Infrared Photography. John Caplis. Joyce Harman Harmany in Nature

Transcription

1 Infrared Photography John Caplis & Joyce Harman Harmany in Nature

2 Why do infrared photography? Infrared photography offers many unique creative choices you can explore in image making Excellent monochrome images Sunlit foliage turns white Blue skies appear very dark False color can be applied for dream like scenes Skin tones are ghostly white Can be shot in the harsh light in the middle of the day

3 A human eye can see light from 400nm to 700nm on the electromagnetic spectrum. This range is called visible light. IR photography uses near infrared light which is in the range of 700nm-1400nm. These wavelengths are longer than visible light and can t be seen by humans.

4 How IR filters work There are two types of infrared filters, ones that block IR light while passing visible light and ones that block visible light while passing infrared light. The IR blocking filters are used in stock digital cameras to prevent unwanted IR light from reaching the sensor, which is sensitive to near infrared. In infrared photography we want the opposite, to block most or all visible light and only pass infrared light.

5 Two ways to do IR photography Stock vs IR-Converted Cameras Stock Camera with Screw-on external IR filter Dim or no preview image No autofocus Exposure metering can be difficult High ISOs & long exposures Requires tripod Converted Camera with Internal IR filter No screw on filter required Normally bright preview image Autofocus using live view Exposure metering can be difficult Low ISOs Tripod not always required Camera conversions Life Pixel Kolari Vision

6 Using Stock Cameras for IR Photography Stock digital cameras have a limited range of sensitivity to infrared light. This is because of a filter placed over the sensor that is designed to block infrared light while allowing visible light to pass. Hot mirror filter reflect most of the nearinfrared light ( nm), stopping it from reaching the camera sensor. This makes any infrared photography near impossible without a high ISO and long exposure. Some unconverted cameras are more sensitive to infrared than others. Nikon is better than Canon for shooting IR with a stock camera. 830 nm IRAY external filter on Stock Canon 5D Mk III, EF L f2.8 II F16, ISO 640, 240 second exposure

7 f8, ISO 800, 88 seconds f8, ISO 800, 148 seconds 830 nm IRAY external filter Stock Canon 5DmkIII, EF L f4

8 Infrared Filter Choices

9 The Deep BW IR filter produces the strongest IR effect. The resulting images are monochrome with a proper white balance set. Since its cut off is so deep, less total light will reach the sensor and longer exposures would be required, usually 2+ stops extra would be needed.

10 Deep BW IR 830 nm Since the image is captured as BW infrared straight out of the camera there is no need to manipulate in Photoshop unless you want to fine tune the BW look. This is our strongest IR filter producing the darkest sky and whitest foliage.

11 Deep IR 830 nm External filter on a Converted camera ISO 800, f14, 1/100 sec

12 The Standard IR filter is a popular choice that has a 50% pass frequency of 720nm. Since this filter also transmits a little bit of the visible deep red light the resulting image has a bit of color in it. With proper adjustment in Photoshop you can achieve the very popular blue sky effect.

13 Standard Color IR Filter 720 nm A great all around infrared filter choice. Color infrared is possible although not as saturated as our Enhanced infrared filter and only the blue sky effect is possible. Black & white IR photography looks great with good tonal range.

14 Standard IR 720 nm Converted camera Image by Tony Sweet

15 The Enhanced Color IR filter transmits a bit more of the visible red light than our standard filter, it s 50% pass frequency is 665nm. Since it passes more visible red light the resulting IR images have more color in them. Not only is the color in the sky, it s also in the foliage as well. Both can be manipulated in Photoshop to produce a very unique result.

16 Enhanced Color IR Filter 665 nm Allows more color to pass and is especially suited for color IR photography with great saturation and color range. BW also looks quite good although with a bit less contrast without adjustments.

17 The Super Color IR filter is our most colorful filter, its 50% pass frequency is 590nm. This filter passes the most visible red light along with IR and therefore the resulting images have the most saturated colors. Which can further be manipulated in Photoshop to produce a dizzying array of effects.

18 Super Color IR Filter -590 nm Provides for a super vibrant foliage and intensely colorful sky. With the red & blue channels swapped the foliage takes on a golden orange tone and sky a beautiful royal blue. The most surrealistic, color infrared filter available. You may be surprised to know this IR filter is also great for black & white IR photography, especially if you want full control of all the elements and love tinkering in Photoshop. The video at the top of this page explains this in more detail.

19 Super Color IR 590 nm Converted camera Image by Tony Sweet

20 The Super Blue IR filter 50% IR pass frequency is 705nm but in addition it also passes blue light with a second pass band of 285nm to 465nm at 50%. With its unique dual band properties it s possible to get a natural looking blue sky right in camera! With the white balance set on a gray card the foliage comes out in a yellow tone and sky a vibrant blue tone.

21 Super Blue IR Filter The super blue filter passes blue light as well as infrared light thus allowing for super saturated blue skies straight in camera! One can also use an external filter to block the blue wavelengths and photograph infrared light, similar to our Standard IR filter.

22 Super Blue IR Filter

23

24 Using External IR filters on a IR-Converted Camera If you had your camera converted to infrared you may still use external infrared filters. Just keep in mind that the external filter needs to be stronger or deeper in the IR than the internal filter. For example, if your camera was converted to the Super Color Infrared filter, which is 590nm you can use a 665nm or 720nm or even deeper to override the internal filter, because what you are doing is blocking a wider amount of IR than the internal filter. This wouldn t work the other way around, say if you had a Deep BW infrared filter (830nm) installed in your camera and wanted to use an external screw-on 590nm filter. 590 nm Super Blue 720 nm 830 nm

25 Infrared Focusing Issues When taking an infrared photograph, something to consider is that infrared light focuses at a different point than visible light. If a lens has a fixed focal length, then the infrared focus shift will be constant. However, if the lens zooms between two focal lengths, the infrared focus shift will vary, making it hard for users to focus properly. Stock Cameras: When an infrared filter is attached to a lens, all visible light is blocked making it impossible to compose and focus through the viewfinder. To compose and focus, the infrared passing filter must be removed. When desired focus is achieved, the infrared filter should be reattached. The focus on the lens then has to be turned by the difference between the current visible focus and the infrared focus mark. Most newer DSLR cameras come with a Live View feature that allows you to actually see live what the camera sensor is capturing and some even have the ability to focus directly from the imaging sensor while the life view is active. This is incredibly useful in digital infrared photography as your camera gives you the ability to see the infrared image before you even take a picture on the camera s rear LCD. (Make sure the Live View focusing is set to Live )

26 Infrared Focusing Calibrations Custom Calibration to a specific Lens Universal Calibration: Most newer DSLR cameras come with a Live View feature that allows you to actually see live what the camera sensor is capturing and some even have the ability to focus directly from the imaging sensor while the live view is active. This is incredibly useful in digital infrared photography as your camera gives you the ability to see infrared light before you even take a picture. You can use any lens to focus using this method.

27 Typical Camera Conversion Cost

28 SLR lenses Lens coatings, glass elements and configuration are all optimized for visible light. A lens that might be a top performer in visible light might fair very poorly in IR, a cheap kit lens may turn out to produce excellent results in infrared light. There are a few reasons that hot spots can occur, the most common culprit is the mate black coating on the inside of the lens barrel. The coating is designed to absorb stray light from bouncing around within the lens and creating hot spots. Unfortunately this coating may behave the opposite in IR light, instead of absorbing light it may reflect it and end up causing a hot spot. The other less common reasons for a IR hot spot would be the coatings on the glass lens elements themselves behaving in a way other than what was intended when used in visible light. Databases are available on the internet that lists IR performance for most lenses.

29 Lens Hot Spots A hot spot is an area in an image (most frequent in the center) that appears to be lighter or brighter than the rest of the image. Fortunately majority of lenses don t have a hot spot issue.

30

31

32

33

34

35 Setting white balance Since IR light is captured predominantly in the red channel your images will be mostly red no matter which preset white balance setting you use. For properly white balanced images you need to set your camera to a custom white balance. You will need to save a custom white balance measurement by taking a picture in the measurement mode or choose a specific photo on your memory card to use as the white balance measurement. The object you measure the white balance off of will depend on the infrared filter you selected for your camera conversion service. The Deep BW Infrared Filter and Standard Color IR Filter work best when the white balance is measured off of a patch of healthy green grass or other green foliage. The Enhanced Color IR Filter, the Super Color IR filter and the Super Blue Color IR, and Hypercolor filters work better with the white balance measured off of a grey or white card. Some sources suggest using green grass or foliage for all filters.

36 Steps for setting a custom white balance 1. Using white balance set to AWB, take a jpeg picture of something green, or a gray/white card. As you will recall, in IR, green foliage appears white. This typically will be green foliage or grass. Make sure you fill the screen. This is sometimes called taking/making a white balance measurement. If you are going to use a screw on IR filter on your converted camera, make sure you set take the white balance image with the IR filter on the lens. 2. Change your camera white balance preset setting to custom white balance. 3. In your camera menus, select Custom White Balance and press Set 4. Select the jpeg image you took for your white balance measurement, and hit Set. 5. Hit Ok for using white balance data from the image as your custom white balance.

37 Custom White Balance for a Super Blue Converted Camera Photo of a white card for setting White balance from image stored On memory card Resulting JPEG files Processed in camera

38 Photo of a green foliage using a 690 nm IR filter for setting custom white balance Resulting JPEG files Processed in camera

39 AWB Photo of a green foliage using a 830 nm deep IR filter for setting custom white balance Resulting RAW and JPEG files in camera