GoPro Exposure Lock Hack

J

Jay Birch

Well-known member
We have had plenty of shots ruined by auto exposure on the GoPro/Phantom, especially when tilting, so I started looking around for exposure lock ideas and actually found something that works.

https://github.com/KonradIT/autoexechack

Click the "Download ZIP" button and you will get all the hacks (I didn't try the single download links).

Then just find the Video Exposure Lock .ash file and copy/paste it to the root of your SD card. (Usual disclaimers apply for adding hacks to a camera, can brick etc)

To use it on a Phantom with a H3-2D, this is the only way I could get it to work:

Switch copter off
Switch GoPro on (it locks expsoure as soon as it switches on, so point it where you want to lock)
Switch copter on
Hit record.

To reset the expsoure, you have to repeat the above steps. To go back to auto mode, delete the file on the root or insert another SD card.

My theory as to why you have to power down the copter is that, with the battery on, the GoPro never does a proper power down cycle because of the power supplied by the gimbal.

For me, it has been a godsend and the guy should be getting similar recognition to ML and Vitaly.. Especially as he is only 15 years old! Insane
 
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It seems to have an effect on the auto focus, so I would suggest using it sparingly, when a drop in sharpness might be worth it, for the exposure lock.

For some reason it only goes out of focus on around 1 in 10 shots.... I will have to run some more tests about where to point the camera when locking exposure.. I would guess that it also locks focus at the same time, so pointing it at the sky may have caused it to struggle with focus.
 
Yea, i think the secret will be getting enough sky in the shot to give a balanced exposure, but enough subject matter to also aid the focusing..
 
I don't think the GoPro has any kind of focus control, does it? My understanding is that it's a fixed-focus camera. Therefore there is no focus-lock to set.

Maybe what's being seen as out-of-focus is actually a change in resolution?
 
There are versions for 3 and 3+ in the .zip

re: focus... If that is the case, then i'm not sure what is going on. There is a clear drop in resolution in certain shots, sometimes even within 1 shot... eg, fly north and it is in focus and nicely resolved, fly west and it drops resolution, fly south, it is fine again. Strange.

Might be something to do with the amount of light hitting the sensor... But I have been filming in plenty of light, sunny. 2-3pm
 
Well it would definitely have to be a change in resolution, I would think. The GoPros are all fixed-focus lenses. Unless it's messing with something else digitally.

So are you saying it sometimes changes focus during a clip? That does seem odd.

Are you using an FPV system? If so, can you actually see on your ground monitor when the focus goes wacky?
 
My FPV is pretty low res... 480p think, so it is hard to tell.

Yea, it happens in flight. It must be something to do with the amount of light on the sensor with a fixed exposure. It is the same muddy look you get when shooting GoPro in low light.
 
I will run a test where I over expose ... That will at least ensure that the shutter/iso are relatively fast/low and not causing any mud
 
click the thumb for a 100% crop from the same video clip... No correction or sharpening. Notice the detail in the bushes.

 
Jay Birch said:
My FPV is pretty low res... 480p think, so it is hard to tell.

Yea, it happens in flight. It must be something to do with the amount of light on the sensor with a fixed exposure. It is the same muddy look you get when shooting GoPro in low light.
Click to expand...

So it's weird that this occurs during shooting. I assume nothing similar happens when not using the hack?
 
Is it possible that, during flight, the lens is fogging up? I found this on a site about GoPro...

Lens Fogging: Fogging happens for a variety of reasons. It can happen when you load a camera in a warm environment into the housing then go out into a cold environment and the camera housing cools off. Since cold air inside the housing can't hold as much moisture as warm air, the moisture condenses on the housing. Another reasons is if you load the camera in a humid environment, then any kind of temperature fluctuation can cause the moisture inside the camera housing to condense.



  • One solution is to buy a 1 gallon baggie, put silica gel bags (or uncooked rice) in it, the put the camera and housing in separately. Leave in for 15 minutes. Then put the camera in the housing WHILE STILL IN the sealed baggie.
  • The easiest way is to put the camera and the housing separately into a refrigerator for about a minute. A/C removes humidity. Then while still in the refrigerator, put the camera into the housing. You may get condensation on the OUTSIDE, but this is just temporary and easy to fix. You can aslo hold in front of your car A/C and then put the camera inside whill in front of the A/C. Keep in mind as soon as you open the camera during the day, you have broken the seal and have to repeat the process over again.
  • And finally, buy anti-fogging inserts from GoPro (read directions!).

http://www.eyeofmineactioncameras.com/GoPro_FAQ_s/1833.htm
 
Interesting thought.... though I don't think it is lens fogging, purely because it comes and goes so quickly. Any time I have had lens fogging in the past, it has taken at least a few minutes to defog, where as this problem can come and go in seconds.
 
Jay Birch said:
Interesting thought.... though I don't think it is lens fogging, purely because it comes and goes so quickly. Any time I have had lens fogging in the past, it has taken at least a few minutes to defog, where as this problem can come and go in seconds.
Click to expand...

Well we're talking about an aerial platform here, right? It could easily fly into and out of localized humidity or cold temperature pockets.

But I'm inclined to think it's a technical glitch having to do with the hack. Just covering all the bases.
 
It's possible to happen very quickly, but to go away again quickly too seems unlikely. From my experience, once it fogs, it stays that way for a few minutes.. Even if you go back to the "normal" temperature.

I have noticed some occasional changes in colour too, when using the hack. It is glitchy, for sure, but it is still a very useful tool.

Appreciate your help and insight.
 
I'm reading that the GoPro has "auto video gain", and there's no way to turn it off. Could be the hack is somehow telling the camera that the light level fell, so the camera is adjusting the video gain to compensate, which causes the resolution hit.
 
That sounds like it could be the culprit. It does seems to happen when there is a change in light (though not always).

The muddy look really reminds me of low light footage, so it makes sense that a gain raise is causing the issues.
 
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