#qualitiesoflight

28th October, 2019

In class we worked on Inverse Square Law and Diffuse Transmission.

I have took images of 2 classmates today to illustrate.

Inverse Square Law states basically that light loses power over distance, however, not exponentially. The charts below helps us visualize light fall-off over distance.

As illustrated, as long as we use the same mode of measurement, whether it is metre, feet, inches or centimetres, this law applies. So, say our subject is 1 metre from the light, that means the power ratio is 1/1 which is full power. If we move our light another metre away, giving us 2 metres of distance from our subject, then we reduce the power to 1/4. That is because we lose 2 stops of power over double the distance. Being that 1 is our power of the light (see chart #2), and our distance is now 2 metres, we now have :

1 x 2 = 2.

2x2 = 4

leaving us with 1/4 power.

Notice how once we move another metre away, to 3 metres, that this is only a loss of 1 stop of light.

#1 (Heniadis, 2019)

#2

#3

Below we have one of my classmates, Nicola who was positioned in a chair 1 metre from the backdrop. Our task was to set up 2 lights of the same power. For example, 500 heads on 1/2 power. Both had to be situated at 45 degree angles to create an image with a 2-stop difference. For instance, the key light, was set to f/11, while the fill light was set to f/5.6. Then we fitted each light with a soft box. For the brief, we were to only take one light metre reading.

Using a measuring tape . . .

- the key light was placed at 1 metre

- the fill light was placed at 2 metres

We then used the light metre and found that we were at f/11 and set our equipment accordingly. The first image I captured was a bit overexposed. Remember, we were to take only 1 metre reading.

@nicolahndphoto​

Changed my aperture to f/13. Much better. Notice that in the left eye we only have 1 catch light now. This is because the nose of the subject is blocking the light from hitting her eye.

Direct Transmission -

Direct transmission is light on our subject that is not diffused in any way. Light rays go through a material with no change to their direction or color. Example: clear plate glass or air. For instance, capturing an image of Nicola with no soft box or diffusers to modify the light. There is a high contrast between light and dark with undesirable shadows and glare.

Diffuse Transmission -

The next task set for the day was to capture images using the Diffuse Transmission technique. This technique was completed using a softbox, however, Diffuse Transmission could be accomplished outside on a cloudy day, through a shower curtain, or even through a dirty window.

We were to use 2 different sizes of softboxes, at different distances. So, first, a small softbox at 1 metre and at 3 metres, and what appeared to be a 5 foot softbox because I am 5 foot tall, and it was at least as tall as me, or taller.

- small softbox 1 metre from subject.

I have not tried to change the image in any way, so the background is fairly mucky. Because we are working with a small lightsource, the shadows are fairly dark, moody and harsh.

Below,the image is cropped in to remove some of the background . . . 

Now we reveal the small softbox at 2 metres away. . .

Notice how the background and face are brighter. The shadows are even more pronounced and harder edged.

Cropped in of above image . . .

Next we will experiment with the giant softbox.

- giant softbox 1 metre from the subject

First noticeable thing is there are no hard edged shadows, only a smooth gradation. The light is spread evenly. There is no puddling on the face.

- giant softbox 2 metres away from subject

At 2 metres away, there is a slight improvement on the exposure levels. No harsh shadows here either, only a smooth transition between the light and dark side of the face. These 2 images are quite beautiful and flattering to both my classmates.

Evaluation - I prefer the giant softbox images. The light transmission is gentle and flattering to both models. I’m quite pleased with the results.

Monday the 7th of October

Diffuse Transmission

SMALL SOFT BOX

Canon EOS 60D | ISO100 | f/8 | f1/100

The two images above are taken using a small soft box. The first image features a soft box 1 metre away from the model whereas the second,  is 2 metres away from the model. As the soft box is very small and close to the face, the light is a little harsh especially in the second one. I noticed that the two images above feature harsher light as it has a smaller range and less light to direct. Comparing this to the larger soft box - photographed below - which has a larger area to highlight. The images below are softer.

@leocoffieldhnd1bphoto​

@hannahhnd1bphoto​

LARGE SOFT BOX

Canon EOS 60D | ISO100 | f/8 | f1/100

The first image is using a very large soft box at a metre from the model with the second image being 2 metres. I find that both images are very successful. They vary in lighting strengths but are both in my opinion, captivating. The large soft box has created a smooth transmission of light with no puddles on the forehead.

@alexproctorhnd1bphoto​

@hnd1bphoto-geraldmcmillan

Question: Can you name a second practical example of using ‘diffuse transmission’?

Another example for when diffuse transmission is used is during an overcast day. Taking a portrait under a clouded sky allows a natural soft lighting. 

Question: Give an example of ‘Direct Transmission’?

Direct Transmission

Nikon D750 | ISO100 | f/8 | f1/125

Above is an image of @seanhnd1bphoto using only a modelling lamp with a small reflector on it. This is considered direct transmission as there is nothing diffusing it like the images above with different sized soft boxes. During photographing this, myself and our group decided to try experimenting with ‘inverted square law’. Trying different soft box sizes at different distances from the model.

a) What is Light?

Light, or Visible Light, commonly refers to electromagnetic radiation that can be detected by the human eye. The entire electromagnetic spectrum is extremely broad, ranging from low energy radio waves with wavelengths that are measured in meters, to high energy gamma rays with wavelengths that are less than 1 x 10-11 meters. 

b) The 3 most important qualities of any light source?

The three most important qualities of light are brightness, colour, and temperature.

c) What is selective absorption without reflection?

Selective absorption describes the tendency of an object to absorb some frequencies of light more than others. An object that appears a certain colour reflects the light frequency that corresponds to that colour, and it absorbs all the other frequencies in the visible light-spectrum. Absorption of a light wave occurs through resonance. When the frequency of a light wave matches the resonant frequency of an object, then the object vibrates at that frequency. The energy of the light wave stays in that object as thermal or vibrational energy.

Sources - https://andor.oxinst.com/learning/view/article/what-is-light

@nicolahndphoto​

@hannahhnd1bphoto​

@leocoffieldhnd1bphoto​

Sunday the 17th of November