Using Circular Polarizers with Infrared

Many photographers don’t use polarizers

Shame on you!  ;-)

Even fewer do infrared

Thus – this post definitely has a very small readership,

The practitioners of this rare combination

Here it is anyway for the three of you out there

and for the others who are merely curious

There is a lesson to be learned

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Click to enlarge

 Surreal Sinuous Path to ?

Wherever Your Imagination Takes You

Nikon 18-70 DX, circular polarizer, tripod

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Summary -

Q – Are there benefits to using a circular polarizer

when making infrared images?

A – Yes, but they are minimal

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A tad more detail -

Q – What might that minimal benefit be?

A – With reflections

The contrast can be improved (sometimes)

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A more complete answer for you three still with me on this -

A CP can help (or not) with three things in normal photography -

1. Sky and cloud color & contrast

2. Flora color (often saturation) and contrast

3. Reflections (but not bare metal)

This applies to both color & B&W photography

(ignoring the color saturation benefits in B&W)

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How about these three areas when it come to IR?

1. Sky & Clouds

IR, by its very nature, always reduces the atmospheric moisture & haze

The very thing that makes a CP sometimes useful

Note the clarity in the clouds – especially at right

Read more here

The effect of IR on haze

Further, IR does it regardless of the camera’s orientation to the sun

As compared to CP’s orientation requirements

Making it a far more useful “sky tool”

CP provides no benefit in this area

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2.  Flora color – no color thus no real benefit with a CP here

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3. Reflections (so far we’re batting zero for two)

Reflection control seems to provide an observable result

Not as “observable” as seen in the viewfinder

and – Not always a “big” improvement

The benefit, where there is one, IMO is

An improvement in image contrast

If the reflection makes a dark area brighter and

The surrounding area is already bright

Using a CP to make the dark darker

Will usually help contrast

This is image (and direction) dependent

Direction because of CP’s directionality dependence

A CP has beneficial potential for 

IR images where reflections occur

Path in this image was wet & “shiny” – especially past the bridge

The CP effect is noticeable (overall darker path)

But not enough to make-or-break the result

Click for full screen

This is about as good as it gets with polarization & IR

Not much to get excited about (but I’ll take it)

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The moral of this story -

Using a circular polarizer when capturing infrared images

Won’t hurt,

and might help when reflections are involved

Not the must-have accessory that it is for color

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Making Digital Infrared (IR) Images Look Film-like

Digital IR creates wonderful images

However, compared to classic film IR

Digital sometimes can look a bit sterile

Here’s a comparison and

A technique to create the “Film Look”

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Click to enlarge

Image from IR converted Nikon D300

Nikon 18-70 DX at 27 mm, tripod

Circular polarizer (more on CP & IR in a future post)

“Film-look” processed version on right

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First – I’m not talking about turning a color image into a “faux-IR”

But, rather, camera captured IR images

Either from a converted camera or

A camera with an IR screw-in filter attached

Both (& more) discussed here

(all of my IR related posts are here)

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What did film IR look like?

The signature characteristic of classic infrared film images was

A halo or glow effect

(Grain was another, but the glow predominated)

Often described as surreal

Here are two examples using the classic Kodak HIE film

Copyrights as noted (fair use)

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How to get from sterile to surreal?

I use a Color Efex Pro recipe that I created for this task

One click and I’m done

The recipe is shown in the following screen shot -

Using three CEP filters as shown in the right side window

The 1st two, Glamour Glow & Soft Focus do as you’d expect

The 3rd, Tonal Contrast,  fine tunes highlights, midtones & shadows

The opacity of each is dialed down from 100%

So as to not overdue the net effect

Click to enlarge

It can be “tweaked” to suit individual images, but

It’s pretty good “straight-out-of-the-box”

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A gallery of images taken on a recent morning walk

Click any image for a slide show

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Setting Black & White Points – Should You Care?

The short answer is – Yes, very much

The longer answer involves more questions -

1 – Do you know what black & white points are?

2 – How they affect your image?

3 – How you set them?

Illustrated answers  & more follow….

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Click to enlarge

Yet Another Big Oak Image, 3

I never get tired of this tree

This image, as compared with the example that follows,

Illustrates what I look for in an infrared image -

Lots of blacks & whites that are truly black & white

Otherwise, without contrast, things tend to blend together

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Click any following image for a larger view

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1 – Do you know what black & white points are?

They define which areas of an image should be black and which areas should be white

They are an image’s

Darkest and lightest points

Usually just short of pure white or black

These may not exist in your image as captured, but

In most images they’re needed and

Can be achieved in post-processing

FYI – The white point is where your printer stops printing

And allows the paper’s white show through

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2 – How do black & white points affect your image?

They control the tonal range of your image which

Maximizes the image contrast

This is true for both B&W and color images

Most images look best when using the full range of dark to bright

Not all though – consider a moody low-contrast fog scene

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3 – How do you set black & white points?

First ask yourself -

Is there a part of the image which should be completely black or white?

Secondly -

Does the  histogram show this?

To achieve the proper histogram appearance

and thus proper black & white points

The Levels & Curves feature of most post-processing  programs can do the job

Here is an excellent tutorial

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I’ll illustrate the general idea of setting black & white points

Using a feature of Capture NX2

a. Starting with this captured (infrared) image (provided by a friend)

Q – We ask whether the black & white is represented?

A – Image contrast is too low for my taste (it is a matter of taste)

Confirmed by the histogram

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b. NX’s histogram allows the problem to be handled directly

1. It allows B&W point thresholds to be found

2. Done by enabling the double threshold (green check)

3. And dragging threshold sliders

until the image’s darkest and lights points are revealed

4. Below I’ve dragged the dark threshold until black shows

Red circle, middle right

5. Lower left notations show this is at a tonality of 64 (0-255)

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c. Similar to the above, I found the white point by

1. Dragging the right slider from 255 to 203

Notice the new histogram below which now encompasses

The entire 0-255 Tonal range

Also notice the actual point that was selected for

The white point (red circle near center)

Black point can be seen in the roof of house at right

The strength of these points can be adjusted to

Change pure black or white to something less, like

Maybe 5 and 250 (or whatever) instead of 0 and 255

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d. Here’s the before|after

Q – Why the color shift?

A – The “black” point I selected wasn’t a neutral color

It should be (especially for a color image)

Not doing so will introduce a color cast

Obviously some red leaked onto the “black roof”

It makes no difference in this IR image since

The B&W processing step will take care of it

Fatal in a color image though

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e. The final step is to do normal post-processing

But – you must do the point setting first

Here is the view in Silver Efex Pro

Once the IR conversion to B&W is complete

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For the complete story enlarge this next image

It’s the upper left & lower right images we’re comparing

A future post will describe the Color Efex Pro step

Giving digital infrared the more surreal IR film look

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One Capture, Multiple Post-Processing Versions

Out for a walk with my camera

No particular goal, just whatever struck my fancy

Decide to try this fire hydrant

Got quizzical looks from passers-by

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Click to enlarge

 

f/2.8?

I wanted as little background detail (distraction) as possible

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Same Scene, Two Very Different Images

Went out today with two Nikon D300′s

One as Nikon built it

One after conversion to infrared

(by LifePixel, recommended)

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Click to enlarge

Yet Another Big Oak Image, 2

This is YABOI, 2 (#1 was yesterday’s post)

I went back today after realizing I missed a better foreground  than the one used with #1

Also, I wanted a color & infrared side-by-side comparison

Color

Infrared

I usually shoot IR at a high ISO

Noise is characteristic of the original infrared film

f/8 IR vs. f/16 color?

I prefer the IR on the “softer side”; again film driven

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Captured in RAW, Aperture Priority, Manual White Balance

Left – as Captured

Right – after post-processing

Click for full screen

Color “after” – Color Efex Pro

Infrared “after” – Silver Efex Pro

Post-processing intent in both was

Improved contrast

This is an example of where I’d choose the color version

The reason?

The foreground is better with the splashes of color IMO

Also the foreground leaf/sky contrast is better

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