Luca Cesari is an Italian fine art photographer, born in 1984 in Italy.

He attended college in Pavia, where he graduated ‘cum laude’ in 2008 in Structural Engineering.

He started playing guitar at fifteen: he used to perform as a lead guitar in a death metal band, Decay, and for a few years music drained all his creative energies.

Photography has become his main artistic interest since 2008.

He is now fully devoted to creating black and white images; removing colors has been his crucial step towards his deeper artistic development.

In 2009 he approached Infrared Photography, and he is currently (early 2012) working on different projects which will be completed during 2012.

- Joel Tjintjelaar

 

My previous article for BWVISION.com was a quick introduction on infrared photography. You can read this introduction to Infrared photography here: Infrared photography part 1 and it is a recommended read for this in-depth look into IR photography.
Today we’ll be taking a deeper look on it, trying to deal with other peculiar aspects of infrared.

First of all, I want to make things clear: I’m not a technical freak! I never look at 100% crops, I don’t care about perfect lens sharpness and all that related stuff; the examples provided here will just help you understand more clearly what I am discussing about.
Art is my goal: camera, lenses and all the accessories are just tools! Don’t ever forget that.

Time to get down to business.

To capture the (technically) best possible image when shooting infrared, there are two critical aspects to always keep in mind (the first one applies to traditional photography, too):

1. Diffraction

Physics tell us that diffraction is directly proportional to the wavelength of light:
d = 1.22 λ N
where λ is the wavelength of the light and N is the f-number (focal length divided by diameter) of the imaging optics.
As you can see (using the same aperture), the longer the wavelength of light λ, the higher the diffraction: since with infrared photography we’re capturing longer wavelengths, this is one of the reasons why diffraction becomes more evident; if you choose to use really dark filters (900 nm and above) you will notice that even a perfectly focused image looks softer.
Anyway, let’s see what happens ad different apertures:
(these are 100% crops from unsharpened RAW files)

EF 70-200 F/4 IS, 200 mm @ f/5.6

EF 70-200 F/4 IS, 200 mm @ f/14

EF 70-200 F/4 IS, 200 mm @ f/22

EF 70-200 F/4 IS, 200 mm @ f/32

Comparison for Loss of quality from diffraction – f/5.6 – f/14 – f/22 – f/32

 

As you can see, there’s a dramatic loss in quality from f/5.6 to f/22 (and f/32).

I therefore always try to avoid apertures narrower than f/9: this prevents the shot from being too soft.

2. Hotspots

Hotspots are caused by internal reflections and show as brighter circles with low contrast (usually in the center of the image).

They are really hard to remove in post-processing(like a strong lens flare), and generally become more evident at smaller apertures.

Hot spot problem

As you can see, this image is far from being usable.; this is another reason to ‘stay away’ from smaller apertures.

There are lenses which suffer more than others; hotspots are usually more evident with faster lenses.

If you want to know if your glass is suitable for infrared, check these links out:

http://dpanswers.com/content/irphoto_lenses.php http://www.lensplay.com/lenses/lens_infra_red_IR.html

Now, since we all love long exposures, it’s time to move to our favorite tool: Neutral Density Filters

You all know how ND filters work in visible light, so, what’s different with infrared?

When you shoot infrared you have to be prepared to ‘surprises’; filters will not (usually) have the same behavior.

Many strong ND filters will not cut infrared light as effectively as they do with shorter wavelengths (visible light).

The B+W ND110 (a 10 stops ND filter) reduces about 6 stops (see image below):

B+W ND Filters transmittance (source: Schneider Kreuznach website)

Notice the loss of effectiveness of the ND110 (the curve at the very bottom) from 650 nm on: until 650 nm it has a 0,1% transmittance, while around 750 nm it rises to more than 0,4%!

The Hoya ND400 (9 stops) cuts five stops, while an 0.9 (three stops) ND Lee square filter is almost completely transparent to infrared.

0.9 ND Lee Filter Test – Configuration

0.9 ND Lee Filter Test – As you can see, no visible effect

 

The only filter (I’ve tried) with the same effectiveness (10 stops)in both visible and IR is the Big Stopper ( Lee filters). This explains its coolest behavior in visible light captures (when compared to the ND110)

I’ve also tried a few GND filters, and none of them seem to be effective.

A good news is that the dynamic range of the scene is usually manageable (from my experiences, 2-3 stops less than in visible light); if you don’t shoot straight into the sun you can (almost) always find a good compromise and get a perfectly exposed negative.

(these are unmodified RAW files, which have just been desaturated for comparison purposes)

Infrared Capture

As you can see from the histograms, while it’s impossible to ‘correctly’ expose the scene in visible light without the help of a GND filter, the infrared camera manages this well.

In my last article I wrote that, since I loved long exposures, I wasn’t considering a permanent modification for my cameras: I have luckily changed my mind.

Last September (2011) I have modified one of my cameras to be infrared sensitive only, and I was swept away with the possibilities. After a few months of practice, I can now say that there’s no substitute for this: using the lowest ISO available and adjusting the shutter speed accordingly to my creative needs (with the use of ND filters, too) without having to deal with the camera poor infrared sensitivity is priceless.

The bottom line is: if you’re willing to take your infrared skills and images to the next level, you should consider a permanent camera conversion.

Ok, that’s all for now: time to show you some of my creations.

(many are coming in the next months, so don’t forget to check my website )

Image 1 – Modified Camera

Image 2 – Modified Camera

Image 3 – Modified Camera

Image 4 - Unmodified Camera with an Hoya R72 filter

Image 5-  Unmodified Camera with an Hoya R72 filter

Image 6 - Unmodified Camera with an Hoya R72 filter

 

For any information, curiosity and question just add a comment, I will be glad to answer in the comment box below.

You can also write me at: luca@lucacesari.com

- Luca Cesari www.lucacesari.com