't have known.

 

[jokiin]

I see. Yeah, since 60Hz is the standard where I live I haven't tested that, so I wouldn't have known.

yeah not something you'd pick up, being it behaves like it's 60Hz when set to 50Hz anyway you wouldn't even be able to replicate the issue even if you set the camera to 50Hz, it's the lighting that shows the problem, not sure what the night results are like in 60Hz areas but the WDR when using 50Hz is shocking for night footage at the moment, they're still working on it so probably just a matter of time

 

[kamkar]

I did not think about trying 60 Hz as i am in 50 Hz territory, but with 50 Hz and 1080/30 + WDR the result is horrific in low light.

1080/60 and WDR i think would be cool to see, but as i understand the hardware on this camera that's a no - no

 

[jokiin]

I did not think about trying 60 Hz as i am in 50 Hz territory, but with 50 Hz and 1080/30 + WDR the result is horrific in low light.

that's putting it kindly

 

[kamkar]

You know me

 

[TonyM]

I did notice some strobe effects on street lights with WDR on yesterday - the 50hz thing would explain why. Similar effect on the led tail lights of a car too which looked rather odd. Do any car electronics run at either 50 or 60hz? I'll upload a clip later.

 

[jokiin]

LED lights will flicker regardless, they run at a higher frequency

 

[Dashmellow]

I did notice some strobe effects on street lights with WDR on yesterday - the 50hz thing would explain why. Similar effect on the led tail lights of a car too which looked rather odd. Do any car electronics run at either 50 or 60hz? I'll upload a clip later.

The high frequency flicker @jokiin is referring to is called PWM - Pulse Width Modulation. With regards to LEDs, PWM means that the LEDs will be pulsed or strobed at a rate so fast that the eye will see the light as being constantly on when in fact it is not. This pulsing or turning the LEDs on and off lowers the potential heat stress on the chemical that makes the light, thus allowing the LEDs to perform longer than anticipated by running cooler. PWM is usually used for dimming LEDs and so on LED flashlights that employ PWM if you wave the light in front of you very quickly in a dark environment you can see the flickering. The flicker you see on dash cam video when it captures an LED tail light or road sign is caused by the fact that the camera easily sees and records the rapid flickering in a way your eyes cannot.

The 50 Hz vs 60 Hz option has to do with the different frequency of oscillations in alternating current used in different parts of the world leading to perceptible change in brightness and flicker of the lamps and effects other things such as how motors or televisions function. You would probably notice the flicker more on fluorescent lamps and some dimmer circuits. If you've ever heard a buzzing bulb on a dimmer circuit you are hearing the frequency oscillations. Cars of course, use DC - direct current. This is a separate issue from the LED lamp flicker recorded by digital cameras. The 50Hz vs 60 Hz setting on a dash cam has to do with whether your television uses PAL (50Hz) or NTSC (60Hz) so that the camera's frequency is matched to your TV when you want to view the video.

I read a fascinating article about how the super high speed flicker of PWM used in LED lighting can be used along with PAM (pulse-amplitude modulation) to encode messages that can be read on a computer or smart phone and this would be imperceptible to anyone else in the room experiencing the lighting. This technology may end up in a future wireless messaging system. The really weird part is that controlling the rate of PWM in office or home LED lighting might possibly be a way to control people's mood and behavior without them realizing it and this is being researched. It has been shown that different lighting can effect students performance in a classroom and this is one of the areas that PWM controlled LED lighting is being studied.

 

[TonyM]

Here's the results of my 'parking mode' test, leaving the M2 running for 2 hours in a warm car, with external battery power and supercapacitor installed. 100% crops from original frames.


Looking closely at details (e.g. the alloy wheel on the van) the focus does not seem to be affected over time. The blue car in front has the impression of being softer, although I think the apparent sharpness and detail are more a result of changes in lighting conditions. Switching WDR does not change the focus, but at least in this static test it produces a much clearer image by cutting out the over-blown highlights.
Full-size frames of the last two images for comparison: