Hugely underexposed in desert with ND8 on auto expose. How did this happen?

[Qoncussion]

Look at this video, at 1/4000 you clearly there's no motion blur at all. If you pause the video you see the object quite sharp. But you do see the flickering I'm talking about.

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The flickering @ 1/4000 is due to the lack of capturing motion, and most certainly not due to black frames - as you've stated. But notice the wall and window in the background - no flickering. That's because each frame is a complete image, as I've said. I understand how to achieve motion blur, and I understand why the ceiling fan looks jerky at 1/4000th of a second, as each frame is missing 99.975% (3999/4000) of the motion - but the image is not flickering. Each frame is a complete images (see wall and window). The fan just appears jerky at the high shutter speed. I fail to see how this relates to your discussion of black frames. And I've never seen or heard anyone discussing the mystical black frames. Nor do they exist. This video just shows how shutter speed affects motion blur (no brainer).

Technically, this is not the type of "flickering" that folks are talking about. You can achieve actual flickering by speeding up footage, that was shot using auto white balance and/or auto exposure, due to the rapid change in exposures between frames from the exposure or white balance changing. That is the type of flicker that most people see and attempt to fix - again, not mystical black frames. You can even get actual flicker when speeding up video shot using the rule of 180. What you posted is just an example of capturing something at too high of a shutter speed. But there is no video flicker present.

Flicker (screen) - Wikipedia

It would be great if you could link me to an article that discusses the black frames issue you've been talking about...

 

[Chirp]

Auto would be fine, but you say you locked it to the sky - so not able to be auto anymore.
Having the ND on was not relevant to the underexposure.

Hi there,



I flew mostly land with a little sky and locked my exposure to that.

Correct me if i'm wrong but I thought locking in the exposure only works for one photo or video and then it disengages as soon as you stop. The next time you shoot you will be back to the settings you had before you set it to auto.

I.

 

[Chirp]

...sure your EV value wasn't accidentally set to e.g -2.0EV?...

Yes make sure your EV is set to zero unless you purposely want to override it...

 

[Qoncussion]

@Lake_Flyer: feel free to start a new thread if you wish to continue this discussion. Let's not hijack this thread any further. I've said my piece and am leaving this thread back to its original topic.

 

[AleksandrOrlov]

So........ My original comments were mostly correct.

There's a youtuber I follow that seems to fly the ND filter flag at every opportunity. Its like he's sponsored by polar pro. I even called him out on the facts, but I don't think he was immensely interested.

I stick by the principles that unless the subject itself is moving they are of no use.

Use the histogram, end of!

 

[Qoncussion]

So........ My original comments were mostly correct.

There's a youtuber I follow that seems to fly the ND filter flag at every opportunity. Its like he's sponsored by polar pro. I even called him out on the facts, but I don't think he was immensely interested.

I stick by the principles that unless the subject itself is moving they are of no use.

Use the histogram, end of!

I would agree, and add that unless the "subject is moving" AND/OR the camera is moving. For drone video footage, the use of ND filters have been greatly blown out of proportion (IMHO). If you read through these forums, you will find several threads where people talk (incorrectly) about how they can totally see the difference their ND filter made; such as, colors are more saturated. The word, "Neutral", in the name of the filter says everything about how it is affecting color ~ which would be - not at all. They are definitely not necessary, and are terribly misunderstood by newcomers to photograph and videography. That said, lowering your shutter speed does have its advantages when it comes to movement in frame. You're on the right path...

 

[silverdragon]

Thanks guys, just this one thread has giving me the same amount of education as if I took a 1 month photography class.

 

[Prismatic]

Again, I don't want to debate about stuff that is open for any opinion. You keep talking about my opinion, but it just pure fact.
<*snip*>
The way you say it defies the science of filming. You made it up yourself. Again, show me your proof. Show me one website with reputation that confirms your theory. Please. People could get confused reading this discussion.

Have you read the info on mediacollege.com I posted at all?

Sorry, but you're simply misunderstanding the author's intent in that MediaCollege article. The quote you posted--Think of the "missing time" as a gap between when the shutter closes and when the next frame begins.--is not meant to say there's a black gap 'recorded' somehow in the media. It's meant to say that there is a period of time during which nothing is being recorded on the media. If your footage is 25fps shot at 1/50th, fully one-half of each second was simply not recorded, nor is it represented in some way as 'black' on the media.

For example, suppose that your footage is a girl doing jumping jacks. As you were shooting the video, her uncle took a flash photo of her, with a 10-millisecond flash. If the video camera shutter happened to be open during that 10ms illumination, it would record it on the media. But otherwise, there will be no record of the flash in the video. (And it would be impossible to exactly match any video frame to the photograph.)

But--and this is crucial--if you digitally analyze a single frame of that footage, you'll find it has exactly the same dimensions as every other frame of every other video you've ever taken at that resolution, regardless of the shutter speeds in various clips.

PS: As a professional technical communicator, I have to say that the MediaCollege article you referenced is utter dreck, including--but not limited to--the graphics.

 

[gnirtS]

In addition to the above, forget all the stuff about filters and remember how cameras work to decide exposure. They try to average out the whole scene to a specific level grey. This normally works. However, it can cause very bright scenes (snow, sand etc) to underexpose as its reducing them to this standard grey and also cause dark scenes (volcanic rock, err black cats?) to overexposure to that.

Thats what EV bias is for.

 

[f8guy]

gnirtS answers the question. If you are using auto exposure you will have to compensate if you are shooting something really light or really dark by either adding or subtracting from your exposure. EV+/EV-

bright white sand isn't 18% gray so you will have to tell the camera that

 

[Dave Maine]

The one piece missing from the facts being debated here is the basic way movies are processed by the human visual sensory process. As correctly stated, all movies are a series of still images. Under the right conditions, viewing the series of still images does not get perceived as s slide show, but instead a movie. This phenomena begins at approximately 16 frames per second, and gets progressively less flickers until 24 FPS. This varies a little between individuals, but for almost everybody, 24 FPS is a movie.

This phenomena is called fusion, and is well researched and documented. When viewing a film projection, there are black periods when the projector’s shutter is closed, but in the viewer’s perception the image is always present, and the black intervals are not perceived.

With video, it is different. There is still the perception of continuous motion, but it results from the creation of line scanned images being presented, in the US, at 60 images per second (50 in othe parts of the world). There is never a time when the screen is totally dark, but lines of pixels in various stages of being refreshed.

Half understood pontificating is rarely helpful.