Record V8 screen in cockpit video with GoPro 13?

[lonkelly]

I record my flights with a GoPro 13 on a suction cup mount on the canopy above my right shoulder. I can see all the flight instruments clearly in the video. I can generally see the LX9000 navboxes well enough if I zoom in. However, the recorded V8 is too dim to read, and it looks like the brightness varies from left to right across the screen. The V8 is easy to read with my eyes, but not in the GoPro recording. Does anyone have ideas? Is there some sort of polarization in the V8 screen I could compensate for at the camera?

[Piet Barber]

Piet's diagnosis: 

There's glare on your screen from the side rail of your canopy that just happens to line up with your V8 screen.  

Option 1: You can move the camera position slightly such that the canopy rail isn't in view of the reflection of your GoPro. 

Pros: Free

Cons: you're probably going to see something else in the reflection. 

Option 2: The fact that it's reflecting can be attenuated by using a CPL filter on your GoPro.  I've found great success with this product for my Hero 11: 

https://www.amazon.com/dp/B09C5MT4R3?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Pros: Makes looking outside the canopy less reflect-ey and glare-ey.  That izod Alligator logo on your polo shirt won't get reflected on the canopy as brilliantly if you have a good CPL filter.   I recommend this option the most, because of this reason alone. 

Cons: 

• If you get the CPL orientation wrong, your whole LX9000 screen could be black, which will be really disappointing when you're trying to upload this footage to YouTube.  You'll have to make sure you got it right before you go do your 1000k flight.  
• there's a cost, however modest, to getting the CPL filters. 
• When viewing the recorded video afterwards, it becomes obvious which instruments have a vertical CPL and which ones have a horizontal CPL.  I get this choice: Do i want the LX9070 and V8 in the screen? or do I want the transponder and Becker screen in the video? It's a hard-set dichotomy and there doesn't appear to be a compromise.  I chose the former, BTW. 

Option 3: Set up your V8 in the LX9000 to have black-text-on-white background.  This tends to attenuate those canopy rail reflections way better. 

Unsolicited Editorial: When I become king of the world, my first act will be to outlaw any displays that have white text on black backgrounds. This applies to all websites and flight instruments. Dark themes suck. I'll die on this hill. 

[Tango Eight]

“Dark themes suck”

Winter instruments enters the chat…

🤣

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[Jeff Stetson]

Action cameras are set up to use the fastest shutter speed possible to capture, well, action. If the shutter speed is faster than the screen refresh rate, you get effects like you see. On my GoPro 10, I use a ND8 neutral density filter. This passes only 1/8 of the incoming light, requiring the shutter exposure time to increase by a factor of 8. (Also lets photos/vids give a nice propeller blur instead of often breaking it up into pieces). You may have to experiment a bit with other choices. Too, an ND filter reduce glare and reflection effects somewhat. Search "telesin gopro nd filter" on amazon for some options.

[lonkelly]

Thanks for the advice. Especially Piet Barber. Here is where I am at this point:

1) Using a circular polarizing filter, I established that my LX9000 mounted in landscape mode is polarized 90° to the V8 mounted with the buttons to the right. So the CPL doesn't help if the goal is to view both screens in the same GoPro video. I can make one screen or the other go black with the CPL, but can't improve on the regular lens for reading both displays.

2) Setting the V8 to have black-text-on-white background (done from the LX9000 setup page) and upping the screen brightness to 90% minimum makes the arrows and text mostly readable when zoomed in on the GoPro recording playing in Quicktime Player.

[Jeff Stetson]

Those weird effects happen because, being an "action" camera, GoPros default to a very fast shutter speed. The displays update much more slowly, so the camera catches them partly done. The solution for me is to use a so-called neutral density filter which cuts down incoming light to force a slower shutter speed. An "ND8", passes 1/8 of incoming light and is about right for my Hero 10. An ND4 wasn't enough. A polarizing filter will also cut down the light somewhat, but doesn't always agree with the screen polarization. Here's a screenshot from a random video. S-100 and other screens are intact. Notice the prop appears as a smear, without the detached blade kind of effects one gets without the ND filter installed. 

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[Piet Barber]

Cool feedback!  The ND8 filter is included in the Amazon link I originally posted.  I've never had much use for it, but it sounds like you've got one. 

To view this discussion visit https://groups.google.com/d/msgid/lxnav-user-group/CALwZbiZnnFcLSqwozVFUPDd5tSR5qJukNue0r5-ic%3DDgZ52FWQ%40mail.gmail.com.

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[lonkelly]

FWIW, I just did an experiment and in full sun on our porch and the metadata from my GoPro Hero13 says it used an exposure time of 1/1510 and ISO 100 with the regular lens and 1/340 and ISO 265 with the ND16 filter. I'll have to wait to do any testing with the LXNav displays. 

1/340 is still a fraction of the LCD refresh rate, isn't it? Google says an LCD screen refreshes a line of pixels at a time, so how would shutter speed make a difference, assuming a refresh rate of ~60Hz? What am I missing?

[Jeff Stetson]

Ionkelly - I can't fault your math. Back in the day with film cameras, things were simpler, and conclusions were clear. While I'm certain that shutter speed is the basic problem, the details of how the screen is updated and what happens to an image inside the camera before it's a "finished product" is mysterious, at least to me. Using an ND8 on a Hero 10, however, for sure works, and especially so for the very slow antique TFT display of the Garmin 430. Speculation? Image stabilization blends several frames together which may have the net effect of a longer exposure. (In low light, I.S. is less effective). IDK, try it and see?

[Mark Mocho]

Part of the problem may lie with the "rolling shutter" characteristic of many, if not most, digital cameras. What many people do not realize is that the data collected by the lens is not presented and stored as a complete image. The sensor "paints" the image line by line. Very quickly, to be sure, but there are still delays and distortion when the object is moving or changing, or in the case of a screen capture, being repeatedly refreshed. You can see this in innumerable videos of spinning propellors. Sometimes the blades appear bent or look like they are being flung away from the hub one after another. Our eyes perceive an image in its entirety, like looking through a window. Digital cameras do not. They are "seeing" the image but recording it incrementally. Thus, mismatches and phase conflicts can often make recording have dropouts and partial imagery when reviewed.