Polar Pro Filters / App and Usage Question...

[nutsnbolts]

So, when you think you know how to use them, I stumble upon something that is confusing me.

Here I am about to fly and I point my drone in the direction I want to capture (away from the sun). I take the reading in manual mode and I adjust the ISO to 100 and then start adjusting the shutter speed till the +/- EV is dialed close to 0. The shutter speed ends up to be around 2000k.

I pop these figures in the Polar Pro Filter App, 100 ISO, 2000 shutter speed, 30 fps and click on calculate.

It tells me that I should do 16 ND filter.

I then put on my 32 ND filter and it dials down to 1/120.

What I'm confused about is that shouldn't it have dialed down 2x the shutter speed (30fps) to 60 fps?

Essentially I'm confused, anyone know what I'm doing wrong?

 

[Grumpy]

The 30fps / 60fps is not shutter speed but frame rate. I don't believe the Spark can change frame rate - even so this would not affect exposure. Shutter speed is in itself a misnomer. The shutter speed actually refers to the time the shutter is open so 1/1000 of a second (or 1 millisecond) for instance.
It may be easier, and more accurate, to adjust the exposure settings with the filter in place rather than compensating from the unfiltered settings.

 

[nutsnbolts]

The 30fps / 60fps is not shutter speed but frame rate. I don't believe the Spark can change frame rate - even so this would not affect exposure. Shutter speed is in itself a misnomer. The shutter speed actually refers to the time the shutter is open so 1/1000 of a second (or 1 millisecond) for instance.
It may be easier, and more accurate, to adjust the exposure settings with the filter in place rather than compensating from the unfiltered settings.

Sorry I didn't mean to mix shutter speed and frame rate. The spark can't definitely change frame rate (fps) because it's at a constant of 30 fps. So when I seek out which filter I use at 30 fps and pointing away from the sun in the direction of what I want to capture. Since it is sunny the shutter speed goes up to like 1/2000.

So I take those numbers and put into the app. 30fps, 1/2000 shutter, and 100 iso

Click calculate and it will tell me what ND filter to use.

In this case ND32. Now I take that filter put it on and shouldn't the shutter speed go down to 1/60 which is 2x the fps? Instead I get 1/120. That is about 1 stop over exposed.

Does this make sense?

My question is why 1/120. I thought it's supposed to go down.

 

[MannyCAM2001]

It’s in multiples of 30; that it’s calculating. As long as the setting reached is divisable by 30 equally, you will get the proper setting to get the normal motion blur one wants to achieve and to also get those values more even. (Less contrast)
If you wanted to reach that number closer, you would need an ND 64 or darken the exposure levels manually.

 

[Grumpy]

OK, sorry about that. Yes 32x is 5 stops so you should get 1/60. However consider that the metering may not be exactly the same, as evaluative metering can vary a lot depending on aiming point. Also the filter may not be calibrated precisely. 1 stop +/- will rarely make a visible difference in real life unless taking stills under exactly the same conditions. it is generally preferable to under expose slightly for better colours / adjusting shadows.

 

[nutsnbolts]

It’s in multiples of 30; that it’s calculating. As long as the setting reached is divisable by 30 equally, you will get the proper setting to get the normal motion blur one wants to achieve and to also get those values more even. (Less contrast)
If you wanted to reach that number closer, you would need an ND 64 or darken the exposure levels manually.

Ok in either case I'm assuming the app isn't calculating as accurate as I would like. Unfortunately I don't have an ND64 so I can't get any lower.

If I understand what you're saying 1/120 is ok? I guess I just don't understand how I would edit this in post production.

 

[MannyCAM2001]

Yes! It’s ok, the footage will look much better. And the test for motion blur is quite simple. Freeze the playback in a video editor, of a moving object or car. If it appears blurred, then you’ve accomplished getting the cinematic look in regards to your motion blur, if its sharp, clear and no motion in the object. Go back to the drawing board. Lol
The idea is having video that doesn’t jitter, particularly evident in slow panning shots. Because at a high shutter speed every frame is rendered sharp. Lower the shutter speed, you get the motion effect.

 

[MannyCAM2001]

Ok in either case I'm assuming the app isn't calculating as accurate as I would like. Unfortunately I don't have an ND64 so I can't get any lower.

If I understand what you're saying 1/120 is ok? I guess I just don't understand how I would edit this in post production.

Puzzled, what does editing have to do with the shutter speed?
I believe you’re confusing shutterspeed with framerate. The frame rate which is crucial for consistent video playback when using different clips from various sources, remains the same in your footage, 30 fps. The shutter speed at the lower numbers will produce smoother more cinematic footage. The only think left is color-grading which is purely at the videographers discretion. Here is where you MUST pay attention to frame rates. You need to keep the same thru the editing process.

 

[Jeff K]

in the case of this exmple, the ideal filter would be an ND64 but Polar Pro dont make one so the calculator can't suggest more than an ND32. That means correct exposure is going to be at a shutter speed of 1/120 or thereabouts. The only thing this affects is motion blur, the ideal being a 180 degree shutter angle (double the frame rate so on the Spark 1/60th of a second) but a 90 degree shutter (1/120) is ok and frequently used in film. Quite honestly, even 1/240 would be acceptable as long as your not panning left and right too quicly