Friday, December 30, 2005 

Again: Large and Small Apertures

Large Apertures

At the largest aperture, a maximum amount of light can pass through the aperture to reach the image sensor. This therefore allows for a fast shutter speed, good for freezing action, at the same time minimising the effect of camera shake (caused by instability.) Resulting pictures are usually not blurred.

A large aperture also provides a shallow DOF. This isolates your subjects nicely, but focusing solely on it, while blurring the background.

Small Apertures

Converse to using large apertures, small apertures are good to work with when you desire a slow shutter speed. While fast shutter speeds freezes action, slow shutter speeds allows for more action, depicting motion.

Small apertures provides a greater DOF. A greater DOF is good for taking landscape pictures, where it is desirable to have the foreground, as well as the background to be in sharp focus.

 

What f2.7 - f3.5/f8 mean?

F-stop numbers represent the size of the aperture. The bigger the f-stop number, the smaller the aperture. Conversely, the smaller the f-stop number, the wider the aperture.

Indicators like f2.7 - f3.5/f8 refers to the range of openings of which a zoom lens can operate within.

In this case, read the indicator as f2.7 - f8 when the camera is most zoomed out (Wide-angle.) Read the indicator as f3.5 - f8 when the camera is most zoomed in (Telephoto.) That is what f2.7 - f3.5/f8 means.

(I still can't figure out something. In this case, f2.7 is at it's wide-angle, because a larger aperture size give rise to a wider viewer range? While at f3.5 is at it's telephoto, because a smaller aperture size means a smaller viewer range?)

 

SNT #2: Depth-of-Field (DOF) #2

The aperture size isn't all that has an effect on the DOF. The distance between the camera and the subject also has an influence on the DOF.

Simply, the greater the distance between the camera and the subject, the greater the DOF. Conversely, the smaller the distance between the camera and the subject, the smaller the DOF.

Therefore we can expect the DOF of macro shots to be shallow (e.g. just the legs of an insect,) while DOF of shots as far as the horizon to be greater.

(Related: DOF #1)

Thursday, December 29, 2005 

File Magazine.com

Have you already heard of this great site yet?

File Magazine hosts an excellent display of side-stream photography. The site publishes photos that treat subjects in unexpected ways.

My favourite from the site: High Speed Photography. Have fun!



(Image from File Magazine)

 

SNT #4: Fill-In Flash

I lug my trusty Canon IXUS v3 with me every where. It's forever in my bag. I take snaps indoors restaurants, in lecture halls during lectures, in my kitchen, of food, and of friends when outdoors. Problem is, for outdoor shots, my subjects usually appear as a silhouette against a brightly lit background. A useful technique to counter the problem, is to employ the use of fill-in flash.

So what is it that causes the camera to under expose the foreground subject, which results in the silhouette effect? Like the human eye, the camera, when 'seeing' a brightly lit light, will 'squint.' For humans, the pupils are constricted to allow less light into the eye, while for cameras, the aperture size is adjusted smaller. As the aperture closes, less light enters the image sensor, causing the foreground to appear darker than the background.

Fill-in flash is used to soften dark areas in the foreground, against a brightly lit background. When shooting under fill-in flash mode, the camera is forced to flash a short burst of light while the shutter opens, illuminating the foreground when the photo is taken. This eliminates the silhouette effect, bringing life to the subject.

Also try, as far as possible, always to take shots that has natural lighting shining on your subject's front.

Wednesday, December 28, 2005 

SNT #3: What is "35mm Equivalent?"

I guess you've heard of this amazing online photo community/application called flickr. With the plentiful of various interest groups, the amount of fun one can get from just viewing the millions and millions of photos is never ending! Having spent quite an amount of time on flickr myself, I often come across things like "38 mm to 115 mm equivalent focal length" or "Focal length 7mm" which just leaves me dumbfounded. What do these terms actually mean?

This is what I've learnt today:

35mm is actually the width of the film (called 135-format) used by "35mm cameras". Most photographers are used to the focal length talk of the 35mm cameras.

The focal length is the distance between the aperture, and the image sensor. For all 35mm cameras, the focal lengths are all the same; Because only 1 type of film is used (the 35mm one.)

However for digital cameras, not all focal lengths are the same. Digital cameras use digital image sensors, like CCD or CMOS. And their sizes, are often smaller than 135-format film, can vary from different manufacturers and even models of the same brand. Therefore, for each particular digital camera, they can have their own specific focal length.

Now, at a certain focal length, say 25mm, the 35mm camera can take shot (of this apple) from a certain field of view, say 45 degrees.



As the digital camera's CCD or CMOS image sensors are of a different size with the 35mm camera's image sensor, to obtain a similar field of view of the apple, 45 degrees, the focal length of the digital camera will be different. In this case, the focal length of the digital camera is 20mm.



In short, there is a "35mm equivalent" because of the many different sizes of the image sensors of digital cameras, it is more convenient to express focal lengths in terms of "35mm equivalent" for easy comparison of cameras from different manufacturers.

Phew! What a long post! Happy Holidays!

Saturday, December 24, 2005 

Composing Your Photos #2

5. When photographing moving subjects (like a fast car,) leave space in front of the direction it is travelling, so that it does not appear as it is leaving the photo.

6. Although horizons and vertical skyscrapers should be off-center, be sure to make sure that the lines aren't tilted!

7. Keep the backgrounds as simple as possible. Cluttered backgrounds distract the audience from the main subject. As far as possible, choose backgrounds with homogeneous colours.

Tuesday, December 20, 2005 

SNT #2: Depth-of-Field (DOF)

DOF refers to distance within wherein the subjects are focused, i.e. how much of a photo is sharp in front and in back of where you focus on the main subject. If most of the photo is in focus, the DOF is high. If most of the photo (background) is blurry, with only the subject focused, the DOF is low. DOF is primarily controlled by aperture size, though DOF effects can be achieved by using photo editing software, or simply by placing a focused subject far away from its background.

F-stop numbers depict the size of the aperture.

Larger aperture sizes are represented by smaller f-stop numbers, and consequently a lower/shallower DOF.

For example:
SMALLER f-stop number (f2.8) = LARGER aperture = SHALLOWER DOF
BIGGER f-stop number (f22) = SMALLER aperture = GREATER DOF

Even more direct:
Small f-stop number (f2.8) = Shallower DOF
Bigger f-stop number (f22) = Greater DOF



(Only the subject is focused, with the rest blurry. Photo with low DOF)

Sunday, December 18, 2005 

How Many Megapixels Do I Need? #2

Megapixels. Sure, I know what resolutions they give me, but how do they translate into print sizes? Sometimes, we have limited memory left in our cards, and have to decide if it will be okay to drop from the highest image resolution, while still getting a decent print. I found a nice graphical diagram to help me with it, so here's it:




(Source: http://www.microsoft.com/athome/morefun/megapixels.mspx, or visit Related #1.)

Wednesday, December 14, 2005 

4 Straight Forward Ways to Save on Battery Power

1. Don't use flash unless necessary. The strong burst of light that comes on when you hit on the shutter-release that takes up load of power from the battery. Instead try to position your subjects to face as much natural lighting as possible.

2. Don't use LCD if you can. The vibrant LCD display is a power drainer. The brighter and more colourful the screen, the more power required. Instead, try taking your shots using the optical viewfinder. If your camera only has a LCD viewfinder, power off your camera in between shots.

3. Avoid accessing the memory card. Stuffs you do like reviewing photos straight after a shot, or deleting photos on the fly, requires frequent access to the memory card. More power is consumed than necessary each time you access the memory card. Instead, try to review and delete photos only at the end of the day.

4. Drain your rechargeables totally before recharging. Batteries that are ran flat before recharging produce better performance and have a longer lifespan.

Of course, it helps to bring an extra battery pack along! (Or borrow from your friends!)

© 2005 The New Photographer.