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INFRARED PHOTOGRAPHY 16/07/2019 ENGLISH / POLSKI

In the entry below, I would like to bring the idea of photographing in the light that is invisible to the human eye. In this case I mean infrared light - more precisely "close infrared".

CHAPTERS:

1. SIGMA SD14
2. CANON 7D
3. OPEN HEART SURGERY
4. IR PICTURES CANON
5. PICTURES BEFORE, PICTURES AFTER
6. SIGMA SD14 VS CANON 7D
7. FILTER REMOVAL AND COLOR PHOTOGRAPHY
8. GALLERY

Perhaps you've seen before photos of trees, which were white, sky was dark, and if there were people, they looked gostly - with a light complexion, visible veins and eyes that can not be overlooked? This is how the world looks like captured on film or camera sensor with reflected infrared light.

1/160 sec F8 ISO 100

A bit of physics - light is electromagnetic radiation, and its infrared variant is a wave longer than visible light, and shorter than radio waves.

SIGMA SD14

A year ago, on my sailing holidays I took a digital camera based on a Foveon layered sensor - Sigma SD14 - which had a second generation sensor made by this company. It is a simple DSLR camera, but it operates on a very interesting principle. Its previously mentioned sensor consists of 3 photosensitive RGB layers (in this case, we could say BGR) - light is reaching at first the layer that filters out the blue light, the next one cuts off the green, and finally we have the layer sensitized to red.

Advantage of the above solution over ordinary RGB sensors based on the Bayer or X-Trans demosaics (Fuji concept) is to get full color information for each individual pixel, instead of interpolating it from nearby pixels and its averaging, which degrades sharpness of an image and exposes it to various errors (moiré). In addition, Sigma engineers decided to add a filter to cut off infrared rays in front of the mirror chamber (not directly in front of the sensor), which I think is great because it prevents dust and dirt from entering the sensor and other elements. And the most important thing in this filter placement is that it is easily accessible and can be dismantled with one finger.

In such a simple way, we get a camera sensitive to infrared radiation. Now all you need to do is cut the visible rays (eg the HOYA Infrared R72 filter in my case) and we can enjoy the camera which can capture the world that our eyes can not see.

Below I present some shots taken during last year trip. As you can see, photos from Foveon sensor are phenomenally sharp and contrasty.

1/200 sec F10 ISO 100

1/160 sec F9 ISO 100

1/200 sec F9 ISO 100

1/200 sec F10 ISO 100

1/200 sec F10 ISO 100

Unfortunately, like any other solution, it has its disadvantages. The camera is already old and doesn't have a live view function, which unfortunately forced me to use an external revolver viewfinder to frame. With normal shooting, you could conveniently use the built-in viewfinder based on a prism, as in a classic SLR. But disadvantage of infrared photography is fact that the filter attached to lens blocks visible light not only for sensor, but through the mirror system and a prism also for human eye. Unfortunately, the external viewfinder made it very difficult for me to work through its small dimensions and moved me back to the times when we had to deal with parallax error - taking place in dual-lens reflex cameras and rangefinders and all other cameras where eye has see shifted image relative to the lens. It was bothering especially at close distances such as portraits, but also in photos in medium distance between portrait and landscape. Of course, normally you can apply appropriate correction on the mentioned viewfinder, but it was scaled for a relatively compact, film rangefinder camera called FED, and not for a large reflex camera, which actually did not help much anyway.

Viewfinder from the FED camera (which was slid into the foot on top of camera)

It ended up so that I stopped using the viewfinder at all and basing on my experience and intuition, I was shooting 'blindly', which turned out to be much more accurate than fighing those disadvantages, especially in the more dynamic situations.

In addition, the Sigma cameras, in particular the slow SD14 model was making taking pictures cumbersome and greatly limiting fun and creativity.

I would like to add that I work mainly on the optics based on the Canon EF mount, which unfortunately can not be easily installed on the Sigma bayonet (SA). I read that the Canon's bayonet can be uneasly attached to Sigma cameras. In addition the electronics is based on similar instructions, and contacts of lenses are in the identical places, so even the autofocus or iris control can be done directly from the camera. But I didn't decide to such interference.

To sum up - why did I finally decide to sell Sigma camera - is fact that photographs were characterized by moderate dynamic range, but above all low color range - final image was monochromatic and only such photos could be received. This is not a problem if we would like to have black and white or pictures in sepia, but if we would like to have some colors, it was not possible. In addition, the truth is that Sigma cameras from that time allowed us to use sensitivity up to 200-400 ISO, which makes it very difficult to work on dynamic scenes. Also the image resolution consisting just over 4 million pixels is very disappointing. It is enough for small printouts and a small cropping, and is equivalent to more or less than 8-12 million pixels in a classic camera (depending on the scene being photographed).

CANON 7D

A year passed, and I was still thinking about this interesting technique and went back to the initial idea of converting Canon camera into infrared photography one. Some time ago I was able to buy cheaply a visually and mechanically worn out camera from Canon - semi-professional Canon 7D. It is quite old equipment, while inside we can find a low noise CMOS sensor with a classic Bayer system and resolution of 18 million pixels. It also has live view function with option of using simple automatic focus system based on contrast detection. So despite the lack of possibility of preview in the viewfinder I will be able to use many lenses of mine and above all... see what I'm doing :)

The trip was getting closer and closer, and I couldn't dig out of work that always have to be finished before vacations. So I couldn't find time to rework the camera.

I was even wondering whether to give up the idea. However, I found that the next trip under the sails would be a great moment to reuse the IR (infrared) technique.
So I packed basic lenses, filter for IR photography, my increasingly battered Canon 7D (in which in the meantime locked up switch to change the mode from film to photo because of desert dust, salty water and melting ice - for my luck on mode photo :) ) and a set of basic tools along with precise screwdrivers of all sorts and a penknife. In the end - it is just miniaturized and raised to the precision limit mechanics and electronics so what could potentially go wrong...

OPEN HEART SURGERY

The weather was difficult, it rained a lot, but thanks to our vigorous helmsmans (thanks to Ariel and Ydaś) and whole crew holding wet ropes, in one of the first days I could leave the deck and start with the camera. Nika and Tomasz, with their cameras, followed mine every move, for which I'm very thankful!

Below I am adjusting the photo-video switch, thanks to which I could record some movies (I will upload them later):

You have to admit that the sight of all these guts fills you with anxiety? On the left in focus there is a shutter and on the right the sensor module with visible external hydrophobic layer with function of ultrasonic vibrations to remove dust. Finally below there is a filter that I will be removing and on the very bottom the RGB sensor:

Finally, I managed to fix the switch and successfully put everything together. Unfortunately, removing infrared filter itself was not so easy. The filter instead of bouncing off has cracked and broke several times making a lot of dust, which fell on the sensor. I was unable to clean thoroughly without my pear for blowing dirt. It will be clearly visible in the pictures :(

IR PICTURES CANON

1/40 sec F3.5 ISO 2500

1/15 sec F5.6 ISO 5000

1/4 sec F5.6 ISO 6400

30 sec F11 ISO 100

8 sec F9 ISO 100

I've also made some black and white conversions. Right after messing with the RAW files I have received colors, that I liked too much to lose them. In the end, I feel that it's not worth it - the results below:

30 sec F10 ISO 100

30 sec F10 ISO 100

Looking at the atmosphere of pictures, which through a large amount of noise, blur from any movement in the frame, drop in sharpness caused by the filter and the fact that the sensor is not fully adapted to work with the infrared - I'm OK with dust on the sensor adding specific feel straight from the Chernobyl. Watching the pictures during post-production, I realized that I have to go there with my camera - the Chernobyl and a ragged camera taking pictures in bizarre colors fit perfectly!

PICTURES BEFORE, PICTURES AFTER

The original raw files look like below - infrared is fluttering between pink, purple and violet. From these tones you can get other effects:

3.2 sec F8 ISO 100

SIGMA SD14 VS CANON 7D

As it always happens, there are no perfect things, same here: from the Sigma we have pictures with excellent contrast and sharpness at low ISO, and the Canon gives us ease of use, preview during framing and interesting colors. It is difficult for me to say clearly what is better and it seems to me that it can not be unambiguously determined. It turns out that both cameras are used to create different effects of infrared photography and both give visually very interesting images.

A big disadvantage is the fact that the Canon sensor is way less sensitive to infrared light than the Sigma one. From my calculations for photos taken in the sun it is around 9EV (!!!!!), which is sometimes an obstacle not to overcome. This is a difference in exposure time of about 600 times if we leave the remaining parameters unchanged. So if we take a picture with the Sigma for 1 second, then with the Canon we would need 10 minutes to obtain same exposure. This is probably related to primary color filters with different IR cutoffs - apparently the Sigma had an outer filter cutting deeper infrared, which is easy to disassemble, whereas in the Canon this range is included in the primary color filter (RGB).

I think that in the future when prices of newer models from Sigma will drop to price of my 7D I will buy another camera with the Foveon sensor, because its predatory specificity of images attracts me like a magnet.

FILTER REMOVAL AND COLOR PHOTOGRAPHY

It seems that if we remove the filter that was installed in the factory, camera will be irreparably damaged and it will not be possible to take normal pictures. In fact, there is some truth in this, because in specific conditions, there may be unpredictable exposure shifts of some parts of image and color shifts towards the pink / purple. And in the first case, unfortunately, we are not able to do anything to get rid of this defect in 100%. However, in the second one, where the problem is not so visible, it will be enough to make simple corrections during the image processing (or directly in the camera, if we photograph in JPG format) and everything looks normal. Also in monochromatic light like LED lamps we won't have any problems at all.

Maybe sometimes colors will not be perfect like from the factory, but looking with an eye of a photographer who has been taking pictures for over 10 years, I can say it doesn't matter. Companies such as Canon / Nikon / Sony / Sigma have color deviations in relation to each other, and even different generations of cameras from the same manufacturer, so do we have to worry about it? Well... Final effect matters - after all, colors of photos conquering the internet often have nothing to do with reality :)

My congratulations if you went through the whole article! Below I will be updating mine images with new, most interesting photos using the IR technique.

Cheers!
Andrzej

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GALLERY:

Utrata 03.08.2019: