CPL vs Variable ND filter

[Barbara]

I've been taking a series of photos of the same scene over the past weeks (M2Z) and sunlight photos have always appeared washed out with this blueish haze in the center. Post processing really didn't help. I'm pretty much a newb to photography, anything beyond fully automatic using a snapshot camera.



So I thought to try my variable ND Filters. I figured that as these use two polarized lenses to simulate ND values I would get the benefit of the polarization. My results:

ND=5


ND=2


Which is better? ND 5 seems dark. Either way, the blue haze is gone. I've ordered a straight CPL filter to try out.

 

[slup]

The haze you see is a result of that the light scatters in all directions from especially that white snowy lake ... so using a polarizing filter in situations like this can help as the light only can go through the filter from one direction. The top pic is also a tad over exposed in the center, this due to the much darker forest areas in relation to the very bright snowy lake ... & that the camera exposure measurement probably was set to "average".

The difference between ND2 & 5 is probably due to how the auto exposure reacted & which ISO & shutter times that was chosen... nothing else

 

[Barbara]

The haze you see is a result of that the light scatters in all directions from especially that white snowy lake ... so using a polarizing filter in situations like this can help as the light only can go through the filter from one direction. The top pic is also a tad over exposed in the center, this due to the much darker forest areas in relation to the very bright snowy lake ... & that the camera exposure measurement probably was set to "average".

The difference between ND2 & 5 is probably due to how the auto exposure reacted & which ISO & shutter times that was chosen... nothing else

AT first I thought it was actually haze in the air. But you are correct, as proved by the photos using the polarized filters.

The ISO was 100 for all three photos, and the shutter speeds 1/1600 s, 1/100 s and 1/320 s respectively.

Exposure was indeed center Weighted Average (CWA) for all three. In the Go 4 App I see where I can change the metering point manually by tapping the screen, in auto mode. Unfortunately, this does not seem to be an option in Litchi, which I've been using for this project. I'm using a Litchi waypoint mission to get repeat photos from the same locations over a period of time. (Unfortunately it's location accuracy isn't near as good as I would like either. Topic for another day)

It will be interesting to see what a plain CPL filter will do.

 

[African wildlife]

Hi Barbara. We almost always use ND/PL filters. We've got a PolarPro ND/PL set (4/8/16/32) for the Phantom 4 Pro Plus. For the Mini 2, we've got the Tiffen set of 6, only three of which are ND/PL (4/8/16) - with the other three being just NDs (4/8/16). (You mainly read about other brands on the forum for the Mini 1 or 2, which might be good, but Tiffen have an excellent 80-year reputation for quality products used by both pro and amateur photographers alike.)

If you're going to whizz around the skies all over the place, filming, the polariser of the ND/PL combination will give you mixed results - which is why many people prefer to use the straight ND filters, disliking an additional polariser. But if you know the footage or still photographs you want to achieve, this isn't usually an issue. You seem serious, so it's good to use a polariser.

In case you don't already know, the polarising effect works best when you're at 90 degrees to the sun. You can check and adjust the circular polariser accordingly before taking off. Straight ND filters - as different from ND/PL filters - will only reduce the amount of light, with the only benefit being you'll be able to reduce shutter speed; there will be zero effect on colour saturation, such as with a blue sky.

I would generally suggest underexposing by -0.3 or -0.7 for best results. And I'm assuming you use manual settings. Never use auto settings if you are using any kind of filter.

If you get everything correct up in the air, post processing should be minimal or even unnecessary.

There are numerous online sources for learning about basic photography, which is unrelated to flying a drone. You''ll learn quickly. And use the "golden hours" for the very best light, even in winter.

 

[Barbara]

Hi Barbara. We almost always use ND/PL filters. We've got a PolarPro ND/PL set (4/8/16/32) for the Phantom 4 Pro Plus. For the Mini 2, we've got the Tiffen set of 6, only three of which are ND/PL (4/8/16) - with the other three being just NDs (4/8/16). (You mainly read about other brands on the forum for the Mini 1 or 2, which might be good, but Tiffen have an excellent 80-year reputation for quality products used by both pro and amateur photographers alike.)

If you're going to whizz around the skies all over the place, filming, the polariser of the ND/PL combination will give you mixed results - which is why many people prefer to use the straight ND filters, disliking an additional polariser. But if you know the footage or still photographs you want to achieve, this isn't usually an issue. You seem serious, so it's good to use a polariser.

In case you don't already know, the polarising effect works best when you're at 90 degrees to the sun. You can check and adjust the circular polariser accordingly before taking off. Straight ND filters - as different from ND/PL filters - will only reduce the amount of light, with the only benefit being you'll be able to reduce shutter speed; there will be zero effect on colour saturation, such as with a blue sky.

I would generally suggest underexposing by -0.3 or -0.7 for best results. And I'm assuming you use manual settings. Never use auto settings if you are using any kind of filter.

If you get everything correct up in the air, post processing should be minimal or even unnecessary.

There are numerous online sources for learning about basic photography, which is unrelated to flying a drone. You''ll learn quickly. And use the "golden hours" for the very best light, even in winter.

Thanks for all the information. I admit I have much to learn about about cameras and how to use them beyond strictly "Auto" mode. Part of that is deciding just how "serious" I really want to get. The difference between my two photos, with and without the polarizer definitely got my attention. I didn't realize you could get fixed ND filters with a polarizer, but that makes sense. I take it you don't recommend the variable ND filters.

So, I may have to rethink my little project, for a number of reasons, and possibly buy some more goodies for the drone. What fun, good thing I'm retired.

 

[African wildlife]

Thanks for all the information. I admit I have much to learn about about cameras and how to use them beyond strictly "Auto" mode. Part of that is deciding just how "serious" I really want to get. The difference between my two photos, with and without the polarizer definitely got my attention. I didn't realize you could get fixed ND filters with a polarizer, but that makes sense. I take it you don't recommend the variable ND filters.

So, I may have to rethink my little project, for a number of reasons, and possibly buy some more goodies for the drone. What fun, good thing I'm retired.

I would get any decent brand of ND/PL filters for your drone., rather than the variable ND filters. If you want video as well as stills, they will help a lot because you want to slow down your shutter speed to get the best results, ideally twice that of your frames per second (fps). So if you're shooting at 25fps, you want a 1/50th second shutter speed - or 1/60th if you're shooting in 30fps.

Using manual mode is easy. First, whenever possible, stick in 100 ISO for best results. Then all you need to do is get the exposure right. You do this by changing either the aperture or shutter speed. (Some drones have a fixed aperture, so it's even easier because it's just the shutter speed to worry about.) This is where the ND/PL filters come in because they reduce light which means you'll automatically be able to use a lower shutter speed.

If this still isn't clear, just search on YouTube for a demonstration. It really isn't that difficult, Barbara, and you'll get better photos when you've got more control. Auto is okay, but manual mode is a lot better.

With best wishes from the UK. I almost emigrated to Canada when I was a very young adult and you've got amazing outdoor spaces in your country.

 

[Barbara]

I would get any decent brand of ND/PL filters for your drone., rather than the variable ND filters. If you want video as well as stills, they will help a lot because you want to slow down your shutter speed to get the best results, ideally twice that of your frames per second (fps). So if you're shooting at 25fps, you want a 1/50th second shutter speed - or 1/60th if you're shooting in 30fps.

This was the reason I initially bought the Variable ND filters. I knew they used two polarized lenses to accomplish this, I wasn't sure how that would affect the video as you changed headings relative to the suns position. I assume a fixed ND/PL filter would behave much the same.

Using manual mode is easy. First, whenever possible, stick in 100 ISO for best results. Then all you need to do is get the exposure right. You do this by changing either the aperture or shutter speed. (Some drones have a fixed aperture, so it's even easier because it's just the shutter speed to worry about.) This is where the ND/PL filters come in because they reduce light which means you'll automatically be able to use a lower shutter speed.

Manual mode has always terrified me, a hangover from days gone by when I used actual "film" (yes, I'm dating myself) Having said that, and having a fixed aperture (M2Z), how slow can I go with the shutter speed before I introduce undesired blur? I've also noticed that if I set the the ISO to 100, and reduce the shutter speed to get a 0 EV, then decrease the EV to a negative value, it does so by bumping the shutter speed back up. Seems self defeating to me.

If this still isn't clear, just search on YouTube for a demonstration. It really isn't that difficult, Barbara, and you'll get better photos when you've got more control. Auto is okay, but manual mode is a lot better.

Indeed, I will watch more videos, but most assume you can control the aperture, which I can't. And I agree, manual shooting should provide better results.

With best wishes from the UK. I almost emigrated to Canada when I was a very young adult and you've got amazing outdoor spaces in your country.

Thank you and best wishes to you too. I have very fond memories of my visit to the UK years back. Loved the "Lake District". I believe Canada is a wonderful place to live, and I am thankful for many reasons. Though I almost ended up being Australian. That was our original destination when we emigrated from Germany when I was but a wee lass.

 

[Dave Maine]

For photos, there is no benefit to ND filters. All they do is steal light, causing you to use a lower shutter speed or higher ISO both of which reduce the quality of your still images. Varying your exposure by shooting in manual, or using the exposure off set will give you the control you want without image quality loss.

 

[African wildlife]

A lot of people get put off by manual mode, but don't let that include you, Barbara. To repeat, if you set the ISO to 100 and you've got a fixed aperture, then all you have to adjust is the shutter speed. And it's best if you can keep this at or near to 1/50th second if you're using 24fps or 25fps by lowering the shutter speed.

You want motion blur, which is the industry standard. But if you're close to the ground, fly slowly.

I lived in the Lake District as a child.

 

[DanMan32]

EV is simply telling auto what target exposure to achieve. In manual, EV is showing you the results after you've made your settings.

If one could set the polarizer angle in flight, that would be ideal since as you flew and shot your subject at different angles, you could adjust the polarity accordingly. But since we can't, we have to judge and set for the ideal and live with that for the entire flight.

ND isn't usually used for stills, but it could be if motion blur is desired. Just remember that what ND does is reduce the light that the camera starts with.

 

[Barbara]

For photos, there is no benefit to ND filters. All they do is steal light, causing you to use a lower shutter speed or higher ISO both of which reduce the quality of your still images. Varying your exposure by shooting in manual, or using the exposure off set will give you the control you want without image quality loss.

I tend to agree, for photos at least. Though I'm still sold on using a CPL filter, which I now have on order.

 

[Barbara]

A lot of people get put off by manual mode, but don't let that include you, Barbara. To repeat, if you set the ISO to 100 and you've got a fixed aperture, then all you have to adjust is the shutter speed. And it's best if you can keep this at or near to 1/50th second if you're using 24fps or 25fps by lowering the shutter speed.

You want motion blur, which is the industry standard. But if you're close to the ground, fly slowly.

I lived in the Lake District as a child.

For videos I will continue to experiment with the use of ND filters and manual mode for that "motion blur" effect. It definitely means a bit more planning when it comes to taking specific shots. But then, I have the time.

 

[Barbara]

EV is simply telling auto what target exposure to achieve. In manual, EV is showing you the results after you've made your settings.

If one could set the polarizer angle in flight, that would be ideal since as you flew and shot your subject at different angles, you could adjust the polarity accordingly. But since we can't, we have to judge and set for the ideal and live with that for the entire flight.

ND isn't usually used for stills, but it could be if motion blur is desired. Just remember that what ND does is reduce the light that the camera starts with.

Yes, being able to set the polarizer in flight would be ideal, but as you said....

 

[Vic Moss]

For photos, there is no benefit to ND filters. All they do is steal light, causing you to use a lower shutter speed or higher ISO both of which reduce the quality of your still images. Varying your exposure by shooting in manual, or using the exposure off set will give you the control you want without image quality loss.

For photos, there is "very little" benefit to ND filters.

I've put them on plenty of times to blur traffic of water in my still photos.

For the vast majority of the time, ND filters are only for video and the 180° rule. But there are occasions where the ISO and/or aperture can't be adjusted enough to get the desired slow shutter speed.