Session 3 - "F" stops and shutterspeeds

And so to the nitty-gritty of "F" stops and shutter speed.

Aperture and "F" stops

I'm not going to go all technical here as I'm no expert. The "F" number is calculated from the relationship between the focal length of the lens and the lens diameter. Oops! That sounds somewhat technical. Ho hum.

F = focal length (mm) / lens aperture (mm).

So a 100 mm focal length lens at an aperture of 25mm will be f4.
         100 mm                                                               10mm will be f10
         100 mm                                                                  5mm will be f20

So, the higher the "F" number the more light is being blocked out.Each whole "F" stop aparently cuts out half the light available to the previous "F" stop.

Image source

The aperture size also has an effect on the sharpness of the resulting image. A small aperture will provide a sharp image as the light is concentrated and less scattering occurs. A larger aperture increases the amount of light scatter and results in a less coherent image. Aperture can be used to control the "depth of field" in a picture. According to Wikipedia "depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image". A shallow depth of field will only have a very limited focus. The image below was taken at F4

A smaller aperture provides a sharper image with a much greater depth of field. This image was taken at F22.

The human eye in daylight conditions is around F8

Shutter speed

The shutter speed controls the amount of time that the sensor/film is exposed to light.
A slow shutter speed would be needed for poorly lit conditions as more time is required to obtain the light. Conversely bright conditions require high shutter speeds to avoid the sensor being swamped.

According to Wikipedia

"The agreed standards for shutter speeds are:

• 1/1000 s
• 1/500 s
• 1/250 s
• 1/125 s
• 1/60 s
• 1/30 s
• 1/15 s
• 1/8 s
• 1/4 s"
• 1/2 s
• 1 s

1/60th of a second is the mid value for shutter speed.

Shutter speed can be used to either blur motion or to freeze it. A fast shutter will freeze an image while a slower shutter will result in blurring.

original source

The See-Saw connection

Aperture and shutter speed work in unison. As the aperture increases in size then the shutter speed must also increase to avoid over exposure. Similarly when the aperture becomes smaller then the shutter speed needs to slow to avoid under exposure. The best pictorial representation I've seen of this is the see-saw diagram. 

See here for the full article 

The initial diagram shows a camera set at F4 and a shutter speed of 1/125th.

The left hand side of the diagram provides the approximate aperture size.

The right hand side provides a clock view representing the shutter speed. The "open" part of the pie represents the fractions of a second that will pass at the particular shutter speed.

ISO

So far in my photography I've played around with apertures and shutter speeds but left my ISO on auto. Now it seems I need to work in full manual mode, so I'd better become acqainted with ISO. I remember once buying a high ISO black and white film for my old Olympus Trip in an attempt to capture some moon shots and star trails. However, I didn't have a tripod or a remote shutter release,  so the results were a blurry, grainy mess!

The ISO number is a measure of how sensitive the sensor / film is to light.

A high ISO (1000+) is recommended for low light conditions.

A low ISO (160) is recommended for strong light.

A medium ISO (400 ish) for dull rainy days in England. Looks like I'll be using 400 a lot!

High ISO generates a lot of digital/pixellated noise giving a grainy texture to the image. Low ISO privides a much sharper image.

ISO can be used in combination with aperture and shutter speed to control the amount of light entering the camera. The basic rule is:

1 "f" stop = 1 shutter speed "stop" = 1 ISO value.

original link

So if an image is overexposed at f8 and 1/60th with an ISO of 400 you could ...

A. Reduce the aperture to f7           OR

B. Increase the shutter to 1/200ths OR

C. Decrease the ISO to 200

All the above would have similar results depending in what you are taking a picture of, and what you want in the final image I.e. frozen motion / Depth of Field / sharpness 

Here are various other pictures taken during the course

Around Tresham college with a camera

f5.6 at 1/60th of a second. ISO 6400. No flash indoor shot. Colour exaggeration added later.

The cheese grater lift housing. f5.6 at 1/60th. ISO 800. Indoor shot. No flash.

Depth of field. f5.6.at 1/60th of a second. ISO 6400 ..no flash indoor shot

Macro madness

Convergent parallel lines

Convergent parallel lines

Mine!

Rain with webbing

After rain 1

After rain 2

Playing with black and white at 50mm

Postie parking lot

Bike graveyard

The Blitz tea rooms (Kettering) as seen in wartime when everything was in black and white

A cup of wartime tea

Playing with depth of field by the "haunted" house

Row boats at Wicksteed park

Photography in the style of Henri Cartier Bresson

The homework for session 2 is to produce a photograph in the style of Henry Cartier Bresson

Rules used to create a Henri Cartier Bresson style of photograph

1. Must be black and White
2. Must contain people
3. Must be in natural light
4. Must be shot at 50mm (i.e. near to what is seen by the human eye)
5. Should have a decisive moment
6. Should not be posed
7. Should adhere to the rule of thirds

Not an easy task! Being January the hours of natural light are limited, especially when I work Monday to Friday nine to five. This leaves me with the weekend. Saturday is already spoken for, so I've just got Sunday to produce something special. Ah well!

As an emergency backup I have a photograph I took about a month ago..

This was taken in a bar in Pilzn (Czech Republic)

This reminds me of an H.E.Bateman style of cartoon.

Perhaps it should be titled "The man who found something on the menu that did not contain pork"

(You need to visit restaurants in the Czech republic to understand this!)

The wood paneling almost divides this picture into 3rds. This was taken at 60mm.

Fortunately for me, Sunday was sunny in parts. I set the custom setting on the GX1 to monotone, zoom resume on 50mm, continuous burst with shutter priority and cycled off to one of Ketterings skateparks.

Decision time ... to go or not?

If a photo is taken on the slant does the rule of thirds grid also need to?

Other skatepark pictures (not necessarily in the style of H.C.Besson)

This wall is probably over 3 metres high

I like the diagonal aspect in this.

Teetering on the edge

Cameras I have clicked with ...

My earliest camera was a Kodak Instamatic. This had a magic flash cube which rotated all by itself when you took a picture. The cassette film load system seemed really futuristic. Oddly enough my last film camera took an updated version of the cassette idea, the Advantix.

I used this for years until it was stolen by a thief who calmly walked through our student halls and lifted whatever took his fancy. The picture quality wasn't brilliant, but would probably now be a cult camera had it been made in the old Eastern bloc. I first learnt the limitations of flash photography on this camera, but I did look forward to using the flash cube as the heat produced would melt the bulb and the surrounding plastic and create a mini molten sculpture.

I borrowed my brothers camera for a few months afterwards. This was a Voigtlander.  A pathfinder camera. I remember this as being quite a significant purchase at the time, in that it seemed to be really expensive. To quote my brother  "I  ended up with the model without the light meter, something of an agonising decision as I recall as I really wanted the one with the meter."

See Ollingers camera collection

This was my first 35mm encounter. However, this had developed a paralax problem in that what you saw through the viewfinder was not necessarily what you were taking a picture of. This led to some frustration when developing the photographs!

An Olympus trip followed

This boasted a solar powered exposure metre and 35mm film. A really good compact camera. I took reels of slide film with this on a number of long distance cycling trips, mostly over mountains. However, Digitally rendered slide film lose a lot!

This was a pretty rugged camera and survived being dropped,  soaked, baked and frozen a number of times. Eventually though it started to leak light in a very retrolux way. After the demise of the Trip came a couple of Advantix cameras. These were fine but not too rugged!

The Advantix film stored the negatives in the original film reel. Quite a neat idea! I'm not too sure what became of my last Advantix camera, but I expect it is probably hidden somewhere at the back of a dusty cupboard.

Finally in 1999 I entered the digital age with a camera that came free with a desktop computer. This boasted a whole 2mb sensor.

Picture quality from this was suprisingly good in bright light, but it was extremely slow at taking anything in reduced light. But I suppose one should never look a gift camera in the lens. This introduced me to the wondrous world of digital image editing. I soon realised what limitations there were to a 2mb image so decided to upgrade to something compact but more powerful. 

The Panasonic DMC-TZ3

This is a camera I can hardly fault at all. Without doubt the best compact camera I have used (although, to be fair there isn't much competition  ... apart from perhaps the Olympus Trip).  I still use it when I don't have space to carry the GX1. This would still be my main camera if I hadn't received a long service lump sum from the company I work for. See my first post!

The GX1 is a powerful beast! This is a micro four thirds camera.

According to Wikipedia  "The image sensor of Four Thirds and MFT is commonly referred to as a 4/3" type or 4/3 type sensor (inch-based sizing system is derived from now obsolete video camera tubes). The sensor measures 18 mm × 13.5 mm (22.5 mm diagonal), with an imaging area of 17.3 mm × 13.0 mm (21.6 mm diagonal), comparable to the frame size of 110 film.^[3] Its area, ca. 220 mm², is approximately 30% less than the APS-C sensors used in other manufacturers' DSLRs, yet is around 9 times larger than the 1/2.5" sensors typically used in compact digital cameras."

I'm still getting to grips with this camera as there are just so many things you can do with it. My latest discovery is the handy "custom mode" which allows for bespoke  settings to be stored and recalled at the merest twidling of a dial. Currently this puts me in black and white, shutter priority, af tracking, multi exposure with a zoom resume set at 25mm (50mm SLR equivalent)

Session 2: Cameras!

Session 2. Cameras!

So many cameras, so very little money! C's talk on the different camera types took me back to my childhood where enticing toy shop windows encouraged nascent  feelings of avarice. But what would I do with so many cameras and how would I ever decide on which one to use? Nevertheless,  it would be interesting to try them out!

The wooden pin hole camera looked very collectible!

While at the other end of the spectrum ... the full frame cameras. These are expensive and heavy bit of kit but they  do provide amazing detail.

These provide between 24 and 36 megapixels and cost from £2,000+. I think I may wait a while before buying one of these! These are the more expensive SLRs. Both use a mirror in the body of the camera allowing the user to look directly through the lens.

Medium format

As used by wedding photographers, fashion shooting. Another high quality, high cost camera. Bulky and slow to use. I suppose it would be handy to have a camera with a back end where you can interchange a number of different films (black and white, Colour, High ISO, low ISO etc), but I don't think I'd ever take one hiking with me! The bellows type allow you to change the focusing plane which can be used to avoid "tomb stoning" when taking pictures of high buildings. There is a "bolt on" lens adapter for "normal" cameras that allow you to do something similar .. the lensbaby. I may have to buy one of these when I next have the odd £100 to spare! These can be used to create the tilt-shift effect.

Here's a picture I took of the market place in Pilzn, taken with a tilt-shift setting. This gives a "toy town" effect

Folk eventually became fed up with carrying  heavy cameras around, so someone eventually came up with a lighter alternative. The "Rangefinders". These have no internal mirror and can be more compact.

This type of camera has been used extensively by documentary photographers such as Robert capa.

This is one of the few frames to survive from the reels of film he took during the Normandy D-Day landings. All the other negatives were lost in a fire.

The "Lomo" camera was the Eastern Blocs' answer to the Leica (and its Canon, Nikon, Olympus etc variants) Rangefinder. These were mass produced and have gained something of a cult following. These have cheap lenses and none too solid bodies and result in pictures with odd colour casts and other unusual elements.

 I must admit to being a fan of lomography and have been known to convert some of my pure and pristine digital images to the grunge like lomo style. Instagram is basically lomography for smart phones.

This perhaps needs more vignetting to be true lomo!

The "Holga" camera does for medium format cameras what the "Lomo" did for the "Rangefinder"

This develops the whole width of a 35mm strip including the gaps between the sprocket holes!

The micro four thirds cameras are the latest "Rangefinder" cameras. These are slimmer and lighter than SLRs as they are mirrorless, but they still have an SLR equivalent sensor and interchangeable lenses. What a marvelous camera type this is! But then I might be biased!