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Shutter Priority Mode - Underexposed Images

Hi MME,

I did a multi-battery grid mission with the latest version of Map Pilot Pro and a P4P.  I used shutter priority mode with shutter speed at 1/320, ISO at Auto, and aperture was greyed out.

Everything looked good in the field.  The live-view preview looked good, and the mission completed successfully.  However, when I look at the resulting images, every image is severely under-exposed.  The ambient lighting in the field was low as the sun was setting, but every image had the ISO stuck at 100 or 200.  The ISO should have gone higher to get a proper exposure.

So, why didn't the ISO adjust correctly?  And why didn't the preview reflect more accurately the current exposure?

I did some bench tests in low light conditions in shutter priority mode, and the relative brightness of the preview appears NOT to track the current exposure settings (i.e. low ISO should be dark, and high ISO should be bright, but the preview always looks the same).  So, this test is making me suspect that there could be a bug in the shutter priority code...?  Or maybe there's something else I'm missing.

I uploaded the images to my account for your review.

Thanks for any insights or guidance,

-Nick

N Wagner124

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It is possible that the aperture setting was too narrow when AP was set so you weren't getting enough light in all the time. We hear this from users occasionally but don't see that it is behaving any differently than the DJI app. The setting of the exposure and the ISO value is something that occurs in the camera and isn't really something we can affect. As long as the ISO and exposure were varying throughout your dataset (albeit badly) there isn't much else we can do with it. 

Zane 0 votes
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Thanks for the quick reply, Zane.  I don't understand.  Why would the shutter priority mode, with ISO in Auto not increase the ISO above 200 to get the proper exposure?

Also, what about the preview? The exposure in the preview looked fine while flying the mission, but the photos were not fine.  How do you explain that?

N Wagner124 0 votes
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Nick, when you bench tested Shutter Priority in Map Pilot, did you run a similar test in GO to determine if there was any difference in behavior from one app to the other?

Dave Pitman 0 votes
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@Dave, DJI Go 4 gives an "underexposed" warning, with red highlighted shutter speeds that correspond to underexposed combinations.  Also, DJI Go varies the ISO to values above 200 when in Shutter Priority mode to get the correct exposure.  Map Pilot Pro appears not to do either of these.

One observation that might be a clue is that DJI Go does not display an underexposed on-screen preview (i.e. a darkened image of the live feed from the camera) in shutter priority mode even when underexposed settings are chosen.  Whereas, in manual mode, the preview does show an on-screen preview of the live feed from the camera that corresponds to the exposure settings (i.e. dark preview if under-exposed and bright if over-exposed).

@Zane, my expectation from Map Pilot Pro is that in Shutter Priority mode, when ISO is Auto, ISO will be varied to get a technically correct exposure.  That didn't happen.  And, I would expect Map Pilot Pro to show me a preview that corresponds to the current exposure (i.e. dark preview if underexposed) but that also didn't happen.

Are my expectations correct?

N Wagner124 0 votes
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The video feed and the camera photo taking are pretty decoupled for certain settings. 

With any of the modes you can lock one thing and the other two are left to adjust as the camera sees fit. 

We will give it a look. 

Zane 0 votes
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Thanks for taking a look, Zane.  I'll be curious to hear what you find.

N Wagner124 0 votes
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Technically, if the camera is in shutter priority mode with iso set to auto, an underexposed image should not be possible until the iso limit of the camera is reached. 

Regarding the video feed not representing the recorded exposure settings, then best hook the histogram at least as a user preference.

Also, I've noticed that the exposure controls do not include an EV field. Adding an EV bias can be helpful in certain conditions.

Dave Pitman 0 votes
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