What do the ND filters, ND4, ND 8, ND16 and ND 32 mean in terms of how many stops down and the effect that has on a Q500.
The 4k camera on the Yuneec Q500 has a fixed aperture of 2.8. The aperture is unchangeable. This is the same for GoPro and other action cameras. To change the camera exposure the ISO or shutter speed must be changed.
For video the shutter should be double the frame rate. At 30 FPS the shutter should not be set lower than 1/60 of a second.
This leaves ISO as the remaining variable. With as small a sensor as the 4k possesses, using an ISO of 400 or 800 is noisy. It’s best to stay within the 100 or 200 ISO range.
A problem at 1/60 shutter at 2.8 aperture in strong sunlight is overexposure. Over exposure creates noise even in an image at ISO 100.
Do not shoot using Auto mode, as the only variable being considered is ISO. Auto mode will select an ISO that is noisy even when there is good light out. Without a ND filter, even when the camera shows good exposure, the image will be noisy as will still select a high ISO.
ND to the rescue
A neutral density filter, or ND filter, is a filter that reduces or modifies the intensity of all wavelengths, or colours, or light equally, giving no changes in hue of the rendered colours. It can be a colourless (clear) or grey filter. The purpose of a standard photographic neutral density filter is to reduce the amount of light entering the lens. Doing so allows the photographer to select combinations of aperture, exposure time and sensor sensitivity that would otherwise produce overexposed pictures. With a DSLR camera, this is done to achieve effects such as a more shallow depth of field or motion blur of a subject in a wider range of situations and atmospheric conditions.
However, since the 4k camera on the Yuneec Q500, and most similar action cameras, have a fixed 2.8 aperture and will only have a shutter speed, usually set to double the frame rate for the video, results in a very slow shutter that creates an abundance of over exposure possibilities.
The Yuneec Q500 4k camera is capable of shutter speeds to 1/1000 of a second, but this is done in the software, electronically, and the accuracy is questionable.
In conditions of extreme light intensity, such as sunshine on snowy mountains or on the beach, or when using a camcorder, ND (Neutral Density) filters are recommended as an essential.
ND filters appear grey to reduce the amount of light reaching the film. They have no affect on colour balance other than having a multi-coated lens for true accurate colour representation.
Uses of ND filters
ND filters have these three main uses:
- To enable slow shutter speeds to be used, as action cams can.
- To allow video cameras which have fixed shutter speeds to film subjects such as snow, sand or other bright scenes which would normally cause overexposure.
The NDS32 is a dark neutral density filter with a 5-stop light loss. Best used in strong sun.
The ND16 is a dark neutral density filter with a 4-stop light loss. Best used in strong sun.
The ND8 is a dark neutral density filter with a 3-stop light loss. Best used when overcast or slightly cloudy.
The ND4 is a dark neutral density filter with a 2-stop light loss. Best used when cloudy.
Test the ND filters you have to see what you like best. Select manual exposure. There is no right or wrong filter. It’s all about personal preference.
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