Tag Archives: diffuser

Exercise: Contrast and shadow fill

The brief:

Set up a simple still-life shot. Leave room for access at the sides of the set, and make sure that neither side is close to a wall. Shoot from the same level as the subject, with camera on tripod. Fix the light about three feet to one side of the object and at its level, so that it is aimed at right angles to the camera’s view. Take the first photograph without a diffuser in front of the lamp, and the second with the diffuser.

Then take a white card and position it about one metre away from the subject on the opposite side of the light and facing it. Take a photograph. Then move the white card in about half a metre and take another photograph.

Take a piece of aluminium foil that will cover the area of the white card and place against the white card, dull side facing the object. Take a photograph. Flip the foil over and with the shiny side facing the object take another photograph. Then crumple the foil and smooth it out again. Place it against the card with the shiny side facing out and take another photo. Compare the results and arrange in order of contrast.

I again used my Nikon speedlight for this exercise, power was set to 1/2 throughout the sequence. My camera settings were f8, 1/160, 45mm, ISO 100. I was very frustrated when setting up my background for this exercise. My background cloth which had been ironed so that there were no creases was intent on showing “bubbles” when lit by the flash. Try as I did, I could not get rid of this. I tried putting extra cloth and black card under the cloth, but nothing really worked. I even taped the edges down after stretching the fabric taut. So please forgive my bubbles. To get the full learning experience from this exercise I have not done any post-processing.

Fig 01 Bare flash

Fig 01 Bare flash

The image with the bare flash has hot spots all the way down the left side of the figurine with the result that the highlights have blown out and the background is washed out (Fig 01).

Fig 02 Flash with diffuser

Fig 02 Flash with diffuser

With the diffuser fitted to the flash the result if much better. There are details in highlighted sections, the background is properly saturated even though the image is a little dark on the right (Fig 02).

Fig 03 White card 3 feet away from subject

Fig 03 White card 3 feet away from subject

With a white card held 3 feet from the subject right side of the image is a tiny bit lighter – mostly noticeable on the cheek area (Fig 03).

Fig 04 White card 1.5 feet away from subject

Fig 04 White card 1.5 feet away from subject

With the white card 1.5 feet from the subject the difference is more pronounced. The right side of the image has lightened up quite considerably and the folds on the skirt are now discernible (Fig 04).

Fig 05 Foil dull side

Fig 05 Foil dull side

It is quite difficult to see the difference between the white card at 1.5 feet and the foil dull side, but I think some subtle highlights have been added back into the cheek area, but it looks as if the skirt has picked up more contrast (Fig 05).

Fig 06 Foil shiny side

Fig 06 Foil shiny side

The foil shiny side has produced more contrast somehow, but I think I must have angled the card incorrect. I did shots with labels to identify which scenario the images were supposed to represent and then removed the label to shoot the photograph again and my labeled image and unlabeled image look a little different, so I’m thinking I must have moved the card slightly after I removed the label. Unfortunately I only discovered this after uploading the images. In Fig 06 there is more contrast down the right side of the subject.

Fig 07 Foil crumpled

Fig 07 Foil crumpled

The crumpled foil lightens the shadow in the underarm crease on the right hand side, casts more of a shadow on the right side of the face, and deepens the contrast of the skirt area.

I have arranged the images in order of contrast going from lightest to darkest in the gallery below.

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Exercise: Softening the light

The brief:

Set up a still-life arrangement, with any object or group of objects. The lighting direction will depend on your subject, and you might like to experiment, but, if in doubt, fix the naked lamp more or less overhead, pointing down.

Using a diffused light source to soften the shadows and highlights take two photographs, one with just the naked lamp, the other with the translucent material held between the lamp and your subject (but out of view). The two exposure settings will be different.

Look at the results, and write down exactly what you see as the differences. Look at the strengths (blackness) of the shadows, their extent, and the hardness of their edges. Look also at the highlights, and at the contrast. Finally was the diffusion an improvement? Record your answer.

 

Fig 1 - Bare flash

Fig 1 – Bare flash
f3.5, 1/80, 50mm, ISO 400

Fig 2 - Flash with diffuser

Fig 2 – Flash with diffuser
f3.5, 1/80, 50mm, ISO 400

I used my Nikon SB 700 speedlight for this exercise and a couple of Yongnuo RF-603N II wireless flash triggers that I bought recently and had not yet put to work. The still life was set up in a light tent, with a black background and a hessian sack roughly arranged on the floor of the tent on which I placed a large log and perched the wooden rooster on top of that.

In fig 1, the photo taken with the bare flash positioned at about 45 degree angle from the rooster. The flash head was pointed one click up from the straight on setting so the light skimmed over the top of the rooster’s head. There is a noticeable shadow behind the rooster’s tail. There is also a hotspot on the rooster’s neck from the flash.

I had actually forgotten to change my exposure when I made the second photograph, but I know that adding a diffuser into the mix can decrease the light by up to 2 stops, so I adjusted the exposure in post processing until the saturation and intensity of the red of the rooster’s head in fig 2 matched that of fig 1. It was only one stop difference, so had I exposed correctly, my aperture would have been f5. The diffuser got rid of the shadow and the black background is evenly lit and more saturated. The hotspot on the rooster’s neck is still there, but it is a fraction smaller and less bright. This is probably where a small gobo should be positioned between the diffuser and the subject to eliminate that hotspot. Unfortunately I did not have enough hands to do that piece. The diffuser causes the flash to cast a more even light as can be seen by the exposure on the hessian sack. It is a little brighter in fig 2 and the shadows in the folds have also lost their harsh edges. Fig 2 is definitely more pleasing to the eye.

The lighting diagram for the setup can be seen below.

Fig 3 Lighting diagram

Fig 3 Lighting diagram