Diffraction Calculator
Discover this groundbreaking tool, diffraction.cAm, where you can select your camera, filter, and ƒ-stop to identify the optimal settings for avoiding diffraction and achieving razor-sharp images. You can learn more about the science behind this tool in the video below and at About diffraction.cAm
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Transcript for Diffraction Calculator. Duration: 4:13.
- 0:00 Are your images sharp? How do you know if diffraction is impacting image sharpness? I've dedicated multiple videos and an entire book chapter to diffraction. But when exactly does diffraction occur? I've done diffraction testing for specific cameras, but is that practical for everyone? Can you calculate when diffraction will appear
- 0:22 for a particular camera sensor or infrared filter or f-stop? I didn't think it was practical, but I was wrong. I found a way. First, a little backstory. In my book, "Color Doesn't Exist, A Practical Guide to Infrared Photography" I said, "If the size of the airy disk is smaller than a pixel on a camera's sensor, there is no
- 0:47 apparent diffraction. If the size of the airy disk is larger than a single pixel, then the effect of diffraction will be visible in the image as reduced. This was a guess. It was an educated guess. Is the size of one pixel the key factor? Or would demosaicing mean that multiple pixel widths would determine when
- 1:09 diffraction is visible? During demosaicing, the raw editor looks at adjacent pixels to sample nearby colors. Therefore, it would be normal for a point of light to be created from a circle three pixels wide on the sensor. The color information from those adjacent pixels is required to define the full RGB color of the central pixel. Recently, I had an
- 1:36 idea, so I sketched it out. I know that you can calculate the size of the airy disk, if you know the wavelength of light and the aperture of your lens. If you compare the size of the airy disk to your sensor, you should be able to calculate when visible diffraction appears. The next step was mocking up the idea in a spreadsheet to see if it would work. So
- 2:01 I did that, and it worked. Finally, I turned it into a website, diffraction.cam, not .com, .cam as in camera. Let's walk through how it works. Using this, you can maximize image sharpness for your specific camera and filter. First, select your camera from this field. About a hundred cameras are supported, and more can be
- 2:26 added. Next, select a filter. If the column is dimmed, that wavelength of light will not be transmitted by the selected filter. Focus on the remaining fields, which represent wavelengths that will be transmitted. Select Hot Mirror for shooting visible light with a regular unconverted camera, or a full spectrum camera
- 2:47 using a UV-IR cut filter. Or select any high-pass filter for infrared. Finally, select the row of the f-stop you wish to shoot at. This will highlight the row. If all of the highlighted fields in the row are green, there will be no visible diffraction with this combination of sensor, filter, and f-stop.
- 3:11 Mild diffraction may be visible if any highlighted fields in that row are yellow. If any highlighted fields in the row are red, diffraction will impact image sharpness. Using this tool, you can determine which f-stop can be selected to avoid diffraction for a specific sensor and filter. This will help you to produce sharp
- 3:34 images. Please give it a spin with your camera and filter. Do the results with your images match the values shown on diffraction.cam? Let us know in the comments. If you're interested in the geeky details behind these calculations, check out the About page on diffraction.cam. If you'd like to learn more about infrared
- 3:54 photography, sign up for my newsletter, Infrared Insights. I'll keep you informed about the latest videos, software, guides, and equipment for infrared photography. A link is in the description. If you find these videos helpful on your infrared photography journey, like, subscribe, or comment. Hope you enjoyed. Thanks.
