What is the proper way of using ND filter?

[JacePhoto]

Hi guys, i need some help.

1) Is there a difference between a Photo ND Filter and a Video ND filter?

The reason why i asked is i tried using a Photo ND filter and it didn't quite work.

2) I used a Photo ND Filter (ND400) and set the camera on Manual mode. When i turned the filter, instead of consistently darkening the picture, the centre became a dark 'X' while other parts are still exposed. In another words, the image cannot be used.

What am i doing wrong? :thumbed:

Thanks!

 

[daredevil123]

They should be the same. ND is ND, whether for stills or video.

For variable ND filters, it is basically made up of two CPL. The side effect of variable ND at high densities and wide focal lengths is cross banding, the effect you noticed with an X. Different quality of variable ND filters will start to exhibit cross banding at different densities and different focal lengths. The higher the density, the wider the focal length, the more possible it is to get cross banding. Getting a better quality variable ND filter may help in certain instances. Try variable ND filters from Kenko, Tiffen or Heliopan. They are not cheap though.

As for photo ND filter, I am not sure what the problem is. If you can explain more I might able to help you more. What density of ND filter are you trying to use? what is the shutter speed you are setting?

 

[Bamboopictures]

The dark X is a well documented phenomenon with variable ND when used with 35mm or wider lens. I have experienced it myself and had to to spend hell of time color correcting away the uneven exposure. This problem does not exist with single layer ND filter or when the ND is behind the lens instead of in front.

 

[JacePhoto]

They should be the same. ND is ND, whether for stills or video.

For variable ND filters, it is basically made up of two CPL. The side effect of variable ND at high densities and wide focal lengths is cross banding, the effect you noticed with an X. Different quality of variable ND filters will start to exhibit cross banding at different densities and different focal lengths. The higher the density, the wider the focal length, the more possible it is to get cross banding. Getting a better quality variable ND filter may help in certain instances. Try variable ND filters from Kenko, Tiffen or Heliopan. They are not cheap though.

As for photo ND filter, I am not sure what the problem is. If you can explain more I might able to help you more. What density of ND filter are you trying to use? what is the shutter speed you are setting?

Hi DareDevil, thanks for coming to my help. Thanks for the info.

Am using a CHN-HK brand called PIXEL.

The X mark happens in both photo and video. Sorry if my statement isn't clear. Tmr i will try it on lenses longer than 50 mm as what Rodney (Bamboo Picture) suggests.

Thanks mate!

The dark X is a well documented phenomenon with variable ND when used with 35mm or wider lens. I have experienced it myself and had to to spend hell of time color correcting away the uneven exposure. This problem does not exist with single layer ND filter or when the ND is behind the lens instead of in front.

Hi Rodney, thanks for the info.

Let me try out on 50 mm and above and see if it removes the problem.

Thanks!

 

[kandinsky]

2) I used a Photo ND Filter (ND400) and set the camera on Manual mode. When i turned the filter, instead of consistently darkening the picture, the centre became a dark 'X' while other parts are still exposed. In another words, the image cannot be used.

It is not showing the cross all the time right? Sounds like you're pushing it too hard? This should only happen at the extreme ends of the ND. If you use it within the recommended range should be fine?

IMPORTANT:
Only use your Variable ND within its recommended 2 to 8 stop range. If you go beyond the “MAX”, you may experience an uneven exposure or color shift that appears as an “X bar” in the image. This is more common when using higher densities on full frame cameras; however, can be experienced on any camera. This is a common issue– it’s the law of physics when combining two polarizing filters; however, this issue can be eliminated. First, adjust your focal length and then reduce the density (stop value) setting by rotating the filter ring until the color shift disappears.

http://www.tiffen.com/displayproduct.html?tablename=filters&itemnum=77vnd

 

[daredevil123]

Hi DareDevil, thanks for coming to my help. Thanks for the info.

Am using a CHN-HK brand called PIXEL.

The X mark happens in both photo and video. Sorry if my statement isn't clear. Tmr i will try it on lenses longer than 50 mm as what Rodney (Bamboo Picture) suggests.

Thanks mate!

Yes, cross banding will appear on both photo and video. Same optics, same sensor, same issues.

There is no fixed focal length where it is guaranteed ok. It depends. the higher the density, the longer the focal length it will be before the cross banding appears. And it is different for different brands/quality of vari-ND.

This is a test done by ephotozine for Lightcraft Workshop's vari-ND filter for amount of ND density range usable before the X-banding appears. The Pixel you have will perform a lot worse than this. Tiffen will perform better than this, and Kenko and Heliopan will perform the best. The numbers are for a APS-C camera. So for FF cameras, just factor in the crop factor when figuring the corresponding focal length. This is the reason why some of us plonk so much money down for good quality vari-ND filters.

http://www.ephotozine.com/article/light-craft-workshop-fader-nd-mk-ii-filter-filter-review-14321

The information below shows the degree of light loss you can achieve at different focal lengths on a cropped sensor DSLR.

12mm: ND4 to ND8 3 stop operating range
15mm: ND4 to ND16 4 stop operating range 

18mm: ND4 to ND32 5 stop operating range

24mm: ND4 to ND64 6 stop operating range

35mm: ND4 to ND125 7 stop operating range

40mm: ND4 to ND175 7.5 stop operating range
50mm: ND4 to ND250 8 stop operating range
70mm: ND4 to ND350 8.5 stop operating range
100mm: ND4 to ND500 9 stop operating range

 

[daredevil123]

Just to add on, if you are interested to know why this happens.

It is the same when you use CPL on UWA lenses. you get uneven polarization. On a vari-ND, that effect is amplified because there are 2 CPLs. when the ND density is low, the CPLs are more closely aligned, so the effect is less amplified. The higher the ND, means the less aligned the CPLs are, causing the uneven polarization to happen more. The wider the FOV, the more you see it, because the uneven polarization happens near the edges more than the center.

The reason why better (more expensive) vari-ND filters handle it better, is because, wider band CPLs get less uneven polarization, reducing the effect. Wider band CPLs are more expensive to make, and when paired, the price difference is doubled. Which is why some folks prefer to use slot in filters for higher densities.

 

[JacePhoto]

It is not showing the cross all the time right? Sounds like you're pushing it too hard? This should only happen at the extreme ends of the ND. If you use it within the recommended range should be fine?

Hi Kandisky, you are right. The X banding appears when i am 3/4 through turning of the filter. Guess i have the wrong concept of how the ND is supposed to work.

Just to add on, if you are interested to know why this happens.

It is the same when you use CPL on UWA lenses. you get uneven polarization. On a vari-ND, that effect is amplified because there are 2 CPLs. when the ND density is low, the CPLs are more closely aligned, so the effect is less amplified. The higher the ND, means the less aligned the CPLs are, causing the uneven polarization to happen more. The wider the FOV, the more you see it, because the uneven polarization happens near the edges more than the center.

The reason why better (more expensive) vari-ND filters handle it better, is because, wider band CPLs get less uneven polarization, reducing the effect. Wider band CPLs are more expensive to make, and when paired, the price difference is doubled. Which is why some folks prefer to use slot in filters for higher densities.

Thanks DareDevil.

Went and read your article on Filters. Certainly very useful. Learned something from everyone here.

I guess i wld be buying fixed ND filter (as opposed to variable) and see if i can keep to the big aperture without other 'side effects'... haha

Other tips will be appreciated. Thanks!

 

[pettypoh]

also had the "x" factor when trying out variable ND, quite common issue apparently, so only can use to about 3/4 of max

bought a separate 10-stop nd to use because of this issue

 

[JacePhoto]

Thanks for the info. Looks like i am gg to do that too, haha

 

[pettypoh]

let me know if you wana test out the filter before buying, the 10-stop i bought is haida - i think the seller is in this forum, they got some testing sessions also

 

[JacePhoto]

let me know if you wana test out the filter before buying, the 10-stop i bought is haida - i think the seller is in this forum, they got some testing sessions also

Oh? No color cast in video? I will think that 10 stop doesn't allow any light to come through and cannot see anything at all?

Was thinking of 2-4 stops ND filter for use under strong sunlight.

 

[pettypoh]

use 10-stop can see on screen, viewfinder not likely. if 2-4stops then wouldn't the variable nd filter be sufficient already? 2-4stops probably won't have "x-factor" right? =D

 

[JacePhoto]

Sorry to bring out an old thread!

I just learned something. When using the variable ND, it works in bright sunlight from light to dark.

But when the light isn't as strong and the ND is slapped on, a Big 'X' appears across the frame.

In a nutshell, i had problems with the X and have the mistaken idea on how to use them. Use them only under strong sunlight!

 

[hamanoshun]

1. Buy mattebox
2. Buy 4x4/4x.5.65 filters
3. Profit