Archive for July, 2009

Photography Basics: Exposure

by Robert Meeks

I had originally written an article on exposure intended to provide a foundation of the basics for novice photographers. Someone had pointed out that it was perhaps a bit too complex for absolute beginners not familiar with some of the terms used in photography; hence, I wrote this simpler introduction to exposure in photography.

One of the most common terms someone will encounter when getting into photography is the term ’stop’. Aside from jokes about paparazzi being told this several times, a stop is actually referring to exposure.

A stop originally was a reference to the aperture in a lens. In the early days of lens development, even before photography, a lens was often a single or double element (piece of glass) which did not provide a very sharp image due to the center of the lens providing a sharper image than the surrounding portion of the lens. Since the lower sharpness of the outer portion of the lens would reduce the sharpness of the image produced by the lens, someone came up with the idea of blocking or ’stopping’ the light which would pass through the outer portion of the lens by placing a metal disk with a hole in it between the lens elements. This metal disk was called a ’stop’. Since a ’stop’ also reduces the amount of light which passes through the lens in a given amount of time, it also requires more time to expose film as the size of the stop decreases.

We now use the term ’stop’ as a reference for exposure differences.

Exposure differences can be caused by adjusting the amount of time the film is exposed (shutter speed) or by varying the size of the opening in the lens (aperture).

Cameras and lenses use shutter speeds and apertures which have a difference of 2. Either twice as much or half as much. This is also the same value ascribed to a stop.

For shutter speed, we are adjusting the amount of time which the film is exposed to light. If we, for example, are using a shutter speed of 1 second, then we decide to use a shutter speed of 2 seconds, we have increased the exposure by 1 stop; meaning that we doubled the amount of time we were exposing the film. If we were using a shutter speed of 1 second, then we decided to use a shutter speed of 1/2 second, we have decreased the exposure by 1 stop; meaning that we cut the amount of time we were exposing the film in half.

Shutter speeds on a camera which can be selected manually have a difference of one stop between them. You can see this in the amount of time of each shutter speed: 1 second, 1/2 second 1/4 second, 1/8 second, and so on.

Aperture is a little more difficult as the numbers are a relation of the opening in the aperture blades to the focal length of the lens, but the aperture number on each lens means the same thing, regardless of the focal length of the lens; so we can completely forget about focal length when it comes to exposure.

Since the aperture marks on a lens are a difference of one stop of exposure, a larger number meaning less light reaches the film, we can adjust the aperture to control the amount of light which reaches the film. If we are shooting with the lens set at 5.6, then we decide to shoot with the lens set a 8, we are allowing one stop less light to reach the film; meaning half as much. If we are shooting with the lens set at 5.6, then we decide to shoot with the lens set at 4, we are allowing one stop more light to reach the film; meaning twice as much light.

*The numbers representing the aperture on a lens barrel are actually fractions. Hence, a larger number on the barrel is actually a smaller opening in the aperture. An f/8 is smaller than an f/5.6; if the numbers confuse you, just put a ‘1′ in front of the number and it will be easier to remember that 1/5.6 is larger than 1/8. The standard scale of aperture on lenses can range, from largest opening to smallest, as follows: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, and 32. Each difference in one number position (e.g. from a 4 to a 5.6) is one stop.

We can see that adjusting the shutter speed and aperture can both control the amount of light which reaches the film. We can use these in combination to control the amount of light which reaches the film. By decreasing the aperture from 5.6 to 8, and the shutter speed from 1/125 to 1/60, we have decreased the exposure by a total of two stops; as we dropped the aperture and the shutter speed each by one stop.

Do keep in mind that stops is a measure of how we can manually adjust the exposure we are providing for the film and not a measure of the amount of exposure which is required by the film for a particular lighting condition. We get the amount of exposure required from the built in meter on our camera or an eternal meter which tells us where we can set our shutter speed and aperture.

Knowing that each adjustment in aperture or shutter speed decreases or increases the exposure by the same amount, we can use this to adjust the exposure if necessary. If we have set our camera, according to our meter reading, for an exposure of 1/60 second at f/11 (1/60 second shutter speed, f/11 or 11 aperture) and we decide that we need a faster shutter speed to capture an action shot, we can increase the shutter speed by one stop for each stop we adjust the aperture. Being that we know that each increase in shutter speed reduces the exposure by 1/2 (1 stop) (example: 1/125 second gives us half as much time as 1/60 second), then to compensate, we need the increase the amount of light which passes through the lens by by twice as much (1 stop) (example: an f/4 aperture allows twice as much light through the lens as an f/5.6). For our example above, where we have our camera set at 1/60 second at f/11, we can get the same exposure value by setting the camera at 1/125 second at f/8, 1/250 second at f/5.6, 1/500 second at f/4, 1/1000 second at f/2.8, and 1/2000 second at f/2.

Film speed also has an equivalent difference of one stop between film speeds when there is a difference of 2 in the film speed. a 200 speed film is twice as fast as a 100 speed film; meaning that a 200 speed film would allow us one stop more exposure with which to play. Conversely, a 400 speed film is 4 times faster than a 100 speed film which gives us 2 stops more exposure with which to play. This becomes important when we may need extra exposure capabilities due to the lighting conditions. Say that we are shooting indoors with lighting conditions which would give us an exposure of 1/15 second at f/2 (providing that is the maximum aperture at which we can set the lens) using a 100 speed film, we would be challenged to get a sharp image if we had to handhold the camera. If we used a 400 speed film instead, this would give us 2 stops more exposure allowing us to use a faster shutter speed of 1/60 second (1/15 to 1/30 is one stop, and 1/30 to 1/60 is one more stop. Hence, we have decreased the shutter speed by 2 stops, which is the same amount of increase the film has given us.

I hope this has provided some understanding for you with regard to exposure in photography. It is the basic knowledge upon which we can build. Having an understanding of exposure provides us with a base upon which we can add. You should be able to take these basic steps and adjust them according to the needs of the moment to get a proper exposure. Beyond that, you can even develop your own techniques by playing with the exposure.

Have fun with your photography; and remember that your primary goal is not only for your enjoyment of photography, but also to make certain that everyone involved with your photography can share in your enjoyment.

Bob

This article is copyrighted 2006 by Robert Meeks. All rights reserved. Webmasters are allowed to use this article on their site so long as the content and copyright information stays intact and a link is provided, on the same page as the article, to Zhorkow’s CargoShip.

Robert Meeks
http://www.articlesbase.com/photography-articles/photography-basics-exposure-74319.html

I could see where a large corporation that is great at developing products, but poor at manufacturing could be liable to this idea. Once the patent runs out competition could come in and develop a supply chain that’s based on current knowledge … then the company could produce at a much lower cost and cut the sales price accordingly.

Does anyone know how to systematically review / hire people to review companies who are making products under patent protection … then do some type of analysis to see if this is a good idea?

Thanks!

My guess is that you have to go to the PTO website and do a patent search by date. This will give you a big list and then you’ll have to research each patent and see if there is any potential for you. This seems like a bass ackwards way to go into business to me but you could come up with some possibilities this way.

Hi ya does anyone have any tips? I’ve just started my own photography business, i’m nervous, excited scared, ready? I recently took some pictures of prince Charles on his Birthday which made me feel so good. I do weddings, events, parties, products, on location phtography shoots. Does anyone know people in London that are getting married. I would do their wedding photography at a discounted price.Then i can send them my link.

Hi.

Cant help you with weddings etc, but for a free online portfolio, have a look at http://www.redbubble.com/

If you want to join, message me, and I will send you a link to my profiles on there.

Good luck in your career.

EDIT.
Thanks for the thumbs down. Just trying to help by telling about a FREE online PF.

I’m trying to take pet photphotography, so I need to take the photos fast and clear. When I press the button down, it takes the picture and says BUSY. Then it clears itself so I can take the next picture. Can someone tell me a setting to take my pictures fast and clear without the BUSY signal? Also, what type of lens do you recommend for pet photography?

In addition to the excellent thoughts above, please check the write speed of your card. If you are using a "basic" memory card (or perhaps a FAKE card from a bad dealer), you may only have a write speed of 4X-12X. This is not going to cut it for large image files, paricularly if you are using a continuous (burst) mode. Check this page for specific information on the XTi buffer and write speeds. http://www.dpreview.com/reviews/canoneos400d/page12.asp

1X is 150 KB per second. 12X is 1.8 MB per second. If you are using the full 10 MP from your XTi, your image files will probably be around 6 MB. If your storage buffer is full, it will take over 3 seconds to dump each successive image to the memory card before you can take another picture. If you are using a 60X card, for instance, in the same scenario, it would write to the card five times faster.

You should have a minimum of a 60X card and faster is better. I suggest either a Sandisk Ultra II (60X) or Lexar Platinum (80X) card, if not faster. Sandisk Ultra II claims a minimum write speed of 60X or 9 MB per second, and a minimum read speed of 66X or 10 MB per second. Sandisk Extreme III claims a minimum write and read speed of 133X or 20 MB per second.

I have spoken with the director of a daycare. We are going to try to have a day when I takes Christmas photos of the kids (set up a Christmas setting and do portraits of each individual child). I need a sheet to be given to each parents with pricing, etc. Should I set a minimum order price and let them create their own packages or create packages myself?

Also, I’m planning on setting up a mock setting with my daughter to use an an example (have the sample photo shown at the daycare).

Any other ideas?

Should I charge a sitting fee per child?

i would try to sell them the idea that their kids look really cute at daycare, and what they missed out on. how little Tommy was cuddling up to BO BO bear for example, and express that they should of seen it. i would reinforce the idea that they are missing out on precious moments and great displays of their children while they are at work. do set minimum order price, and feel free to create your own packages. I’d just let it be quietly known that i am flexible adjust or alter deals if necessary. mainly I’d just try to push the fact that the Christmas photos are extremely important in the family albums. if parents are saying the cost is high, they are really saying they didn’t see the product being of that value, and what parent is gonna not see the value in their children’s Christmas photos. which is a major heirloom as the child grows on. i wouldn’t charge a sitting fee, however if queried on the cost of photos, I’d say that’s added into the overall price.

I have taken basic photography and would like to learn digital photography.

In photography, the differences are the prints. The larger the film gets the more pixels it gets. In 35 mm SLR - shooting the best shots, with using a very good lens, you can get 20 millions pixels. Right now I have only seen 12.2 million pixels (in Digital SLR), and have heard of 16 millions pixels (however, I don’t know if they have it on DSLR - Digital single lens reflex).
The single-lens reflex (SLR) camera uses an automatic moving mirror system which permits the photographer to see exactly what will be captured by the film or digital imaging system, as opposed to non-SLR cameras where the view through the viewfinder could be significantly different from what was captured on film.
Without getting too technical, films tend to capture color more in depth than with digital. Although, digital is getting there, or maybe it’s there already - as the pixels gets bigger and the color coding gets better. The bigger the print the more pixels you need for certain clarity you are looking for - mostly if you are commercial photography or as an artist. There are also larger film formats like 220 mm.
Then there’s that environmental factor to consider, too. With films, you need chemicals to process them. With digital, you have LCD you have to think about when disposing your digital camera. Films do however, use more chemicals.
Although digital camera is expensive to buy, in the long run, it is cheaper because you don’t have to buy films and have it processed.
You can still make a good living with both digital and film cameras. It is a matter of who is taking the picture.
One big differences I think with both style of photography, is Discipline. You don’t want to make a lot of mistake with film because of time and cost.
Film is still used mostly in movies that are produced today, why do you think that is still the case.

Nudity is an art form even in the time of the Greeks. This can be seen in the various statues that were made which depicted the Gods to the paintings done by sculptors and painters until today. Not everyone is talented in doing this so people who want to excel in this art form will use the camera and bring this out.

Nude photography can be done showing either half or the entire body. This can be done in various poses and locations, which has made people perceive this to be pornography. There are no rules classifying one from the other and this will all depend on the opinion of the viewer.

Anyone can shoot a nude model using a camera. In order to save time, more professionals prefer to use a digital model so that an image can be taken again if the proper lighting was not achieved.

This also allows the specialist to shoot more than a hundred shots in one session without the need to change the film that was done conventionally in the past.

Point and shoot is the only way to get the desired image. First timers who want to get into the business of photography are advised to use digital cameras because the user an adjust the settings to get the right contract and color.

This will make the individual more focused in shooting at different angles instead of worrying how it will look when it is developed.

The key to getting the right nude photograph depends on three things. The first is a good digital camera. There are different brands out there and each of these can help start the artist’s career.

The second is the model. This person should be someone who is open and comfortable being nude in front of the camera. Some people have shot the woman with clothes on first before deciding to take it all off.

The location is not that hard to find compared to the first two. This is can be done anywhere such as the beach or the park because natural light can really bring out the skin color of the model.

Nude photography may have some erotic element every time someone sees it. This just proves that sex sells and magazines such as Playboy and Penthouse among others are making a lot of money from it.

Those who want to start a career in nude digital photography should use these three elements and become famous from it.

Low Jeremy
http://www.articlesbase.com/computers-articles/nude-digital-photography-110659.html