Is there any way to increase the amount of light entering a (digital) camera for high-speed photography?

Question

I know that increasing ISO value is one way to compensate for low light levels, but I don't like the accompanying increase in noise. I'm thinking of something that does the opposite of a circular polarizing filter, something that lets me use a faster shutter speed at a given light level.

Answer 1

Ways to increase the amount of light:

1) Slow down shutter speed.  Probably not acceptable since you are doing high-speed photography.  Slowing down the shutter speed will most likely blur the subject.

2) Open up the aperture.  Get a lens with a larger maximum aperture.  Look for something as close to f/1.0 as you can afford.  

3) Increase the sensitivity of the sensor.  This is usually done by increasing the ISO.  This increases noise, which you don't want.

4) Increase the light itself.  Use strobes (flash) if you don't need a continuous increase in light.

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5) Do a combination of the first 3.  If that is not enough, do a combination of the above 4.

Unfortunately, it's probably not going to be cheap to achieve what you want.  1 and 3 are the cheapest to do, but will probably defeat the purpose of high speed photography.  2 and 4 will probably help give you the results you want, but at a considerable cost.

BTW: A circular polarizer, while it does allow you to slow down the shutter speed... that isn't what it is primarily used for.  Use a circular polarizer to darken a blue sky (under the right conditions) and remove glare from leaves, glass, water, or other nonmetallic items that have glare.  A filter that is strictly used for allowing slower shutter speeds is called a Neutral Density filter.   If you could make a reverse neutral density filter... you'd probably be set for life as far as $$$$$$ is concerned.

Answer 2

In addition to what j_acuff said,

There isn't a type of filter that magically adds light. Unfortunately I suspect you have a basic digital camera which has limitations.

An alternative to taking lousy pictures or spending $1500 on  a new fancy DSLR to take photos of one event, is to go retro. There are many high-quality film SLRs + lens that are on sale for under $100. Load it up with some 400 speed film and you are good to go.

Answer 3

Remove any filters and don't use any  teleconverters or extension tubes...These all rob light. Other than that faster glass is about all you can do other than cranking up the ISO...

Answer 4

Unfortunately there is no filter that will admit more light than what is available. If you can repeal the laws of physics you might be able to make such a filter.

In low-light photography lens speed is of the essence. If the maximum aperture on your lens is f3.5 then you are limited to that. Your only choice is to either invest in a very fast prime lens like a 50mm f1.4 or use a higher ISO.

Here is a hypothetical chart which shows, accurately, the relationship of lens speed and shutter speed at several ISO settings.

ISO 100

f1.4 @ 1/125

f2 @ 1/60

f2.8 @ 1/30

f3.5 @ 1/20

f4 @ 1/15

ISO 200

f1.4 @ 1/250

f2 @ 1/125

f2.8 @ 1/60

f3.5 @ 1/40

f4 @ 1/30

ISO 400

f1.4 @ 1/500

f2 @ 1/250

f2.8 @ 1/125

f3.5 @ ~1/80

f4 @ 1/60

ISO 800

f1.4 @ 1/1000

f2 @ 1/500

f2.8 @ 1/250

f3.5 @ ~1/160

f4 @ 1/125

The faster the lens the faster the shutter speed at a given ISO.

Answer 5

acuff is right.   In addition, there are devices that actually amplify the light.  These are called light intensifier tubes, also known as nightvision.  With today's technology the result is monochrome (not full color), and the image isn't that great, but it works really well in some circumstances.  These are expensive so if money weren't an object, I agree with getting a lense that has a very large aperature.