Am I understanding exposure correctly ?

[Storyline]

Very new to the Mavic camera and have read that the nicest results are when the frame rate is 24fps and also have read that the shutter speed should be twice the frame rate ie 50.

If I set the camera to this it is grossly over exposed - so much so that I have had to buy a ND filter set (4/8/16 PL). Even they were not enough so had to get a 32 NDPL. This works for the land but I am still getting blown out highlights in the sky.

Is this correct or am I missing something

 

[Mr. Salty]

You do need to use ND filters to get the correct exposure if you're going to manually select shutter speed since the Mavic's camera doesn't have an adjustable aperture. You also want to manually set the ISO to 100.

On really bright days I sometimes even bump up to an ND64.

I'm not a fan of 24fps. Some people fawn over that because it's what theatrical movies use. I think you're better off shooting in the frame rate that's native for video in the country where you live. In the U.S., that's 30fps.

 

[Storyline]

Thanks for the reply

Excuse my ignorance but what is native frame rate and why should it be different in the UK as apposed to the UK

(I did try a quick Google but could not find anything obvious)

 

[gnirtS]

Very new to the Mavic camera and have read that the nicest results are when the frame rate is 24fps and also have read that the shutter speed should be twice the frame rate ie 50.

If I set the camera to this it is grossly over exposed - so much so that I have had to buy a ND filter set (4/8/16 PL). Even they were not enough so had to get a 32 NDPL. This works for the land but I am still getting blown out highlights in the sky.

Is this correct or am I missing something

Sounds right. Your understanding is correct.

If you insist on the shutter > 2x frame rate then yes, you're going to need sunglasses (ND filter) for the drone.
Depending how bright things are you may need anything from ND4 up to a 64 and that'll change from flight to flight.

You can still end up with burnt out sky and so on - the mavic camera is pretty awful and has very poor dynamic range. That means on scenes with lots of contrast (big differences between light and dark area) the camera simply cant record all the different light levels. No ND filter can help with a scene that has too much dynamic range for the camera.

Dont get too hung up about shutter being double the frame rate. Its far better to have a 1/100th or 1/125th shutter and a properly exposed image than a 1/50th which is burnt out and useless.

The point of an ND is to blur motion so the scene doesn't jerk. Ultimately this is only an issue in scenes with lots of motion. So for example high altitude, smooth panning over a scene that moves slowly you may not need any filter and any shutter speed will do whereas flying very low and fast over a field etc you will.

Not sure why you're using PL filters though. Polarising is something different altogether and requires exact setup on the lens prior to the flight and works in a small set of fixed angles in the sky. I'd just use a set of non polarised NDs. And make sure you never use an ND for still photos if you want the best quality.

 

[gnirtS]

Thanks for the reply

Excuse my ignorance but what is native frame rate and why should it be different in the UK as apposed to the UK

(I did try a quick Google but could not find anything obvious)

Its a historical hang up dating back to the old analogue TV days.

Most of the world used the PAL format which gave 625 lines on an image at 25 frames per second. The US used Never-The-Same-Colour (NTSC) instead which gave a lower resolution of 525 lines but a higher frame rate of 30fps instead so you'd always shoot video for the format it'd be watched in.
HOWEVER, these days everything is digital so it makes no difference any more. The concept of scan lines and analogue doesnt exist any more so its not really an issue.
That said, its neater to downsample some frame rates to the other without skipping uneven numbers of frames. This yields smoother video. Ultimately, just shoot at 30fps and you're fine

24fps is a "cinematic" rate with a fair amount of blur but silky motion. It looks a bit dramatic. However 30fps is a cleaner, crisper image and is generally more used for documentary and so on.

 

[Storyline]

Thanks gnirtS. I have just started another thread about the Pl filters as I also cannot understand how it is possible to mount them correctly. I got a combined filter as I need Pl for my target photography which is over the coastline which means that not only have I a lot of water in the scene but the light levels are very high due to so much reflected light. As I realised I could not stack them as I am used to I thought to get a combined set

 

[Storyline]

.....
24fps is a "cinematic" rate with a fair amount of blur but silky motion. It looks a bit dramatic. However 30fps is a cleaner, crisper image and is generally more used for documentary and so on.

Yes, the three or four videos I have made so far have been at 24fps and they are almost dreamily smooth but they seem a bit too soft. I will try 30fps next time - thanks

 

[gnirtS]

Also make sure you have sharpness +1 set in the recording. Otherwise the mavic noise reduction kills detail. That makes things soft too.

Welcome to the world of the mavic - its all about work-arounds

 

[Storyline]

Seems to me that there should be the equivalent of RAW for video too

 

[gnirtS]

Seems to me that there should be the equivalent of RAW for video too

There is. Available on high end camera with absolutely obscene amounts of storage and high end computers to crunch it.

On a budget consumer drone, no.

 

[Storyline]

Yes, I am starting to have to think in different ways about file sizes. To me one gigabyte has always seemed huge but now, having downloaded the 4K video files from my first Mavic flights one gig is nothing !!
In fact, now I am thinking about it, I need to buy another 3TB disk for my NAS so I have enough space for backing up all this video.

 

[Dtmbizzle]

This video explains PL filters pretty well. Only thing i dont understand is i belive the mavic lens rotates a bit when focusing which would not work with a PL lens. I only use reg filters.

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[gnirtS]

It does rotate a bit focusing but not massively.
A main problem is the actual camera physically rotates when you switch portrait to landscape so if its set up for 1 orientation it'll be exactly wrong in the other.