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infrared photography

www.ayton.id.au_gary_photos_victoria_ga_ir_gumtree_2k0c3295.jpg

Introduction:

  • classic near IR photography requires detection of the 700-900nm range of IR 
  • photography of infra-red region of the light spectrum allows:
    • unusual landscape photos with false color or unusual monochromatic effects
      • suggested subjects:
        • graveyard shots - grass will go almost white leaving the tombstone floating in an eerie space, similarly for standing stones.
        • derelict buildings covered in creepers - again the contrast of stone and vegetation. See Pete Schermerhorn's excellent article on castles in Ireland.
        • people on the beach - sky and skin, water reflecting sky
        • nudes in a landscape - skin and vegetation and/or sky
        • haze reduction - only reduces blue haze, but try it
        • hot houses - vegetation
        • people with sunglasses - it is sometimes possible to see the eyes behind seemingly opaque sunglasses.
      • composition hints:
        • visualise the elements in the photograph by the way that they reflect infrared light.
        • blues, browns, dark greens in shadow will all appear dark in the final print. Reds, whites, greens in sunlight will appear light in the final print.
        • the eye is drawn initially to areas of high contrast in a photograph, so frame the elements to lead the viewer into the scene from the high contrast starting point.
        • try using strong graphical shapes with high contrast to lead the viewer into the photograph and place important elements using the rule of thirds.
        • finally, every so often throw the rules out and do something just because it feels right or because you want to experiment
    • portrait photography, esp. to minimise skin complexion problems such as acne.
      • skin looks bleached and may show veins
      • eyes are dark, brooding & dramatic
    • scientific uses
    • astrophotography - most nebulae have strong emissions in the infrared H-alpha band
  • general hints:
    • there is more infrared light around when there is bright sunlight. This doesn't mean you should avoid using IR film in other conditions but that the effects are stronger when the sun is out.
    • largest amount of IR: the hours just after sunrise and before sunset (due to the angle of the sunlight through the atmosphere), the effect is most dramatic (i.e deep black sky) when photographing with the sun behind the camera.
    • an electronic or bulb flash will increase the amount of IR as well as visible light.
      • Electronic flash guns and flash bulbs emit plenty of infrared light together with visible light. This means that you can use fill-in flash and flash alone for shooting in infrared. You will need to calibrate your flash for the infrared film of choice through test exposures.
      • The use of flash allows an interesting possibility - you can use a filter over the flash to reduce or eliminate the visible light output and take infrared photos in the dark without any apparent light. This means that you can take photos without out disturbing your subject or alerting them to the fact that a photo has been taken. If there is no ambient light then an infrared filter over the flash gun is all that is required. If there is ambient light then a filter will also be required over the lens as most infrared film is sensitive to some visible light.
    • thermal radiation will not be recorded by infrared film; infrared films are not sensitive to a long enough wavelength to show such things as heat patterns, however, IR can be used to photograph self-luminant objects as cool as 250 degrees C.
  • creating a IR-pass filter for an electronic flash:
    • A cheap and cheerful way of making a flash filter is by using two strips of unexposed but developed E6 film as an approximation to a Wratten 87 (for more info. contact: Andrew Davidhazy). Be careful on the frequency of flash use.
    • It appears that one thickness of E6 film is roughly the equivalent of an 87 filter but with a broader spectral response and with some 1% transmission valleys at 500 and 600 nm. Its transmission starts to drop from 1% at 700 nm to about 95% at 800 nm. Two thicknesses of D max E6 are basically visually opaque with transmission starting at 720 nm and dropping quite rapidly to 90% or so at 850 nm.
    • Basically the two sheets of E6 simply do not have a cutoff as steep as the Wratten filters nor is the maximum transmittance of light as good. But they are serviceable, particularly for placing over a flashgun where the expensive thin gel Wratten filters tend to fry and buckle!
    • There is another option for the DIY fanatics - paint your own filters and bulbs. The formula for the infrared paint requires a range of chemicals, some of which have to be purchased in bulk. This could be an expensive exercise, however the formula and instructions on concocting the brew are in this article.

 

Infra-red filters:

  • whether using IR film or a digital camera, you need a IR filter which allows IR light but blocks most or all visible light if you want to get IR effect.
  • the degree of IR effect is higher as the cutoff frequency increases, but the filter also becomes darker so composition through it may be impossible to visualise, necessitating that composition is performed PRIOR to adding the filter UNLESS you have a live preview digital camera that is sensitive to IR (ie. does not have an IR blocking filter as most have).
  • as infrared filters get very expensive above 58mm and in most SLR cameras are too dark to compose, consider hand held square IR filters such as Cokin 007 (#89B), Heliopan RG715 and Infrarex IR filter set of red (RG1), dark red (RG2) and black (RG3) but note that the RG3 is of no use on the Rollei IR 820/400 IR film but may be of use on some digital cameras. 

red filters:

  • general notes regarding use of these filters:
    • for most digital and film work, the IR effect will be minimal unless using Kodak HIE film or Konica IR750 film.
  • Hoya 25A (Wratten #25):
    • min. wavelength 580nm - actually a red filter
  • Wratten #29 (B&W #91):
    • min. wavelength 600nm - dark red filter, only needs 3 f-stop increase in exposure, OK for portraits and Kodak HIE film 
  • Wratten #70 :
    • min. wavelength 640nm
    • less pronounced than & lose the light-coloured trees effect as with Hoya R72 but only need exposure increase of 7 f-stops which may allow hand-held photos with some digital cameras
  • B&W 092 (89B, RG695, Cokin IR007):
    • dark red filter is for black and white infrared films and filters at light below approximately 650nm. It allows pictures of a pure red image while making good use of the relatively low sensitivity of infrared films. Filter factor is approx. 20-40
    • good IR for Kodak HIE and Konica 750 film
    • not really deep enough for digital IR
    • blocks nearly all below 650nm;
    • blocks ~50% between 650-700nm;
    • blocks ~10% between 730-2000nm;

usual "infrared" filters:

  • general notes regarding use of these filters:
    • for most uses, you will not be able to compose through the filter as it is too opaque and thus you need to compose first then place the filter on, unless:
      • using it on a digital camera with live preview with good IR sensitivity
      • using it on a rangefinder or twin lens reflex film camera
      • install the filter in front of the film or sensor but behind the SLR mirror so it doesn't block your viewfinder image.
    • exposures will be longer as the minimum wavelength increases and may become very long if exceeds the film or sensors wavelength sensitivity:
      • Konica 750 film has minimal sensitivity at > 800nm ⇒ best to use R72 or lighter filters;
      • Kodak HIE film has minimal sensitivity at > 940nm
      • Kodak TMax 400 has minimal sensitivity at > 680nm
      • Rollei IR has minimal sensitivity at > 820nm
  • Hoya R70:
    • peak at 700nm;
  • Hoya R72:
    • min. wavelength 700nm; 50% by 720nm and 85% by 750nm;
    • probably the best IR filter for general use
    • works well on digital cameras as long as subject is not moving and you use a tripod, although you may have difficulty composing even with live preview digitals, although in bright sunlight, can use Olympus models with their live boost ON and a f/2.0 lens.
    • composition impossible with unmodified Nikon, Canon dSLRs
    • gives good IR effect with all IR films and is usually the most affordable filter, but still gets expensive in sizes > 67mm.
  • Wratten #88A (Heliopan 5715):
  • XNite 715:

more extreme IR filters which may not work on some digital cameras

  • Lee IR technical 730nm:
    • min. wavelength 730nm
    • works on Canon 1DMIII for IR (ISO 400, f/5.6, 25sec for bright sunlight)
    • the IR blocking filter on the Canon 5DMII is too strong and gives NO IR effect with this filter but just acts as a ~26 stop neutral density filter! - ISO 3200, f/4, 30sec in bright sunlight but no Wood's effect
  • Hoya R76:
    • peak at 760nm;
  • Wratten #87 (Heliopan 5780):
    • min. wavelength 740nm, cuts off all visible light but then can't see image to compose with so limited use
  • Hoya R80:
    • peak at 800nm;
  • B+W Infrared 093 (Wratten #87C / Heliopan 5830 / RG 830):
    • min. wavelength 800nm;
    •  Unlike the 092 infrared filter, it makes pure infrared photographs possible without the visible red component. Its transmission only begins to exceed 1% at 800 nm, rising to 88 % at 900 nm, and remains that high far beyond the upper limit of sensitization covered by infrared films. In the scientific field, materials research and forensics, the limitation to a strictly infrared range is often important. The filter factor is very dependent on the illumination and on the characteristics of the film.

filters which are too extreme for current films but were good for Kodak HIE

  • Hoya R83:
    • peak at 830nm;
  • Hoya R85:
    • peak at 850nm;
  • XNite 830:
  • Hoya RM86:
    • peak at 860nm;
  • Wratten #87B (Heliopan 5850 / RG 850?):
    • min. wavelength 820nm; 50% transmission at 930nm;
  • Hoya RM90:
    • peak at 900nm; $A247 for 58mm! cannot compose image though;
  • XNite 850:
  • Wratten #87A (B&W 094 / Heliopan 5100 / RG 1000):
    • min. wavelength 880nm; 50% transmission at 1050nm;
  • Hoya RM100:
    • peak at 1000nm;
  • XNite 1000:

Infra-red film:

  • IR film has an emulsion that is sensitised to respond to a wider range of light and radiant energy than standard film, allowing it to record not only visible light, but also the near infra-red end of the spectrum.
  • in contrast, normal “panchromatic” B&W films record only to about 700nm & eyes are sensitive from ~400 to 760nm
  • it is a B&W film that is used for creative purposes as images will show a sharp shift in tonal values, esp. in bright sunny weather when objects transmit & reflect a lot of infrared light such as healthy foliage, which then record almost white & luminous. In contrast, open blue skies & bodies of water that reflect little IR, are printed very dark which can create stunning contrasts with clouds. Portraits can be interesting as it causes skin tones to look bleached, may expose veins, whereas eyes look dark & brooding, allowing a dramatic or spooky or more magical effect.
  • IR film also cuts through haze in distant landscapes & can also be used at night in the dark if there is a IR lightsource.
  • see comparison of films here

IR films:

Kodak HIE:

  • discontinued Dec 2007.
  • the most sensitive (to 900nm, peak 750-840nm) & provides the most spectacular results
  • low sensitivity to green; fine grain & very sharp;
  • no anti-halation layer & must be loaded in total darkness;
  • the dimpled pressure plate of Olympus OM cameras is only a problem with 87 or deeper filters, and only on bright scenes.
  • good IR effects even with Wratten 25:
    • bracket exposures, Kodak recommends starting with the following settings with a Wratten 25 filter:
      • for bright to hazy sunlight or electronic flash: 
        • use 50-100ISO metered without the Wratten 25 filter in place, or,
        • 1/125th f/11 for distant objects (f/16 without a filter)
        • 1/60th f/8 for nearby objects
      • for tungsten lighting, effective ISO increases by 1 to 1.5 stops. 
    • add 0.5-1 stop for R72 filter (?use ISO 50),and 1-2 stops for #88A filter (?use ISO 25) and ~2-3 stops for Hoya RM90 filter (?use ISO 12);
  • relatively expensive and unfortunately not available in 120 format
  • although gives the best Woods IR effect, it tends to lose highlight detail in high contrast scenes more than the other films, and is much more grainy (the other films have similar grain to Kodak TMax 400)
  • Unfortunately Kodak is discontinuing manufacture of this unique film in Dec 2007, so Kodak HIE will be no more - see link

Efke IR820c

  • formerly, Maco IR820c
  • Croatian film manufacturer Efke uses same recipe as for Maco IR820c to make this film
  • need IR filter for Wood's effect (25A red filter will not give IR effect as with Kodak HIE film)
  • fine-grained, sharp;
  • “very high” sensitivity up to 820nm then sensitivity rapidly falls and cuts off at 850nm and thus the manufacturer does NOT recommend extreme filters such as #87B 1);
  • closest rival to HIE but 2 stops slower;
  • 135 film should be loaded in total darkness;
  • 120 film size available can be loaded in very subdued light.
  • for each series of bracketed exposures, shoot one frame without a filter exposed at ISO 100 to help address processing issues
  • has an anti-halation layer (processed out during development leaving a clear base); 
  • AURA version gives halo effect.
  • can use TTL metering set at ISO100 if using yellow, orange or red filters but not if using infrared filters.
  • if using a handheld lightmeter, set to ISO12-25 when using a 25A filter and ISO 1-6 if using an IR filter.
    • decrease exposure by about 0.5 stop if shooting in tungsten light instead of daylight
  • reciprocity failure: double exposure at 4secs; triple exposure at 8 secs; results will be more contrasty with deeper shadows.

Rollei 400 / Rollei IR 820:

  • peak sensitivity at 670nm then drops rapidly to 820nm 
  • fine grained; sharp; suitable for scanning;
  • 135 film should be loaded in total darkness;
  • 120 film size available can be loaded in very subdued light.
  • film should be kept below 8degC if possible and developed ASAP after exposure.
  • halo / aura effect by over-exposure.
  • similar to Maco IR820c but rated at ISO 400 without filters.
  • yellow (#8) then rate at ISO 200-320
  • dark yellow (#15) then rate at ISO 200
  • yellow/green (#11) or orange (#21) then rate at ISO 100-200
  • red(#25), RG 715 (Heliopan) or Kodak #88A IR filters, then rate at ISO 25
  • Hoya R72, try ISO 12 (but this will over-expose sunlit skin)
  • RG 780 or #87C and higher not recommended as no image will be obtained
  • only mild IR effect with 25A red filter - blue sky is rendered as mid-grey.

Konica IR 750:

  • slower, very fine grain; speak sensitivity 700 to 740nm with minimal semsitivity beyond 750nm; not sensitive to green;
  • easy to handle as has an anti-halation layer & can be loaded in subdued light
  • lovely tonal rendition with Wratten 25 (effective ISO ~6) but needs 89B (effective ISO = 3-8) for best IR effects;
  • use ISO 3 with Hoya R72 filter and ISO 1.5 with #88A filter;
  • stocks only produced once a year around April.
  • maybe available in 120 film size;
  • spectral curves have two peaks:
    • 360-510nm with peak at 440nm;
    • 650-800nm with peak at 750nm;

Ilford SFX 200:

  • not a true IR film, and the least sensitive of the four, only to 740nm (peak 720nm); easy to handle as has an anti-halation layer & can be loaded in subdued light
  • large grained, great for dramatic high-contrast effects only; latitude +1 to -1 stops
  • need Wratten 89B or Ilford's own SFX filter to give good IR results
  • Kodak Ektachrome color IR film:
  • has 3 layers:
    • yellow 350?-600nm
    • magenta 350?-700nm
    • cyan 350?-920nm
    • THUS, film can be scanned and processed as cyan - (yellow + magenta) and used for similar effect to Kodak HIE with 89B without need for an IR filter!

precautions using IR film:

  • most must be loaded into camera in complete darkness as its lack of anti-halation layer which normally prevents flare from bright lights, in addition to giving the film its wonderful glowiness in the highlights, makes it extremely sensitive to fogging by stray light.
  • must be loaded into a IR-safe processing tank (eg. Paterson tank) in complete darkness
  • should be stored in its original container in the fridge or freezer until ready to use then defrosted to room temperature before opening to avoid condensation
  • must be stored lower than 55degF if possible as high temps will cause fogging - ie. a cool place ⇒ NOT in the car!
  • to keep out visible light which would take away its effects, must use a red filter such as Hoya 25A (Wratten 25) - can use a deeper filter such as Hoya R72 (Wratten 89B) but this appears opaque and one can not focus or compose through it, and thus it must be applied just prior to taking the photo.
  • there is no ISO rating like normal films, so have to bracket exposures +/- 2 stops in 1 stop increments, try using the following for Kodak HIE film with Hoya 25A filter:
    • bright sunshine in warm summer conditions: set ISO to 400 & use TTL meter as a starting point
    • cooler but bright sunny days in spring/autumn: set ISO to 200
    • cooler, overcast day: set ISO 100
  • focusing issues:
    •  IR focuses slightly closer than visible light which is an issue with simple lenses and achromatic lenses but not a real problem on apochromatic lenses or pure mirror lenses.
    • on many SLR lenses, there is a red marker to indicate IR focus
    • it usually is not a problem if there is sufficient depth of field such as when using a wide angle lens for a landscape.
    • beware that stopping down a lens to create depth of field may make things worse as the diffraction limits are much worse for IR and thus you need to use a larger aperture to avoid this (eg. f/8 is normally the smallest aperture on prosumer digitals due to diffraction issues, for IR, you may need to settle with f/5.6 or 6.3 being the smallest aperture).

processing IR film:

  • home processing Kodak HIE:
    • standard developer such as Kodak D-76 or Ilford ID11 using stock solution
    • 11 minutes at 20degC in a small Paterson tank, agitating continuously for the 1st 30 secs, and then once every minute (5 inversions).
    • this is followed by a brief stop bath of 30sec then a fix of 2-4 minutes
    • wash the film for 15-20min at temp. within 5deg of processing temperature

printing IR film:

  • make a contact strip and look for frames where black of scene matches the black of the film base with a density roughly equivalent to normal negatives
  • remember to allow highlight areas to glow & sparkle
  • dense HIE negatives show a rapid increase in grain and reduced tonal separation and will interpret ghostly, grainy & dramatic.
  • experiment with the different moods.

 

IR photography with digital cameras:

  • summary of what you need:
    • digital camera with:
      • filter thread to allow infrared filter eg. Hoya R72 (although you can handhold it if desperate)
      • a way of composing the image:
        • optical viewfinder (non-TTL) may be best as one can actually see, or,
        • live preview LCD screen - although may still be difficult to see image
        • ie. NOT a digital SLR unless it does have live LCD screen or live AV out to an external LCD.
      • preferably a mode that removes the usual IR-blocking filter eg. Sony nightmode style, or at least a camera known to be reasonably sensitive to IR
      • a sturdy tripod - most exposures will be 1-5 secs at least unless the IR-blocking filter has been removed.
      • ability to save in RAW mode to get the best results, although TIFF is OK, although big - use jpeg as last resort as the substantial image processing will lead to excessive artefacts.
    • image processing software such as Photoshop
  • most digital cameras have a CCD sensitive to near IR light up to ~1100nm, but also have a special IR-blocking filter in front of the CCD as the IR light would otherwise degrade the image, thus sensitivity ranges are usually:
    • normal digital cameras with IR & UV blocking filter: 400nm to 750nm
    • normal digital camera with IR & UV blocking filter removed: 280nm to 1200nm, but because CCD sensitivity is reduced at the extremes, the practical range is approximately 325nm to 1100nm.
  • the best time to shoot IR is either in the late morning or early evening. When the sun is directly overhead, it is hard to get good contrast between IR sensitive objects and the sky.
  • focusing:
    • ideally, the live preview on your camera will display sufficient detail with your IR filter on so that you can manually focus
    • if your camera will not focus with your IR filter in place, then consider using a old manual focus lens with IR marker, then without the IR filter focus then adjust focus to the IR marker then replace the IR filter.
  • IR-pass filters which must be used:
    • as with film cameras, for daytime use, still need to use a filter to block normal visible light.
    • see above under filters;
  • exposure:
    • digital cameras have the advantage that their auto-exposure & auto-focus should still work BUT be aware that the camera will try to adjust exposure so that average of all 3 RGB channels is correctly exposed, BUT THIS IS NOT WHAT WE WANT as the main channel we are interested in, the red channel will be grossly over-exposed, so you need to set exposure compensation perhaps to -1 to 2 EV. You will not be able to rely on the camera's histogram either unless it shows the 3 RGB channels rather than the resulting jpeg image histogram. Thus your exposure will need a bit of trial and error comparing your red channel results with your camera exposure compensation setting. 
  • monochrome images:
    • ideally one should shoot in RAW mode, then in Photoshop, select the red channel and convert to monochrome then adjust the levels to improve the contrast.
    • some cameras allow in-camera generation of monochrome images by selecting Black and White option but this will use all 3 RGB channels which is not what we want.
  • color IR images:
    • colour IR is not easy to achieve on cameras with high IR blockade, while they are possible on the Sony F7x7 with a R72 filter, the Sony F828 appears to give better colour IR is one uses a deep red 29 filter instead. 
    • try setting WB to manual and metering with filter on for interesting colour effects - sepia-like
    • or, take 2 identical photos, 1 with the filter and 1 without the filter but exposed normally but at same aperture to ensure consistent depth of field
    • post-processing method 1:
      • selecting the color image, selecting the entire image (ctl-A), clicking on the “Channels” tab and selecting the green channel and copying this (ctl-C), selecting the blue channel and pasting (ctl-V). Repeat the process to copy the red channel into the green channel. Select the IR image, select the entire image, copy the red channel, return to the color picture and paste it into the red channel.
      • this may produce “crazy” colors
    • post-processing method 2:
      • Take the color image and convert it into “Lab Color” mode. Take the IR red channel and copy into the “Lightness” channel. This creates color images that “pop” very well and have very dramatic skies.
    • post-processing a Sony green nightshot image with R72 filter on:
        • create duplicate layer
        • open hue/saturation and set green saturation to minus 100%
        • then change master to: hue = +124 and saturation = +50 to 60
        • use Gaussian blur of 3-5 pixels radius on background copy layer to reduce noise
        • change background copy layer to layer method “colour”
        • use auto-levels on background layer
        • open hue/saturation on background layer & set red saturation to minus 100%
        • flatten the layers
    • post-processing via Daniella (“zylen)” method using a Dimage 7:
      • take a good photograph with good subject, white balance to tungsten, color saturation to -3 or -2 and contrast to -2.
      • copy the layer and apply auto-level. Adjust the slider to adjust the result. Once the result is ok, merge them.
      • copy the layer again, then adjustment, channel mixer and swap the blue and red channel. Keep the unswapped image underneath. You can add a layer mask and blend the swapped and unswapped image, and reveal or hide part of the swapped image that you want or don't want.
      • create a new layer and use “color” mode for the blend. Then use the color that you want and spray the area to tint the area that you want to correct.
    • post-processing via Ralph Croning's method:
      • take a photograph using custom WB on sunlit grass through the R72 filter
      • Image > Adjustments > Channel mixer:
        • in RED channel: red = 0% and blue = 100%
        • in BLUE channel: red = 100% and blue = 0%
        • Click OK
      • Image > Adjustments > Hue and Saturation
        • From the drop down menu choose Reds and desaturate to minus 100
        • From the drop down menu choose Magentas and desaturate to minus 100
        • If the pic is dark choose Blues from the drop down menu and adjust lightness to plus 70 or to your taste
        • If your photograph is overexposed all the overexposed areas will show up as yellow.
          • In this case you will then also choose Yellows from the drop down menu and desaturate to minus 100 or according to your taste
          • While in yellow also adjust the lightness slider to the positive side till you achieve the desired brightness
        • When done click OK
    • Photoshop actions for digital IR post-processing:
  • cameras that have fixed IR-blocking filters:
    • very weak IR blocking allowing full sun exposures approx. 1/8 to 1/2 sec for f/4 at 100ISO:
    • Weak IR blocking allowing full sun exposures approx. 1-2 sec for f/4 at 100ISO:
    • Medium IR blocking allowing full sun exposures approx. 3-5 sec for f/4 at 100ISO:
    • Strong IR blocking requiring 15sec exposures in full sun at f/4, 100ISO:
        • results without modifying the camera and using a R72 IR filter on the lens outdoors on a partly cloudy day:
          • set Live Preview boost mode so composing and focusing IR is easier (can't do this with the 1DMIII which is much more difficult to compose and focus)
          • with the Olympus E510 Live Preview you can turn IS on which makes accurate focusing even easier if hand held
          • sunlit exposure on the E510 of ISO 800, f/2.0, 1/5th sec
          • interestingly, unlike many other dSLRs, the blue channel does not have as much sensitivity to IR
          • AWB gives a yellow-green caste which as usual for digital IR needs processing in PS.
          • in my opinion, of all the latest versions of unmodified dSLRs (excluding the Fuji IR dSLRs), the Olympus E510 is the easiest to use for IR work in bright sunlight. 
      • Canon 1D Mark III - 3200ISO, f/1.8, 1/15th sec at EV 14 (sunlit with some high cloud) but very difficult to use the Live Preview for IR, unlike the Olympus E510.
    • Nikon D70 is better than the Canon 10D/300D (see comparison tests):
      • Nikon D70 landscape with RG9 filter f/13, 800ISO, 1/2 sec;
      • Canon 10D landscape  with RG9 filter f/13, 800ISO, 8sec;
    • Canon S30 with handheld R72 filter, 400ISO, f/3.2, 1/15thsec, RAW with desaturation and histogram levels adjusted:
      • eg: www.ayton.id.au_gary_photos_victoria_ga_ir_seat_crw_0138_adj.jpg
  • cameras that do not have a IR-blocking filter:
  • cameras that have a non-IR-blocking mode:
    • some cameras allow you to remove the IR blocking filter, but as this allows one to take “see-through” photos through dark clothing, the manufacturers such as Sony prevent this from being used in daylight
    • Sony nightshot mode:
      • Nightshot IR pictures are taken by setting the dial on the cam to Auto and the Nightshot switch to “Nightshot”. The aperture will be forced to open all the way up (F2 to F2.4), and fastest shutter speed will be limited 1/60th sec with a 7*7 or 1/30th with a V1 or 828. You will most likely need one or more ND filters to darken the scene plus your IR filter, as the pictures will be overexposed otherwise. In nightshot, the IR hot mirror is removed from in front of the CCD, and the camera will be very sensitive to IR light. These pictures can be taken handheld, and come out looking  green.
      • Another good thing to have when shooting in Nightshot is a donut cover for the IR emitters. These are the two little holes that are around the lens near the top. If you don't cover these, you will get a round circular reflection near the top of your pictures from the IR light reflecting off of your filter. You can make a donut out of cardboard and cut the outside diameter by using my lens cover, and the inside diameter adjusted until it was just outside of the lens. Pop the donut on and then stick your IR filter on over the top. (not required on the F828).
      • may need to set EV from 0 to -2 and ISO to lowest setting (64-100) - DON'T use auto-ISO!
      • filter options:
        • R72 stacked with neutral density filters +/- polariser filter to give correct exposure:
          • to select the level of ND filter, keep going up to a higher level of ND until the shutter speed just drops below the 1/60th second or 1/30th second maximum (depending on the camera model). Otherwise the photo will be overexposed. Remember to stay near the maximum shutter speed, especially for hand held shots.
          • bright sunny days require an ND8X filter (3 stops). This is the usual filter.
          • on dim days, or for photos in shade use an ND4X (2 stops), or perhaps even an ND2X (1 stop).
          • the number of stops is additive, and a polarizer is equivalent to an ND4X  (2 stops).
          • also, don’t forget the possibilities of a graduated ND filter for shots with extreme dynamic range.
        • ND-400 filter:
          • cuts visible light by ~99.75% - so visible light exposure needs to increase 500x - thus a normal visible light photo taken at 1/500th sec requires 1sec using this filter.
          • even though it cuts the visible spectrum way down, the infrared sensitivity of the camera in NightShot mode is way up. The IR light makes pictures, and the visible light is almost completely drained from the shot. But not absolutely completely.
          • Blue sky still has some faint color. Bright neon signs can show color, too.
          • a true IR filter such as R72 gives a cleaner IR result but more vignetting as it needs stacked NDs.
      • if you shoot with “Daylight” WB, your pictures come out with a Reddish tint. With “Indoor”, you will get a purplish tint. If you use the “Manual WB” button. This will make the foliage green and the sky reddish.
      • in Nightshot mode, the camera’s metering pattern is center-weighted averaging.
      • other features that still work when in Nightshot mode:
        • Macro mode, Sepia tone, Exposure bracketing (F7X7), Burst mode (F7X7)
  • modified cameras with IR blocking filter removed:
    • modified cameras have limited use for daytime photography without additional filters.
    • digital SLR modifications:
      • Hutech sells modified new Canon, Nikon, Olympus and Panasonic Micro Four Thirds  digital SLR cameras with the IR blocking filter removed, in addition they sell pop-in filters that users can insert in front of the sensor such as a IDAS filter to reduce light pollution for astrophotography, or a “type I H alpha filter” for nebulae photography.
        • used without any filters, daylight exposures are some 2 stops greater than an unmodded camera but you will not be able to colour balance
        • by purchasing additional screw-on or pop-in filters such as:
          • Hoya R72 screw on: IR photos - require ~0.5 stops more exposure than unmodded camera without R72 - ie. short exposures of 1/640th sec are possible, but you cannot compose through the viewfinder.
          • Hutech type UV + IR block pop-in filter - as for unmodded camera but with some extended IR range & good colour balance possible
          • Hutech IDAS LPR pop-in filter - light pollution filter for astrophotography but can be used in daylight with exposures ~ 0.5 stops less than unmodded camera, while colour balancing is feasible.
      • NB. the pop-in filters sit behind the lens and thus help to protect the sensor from dust, while obviating the need for larger, more expensive filters for the lens, but cannot be used with EF-S lens as these protrude into the body too much and would hit the filter.
      • MaxMax will modify your dSLR
      • self-modified camera, for example:

Portrait photography with IR:

  • IR can almost totally eliminate many complexion problems—even acne pockmarks—as long as your subject is evenly frontlit. Infrared film, when exposed through a red filter and printed high-key (in other words, light) on a contrasty black-and-white enlarging paper (as in the portrait, left), will reproduce Caucasian skin tones in creamy, almost ghostly whites. Pimples and other surface imperfections simply disappear.
  • A black-and-white film that's sensitive to visible light plus the 750–840nm wavelengths of infrared radiation, HIE is easier to learn to use and, at $12 per 36-exposure roll, is a fraction of the cost of Adobe Photoshop. The film is very grainy, especially when overexposed, so meter carefully and don't plan on making wall-spanning enlargements. The lighter and more contrasty you print it, the less objectionable the grain becomes. Unless you have a darkroom, you'll probably need a custom lab for the film processing and printing.
  • Correctly exposing infrared film isn't your only challenge. Because camera lenses don't focus infrared radiation in the same plane as visible light, for maximum sharpness, first focus normally, then shift focus slightly toward infinity. Many lenses indicate the degree of shift with a tiny index mark on the focusing scale. One last thought: You'll need to use a deep red Wratten #25 filter to block red (i.e., blemish-colored) light from reaching and overexposing the film.
  • Test infrared film under your shooting conditions to explore its idiosyncrasies. You may need several test shoots, altering the lighting, exposure, and printing.
  • Infrared film responds differently depending on the light source. Whenever you change lighting, retest.
  • While the effects are not as dramatic, try Ilford's near-infrared film, SFX 200. It's easier to use and less expensive than HIE.
  • If the complexion problem is minor, any black-and-white film (or monochrome mode in digital) shot through a red filter may mask the skin condition.
  • Some 35mm SLRs' film advance systems use film-fogging infrared light beams. Check your camera manual.
  •  

Various Photoshop post-processing techniques for digital IR photos:

    • many run NeatImage after converting to grayscale image, then run unsharp mask
    • 1.[ image]→[Adjustment]→then[Hue/Saturation]
      2. Select [Green] From the dropdown menu, adjust the [saturation] to -100
      3. Select [Master] From the dropdown menu,
      4. Adjust [saturation] to +50 & adjust [Hue] to +120
      5. [image]→[Adjustment]→then [Brightness/Contrast]
      6. Adjust Contrast to +15
      7. Finally, do the [Auto Level]
    • using Nightshot mode on a 707. IIRC, the filters were Hoya r72, ND8 and polarizer. Post processing is seat of the pants type. Generally, with IR, I use PSP's Hue/Saturation/Light filter to desaturate, then apply contrast filter. I frequently then use PSP's Clarify filter, which is a special contrast filter, sometimes applying it twice. Then I use unsharp mask and apply a color tone using HSL.
  • Dave Nitsche switches red and blue channels
  • Lou Gonzalez:
    • using Sony and 87A filter (this doesn't work with Sony 828):
      • When the images come out of your camera, they will have a dark green cast.

        1. Go to Image / Adjustments / Levels to boost brightness/darkness (use right most and left most sliders).
        2. The go to Image / Adjustments / Channel Mixer, check Monochrome, then use the specific RGB channels to boost certain characteristics of the image.
        3. Then do Image / Adjustments / Auto Contrast to add more punch. Or adjust Contrast to you liking using curves or other technique.
        For the colorized IR shots below, I used the following method:

        1. Image / Adjustments / Levels.
        2. Image / Adjustments / Hue/Saturation.
        3. Select Green From the dropdown menu, adjust the Saturation to -100.
        4. Select Master From the dropdown menu.
        5. Adjust Saturation to +50 & adjust Hue to +130 (for blue effect) or -60 (for red effect), or customize to taste.
        6. Adjust Contrast (optional).
        7. Finally, do the [Auto Level].
    • Take two images, one color, one IR.
    • In PS copy the IR and paste it as a second layer on top of the color version.
    • Level the IR layer to become close to B&W.
    • Set the blending mode to luminosity.

Thermography:

  • thermography uses special infra-red cameras to image & measure radiant heat from objects
    • a body radiates heat in various frequencies of e-m radiation, and its peak frequency becomes higher in proportion to the temperature of the body and can be calculated from Wien's displacement law:
      • peak wavelength radiated in microns = 2897.2/(temperature in Kelvin)
  • cameras typically measure temperature ranges of minus 20deg C to 300 deg C with resolution of 0.1degC, although some will measure up to 900degC or more.
  • whereas digital cameras usually only detect 0.4 to 1 micron wavelengths, thermal cameras that detect heat use a different sensor technology (Microbolometer Uncooled Focal Plane Array (MUFPA)) and fall into two main groups:
    • mid IR (MIR) - detect 4-6 micron
    • far IR (FIR) - detect 8-14 micron
  • can show areas of a house where heat is being lost or the different skin temperatures on a person
  • most only have resolution of 320×240 pixels
  • US law means that these cameras cannot be sold to non-US citizens apparently
photo/infrared.txt · Last modified: 2014/01/09 23:54 by gary1