Category Archives: 17 The intensity of light

Exercise: Higher and lower sensitivity

The brief:

For the first part of this exercise take similar shots at both normal and high sensitivity. Choose a situation which is marginal; that is where the mixture of light level and subject movement or depth of field is only just possible, eg a busy street market on an overcast day. Shoot first at normal sensitivity (ISO 100), then change to higher sensitivity (ISO 800).

Compare the two kinds of image close up (enlarge the digital view on the computer to 100%). Look in two kinds of area in the picture – those that are smooth, with little detail and neither particularly bright nor dark, and also in the deep shadow areas. What is the obvious difference?

For the sake of this exercise I have not done any post processing work, apart from the occasional crop. All the photos were taken during my lunch hour close to my office. For the most part I tried to get comparative images, but this proved a little difficult when photographing people walking down the sidewalk. However, I think, for the sake of this exercise, it worked quite well.

Fig 01 - Hostel - low sensitivity

Fig 01 – Hostel – low sensitivity
f3.5, 1/160, 18mm, ISO 100

Fig 02 - Hostel - high sensitivity

Fig 02 – Hostel – high sensitivity
f3.5, 1/1000, 18mm, ISO 800

By increasing the ISO to 800 I was able to reduce my shutter speed by two and one-third stop allowing for quicker exposure. The exposure in fig 02 is overall brighter than fig 01, although I feel the brighter areas in fig 01 are a truer reflection of the actual building. When viewed close up, the noise increase in the lighter areas is not too bad, while the darker areas are really very noisy as can be seen in the closeup sections below.

Comparison of bright areas in Fig 01 and 02

Comparison of bright areas in Fig 01 and 02

Comparison of dark areas in Fig 01 and 02

Comparison of dark areas in Fig 01 and 02

Fig 03 Beatty Street - low sensitivity

Fig 03 Beatty Street – low sensitivity
f4, 1/60, 22mm, ISO 100

Fig 04 Beatty Street - high sensitivity

Fig 04 Beatty Street – high sensitivity
f4, 1/400, 22mm, ISO 800

With lighter coloured objects the increase in noise is definitely less noticeable. Again the image taken with the higher ISO is overall much brighter, even though it was a cloudy day and the photos were taken under a heavily shaded awning. The noise on the grey wall is fairly acceptable in fig 04, but the noise in the sign is very unpleasant when viewed close up. However, when viewed normally, it is fine. The side by side closeup comparisons are below.

Comparison of bright areas in Fig 03 and 04

Comparison of bright areas in Fig 03 and 04

Comparison of dark areas in Fig 03 and 04

Comparison of dark areas in Fig 03 and 04

Fig 05 - Red scarves on Robson Street - low sensitivity

Fig 05 – Red scarves on Robson Street – low sensitivity
f5, 1/60, 38mm, ISO 100

Fig 06 - Men on Robson Street - high sensitivity

Fig 06 – Men on Robson Street – high sensitivity
f5, 1/640, 38mm, ISO 800

With a busy street scene the difference between ISO 100 and 800 is more noticeable on the faces, especially with my camera as it is notorious for not taking great photos in low light, as is evident in the closeup portions of these two images below. The noise level in the dark areas is not attractive.

Comparison of bright areas in Fig 05 and 06

Comparison of bright areas in Fig 05 and 06

Comparison of dark areas in Fig 05 and 06

Comparison of dark areas in Fig 05 and 06

Fig 07 - Man walking Robson Street - low sensitivity

Fig 07 – Man walking Robson Street – low sensitivity
f5.3, 1/30, 46mm, ISO 100

Fig 08 - Girl walking Robson Street - high sensitivity

Fig 08 – Girl walking Robson Street – high sensitivity
f5.3, 1/320, 46mm, ISO 800

Shooting at ISO 100 (fig 07) caused a low shutter speed of 1/30 seconds and resulted in a motion blur while the man is walking along the side walk. At ISO 800 (fig 08) the girl’s stride is clear and frozen in time. Noise is less noticeable on lighter colours than dark.

Comparison of bright areas in fig 07 and 08

Comparison of bright areas in fig 07 and 08

Comparison of dark areas in fig 07 and 08

Comparison of dark areas in fig 07 and 08

Fig 09 - Homer Street corner - low sensitivity

Fig 09 – Homer Street corner – low sensitivity
f5.3, 1/30, 45mm, ISO 100

Fig 10 - Homer Street corner - high sensitivity

Fig 10 – Homer Street corner – high sensitivity
f5.3, 1/320, 45mm, ISO 800

Once again, at ISO 100 a lot motion blur was captured in fig 09 as my shutter speed was below my focal length, while fig 10 is sharper at the higher shutter speed and higher ISO.

Comparison of bright areas in fig 09 and 10

Comparison of bright areas in fig 09 and 10

Comparison of dark areas in fig 09 and 10

Comparison of dark areas in fig 09 and 10

Fig 11 - Man in wheelchair - low sensitivity

Fig 11 – Man in wheelchair – low sensitivity
f5, 1/60, 36mm, ISO 100

Fig 12 - Man in wheelchair - high sensitivity

Fig 12 – Man in wheelchair – high sensitivity
f5.6, 1/250, 52mm, ISO 800

I tried to follow this gentleman in the wheelchair with my camera to get similar shots, but unfortunately he was too fast for me while I was changing ISOs, so I had to shoot him from the back. In fig 11 there is a motion blur on the spokes of the wheels and well as on his hands as he turns the wheels. In fig 12 there is no blur at all. The noise level on this photograph is quite acceptable to me. It really is hit and miss with low light for my camera.

Comparison of bright areas in fig 11 and 12

Comparison of bright areas in fig 11 and 12

Comparison of dark areas in fig 11 and 12

Comparison of dark areas in fig 11 and 12

I’ve promised myself an camera upgrade once I’ve completed TAOP so that is something to look forward to. Definitely one of the “must haves” on the list will be a sensor that can cope with low light scenarios.

Exercise – Measuring exposure

The brief:

Part 1: take between four and six photographs which are deliberately lighter or darker than average and say why in your written notes.

Fig. 01 - Alley patio

Fig. 01 – Alley patio
f8, 1/400, 38mm, ISO 200

Fig. 01 is deliberately darker as it was an extremely bright day and my previous shots of this scene had the sky blowing out. So I underexposed to accommodate the highlights and worked on bringing back shadow detail in post processing.

Fig. 02 - Commodore Ballroom

Fig. 02 – Commodore Ballroom
f7.1, 1/200, 24mm, ISO 200

Fig. 02 was made lighter to bring out the details of the brick work of the Commodore Ballroom, one of Vancouver’s old heritage buildings. The ballroom is actually below ground. However, in lightening the image I have lost quite a bit of detail in the highlights on the skyscrapers in the background, so I probably lightened it a little too much. For the purpose of this exercise, I have not done post processing on this image.

Fig. 03 - Maple tree

Fig. 03 – Maple tree
f4.8, 1/250, 122mm, ISO 200

I wanted to show more saturation in the gorgeous autumn colours of this maple tree in fig. 03, so I deliberately underexposed for this image.

Fig. 04 - Sunset at Ambleside Beach

Fig. 04 – Sunset at Ambleside Beach
f5.6, 1/125, 55mm, ISO 100

To get the orange saturation of the sunset (fig 04) I underexposed by about 2 stops. This resulted in a silhouette of the mountains in the distance, apartment buildings, pier and kayakers, while still retaining some colour in the sea.

In looking through my archives, it looks as if I have a tendency to expose either to the average mark or to underexpose slightly. Probably not a bad thing.

Part 2: take five or six different photographs, of any subject, but for each one make five exposures, arranged around what you have measured as the best exposure. The first should be one stop darker, the second half a stop darker, the third average, the fourth half a stop lighter and the fifth one one stop lighter.

For this part of the exercise I headed over to Grand Boulevard, an urban park modeled after the Champs Elysee, that cuts a green belt through our residential area for about 11 blocks which is very popular with runners and dogs.

For the images of the gnarly tree (fig 01 – 05) I found that all are acceptable to me. Fig 01 is a little oversaturated, but there are still good details in the shadows. Fig 03 – the average reading is pretty much as expected and probably truer to the actual scene. The tree bark in Fig 05 is much lighter than in the other images, although no highlights have blown out. Fig 02, 03 and 04 are the most usable images.

All the images of the gnarly tree’s shadow (fig 06 – 10) work for me, except fig 10 which is on the verge of blowing its highlights in the brighter patches of dead grass. I think fig 09 is the closer replica of the scene than fig 08 is.

The photographs of the park bench (fig 11 – 15) are all fine. Fig 15 is too light for my personal taste (highlights are close to blowing out) and the wooden slats are beginning to lose detail in the wood grain. I think fig 13 is a fair replica of of the actual scene. Personally I would tend more towards fig 11 and 12.

I’m not sure what went wrong with my settings on this set (fig 16 – 20) as my shutter speed changed in the last two shots. I’m going to put it down to cold fingers. Notwithstanding this slip, the exercise still works as the average image (fig 18) is a fair representation of the scene. Fig 19 is very close to blowing highlights, but is still acceptable, but in fig 20 details in the branches and the man’s jacket are totally blown out. My favourite in this set is fig 17.

In the final set of images of this fire-like bush (fig 21 – 25) fig 24 and 25 are not acceptable, although only fig 25 has blown highlights. Because the scene was front lit by the sun which caused a fair bit of desaturation in fig 24 and 25,  I think fig 21 and 22 work the best. Fig 23 is a little lighter than expected.