Note: We have a limited range of B&W cameras available. Please click on the Order button to see available models.
One project we have been working on for a few years is physically converting a color DLSR camera to Black & White. Why? An equivalent monochrome camera will always take a much sharper image than a color camera because resolution is dependent on the color content in the picture.. To understand why, you have to understand how a color camera sensor works. We have a rather technical explanation for those so inclined. For the artistic types that aren't interested in the science, please just consider the two pictures below.
Stock Canon 30D taking a black and white picture Our modified Canon 30D with Color Filter Array (CFA) removed
Which picture looks better to you? These pictures are an area of a larger picture zoomed to 100% in Photoshop which can be seen here.
Some history. Kodak made a series of monochrome DSLR cameras starting with the DCS-420m (1.2 megapixel), DCS-460m (6 megapixel) and lastly the DCS-760m (improved 6 megapixel). The DCS-760M sold for $10,000.00 in 2001. Unfortunately, the market for B/W DSLR cameras is quite small and Kodak discontinued the line. Today, Kodak has discontinued all DLSR cameras and the company is a small fraction of the size it once was. No manufacturer is making a B/W consumer digital SLR camera. Some medium format monochrome data backs are available, and they are quite expensive.
A camera sensor is composed on many different layers. From the top, the first layers are:
The picture above shows the structure of a red pixel. A green pixel will have a green color filter, and blue pixel will have a blue color filter.
Pixels are arranged usually in a Bayer Red-Green-Blue-Green pattern Green is used twice as much as red and blue in an effort to more closely mimic the human eye which sees green better than red or blue. Humans see green the best of any color.
Canon 450D image sensor showing the CFA
For size comparison, the lines above are 0.01mm apart
With most camera resolution reviews, tests are performed with a black and white test target under white light. A black and white target will show the maximum resolution of which a color camera is capable. This is because the black and white target only has luminance (brightness) data. The black and white target has no chrominance (color) data. Why is this important? Remember, for every four pixels on a color sensor, you get 2 green, 1 red and 1 blue. So suppose the target as illuminated with a blue light? You would only get 1/4 of the pixels possibly seeing the blue light. Effectively, your 10 megapixel just turned into a 2.5 megapixel camera.
The color content of the picture will change a color camera's resolution. This is why a red rose sometimes looks blurry in comparison to other parts of a picture. The red rose is only triggering 1/4 of the pixels.
To test our theory, we performed the following test.
First we will show the MTF of the two cameras. The monochrome camera is the left column. For those who would like to understand more about MTF, Luminous Landscapes has a good discussion here. Basically, MTF is a mathematical way to quantify lens and camera sharpness. One can easily look at a picture and see that one is sharper than the other, but the question is "How much"? MTF allows us to put numbers to what we can see.
The further the MTF goes to the right and the higher it is, the sharper the picture. There are four MTF graphs for each camera. The first shows white light sharpness. Next is green, then blue and lastly red. The blue light was the weakest light, so the blue MTF showed the worst performance from both cameras. You can see that the B/W camera has much higher performance. At 0.2 cycles/pixel, the monochrome camera has twice the sharpness and at 0.30 cycles, has 5x the sharpness.
You can see that in every case, the monochrome camera substantially outperforms the color, stock version.
Real life performance. The titles of the different pictures will tell you about the particular test. First, we show the color camera taking the same picture under green, blue, red and white light. Note that the green picture has the highest resolution because there are twice as many green pixels compared to red or blue. Notice that the blue picture shows the highest noise which may relate to the blue light being dimmest and/or the response of the sensor to blue light. Notice the difference between the color and monochrome cameras.
You can click on the pictures to download a TIFF version.
At 50% in Photoshop
At 100% in Photoshop
That's why a monochrome sensor has an advantage over a color camera when taking black and white pictures.
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