Depth of Field Table

Depth of Field Converter Table

Depth Of Field

Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field


CIRCLE OF CONFUSION






Since there is no critical point of transition, a more rigorous term called the "circle of confusion" is used to define how much a point needs to be blurred in order to be perceived as unsharp. When the circle of confusion becomes perceptible to our eyes, this region is said to be outside the depth of field and thus no longer "acceptably sharp." The circle of confusion above has been exaggerated for clarity; in reality this would be only a tiny fraction of the camera sensor's area.


When does the circle of confusion become perceptible to our eyes? An acceptably sharp circle of confusion is loosely defined as one which would go unnoticed when enlarged to a standard 8x10 inch print, and observed from a standard viewing distance of about 1 foot.


At this viewing distance and print size, camera manufactures assume a circle of confusion is negligible if no larger than 0.01 inches (when enlarged). As a result, camera manufacturers use the 0.01 inch standard when providing lens depth of field markers (shown below for f/22 on a 50mm lens). In reality, a person with 20-20 vision or better can distinguish features 1/3 this size or smaller, and so the circle of confusion has to be even smaller than this to achieve acceptable sharpness throughout.

A different maximum circle of confusion also applies for each print size and viewing distance combination. In the earlier example of blurred dots, the circle of confusion is actually smaller than the resolution of your screen for the two dots on either side of the focal point, and so these are considered within the depth of field. Alternatively, the depth of field can be based on when the circle of confusion becomes larger than the size of your digital camera's pixels.

Note that depth of field only sets a maximum value for the circle of confusion, and does not describe what happens to regions once they become out of focus. These regions also called "bokeh," from Japanese (pronounced bo-ké). Two images with identical depth of field may have significantly different bokeh, as this depends on the shape of the lens diaphragm. In reality, the circle of confusion is usually not actually a circle, but is only approximated as such when it is very small. When it becomes large, most lenses will render it as a polygonal shape with 5-8 sides.
CONTROLLING DEPTH OF FIELD

Although print size and viewing distance influence how large the circle of confusion appears to our eyes, aperture and focal distance are the two main factors that determine how big the circle of confusion will be on your camera's sensor. Larger apertures (smaller F-stop number) and closer focusing distances produce a shallower depth of field. The following test maintains the same focus distance, but changes the aperture setting:
f/8.0
f/5.6
f/2.8

note: images taken with a 200 mm lens (320 mm field of view on a 35 mm camera)
CLARIFICATION: FOCAL LENGTH AND DEPTH OF FIELD

Note that I did not mention focal length as influencing depth of field. Even though telephoto lenses appear to create a much shallower depth of field, this is mainly because they are often used to magnify the subject when one is unable to get closer. If the subject occupies the same fraction of the image (constant magnification) for both a telephoto and a wide angle lens, thetotal depth of field is virtually* constant with focal length! This would of course require you to either get much closer with a wide angle lens or much further with a telephoto lens, as demonstrated in the following chart:

Focal Length (mm)Focus Distance (m)Depth of Field (m)
10 0.5 0.482
20 1.0 0.421
50 2.5 0.406
100 5.0 0.404
200 10 0.404
400 20 0.404


Note: Depth of field calculations are at f/4.0 on a Canon EOS 30D (1.6X crop factor),
using a circle of confusion of 0.0206 mm.

Note how there is indeed a subtle change for the smallest focal lengths. This is a real effect, but is negligible compared to both aperture and focus distance. Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below:

Distribution of the Depth of Field
Focal Length (mm)RearFront
10 70.2 % 29.8 %
20 60.1 % 39.9 %
50 54.0 % 46.0 %
100 52.0 % 48.0 %
200 51.0 % 49.0 %
400 50.5 % 49.5 %


This exposes a limitation of the traditional DoF concept: it only accounts for the total DoF and not its distribution around the focal plane, even though both may contribute to the perception of sharpness. A wide angle lens provides a more gradually fading DoF behind the focal plane than in front, which is important for traditional landscape photographs.

Longer focal lengths may also appear to have a shallower depth of field because they enlarge the background relative to the foreground (due to their narrower angle of view). This can make an out of focus background look even more out of focus because its blur has become enlarged. However, this is another concept entirely, since depth of field only describes the sharp region of a photo — not the blurred regions.

On the other hand, when standing in the same place and focusing on a subject at the same distance, a longer focal length lens will have a shallower depth of field (even though the pictures will show something entirely different). This is more representative of everyday use, but is an effect due to higher magnification, not focal length.

Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view (see thetutorial on digital camera sensor sizes for more on this topic).

*Technical Note: We describe depth of field as being virtually constant because there are limiting cases where this does not hold true. For focal distances resulting in high magnification, or very near the hyperfocal distance, wide angle lenses may provide a greater DoF than telephoto lenses. On the other hand, at high magnification the traditional DoF calculation becomes inaccurate due to another factor: pupil magnification. This reduces the DoF advantage for most wide angle lenses, and increases it for telephoto and macro lenses. At the other limiting case, near the hyperfocal distance, the increase in DoF arises because the wide angle lens has a greater rear DoF, and can thus more easily attain critical sharpness at infinity.
CALCULATING DEPTH OF FIELD

In order to calculate the depth of field, one needs to first decide on an appropriate value for the maximum allowable circle of confusion. This is based on both the camera type (sensor or film size), and on the viewing distance / print size combination. Needless to say, knowing what this will be ahead of time often isn't straightforward. Try out the depth of field calculator tool to help you find this for your specific situation.
DEPTH OF FOCUS & APERTURE VISUALIZATION

Another implication of the circle of confusion is the concept of depth of focus (also called the "focus spread"). It differs from depth of field in that it describes the distance over which light is focused at the camera's sensor, as opposed to the subject:


Diagram depicting depth of focus versus camera aperture. The purple lines represent the extreme angles at which light could potentially enter the aperture. The purple shaded in portion represents all other possible angles. Diagram can also be used to illustrate depth of field, but in that case it's the lens elements that move instead of the sensor.

The key concept is this: when an object is in focus, light rays originating from that point converge at a point on the camera's sensor. If the light rays hit the sensor at slightly different locations (arriving at a disc instead of a point), then this object will be rendered as out of focus — and increasingly so depending on how far apart the light rays are.
OTHER NOTES

Why not just use the smallest aperture (largest number) to achieve the best possible depth of field? Other than the fact that this may require prohibitively long shutter speeds without acamera tripod, too small of an aperture softens the image by creating a larger circle of confusion (or "Airy disk") due to an effect called diffraction — even within the plane of focus. Diffraction quickly becomes more of a limiting factor than depth of field as the aperture gets smaller. Despite their extreme depth of field, this is also why "pinhole cameras" have limited resolution.

For macro photography (high magnification), the depth of field is actually influenced by another factor: pupil magnification. This is equal to one for lenses which are internally symmetric, although for wide angle and telephoto lenses this is greater or less than one, respectively. A greater depth of field is achieved (than would be ordinarily calculated) for a pupil magnification less than one, whereas the pupil magnification does not change the calculation when it is equal to one. The problem is that the pupil magnification is usually not provided by lens manufacturers, and one can only roughly estimate it visually.

Cyanotype processing

The cyanotype process was one of the first non-silver technologies used to create photographic images. Originated in the 1840's, it was not utilized in mainstream photography and was adopted as a copying technique, becoming known by the term "blueprint", with its blue background reproductions of large architectural and mechanical drawings.

http://www.alternativephotography.com/wp/processes/cyanotype/cyanotype-classic-process

Salt printing

Morning all! I watched a tutorial this morning on how to make your own photosensitve paper using natural salt, silver nitrate. See this link to view video

My 35mm film STREET PHOTOGRAPHY

Today I hit the streets of St Helens....oh whats sights!

I loaded my old Canon EOS 500 with a black and white 400iso film and mooched around inconspicuously.

Most of the images captured were taken at the hip so I could catch the people of St Helens off guard. My camera setting was on a 1/125 TV (time value) and the aperture (f stop) was either set at 4.5 or 5.6 with the lens wide open, set at 35mm.

It only took me half an hour to use the film up so I headied straight back to the darkroom to follow the below process 
loading a 35mm film into a developing tank

I then processed my negs click on this to see a similar process
My chemicals were ready mixed so I needed 300ml for each spool. In my tank was 2 so obviously I need 600ml of each chemical.
Dev process was 20 min, Stop process was 1 min and Fix was for 6 mins. I then rinsed for twenty minutes in water at a temp of 22c,
Last but not least I hung and dried out in the neg dryer for 20 mins.

I was so pleased with the results, I have attached below a contact sheet of my negatives for you to assess!

My contact sheet was made via photoshop cs4 using the app contactsheetII

I loaded my negs onto the comp via neg scanner

Garry Winogrand 35mm Film Photography

Garry Winogrand

 (14 January 1928, New York City – 19 March 1984, Tijuana, Mexico) 

Im in LOVE with his work!

Garry Winogrand shot with a 28mm lens for most of his life, which meant that for the majority of his shots he had to be quite close to his subjects (and in front of them). Therefore Winogrand wasn’t Henri Cartier-Bresson (trying to be invisible) but was actively a part of the action and immersed in the crowds. He would be very obviously taking photographs in the streets and would stick out like a sore thumb.

Here are a few of my favourite images 

Street Photography: NYC Above and Below

Our group presentation

Our group presentation

As promised, here is the link for the presentation I did with a few other students, as quoted in my earlier blog, we discussed the composition of each chosen photograph, including juxtaposition, ambiguity, leading lines and angles.

Take a look x

Composition presentation

https://docs.google.com/open?id=0ByO-swIa1GhEcjRxbmpFY19XRVE

Uploaded images

Managed to find the time to upload some images I captured over the weekend tonight. Was quite pleased with the outcome considering I was mainly on the move and rarely had time to sit in one spot!!
I will be uploading some more tomorrow.

I am finding its easier to talk about and understand the composition of my images after doing lots of research for eg Composition Tips  I visit this site quite often and have found this particular article very useful as it covers a variety of key factors for composition in photography

TTFN

Tick Tock

Manual, ISO 400, F/7.1, SS 1/125, 70mm

I love this photograph, home is where the heart is!

The composition is well balanced and almost perfectly symmetrical. It ambiguitive as you very rarely look at the liver buildings from this point of view.

Great juxtaposition due to the angle of the photo, making the two clock faces side by side.

Dew drops

ISO 3200, F/5.6, SS 1/30. 55mm

Behind the lens

Behind the lens

ISO400. F/7.1, shutter speed 1/320 70mm

One of my best shots, this image has great shallow depth of field. It also has no negative space, the composition is very dynamic. The viewers eyes start at the main focus point, the ladies sunglasses, onto the looking space in front of her ( the fountains) which is where her companion appears to be looking, then, back to her.

Although their heads are at different angles I think there is quite a strong juxtapose as their bodies positioning is almost identical. The ladies expression is very distant, I cant quite figure out if she is happy in the NOW or appears to be happy thinking of pastimes?

Depth of field

I have attached a few pics of mine I did back.in Australia that demonstrate narrow and wide depth of field. Take a look x

Should be in ALL street photographers pockets!

Whilst researching the internet on street photography I came across this handy little doc. It gives you advice on all the sticky situations you may find yourself in when engaging in street photography. Im gonna print it off and keep it with my cam at all times

The photographers right

Go take a look

Street is the word!

I went to Liverpool and nature walk with my family this weekend armed with my camera to experiment with street photography and my settings on my dslr camera. I played about with aperture priority and a shutter speed of 1/125 and went hardcore and opted mostly for completely manual, yes u read right MANUAL! Was very difficult at times asbo was constantlt moving through shadows and in the shade then into bright Sunlight etc so I had to change my settings almost everytime I went to snap. Was real fun though and getting a bit.more confident about photographing in public.
I will be uploading a few images tomorrow after finding some spare time to go thru them, I'm sure there are some keepers, or at least I hope so!
Ttfn x

Depth of Field Assignment

New Task!

After completing my workbook I have been given a new task, A TWO WEEK PROJECT- FIGURE AND LANDSCAPE



During this task I will be researching Depth of Field, both narrow and wide. Upon researching and experimenting various tchniques I will produce a number of 35mm photographs displaying the effect of both narrow and wide depth of field.

Today we began by researching different photgraphers whom are famous for their 35mm photography such as

• Henri Cartier Bresson
• Rodchenko
• Lee Freidlander
• Josef Koudelka

These guys were famous for capturing the moment, street photography. An example below is by Henri Cartier Bresson

This image includes the rule of thirds in its composition, also repetition of variation regarding the doors/windows all being of similar colour and shape. The geometry of the the stairs leading up.

We also had a mini task given to us to do a presentation based on photographs representing all of the below

• Repetitions
• Depth of Field, both wide and narrow
• Juxtaposition
• Narrative
• Geometry
• Ambiguity

I will attach our finished presentation in the next post.

TTFN

My Photograms

I FINALLY get my container with all my worldly possessions delivered from Oz in the morning. This includes my other 35mm camera, lenses for my DSLR AND my scanner YAY!!
I will then be blogging til kingdom come over the weekend uploading my scanned photograms, pinholes and 35mm negs along with notes on my journey while producing these cool images!!
See you over the weekend x

All has gone quiet on the blog, my scanner has died :(

I will be back!

Photograms finito!

Photograms task complete! 

Today, I finally completed the photogram task yippeeee! As I started my course late I missed out on the opportunity to do photograms in the darkroom with my class so I did them on my lonesome in the darkroom this arvo.
I really enjoyed the whole process having the added benefit of a few days research in advance. Including the below darkroom rules I discovered online.

So first of all I gathered all of my materials needed including: 

3 or 4 chemistry trays: The first tray for the developer solution, the second for the stop bath solution, the third for the fixing solutions and the fourth for the plain water rinsing. 




              Black and white photography paper 











Last but not least, image props/objects which can be any three dimensional or two dimensional objects (i.e. paper cut outs, cutlery, toys, your own fingers/hands/feet, flowers etc


One of the most important things to remember when setting up a photogram is that the ONLY light to have on is the SAFELIGHT. If you have any other light hitting the light sensitive paper it will become prematurely exposed.

• I placed my paper shiny side up underneath my light source ensuring that it was in the correct position by ling up with the guidelines masking tape. I then arranged the composition of my image by placing several chosen objects directly onto the paper.

• Once I was happy with the composition i hit the timer and exposed my images for an average of 9 seconds (some a little longer some less depending on how much exposure i wanted)

• Clearing away the objects I then placed the paper into the developer face down and agitated it a little for two minutes and turning to face up.

• I then removed from the developer and placed and agitated the paper in the stop bath for 30 seconds  ensuring the developer was rinsed.

• The next step was to place the paper in the fixer tray after letting the paper drip for a few seconds. With a little tap ensuring the paper was fully submerged I left the paper for 4 minutes

• After the 4 minutes were up I removed the paper to drip for a few seconds then submerged the paper into the water rinse for 5 minutes

VOILA!!! Your photograms are processed! Remove from the water rinse and dry :)
Tomorrow I will scan and upload my good and not so good photograms and let you be the judge of them -_-
 

more photograms!!!

Sunday evening, raining outside and sat here at the comp wth a belly full of sunday dindins and a glass of vino mmmm

So I thought now would be a perfect time to do a little more research on photograms, here are my findings..............

I came across a number of photograms while searching the internet but these in particular caught my eye.

This photogram was by a lady named 
Anna Atkins 

She lived from 1799-1871

Atkins was friends with Herschel and Talbot, other well known photographers. She had a large interest in botany, and used the cyanotype process to photograph plants. Throughout her career as a photographer she made a book with these plant photographs, and was credited with making the first book of photos. Anna Atkins is also credited for being the first female photographer.

The image caught my eye as I love POPPIES and this image is full of them.
I particularly like the way the light has captured the depth of the flowers, it shows how strong the stems  are and how delicate and near transparent the petals are.
The image also has balance with equal amount of stems on the bottom half of image to similar amount of petals (flower heads) on the top half of image.




Now this image is by an unknown artist going by the name of  asdjklfg
They achieved this photogram by placing real flowers on the bottom half of the photo paper and then placed a cut-out hot air balloon on the top right of the paper.
The outcome is lovely. Almost fable/fairytale like. It holds an adventurous story in it thats beginning, middle and end could vary every time you look back at it.









So, I now have more ideas for my own photograms which I will hopefully be making on Tuesday. Each photogram must contain a mood or emotion. So far I have heart broken, celebratory, generous, hungry, mow I best get my props sorted heehee xoxo 

The lowdown on Photograms

So....My first task is Photograms.

What its all about?

A photogram is a photographic image made without a camera by placing objects directly onto the surface of a light-sensitive material such as photographic paper and then exposing it to light. 
The usual result is a negative shadow image that shows different kinds of tone that depends upon the transparency of the objects used. Areas of the paper that have received no light appear white; those exposed through transparent or semi-transparent objects appear grey.

Now this is all new to me, the traditional side of photography so I hit the web to do some research to prepare me for my first dark room session tomorrow.

One word comes to mind WOW

I never knew something so simple could produce something so complex and interesting.
The versatility of one object is amazing. With the form of photogram you are able to add depth or movement or emotion to an image from just one object.

I have added a few links of some of my findings so far


an-introduction-to-photogramsshadow catching
photograms-a-cameraless-image


Below are a couple of  photograms that caught my eye:

Make Love Not War
A simple water pistol with a daisy inserted!

Mark Magnan
These images remond with of fairies or elfins, created with large photosensitive papers and a person lay flat or  on back with knees up position

My Four Week Project

This blog is to document my findings over the next four weeks on the below three subjects:

• Photogram (Emotion)
• Pinhole (Reflection)
• SLR 35mm (Perspective)

I have to analyse, evaluate and experiment techniques to produce a number of photograms, pinholes and SLR 35mm images to show that I can recognise the full potential using materials, techniques and processes.
I will source this info from lectures, presentations, handouts and demos as well as the internet etc