BE­YOND THE RAIN­BOW: INFRARED PHOTOGRAPHY, PART TWO

In this sec­ond in­stal­ment, Hans We­ich­sel­baum ex­plores the phe­nom­e­non of infrared photography, dig­ging deeper and dis­cov­er­ing just what infrared photography does with ‘nor­mal’ colours

New Zealand D-Photo - - CONTENTS -

In this sec­ond in­stal­ment, Hans We­ich­sel­baum digs deeper into the phe­nom­e­non of infrared photography

In the first part of this se­ries, we looked at some prac­ti­cal infrared photography us­ing a mod­i­fied cam­era. In this sec­ond part, we’ll ex­plore the pos­si­bil­i­ties a bit fur­ther, and find out what infrared does to all our fa­mil­iar rain­bow colours. Ded­i­cated infrared photography doesn’t come cheap, so we’ll also look at how you can sim­u­late a gen­uine infrared image by start­ing from a nor­mal, ev­ery­day shot. Peo­ple have al­ways been fas­ci­nated by the world of the in­vis­i­ble. The vis­i­ble rain­bow spec­trum is only a tiny sliver of the en­tire elec­tro­mag­netic spec­trum, stretch­ing from X-rays to ra­dio waves. In Image 2, you can see the part of the spec­trum com­ing from the sun that is im­por­tant to us pho­tog­ra­phers:

The ul­tra­vi­o­let re­gion is not very in­ter­est­ing to photography, un­less you want to see the

world through the eyes of a bee. This band is well blocked out by the fil­ter in front of your sen­sor. If you want to dab­ble in ul­tra­vi­o­let photography, you need to re­move this fil­ter. Se­condly, you need a (very ex­pen­sive) quartz glass lens — and then you’ll find there is not much ul­tra­vi­o­let around any­way, be­cause the at­mos­phere fil­ters out most of the ul­tra­vi­o­let from the sun.

So, we are ba­si­cally left with the infrared re­gion to ex­plore. Keep in mind that more than half of the sun’s ra­di­a­tion reaches us in the form of infrared — there’s a lot of infrared around!

Image 2 also shows you the near-infrared band that’s in­ter­est­ing for us pho­tog­ra­phers, stretch­ing from about 700nm to 1000nm. Be­yond that comes the far-infrared ra­di­a­tion band — the re­gion used for ther­mal photography, which is not shown in this di­a­gram.

Infrared photography lit­er­ally opens up a whole new world, be­cause it’s a world of the un­seen. If you are into fine-art photography, you should have a se­ri­ous look at infrared. It will make your land­scape photography stand out, but it also works for por­trait and wed­ding photography.

The quick­est, eas­i­est, and least ex­pen­sive way of get­ting into infrared photography is to use an infrared fil­ter on your lens — as­sum­ing that you can fit a fil­ter on your lens. The ul­tra­vi­o­let fil­ter that you put on your lens blocks out the ul­tra­vi­o­let, and you might be for­given for think­ing that an infrared fil­ter does the same, block­ing out the infrared part of the spec­trum. How­ever, it’s the op­po­site.

Infrared fil­ters are trans­par­ent to infrared and block out the vis­i­ble light spec­trum! It’s a bit confusing, but once you get your head around the con­cept, it makes sense. You don’t want to cap­ture the vis­i­ble rain­bow colours, but only the infrared spec­trum that’s re­flected from your sub­ject.

Image 3 shows you an R72 fil­ter, which blocks out the vis­i­ble spec­trum with a cut-off around 720nm. Image 4 de­picts the trans­mis­sion char­ac­ter­is­tics of a num­ber of infrared fil­ters. You can see that all of them have zero per cent trans­mis­sion for light below about 700nm. Th­ese fil­ters are re­ally black — but never use them to look di­rectly into the sun. The infrared light that gets through the fil­ter will dam­age your eye!

All dig­i­tal sen­sors are very sen­si­tive to infrared, and you might think that put­ting an infrared fil­ter on your lens will do the trick. Even though it does work, all cam­eras also have an infrared block fil­ter mounted in front of the sen­sor. There is al­ways some infrared light trick­ling through, but very lit­tle. This means that you have to push the ISO re­ally hard and still need ex­po­sure times that run into sec­onds, even in plain sun­light. For or­di­nary photography, you’ll need a cam­era that has been spe­cially mod­i­fied for infrared.

Most infrared pho­to­graphs are black and white, al­though you can bring in some colour if you go for a fil­ter with a cut-off below 700nm. The ob­vi­ous ques­tion that comes to mind is: how does infrared photography rep­re­sent our fa­mil­iar rain­bow spec­trum on a white-to-black greyscale?

I went to great lengths to find this out by tak­ing shots of a colour chart un­der infrared. How­ever, this ex­er­cise is not re­ally use­ful be­cause it all de­pends on the ma­te­rial the colours are printed on, not so much the colours them­selves. If the ma­te­rial is re­flec­tive to infrared, it will show up as light grey or white. A good ex­am­ple is my photography bag, which is fairly black in or­di­nary light, but comes out as white un­der infrared (see Image 5). The man­u­fac­turer ob­vi­ously used a ma­te­rial that re­flects infrared, oth­er­wise my cam­era gear would cook in the sun. I as­sume that the bag could have been tinted blue or red and would still have shown up as white un­der infrared.

What im­me­di­ately sets most infrared pho­tos apart from nor­mal black-and-white shots is that green veg­e­ta­tion comes out as very light. Green plants re­flect infrared, pro­duc­ing the so-called wood ef­fect. The con­trast was very ob­vi­ous when I put a leaf on the match­ing green colour patch of a colour chart (see Im­ages 6 and 7). How­ever, the green patch on the colour chart could have turned out lighter or darker un­der infrared, de­pend­ing on the ma­te­rial used.

An­other in­ter­est­ing char­ac­ter­is­tic of infrared light is its abil­ity to smooth out skin tones. That’s why por­trait and wed­ding pho­tog­ra­phers love to work with infrared. You get a milky smooth skin, and all the freck­les are gone. The eyes can get too dark and overem­pha­sized, so some post-pro­cess­ing might be nec­es­sary.

My shot of Brooke was per­fect straight out of the cam­era (see Image 8). Her skin was smooth to start with and the infrared light couldn’t re­ally show off its abil­ity to get rid of skin im­per­fec­tions. Her blue eyes didn’t need any post-pro­cess­ing, ei­ther, but you do need to watch out if your model has very dark eyes. In­ci­den­tally, pho­tograph­ing un­der ul­tra­vi­o­let light does the op­po­site — it ac­cen­tu­ates skin im­per­fec­tions and will show freck­les that aren’t even vis­i­ble in nor­mal light.

The best time of day for infrared photography is mid­day un­der full sun. Ide­ally, you should have a clear sky with some clouds for ef­fect. Over­cast skies of­ten leave things look­ing flat with­out enough con­trast, al­though you might pre­fer that for por­trait shots. A cloud­less sky of­ten looks like a vast black void and isn’t very

in­ter­est­ing. A few clouds come in handy for infrared photography.

Infrared sim­u­la­tion with Pho­to­shop

If your cam­era is not suit­able for infrared photography, or if you’re wait­ing for a new infrared fil­ter to ar­rive, why not try to sim­u­late the ef­fect in Pho­to­shop? Do keep in mind that infrared photography cap­tures sub­tle tonal­i­ties that don’t show up in a shot taken in day­light. No amount of dig­i­tal edit­ing can re­trieve th­ese nu­ances, but we can get a rea­son­ably good ap­prox­i­ma­tion to the real thing.

The key tool for trans­form­ing a colour photo into an infrared black-and-white sim­u­la­tion is Pho­to­shop’s Chan­nel Mixer. The idea is to take the green chan­nel to the max­i­mum 200 per cent, and re­duce both the red and blue chan­nels to com­pen­sate.

• Make a du­pli­cate layer. This is not strictly nec­es­sary if you work with ad­just­ment lay­ers, but it’s al­ways handy if a mis­take slips in. • Open the Chan­nel Mixer from the ad­just­ments panel, or go to Ad­just­ments > Chan­nel Mixer. Choose the black-and­white infrared pre­set and you will see the green chan­nel slider jump­ing to its max­i­mum set­ting of 200 per cent (see Image 10). The op­ti­mal set­tings for the other two chan­nels will de­pend on your par­tic­u­lar image, but the per­cent­ages should add up to around 100 per cent. The Con­stant slider al­lows you to fix the over­all tonal­ity. Don’t for­get to check the Mono­chrome box. • Make the image layer ac­tive again by click­ing on it. Then se­lect the green chan­nel in the chan­nel palette and add Gaus­sian blur (ra­dius around five pix­els). • Go straight to Edit > Fade, re­duce the opac­ity to 30 per cent, and set the blend­ing mode to Over­lay. Also try blend­ing in screen mode. This will give the green chan­nel the typ­i­cal lu­mi­nous glow. • Click on RGB in the chan­nel palette, then

re­turn to the layer palette. • Noise can be added to sim­u­late film grain. I like to insert a hue/sat­u­ra­tion ad­just­ment layer be­tween the Chan­nel Mixer and the image layer to have more con­trol over the tonal­i­ties of the var­i­ous colours, e.g. blue of­ten needs to come out darker.

This is a sim­ple recipe that can be made into an ac­tion. You can go a step fur­ther and pre­pare sep­a­rate se­lec­tions, e.g. a se­lec­tion for the veg­e­ta­tion and an­other one for the sky, and then work on them in­di­vid­u­ally. This will give you su­pe­rior re­sults, but it is time-con­sum­ing and does not lend it­self to a sim­ple ac­tion.

See my re­sult of the infrared sim­u­la­tion in Image 11, and com­pare it with the gen­uine infrared photography seen in Image 12. The char­ac­ter­is­tic glow of the real thing is miss­ing in the sim­u­la­tion. There was an over­cast sky, so the typ­i­cal black sky wasn’t there, ei­ther.

The Light­room en­thu­si­ast will find a pre­set in the De­velop mod­ule called Infrared. This is a good start­ing point for any fur­ther colour tweak­ing for best re­sult. If you have the Nik Soft­ware plug-in, which you can down­load free, you’ll find an Infrared Film pre­set in the Color Efex mod­ule. Af­ter se­lect­ing the fil­ter, the soft­ware gives you tons of ad­di­tional con­trols to tweak bright­ness, con­trast, shad­ows, and high­lights.

I hope that this in-depth in­tro­duc­tion to infrared photography will en­cour­age you to have a se­ri­ous look at dig­i­tal infrared photography. A sim­ple infrared fil­ter on your lens, plus a tri­pod, can get you started. If you like the re­sults, you might con­sider get­ting one of your old re­dun­dant cam­eras con­verted into a ded­i­cated infrared shooter. I can highly rec­om­mend Ko­lari Vi­sion (ko­lar­iv­i­sion.com), if you are se­ri­ously think­ing of get­ting into infrared photography.

IMAGE 1 — AUCK­LAND DO­MAIN IN INFRARED LIGHT

Hans We­ich­sel­baum has been on the dig­i­tal-imag­ing scene since Pho­to­shop 3 in 1994. He has shared his ex­per­tise in work­shops coun­try­wide and in ar­ti­cles for three dif­fer­ent pub­li­ca­tions.

Hans is a per­fec­tion­ist and pas­sion­ate about photography. His back­ground in sci­ence and phi­los­o­phy lets him look out­side the box when prob­lem-solv­ing. His busi­ness spe­cial­izes in Pho­to­shop tu­ition, high­qual­ity film scan­ning, large­for­mat print­ing, and colour cal­i­bra­tion.

hans@dig­i­tal-image.co.nz

IMAGE 2 — THE SUN’S SPEC­TRUM THAT IS USE­FUL FOR PHOTOGRAPHY

IMAGE 4 — TRANS­MIS­SION CHAR­AC­TER­IS­TICS OF SOME INFRARED FIL­TERS

IMAGE 5 — A BLACK CAM­ERA BAG UN­DER INFRARED

IMAGE 3 — AN INFRARED FIL­TER

IMAGE 8 — INFRARED POR­TRAIT

IMAGE 6 — A GREEN LEAF UN­DER NOR­MAL LIGHT

IMAGE 7 — A GREEN LEAF UN­DER INFRARED

IMAGE 9 — GAR­DEN IN NOR­MAL LIGHT

IMAGE 10 — THE CHAN­NEL MIXER FOR INFRARED SIM­U­LA­TION

IMAGE 12 — GAR­DEN SHOT WITH INFRARED-MOD­I­FIED CAM­ERA

IMAGE 11 — GAR­DEN IN SIM­U­LATED INFRARED

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