Jonathan Ames
September 18th, 2006, 10:31 AM
Day for Night Filter
On the other end of the spectrum, there are times when you’ll want to give your warm, sunny days a cool look and for that you can use either a pair of 82A and B filters or simply the DFN ort Day for Night filter. This filter does exactly what the 812 filter does only in reverse. Be careful not to include a sunny sky in the background and the blues that are exacerbated with the DFN filter will cool your shots enabling you to effectively match shots you took on an actual gloomy day a few days later when time and schedule permit. And finally, another note; Watch your shadows! Overcast days don’t produce pronounced shadows and while using a DFN filter will give the esoteric feeling of a cooler day, jusrt as accidentally including the sky in your shot, shadows will scream “FAKE” just as vocally.
Neutral Density Filters
As previously noted, all lenses have a “sweet spot” where the lens performs most predictably and best. What is that for your lens? Only your lens manufacturer knows for sure but know one thing; there are so many myths out there that confusion reigns supreme. What is “sweet spot”? It’s the aperture of “F” or “T” spot at which the lens performs best between the available apertures and there are a number of variables that determine the sweet-spot; focal length zoom vs. prime, glass quality, resolving power, contrast of the lens glass, longitudinal and lateral chromatic aberration, refractive index, low-dispersion glass, volume of fluorite in a lens, diffraction and acutance just to name a few. And just to clear up some confusion, "F-stop" refers to the theoretical amount of light transmitted, and "T-stop" refers to the actual amount. Of the two, "F-stop" is more commonly heard so, get with your manufacturer on their web site and find out where your lens’ sweet spot is. There’s no sense saving every penny to invest in an new HD camera and HD lens and not know where they are performing best.
Cameras also have a range within which they too perform best separating dark grays from blacks (crushing) and, at the other end, bright whites from blow-out white (blown out). Perhaps not curiously, the more expensive the camera, the wider the range. Our Sony F-350s for example are performing thus far to a bout a 7-stop range where a F-900 would have a 9-stop range. Now, for argument sake, the 900 will perform to an actual 11-stop range but accounting for roll-off, the safe zone is at 9. The human eye, for reference, is capable of instantaneous (where the pupil size is fixed by looking at only one image in constant light without moving the eye) range of 10-14. Move the eye to allow for pupil expansion and contraction and you have a 24-stop range. The trick is to discover what exactly is the range of your camera and lens and light to that range where the highlights and lowlights are within the limits. For this reason, ND filters are indispensable in controlling the scene to fit your camera and lens and where the light meter, waveform monitor or well-lined up studio-grade monitor comes in. My personal preference is such that nothing beats a great studio monitor that’s well-aligned. The down side is that they’re expensive. The Panasonic 2600 for example is about $4000 BUT what you see is what you get.
Now, with all that said, ND filters allow you to control the amount of light coming in through the lens such that you can better balance the shot to keep it within the camera’s tonal range and closest to the sweet spot. True, your camera will probably have three settings on the internal ND wheel but what if your needs exceed that or what if your camera doesn’t have an internal set of ND filters. This is where the Tiffen ND filters come in. If I want the sharpest picture I can get and I know that it has the sweet spot at 5.4, then I’m first going to deploy the internal ND filters to get me as close as they can and then add an external filter to get me the rest of the way there. What remains is taken care of by the lighting I use. Further, the ND filter, by its very nature, allows for the reduction in the depth of filed. The wider the aperture, the shallower the depth of field giving the shooter the ability to draw the attention to a particular part of a frame, something desirable but not always available in video. By reducing the amount of light entering the lens, the wider the aperture need and the shallower the depth of field.
Now, your question should be, “Why Tiffen?” And I’d say because just like the clear glass protectors, all glass isn’t created equally. Good, clear glass in an ND filter cuts just the light without affecting any other part of the image and on a bright, clear day, you’ll appreciate the filter more than you can know.
Before we leave this filter, there are a couple of things you should know about lenses and the cameras that use them. First is relative to the aperture system itself. Just because there’s a “16” aperture available, it doesn’t mean you should use it. The smaller the lens opening through which the light of an image passes, the more subject it is to “diffraction”. Diffraction refers to the breaking up of light or other waves and when an aperture is very small, it can have a more profound affect on light waves because the edge of the aperture interacts with the waves of light. Generally speaking, without knowing from the manufacturer what the exact sweet spot is, the more towards the center you are, the cleaner the image that will be recorded. And about the tonal range of your camera, there is a relatively easy way to determine where your camera’s is. First, for a few bucks at virtually any camera store, purchase a standard Kodak 18% Gray Card Plus. When you do, you’ll note that it has a black and a white patch on both sides of the gray. Set it in front of you camera and light it evenly at a mid-range t or f-stop, 4 or 5.4. Now, this is where a good, lined-up monitor comes in but if you don’t have one, use the side swing out or viewfinder. It won’t be exact but it‘ll give you a pretty good idea. Now, without touching the lens, reduce the lighting until the grey is only fractionally lighter than the black patch next to it and, using a borrowed, bought or rented spotmeter, test the light at the board. The resulting number will be the camera’s lower end of the tonal range. Now reverse the process raising the light until the gray area of the card is only fractionally darker than the white patch and take another reading. This will be the upper end of the camera’s tonal range. By keeping the colors just darker than and just lighter than the gray, you avoid the lenses limits and it is by this testing that I know that the F900 is capable of 11 stops and the F350 is capable of 9.
So there you have it. The first of three filter sets being prepared for 2nd Unit. They can be ordered through this site before the store goes on line by just e-mailing us and letting us know you’d like one and after the store goes live in the usual fashion.
On the other end of the spectrum, there are times when you’ll want to give your warm, sunny days a cool look and for that you can use either a pair of 82A and B filters or simply the DFN ort Day for Night filter. This filter does exactly what the 812 filter does only in reverse. Be careful not to include a sunny sky in the background and the blues that are exacerbated with the DFN filter will cool your shots enabling you to effectively match shots you took on an actual gloomy day a few days later when time and schedule permit. And finally, another note; Watch your shadows! Overcast days don’t produce pronounced shadows and while using a DFN filter will give the esoteric feeling of a cooler day, jusrt as accidentally including the sky in your shot, shadows will scream “FAKE” just as vocally.
Neutral Density Filters
As previously noted, all lenses have a “sweet spot” where the lens performs most predictably and best. What is that for your lens? Only your lens manufacturer knows for sure but know one thing; there are so many myths out there that confusion reigns supreme. What is “sweet spot”? It’s the aperture of “F” or “T” spot at which the lens performs best between the available apertures and there are a number of variables that determine the sweet-spot; focal length zoom vs. prime, glass quality, resolving power, contrast of the lens glass, longitudinal and lateral chromatic aberration, refractive index, low-dispersion glass, volume of fluorite in a lens, diffraction and acutance just to name a few. And just to clear up some confusion, "F-stop" refers to the theoretical amount of light transmitted, and "T-stop" refers to the actual amount. Of the two, "F-stop" is more commonly heard so, get with your manufacturer on their web site and find out where your lens’ sweet spot is. There’s no sense saving every penny to invest in an new HD camera and HD lens and not know where they are performing best.
Cameras also have a range within which they too perform best separating dark grays from blacks (crushing) and, at the other end, bright whites from blow-out white (blown out). Perhaps not curiously, the more expensive the camera, the wider the range. Our Sony F-350s for example are performing thus far to a bout a 7-stop range where a F-900 would have a 9-stop range. Now, for argument sake, the 900 will perform to an actual 11-stop range but accounting for roll-off, the safe zone is at 9. The human eye, for reference, is capable of instantaneous (where the pupil size is fixed by looking at only one image in constant light without moving the eye) range of 10-14. Move the eye to allow for pupil expansion and contraction and you have a 24-stop range. The trick is to discover what exactly is the range of your camera and lens and light to that range where the highlights and lowlights are within the limits. For this reason, ND filters are indispensable in controlling the scene to fit your camera and lens and where the light meter, waveform monitor or well-lined up studio-grade monitor comes in. My personal preference is such that nothing beats a great studio monitor that’s well-aligned. The down side is that they’re expensive. The Panasonic 2600 for example is about $4000 BUT what you see is what you get.
Now, with all that said, ND filters allow you to control the amount of light coming in through the lens such that you can better balance the shot to keep it within the camera’s tonal range and closest to the sweet spot. True, your camera will probably have three settings on the internal ND wheel but what if your needs exceed that or what if your camera doesn’t have an internal set of ND filters. This is where the Tiffen ND filters come in. If I want the sharpest picture I can get and I know that it has the sweet spot at 5.4, then I’m first going to deploy the internal ND filters to get me as close as they can and then add an external filter to get me the rest of the way there. What remains is taken care of by the lighting I use. Further, the ND filter, by its very nature, allows for the reduction in the depth of filed. The wider the aperture, the shallower the depth of field giving the shooter the ability to draw the attention to a particular part of a frame, something desirable but not always available in video. By reducing the amount of light entering the lens, the wider the aperture need and the shallower the depth of field.
Now, your question should be, “Why Tiffen?” And I’d say because just like the clear glass protectors, all glass isn’t created equally. Good, clear glass in an ND filter cuts just the light without affecting any other part of the image and on a bright, clear day, you’ll appreciate the filter more than you can know.
Before we leave this filter, there are a couple of things you should know about lenses and the cameras that use them. First is relative to the aperture system itself. Just because there’s a “16” aperture available, it doesn’t mean you should use it. The smaller the lens opening through which the light of an image passes, the more subject it is to “diffraction”. Diffraction refers to the breaking up of light or other waves and when an aperture is very small, it can have a more profound affect on light waves because the edge of the aperture interacts with the waves of light. Generally speaking, without knowing from the manufacturer what the exact sweet spot is, the more towards the center you are, the cleaner the image that will be recorded. And about the tonal range of your camera, there is a relatively easy way to determine where your camera’s is. First, for a few bucks at virtually any camera store, purchase a standard Kodak 18% Gray Card Plus. When you do, you’ll note that it has a black and a white patch on both sides of the gray. Set it in front of you camera and light it evenly at a mid-range t or f-stop, 4 or 5.4. Now, this is where a good, lined-up monitor comes in but if you don’t have one, use the side swing out or viewfinder. It won’t be exact but it‘ll give you a pretty good idea. Now, without touching the lens, reduce the lighting until the grey is only fractionally lighter than the black patch next to it and, using a borrowed, bought or rented spotmeter, test the light at the board. The resulting number will be the camera’s lower end of the tonal range. Now reverse the process raising the light until the gray area of the card is only fractionally darker than the white patch and take another reading. This will be the upper end of the camera’s tonal range. By keeping the colors just darker than and just lighter than the gray, you avoid the lenses limits and it is by this testing that I know that the F900 is capable of 11 stops and the F350 is capable of 9.
So there you have it. The first of three filter sets being prepared for 2nd Unit. They can be ordered through this site before the store goes on line by just e-mailing us and letting us know you’d like one and after the store goes live in the usual fashion.