Advantages of Using a Neutral Density Filter for Video in 2019
I'm starting to increasingly use the amazing video features of my Canon 7D. When I do, I generally choose "24 fps" mode, as this frame rate is considered the universal standard for movies.
I want to look like a "movie" that people are familiar with, and avoid similarities to home video camcorders. In my opinion, the look of the movie can be summed up as
a) Extremely shallow depth of field when required and
b) Smooth motion blur (ie adequate amount of blur in each frame).
For shallow depth of field, prime lenses with fast maximum apertures such as f / 1.8 and f / 1.4 or large telephoto lenses (eg 200 mm @ f / 4) are required. The motion blur aspect, however, is determined solely by the shutter speed.
NOTE: Shutter speed and frame rate are not the same. 24 fps video uses 24 frames per second, but these frames can be recorded anywhere between 1/8000 and 1/30 second each (just can't be slower than the frame rate itself).
You can use the ND filters with the Canon lens for videos to make the image quality more attractive. To match the motion blur you expect from traditional movies, the camera's shutter speed should be twice the frame rate (or as close as possible to the value with the camera). Therefore, I set the shutter speed to 1/50 second for all 24 fps video. This duplication has to do with how blinds work on traditional film cameras and are known as the 180 degree shutter rule.
You can shoot at faster shutter speed, but if you go too far, it will look like the opening sequence of Saving Private Ryan (ie each frame is very sharp and noticeable). Useful for purpose, but not for what I am looking for in general.
A major obstacle to video is that you have less control over exposure due to shutter speed restriction. This becomes a big problem outdoors. Your camera cannot be below ISO 100 and the shutter speed is now "locked" at 1/50. The only remaining variable is its opening, right?
UPDATE: You should really set your ISO 160 instead of 100 for best results. Find out why multiples of 160 are the best video ISOs.
As part of the attraction of shooting video with a DSLR is getting a very shallow depth of field, closing the aperture down is a real compromise and can even ruin all the aesthetics.
For example, if 1/50 of a second. @ f / 1.4 @ ISO 100 creates an overexposed video on a clear day, you have three ways to solve the problem:
Increase shutter speed (for example, move up to 1/500), but video becomes too sharp or uneven
Close aperture (for example, reduce to f / 5.6), but shallow depth of field is lost
Use a dimming lens filter to block the amount of light reaching your sensor!
This category of ND filters is often referred to as a fader ND filter and they can usually block from 1 to 8 light points with a single revolution. They usually cost more than a single ND filter, but have many advantages such as size, speed and ease of use.
NOTE: Remember that a "stop" light only means half or double light, so it's exponential (for example, 2 stops less light is only 1/4 of the total amount you started with).
What I like about this filter, besides the price, is that it is very thin. It also avoids vignetting by making the front element larger than the rear element. I haven't seen any color projection yet, but even if it does, it's something you can tweak in a video editing program.
While my son Keane was playing outside on a clear day, I took the opportunity to create a test video to show that this product worked compared to two other exposure adjustment options (shutter and aperture). I recorded and posted this video in 1080p so you can see the quality and color in all its glory. My poor son has no idea who I'm talking to.
In this video, I don't see any obvious colors, so I'm satisfied overall. I really like the ease of adjustment compared to searching for separate filters (especially square filters with brackets!).
In addition to video, these filters are useful for getting slow shutter speeds on a clear day. This is usually done to blur moving water or to set a slow shutter to capture panoramic images.
You can be sure that the most expensive suppliers use better glass, but I would not assume that the higher priced option is necessarily the best overall option. Keep in mind that if this purchase is primarily for video, you may experience some loss of sharpness as 1080p is "low resolution" when compared to a still photo. 1080p video uses only 2 megapixels from its 18 megapixel camera.
If you buy or own one of these, post a comment below to say what your experience was like.
I want to look like a "movie" that people are familiar with, and avoid similarities to home video camcorders. In my opinion, the look of the movie can be summed up as
a) Extremely shallow depth of field when required and
b) Smooth motion blur (ie adequate amount of blur in each frame).
For shallow depth of field, prime lenses with fast maximum apertures such as f / 1.8 and f / 1.4 or large telephoto lenses (eg 200 mm @ f / 4) are required. The motion blur aspect, however, is determined solely by the shutter speed.
NOTE: Shutter speed and frame rate are not the same. 24 fps video uses 24 frames per second, but these frames can be recorded anywhere between 1/8000 and 1/30 second each (just can't be slower than the frame rate itself).
You can use the ND filters with the Canon lens for videos to make the image quality more attractive. To match the motion blur you expect from traditional movies, the camera's shutter speed should be twice the frame rate (or as close as possible to the value with the camera). Therefore, I set the shutter speed to 1/50 second for all 24 fps video. This duplication has to do with how blinds work on traditional film cameras and are known as the 180 degree shutter rule.
You can shoot at faster shutter speed, but if you go too far, it will look like the opening sequence of Saving Private Ryan (ie each frame is very sharp and noticeable). Useful for purpose, but not for what I am looking for in general.
Adjusting exposure in video mode
A major obstacle to video is that you have less control over exposure due to shutter speed restriction. This becomes a big problem outdoors. Your camera cannot be below ISO 100 and the shutter speed is now "locked" at 1/50. The only remaining variable is its opening, right?
UPDATE: You should really set your ISO 160 instead of 100 for best results. Find out why multiples of 160 are the best video ISOs.
As part of the attraction of shooting video with a DSLR is getting a very shallow depth of field, closing the aperture down is a real compromise and can even ruin all the aesthetics.
For example, if 1/50 of a second. @ f / 1.4 @ ISO 100 creates an overexposed video on a clear day, you have three ways to solve the problem:
Increase shutter speed (for example, move up to 1/500), but video becomes too sharp or uneven
Close aperture (for example, reduce to f / 5.6), but shallow depth of field is lost
Use a dimming lens filter to block the amount of light reaching your sensor!
Neutral Density (ND) Filters
You guessed it, the last option is the best option as it ensures that you don't have to make the first two appointments. This type of filter is called a "neutral density" (ND) filter and acts as sunglasses for the camera lens. It is neutral that the colors remain "true" (ie less light, same colors). Like most filters, these are purchased to match the size of your lens front thread (for example, 58mm, 77mm, and so on). They come in various "densities", which represents how much light they block.Variable ND Filters
To ensure that you can handle any number of lighting situations, I recommend a variable density neutral filter instead of buying multiple fixed density filters. This will save time, money and space. These special filters are constructed of two pieces of glass that allow the twisting of the front element to vary the darkening effect in real time.This category of ND filters is often referred to as a fader ND filter and they can usually block from 1 to 8 light points with a single revolution. They usually cost more than a single ND filter, but have many advantages such as size, speed and ease of use.
NOTE: Remember that a "stop" light only means half or double light, so it's exponential (for example, 2 stops less light is only 1/4 of the total amount you started with).
Phil's Choice: ND Fader by Cameron Multi-Coat (MC)
There are a variety of Fader ND filters on the market, but I recently found one at my local camera store that seems to be a good balance between quality and price. At $ 90, it certainly doesn't break the bank and is even cheaper in the US. The product is called Cameron Multi-Coat (MC) Fader ND. Like others of its kind, it is referred to as having a range of "ND 2 to 400" and is the same as saying it ranges from 1 to 8 stops.What I like about this filter, besides the price, is that it is very thin. It also avoids vignetting by making the front element larger than the rear element. I haven't seen any color projection yet, but even if it does, it's something you can tweak in a video editing program.
While my son Keane was playing outside on a clear day, I took the opportunity to create a test video to show that this product worked compared to two other exposure adjustment options (shutter and aperture). I recorded and posted this video in 1080p so you can see the quality and color in all its glory. My poor son has no idea who I'm talking to.
In this video, I don't see any obvious colors, so I'm satisfied overall. I really like the ease of adjustment compared to searching for separate filters (especially square filters with brackets!).
In addition to video, these filters are useful for getting slow shutter speeds on a clear day. This is usually done to blur moving water or to set a slow shutter to capture panoramic images.
Variable ND Filter Providers
Here are some providers of these filters. You will find that they vary greatly in price as they range from $ 24 to $ 420. Note that part of the price is also determined by the size of the filter (for example, 82mm will cost more than 58mm):- Cameron - Fader ND Filter (my choice)
- Light Craft Workshop - Fader ND Mark II (similar price to Cameron)
- Tiffen - Variable ND Filter (New June 2011)
- Genre - Fader Filter (expensive and ranges from 1 to 4 stops only)
- Singh-Ray - Vari-ND (Expensive)
- RainbowImaging (cost so low you need to question quality)
- Unbranded eBay Versions
You can be sure that the most expensive suppliers use better glass, but I would not assume that the higher priced option is necessarily the best overall option. Keep in mind that if this purchase is primarily for video, you may experience some loss of sharpness as 1080p is "low resolution" when compared to a still photo. 1080p video uses only 2 megapixels from its 18 megapixel camera.
If you buy or own one of these, post a comment below to say what your experience was like.
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