Digital Infrared Resource Page

by Gisle Hannemyr

Table of Contents

  1. Introduction
  2. IR and Sensors
  3. IR and Lenses
  4. IR Filters
  5. Exposure Value
  6. Technique
  7. Infrared Linkfarm

1. Introduction

All digital cameras have sensors that to some extent are sensitive to infrared light. This is simple to verify. Standard remote controls uses infrared light to signal a TV or a VCR. Take a TV or VCR remote control, point the remote at your digital camera and push one of the buttons. No visible light can be seen, but if you look at the preview or review of the remote on your camera's LCD screen, you should see the infrared light emitted by the device as a bright spot.

Unfortunately, the sensitivity of different digital cameras to infrared light vary a great deal, and this simple test with a remote can not tell much about your camera's sensitivity to infrared light.

A better test of your camera's infrared capabilities would be to borrow or buy a cheap IR-pass filter such as Hoya R72 or Wratten 89B and go out on a bright sunny day to photograph scenes with a lot of green foliage. Or, if you don't have access to a real IR-pass filter, do the test using an unexposed (black) frame of slide film taped in front of the lens. (Slide film has about the same transparancy to near-IR light as the Hoya R72, but it is probably not as good, optically speaking.) A look at the resulting images and the histogram should tell you a lot of how capable the camera is in the infrared part of the spectrum.

For people to lazy to test, I've started this project to keep a record of the IR-sensitivity of the sensors in digital cameras, the IR-suitability of interchangable lenses and a list of filters suitable for IR photography.

2. IR and Sensors

Do you shoot infrared? Please click here to report your settings. I'll then include them in the table below.

This table indicate the relative IR-sensitivity of a number of popular digital cameras, sorted according to sensor and average EV. The higher the average EV, the more sensitive the sensor is to infrared light. For comparison, a camera's sensitivity to a scene lit by bright sunlight corresponds to EV around 15. To find out how less sensitive the camera is to infrared light, you subtract the Avg. EV in the column below from EV 15, and the result is the difference in number of stops.

Example: The Epson 850Z infrared light sensitivity with the Hoya R72 filter is EV 9, so it is about 6 stops (15-9) less sensitive to infrared light than to visible light with this particular filter.

Sony 1/2" 2.11 MPx
Camera Avg. EV Max f/ EV      T      f/ ISO Fltr. Link
Epson 850Z 9.0 2.0 8.9 1/60 2.8 100 R72 ddb #1
9.2 1/75 2.8 100 R72 ddb #2
Oly C20x0Z 8.1 2.0 8.6 1/100 2,0 100 R72 gd #1
7.9 1/30 2,8 100 R72 gd #2
7.9 1/60 2,0 100 RG715 jr #1
7.9 1/60 2.0 100 R72 gh #1
Nikon Coolpix 800 7.9 3.5 7.9 1/19 3.5 100 R72 rh #1
 
Sony 1/1.8" 3.34 MPx
Camera Avg. EV Max f/ EV     T     f/ ISO Fltr. Link
Canon G1 6.0 2.0 6.0 1.6 7.1 50 R72 cx #1
Minolta DiMAGE 5 6.0 2.8 6.0 1/8 2.8 100 R72 fm #1
 
Sony 1/1.8" 4.0 MPx
Camera Avg. EV Max f/ EV     T     f/ ISO Fltr. Link
Canon G3 5.3 2.0 5.3 1/5 2.0 50 ? ml #1
Canon A80 5.0 2.8 5.0 2 5.6 50 R72 cac #1
 
Sony 2/3" 5.24 MPx
Camera Avg. EV Max f/ EV     T     f/ ISO Fltr. Link
Minolta DiMAGE 7 7.3 2.8 7.5 1/30 3.5 200 ? rt #2
7.0 1/16 2.8 100 R72 dt #1
7.5 1/45 2.8 200 RG715 jr #2
 
Other compacts
Camera Avg. EV Max f/ EV     T     f/ ISO Fltr. Link
Canon G5 3.2 2.0 3.0 8 5.6 50 R72 ds #2
3.4 1 3.2 100 R72 gh #2
Panasonic DMC-FZ7 3.0 2.8 2.4 6 5.0 90 B+W092 grr #1
3.6 4 6.3 80 B+W092 grr #2
Oly 5050Z 2.4 1.8 1.0 3.2 2.0 64 ? kt #1
1.5 3 2.3 64 ? kt #2
2.6 1 2.0 64 ? kt #3
3.4 1 2.6 64 ? kt #4
3.3 1/2 1.8 64 R72 hc #1
Casio QV-4000 -0.6 2.0 -0.6 6 2.0 100 ? ca #1
 
DSLRs
Camera Avg. EV Max f/ EV     T     f/ ISO Fltr. Link
Nikon D100 7.6 - 7.6 1/6 8.0 200 IR720 ss #1
Nikon D70 7.0 - 5.3 1/3 8.0 400 R72 rt #1
8.7 1/13 8.0 200 W89B br #1
Nikon D50 6.5 - 6.5 1/15 3.5 200 R72 wjc #1
Fuji S2 6.0 - 6.0 1/4 5.6 200 R72 ddb #3
Oly E-300 4.3 - 4.3 1/4 4.5 400 R72 sh #1
Canon D30 4.3 - 4.9 4 11.0 100 B+W092 cs #1
4.0 2 8.0 200 R72 cx #2
4.0 1 5.6 200 R72 ca #2
Canon 350D 1.6 - 1.6 2.5 11 1600 R72 nn #1
2.7 10.0 8.0 100 R72 pn #1
0.7 0.8 4.5 1600 R72 fe #1
Fuji S3 1.5 - 1.5 23 8 100 W89B cm #1
1.5 23 8 100 W89B cm #2
Canon 10D/
Canon 300D
1.1 - 1.5 0.71 1.4 100 R72 bc #1
1.4 6.0 8.0 400 R72 aa #1
0.4 6.0 4.0 200 R72 gs #1
Canon 1D Mk2 0.7 - 0.3 4 9.0 1600 R72 nn #2
1.1 15 8.0 200 R72 nn #3
Nikon D200 -1.3 - -1.3 25.0 4.5 200 R72 an #1
Canon 20D -2.0 - -1.0 15 11 1600 R72 nn #4
-3.0 20 4.5 800 R72 ck #1
 
IR-modified / without IR-blocking filter
Camera Avg. EV Max f/ EV     T     f/ ISO Fltr. Link
Nikon D1 ir 15.3 - 15.3 1/320 16.0 200 W89B  
Canon 10D ir 13.8 - 14.0 1/1000 8.0 400 R72 je #1
13.6 1/400 11.0 400 R72 jwk #1
Oly 2040Z ir 13.3 1.8 13.3 1/500 4.5 100 RG715 jr #3
Sigma SD10 13.0 - 13.3 1/160 8.0 100 W87C ca #1
13.0 1/125 8.0 100 B+W093 spm #1
12.6 1/50 11.0 100 W87C rd #1
Canon D30 ir 11.9 - 11.9 1/60 8.0 100 W89B jrs #1
Nikon E990 ir 11.6 2.5 11.6 1/158 4.4 100 W87 rdh #1
Sony f828 ir 11.3 2.0 11.5 1/60 5.6 64 ? aw #1
11.0 1/200 4.5 200 ? aw #2
Minolta D7 ir 11.3 2.8 11.3 1/125 4.5 100 RG715 jr #4
Kodak DCS 460 8.4 - 8.4 1/16 3.3 80 R72 gh #3

How to read the table: The first column (Camera) list the camera model, the second the average Exposure Value (Avg. EV) computed for the camera, and the third the maximum aperture (Max f/) for the particular camera. Then the next six columns list image specific data: The EV for the particular image (EV), the shutter time (T), the aperture (f/), the ISO setting (ISO), the filter(s) used (Fltr.), and finally, in the Link column, the photographers initials, with a a link back to the page with the original image

Methodology: The EV numbers listed in the table are computed from images taken by different photographers, at different times and under different conditions. It would obviously have been better to make comparisons by setting up all the different cameras under identical conditions and make fair and direct measurements. However, I don't have the resources to do such a controlled experiment, and those who have (e.g. DPreview) are not suffiscient interested in ir-photography to include ir-sensitivity in their standardized testing suite. I give priority to images taken under roughly the same conditions, depicting the same subject matter. This means that if possible, I use images taken with a filter with an IR pass point of 720 nm (Wratten 89B or equivalent) depicting a bright sunlit landscape (EV 15 in the visible spectrum) with plenty of foliage. While these constraints are not suffiscient to eliminate all errors, it is the best I can do. What I eventually hope, is to have a large number of samples from each camera. By computing an average EV I hope that the “law of large numbers” eventually will even things out.

Disclaimer: Many of the samples linked to has been extensively post-processed by skilled artists. Do not assume that this is how the image appears out of the camera. The samples indicate at most what can be expressed by a skilled craftsman or artist and a particular camera, lens and filter combination.

3. IR and Lenses

hot spot exampleIn addition to the sensitivity of the sensor the quality of digtal infrared depends on the characteristic of the lens.

For example, the Canon EF-S 18-55mm f/3.5-5.6 typically produces a pronounced hot spot as can be seen in the sample picture to the left. The hot spot is a a result of internal reflections within the lens produced by the lens' coatings. Some types of coating are not transparent to near-infrared wavelengths. Almost any lens will exhibit more flare and ghosting at near-infrared wavelengths.

Below is a preliminary list of various lenses and whether they are suitable for digital infrared or not. The list is not a result of systematic testing, but com­piled from observations submitted by readers. The lenses listed in the intermediate category - May produce a hot spot, etc. - are those where I have inconsistent reports, or where the hot spot, flare and/or ghosting is so unobtrusive that modest post-processing will clear things up.

If you want to add to the list, or comment on one of the entries, please use the comment facility in my blog. If you want to read the original comments by the testers, and not just the summary below, the blog is also the place to look.

The recommended way of testing a lens' susceptibilty to the hot spot problem is to make an IR photograph of a sheet of white plain typing paper.

Fixed focal length

Recommended for IR:
Asahi Super-Takumar 55 mm f/1.8 MF (*)
Canon EF 28 mm f/2.8
Canon EF 35 mm f/2.0 (*)
Canon EF 50 mm f/1.8 MKI
Canon EF 50 mm f/1.8 MKII
Canon EF 100 mm f/2.8 macro
Canon EF 135 mm f/2.0 L
Lensbaby 50 mm f/2.8
Nikon 20 mm f/2.8 D
Nikon 20 mm f/3.5 AI-S
Nikon 28 mm f/3.5 PC AI-S
Nikon 85 mm f/1.8 Pre-AI MF (*)
Peleng 8 mm fisheye
Phoenix 100 mm f/3.5 macro
Sigma 105 mm f/2.8 EX DG macro (*)
Vivitar 24 mm f/2.8 MF (*)
May produce a hot spot, etc.:
Canon EF 85 mm f/1.8
Canon EF 200 mm f/2.8 L
Gives hot spot:
Canon EF 20 mm f/2.8
Canon EF 24 mm f/2.8
Canon EF 50 mm f/1.4
Canon EF 50 mm f/2.5 macro
Carl Zeiss Planar T* 50 mm f/1.4 (for Contax)
Nikon AF 50 mm f/1.8 D
Sigma 30 mm f/1.4

Zoom

Recommended for IR:
Canon EF-S 10-22 mm f/3.5-4.5 USM
Canon EF 17-40 mm f/4 L
Canon EF 24-70 mm f/2.8 L
Canon EF 24-105 mm f/4.0 L
Canon EF 28-135 mm f/3.5-5.6 IS
Canon EF 70-200 mm f/4.0 L
Canon EF 75-300 mm f/4.0-5.6 IS
Canon EF 100-400 mm f/4.0-5.6 IS L
Nikon 18-55 mm f/3.5-5.6 G AF-S ED DX
Nikon 24-70 mm f/2.8 ED G AF-S
Nikon 24-70 mm f/3.5-5.6 UC
Nikon 35-70 mm f/2.8 AF-D
Nikon 35-70 mm f/3.3-4.5 AF (1986) (*)
Nikon 35-135 mm f/3.5-4.5 AF
Nikon 70-210 mm f/4.0-5.6 AF-D
Nikon 70-300 mm f/4.5-5.6 G IF ED AF-S VR
Sigma 12-24 mm f/4.5-5.6 EX
Sigma 18-50 mm f/3.5-5.6 DC (*)
Sigma 55-200 mm f/4.0.5.6 DC (*)
May produce a hot spot, etc.:
Nikon 18-70 mm f/3.5-4.5 AF-S G ED DX
Sigma 10-20 mm f/4.0-5.6 EX DC HSM (*)
Sigma 70-200 mm f/2.8
Gives hot spot:
Canon EF 16-35 mm f/2.8 L
Canon EF-S 18-55 mm f/3.5-5.6
Canon EF 24-85 mm f/3.5-4.5 USM
Canon EF 28-70 mm f/2.8 L
Canon EF 35-80 f/4.0-5.6
Canon EF 70-200 mm f/2.8 L IS
Nikon 12-24 mm f/4.0 G IF ED AF-S DX
Sigma 18-50 mm f/2.8 EX
Tamron 17-35 mm f/2.8-4.0 SP AF Di
Tamron 17-50 mm f/2.8 SP AF XR Di
Tamron 18-200 mm f/3.5-6.3 AF XR (IF) Di-II
Tamron 70-300 mm f/4.0-5.6 AF LD macro
Tokina 12-24 mm f/4.0

Lenses marked with a (*) has been tested by me.

4. IR Filters

spectrum Visible light ranges from 400 nm (violet/blue) to 700 nm (red). Wavelengths above 700 nm and up to about 5000 nm are known as near infrared - but most digital sensors lose their sensitivity around 950 nm, so “infrared photography” is really about capturing light at wavelengths between 700 and 950 nm.

In infrared photography, the camera is used to capture infrared light reflected from a body. This may be used for artistic effect. Some scenes - in particular foliage - reflect near infrared light different from visible light. (Note that this has nothing to do with thermal photography, where the idea is to capture heat emitted by a body. Thermal photograhy uses the mid-infrared spectrum (above 5000 nm) - and to capture it you need a specialized thermal camera.)

To capture near infrared with ordinary digital sensors, we need to stop visible light from overexposing the sensor. To do this, we fit an visible light blocking filter (usually referred to as an IR-filter) to the lens. To get most of the IR-effect many photographers are interested in (white foliage, etc.), you should use a filter that cuts as much visible light as possible, while letting through infrared light in the band that the camera's sensor is capable of recording. Which filter is optimal depends on the camera's sensitivity to near infrared light, the cutoff wavelength of the hot mirror most cameras are fitted with, and the effect desired. You may need to experiment to find the right filter.

The table below gives the IR pass point (the first wavelenght for which the absortion is less than 50%) for a number of popular filters. For good measure, I've also included some filters with a pass point in the red end of visible light, as well as some filters with a pass point too high for most standard digital cameras.

nmWrattenHoyaHeliopanB+WOtherComments
600 W25 25A 1025 B+W090-Red
625 W29 - - B+W091-Deep red
680 W70 - - - -Dark red
695 - - RG695 B+W092--
700 - R70 - - --
715 - - RG715 - --
720 W89BR72 - - Cokin A/P007-
750 W88A- - - --
760 - IR76 - - --
780 - IR80 RG780 - Tiffen 87-
795 W87 - - - - -
830 - IR83 RG830 B+W093--
850 W87CIR85 RG850 - --
860 - RM86 - - --
930 W87BRM90 - - --
1000- RM100 RG1000B+W094--
1050W87A- - - --

An abbreviated notation is used. The prefix “W” designates the Kodak Wratten series (e.g. W89B is Wratten #89B), the prefixes R, IR and RM is used by Hoya, RG is used by Heliopan, and B+W is used by Biermann+Weber.

The data from the manufacturers don't always add up. I've compiled the table above by using the Schott Glass (manufactures filters for Heliopan and B+W) and Hoya spectral curves and Wratten compatibility charts as reference, and placed the others according to their own Wratten compatibility charts. However this does not always match the data sheets.

The table show which filters have similar 50% pass points, but it does not tell the whole story. For example: Some filters, like the Hoya R-series, have a sharp cutoff gradient, others, like the Hoya RM-series, are more gradual, and some have a weird slope. To study this slope, you need to refer to the filter's spectral curve or transmittance chart. Use the table as a rough guide - nothing more.

There is no “ideal” IR-filter, but Hoya's R72 filter is very popular. This is probably because it is relatively cheap (at least when compared to some of the others), and widely available. It also have a very low cutoff point, so it can used with cameras whose sensitivity in the near-IR region is low, If you are starting out with infrared, and don't know which filter to get, I suggest you start out with the Hoya R72 or similar. The stronger filters, such as RM90, will cut of much more visible light and produce a more pronounced “IR-effect” - but may not work at all with an unmodified camera.

Thanks to Joseph S. Wisniewski for corrections.

5. Exposure Value

The exposure value (EV) system was invented in the 1950s to give an absolute measure of expo­sure needed. You get an EV when you combine sensor sensitiv­ity, shutter speed and aperture. Sensor sensitivity settings, shutter speed and aperture combina­tions that results in the same exposure have the same EV (e.g. ISO 100, f/8 and 1/125 have the same EV as ISO 100, f/5.6 and 1/250 and ISO 200, f/8 and 1/250, and so on). EV is designated by integers such as ..., -2, -1, 0, 1, 2, 3, 4, 5, ... . Each increment of 1 EV corresponds to a increase in the light reaching the sensor by a factor of 2 (letting you use half the ISO value, double the shutter speed, or close the aperture down 1 stop).

Formally, at ISO 100, EV 0 corresponds to a shutter speed of 1 second and an aperture of f/1.0:

EV 0 = (ISO 100, f/1.0, 1 second)

EV 0 is very dark, e.g. a night scene with dim ambient light. By comparison EV 15 is f/16 at 1/125th second, at ISO 100 - this is what you would use for a landscape in bright sunlight (aka known as “sunny sixteen”). EV 8 corresponds to f/2 at 1/60th of a second at ISO 100. To use a digital camera for handheld infrared photography, I think it should have an EV of eight or more if its maximum aperture is f/2.0, and nine or more if its maximum aperture is f/2.8 (YMMV).

A basic problem with digital IR photography is that thermal noise increases and “hot” pixels appear due to the long exposure times involved. This means that EV is not the only thing that determines suitability of a particular sensor. If a less sensitive sensor has better noise characteristics, then it may be give an overall better IR-performance than one with a higher EV number but worse noise characteristics.

See Fred Parker's Ultimate Exposure Computer if you are interested in learning more about EV.

Note: There is some confusion whether EV takes film speed into account or not. Some insists that EV is only valid for ISO 100, and use a different term, such as light value (LV), or actual EV (aEV) for a number that is a function of the film speed, aperture and shutter triplet. To cut a long story short, the most useful metric for digital, where film speed is just as variable as the other two, is one that takes film speed into account, so that is what I use and call EV. Please note that the calculator featured in the excellent glossary at DPreview is in agreement.

6. Technique

Focus Shift

To get an infrared image in focus, it must be short focused (i.e. you need to focus closer than you normally would). Most fixed focal length lenses have a mark, e.g. a red “R”, a small red dot, or some other indicator of the focus shift to apply at infinity.

IR focus marksOn the 28-85 mm zoom depicted to the right, there are two focus shift marks engraved on the lens, representing two different focal lengths of the zoom.

If the focus shift mark is missing, focus well in front of the closest subject of interest. For a 28 mm wide-angle lens, a focus setting around 5-10 m will be suitable for an infinity infrared shot. Experiment with your lenses to learn the right amount of focus shift to apply. If you are doing close-ups using bellows, a rule-of-thumb is to increase the extension by 10% to compensate for the focus shift.

Another way to compensate for the IR focus shift is to use a large DoF. Small apertures increases DoF, but long exposure times may result in motion blur from leaves moved by the wind, etc. A wider angle also increases DoF, but wide angles tend to have a larger focus shift.

Viewfinder blackout

Because an ir-pass filter is opaque to visible light, the viewfinder of a DSLR camera will not let you frame the subject with the filter in-place. One work-around is to use an accessory viewfinder in the camera's accessory shoe.

Voigtländer KonturThe image to the right shows a used Voigtländer Kontur 50 mm accessory viewfinder. Originally made for the Voigtländer Vitessa in the 1950ies, it was picked up at eBay for less than $20 (expect to pay a lot more for a unit in mint condition). It has a very unusual design. The center of the viewfinder blacked out. Instead, it shows the frameline for the field of view of an f=50 mm objective when using 35 mm film (the “35 m/m” legend on the front refers to film format, not field of view). The idea is that you look through it with one eye, keep the other eye open, and your brain combines the two images to show you the scene with a bright frameline and excellent peripheral vison. With some experience, you should be able to use the Kontur to frame almost any focal length, by mentally adjusting for the smaller or larger field of view.

When using an accessory viewfinder on a digital camera, one need to adjust for the crop factor. If one uses the Voigtländer Kontur shown above on a camera with 1.5x crop, its field of view will correspond to 50 mm/1.5=33 mm actual focal length.

Aperture

Because of the longer wavelength of near IR light, diffraction works differently. Standard diffraction limits is based upon a mid-green wavelength around 550 nm. When you capture near-IR light, with (say) a R72-filter your spectrum is centered around 850 nm. In practice this means that your running into diffraction problems 1-2 stops before you do with visible light, so a lens than performs at its sharpest at f/11 with visible light will be best at f/5.6 or f/8 when used for near-IR photography.

7. Infrared Linkfarm

Tutorials, Techniques & Resources:
Ross A. Alford: Experiments with digital infrared photography
Stephen R. Brown: Infrared photography with digital cameras
Gerard Buckleman et al: Infrared Photography Forum
David Burren: Digital IR Choices
David Burren: Infrared images with a digital camera
Brad Buskey: Infrared Photography Techniques
E. Cheng: Digital Infrared Photography
Wayne J. Cosshall: Camera Tests for IR Photography
Andrew Davidhazy: Infrared photography
Dale O'Dell: Digital Infrared Photography Made Easy
dpFWIW: Infrared basics for digital photographers
Andy Finney: Books on Infrared Photography
Rob Galbraith Forums: Kodak DCS and IR
Peter iNova: Pictures of a Warm World
Dave Larson: Infrared Conversion Work Flow
Jerry Lodriguss: Canon EOS 1DM2 and 20Da IR Daylight Tests
Maher & Berman: How to shoot IR
S. P. Merrill: Infrared Post Processing with Sigma Photo Professional 2.1 + PS
Bjørn Rørslett: IR Colour Photography
Jens Rösner: Infrared and modding
Luben Solev: Infrared Photography Tutorials
Clive Warren: Infrared Photography Faq
Wikipedia: Infrared photography
R. R. Williams; Digital Infrared Nikon D100
J. A. Wrotniak: Infrared photography with a digital camera
Removing the hot mirror and IR-sensitive cameras:
Canon G-series (Tony Kaplan)
Fujifilm FinePix S3 Pro UVIR (DPreview)
Minolta D7x (Jens Rösner)
Nikon 950/990 (James Wooten)
Nikon D70 (Astrosurf)
Olympus Cx0y0 (Jens Rösner)
Sigma SD10 (Gisle Hannemyr)
Webcam ir hack (Geoff Johnson)
David Burren IR-enables many DSLRs + compacts
Hutec: IR-enables various Fuji and Canons
Lifepixel: IR-enables Canon, Fuji and Nikon cameras + DIY tutorials and materials
Maxmax: Sells IR-enabled digital cameras
Galleries:
Daniella: Infrared with DiMAGE 7
Don Ellis: Kleptography (IR enabled Canon G1)
Chris Maher: Fine Art Infrared Photography
Cory Shubert: Nikon 990 Infrared Gallery
Corry Lee Smith: Infrared
David Twede: Surreal Color Photography
Science:
Sue Ann Bowling: Two kinds of infrared
Gilblom & Yoo: IR and UV imaging with the Foveon X3 sensor
Ipac: Near, Mid & Far Infrared
Williams & Williams: Pioneers Of Invisible Radiation Photography
Misc (blogs, boards, communities):
Flickr Groups: Digital Infrared
Flickr Groups: Infrared
Yahoo Groups: Infrared Photoraphy

Copyright © 2007 Gisle Hannemyr


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