intro to Digital Photography Episode 2 "Exposure" Show Notes

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Welcome to the Second episode of JEBVision on Digital photography, I am your host Jacob Boenisch. Every Episode we will be exploring some of the basic facets of digital photography to help arm the inspired amateur with the tools and knowledge necessary to explore their passion and in the end, create a beautiful image.

This Episode we will be discussing The Exposure "Triangle".

Bryan Peterson, Author and Photographer extraordinaire is typically credited with coming up with the term Exposure Triangle. In his acclaimed book "Understanding Exposure" Bryan explores the importance of Aperture, Shutter Speed and ISO. We will also look at these three components and how explain how knowing them can help improve your pictures as well as your enjoyment of photography. (Understanding Exposure )

And now....Let's Get Started........





Ok to start off let me make a quick correction regarding the last episode. When I discussed Computer Programs I accidental mentioned Photoshop Express as an expensive program, what I meant was Photoshop CS4. Photoshop express is a flash based program, while CS4 and its iterations are pro level tools.

Sorry about that confusion.

Ok........

Lets get started talking about Exposure, by first discussing Aperture....


now I have included three separate images in the show notes to help guide us along in our discussion of Aperture.

You can access the show notes at http://jebvisionpod.blogspot.com /

Wikipedia states: In optics, an aperture is a hole or an opening through which light travels. http://en.wikipedia.org/wiki/Aperture

Understanding this, we can see that the larger the hole, the more light goes through the lens to the sensor. Inversely, the smaller the whole the lower the amount of light gets captured.

Aperture size also has a artistic effect on your photos. The wider the aperture , the lower amount of detail you get in the background and the smaller the aperture, the crisper the background of the image. Some times it is a good idea to use a wide aperture (smaller f stop) to separate the subject from the distracting details in the background.

On the flipside, sometimes (like in landscape photography) it is wise to use a smaller aperture (Larger f stop) to bring the background detail into crisper view.

Now your like wait jake..........You said the wide aperture has a small f/stop and a small aperture has a larger f/stop number.

That's correct. I know it can be confusing but it is essential you get this correlation so you can call upon your aperture setting skills to get the effect you desire.

now I have included some info on this in the show notes, citing wikipedia as the source.

In optics, the f-number (sometimes called focal ratio, f-ratio, or relative aperture[1]) of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms, the f-number is the focal length divided by the "effective" aperture diameter. It is a dimensionless numberthat is a quantitative measure of lens speed, an important concept in photography. (http://en.wikipedia.org/wiki/F-number )

You can quickly experiment with the concept of aperture without even using the camera.

Hold a pencil in front of your eyes and squint to focus on the pencil,(do you see how the background is blurry?) now move the pen back and open your eyes and focus on both the pencil and background. Things should be more clear. The act of squinting actually allow less light to hit your eye, blurring the background.

Here is another experiment. Take your camera and go to its aperture settings (on my camera I spin the dial until I select the "A" it's "AV" for Canon)

now set up an object close to your frame, and then stick something of interest in the back of the frame. Set your cameras aperture to its largest aperture and take a shot (small f/stop #). Now, set the aperture to the smallest aperture (large f/stop #) and take another shot. Try to use a tripod if you have one. Now on your viewfinder, compare the images. You should see that in the first photo the background is a little blurry and the object in front of the frame is crisp. In the second image, you should see that both subjects are clear and in frame.

I recommend that you walk around for the next couple of minutes with your camera set on Aperture Priority mode and take pictures of various subjects using the different settings. Now pause this podcast and get shooting.....

When you come back, we will discuss another cool feature of your camera, Shutter Speed.....



Welcome back.......

Ok.....

Now lets get into the second part of this three part podcast and discuss shutter speed...

Once again, if you have access to the show notes I have dropped a couple of pictures in there to demonstrate the affect of using different shutter speeds......


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Shutter speed helps make your photographs creative in several different ways. It can either catch a moment in time like a kid playing soccer or it might help imply motion by creating a blurred effect of the subject in motion. Slower shutter speeds create for of a blur, sometimes this blur is distracting to the photo, but if you use it in a technique like panning, were you pan the camera with a moving subject to isolate its image and creating motion in the background. Another classic example of increasing the shutter speed is capturing a waterfall and giving the water a whispy charachteristic.

You can also set a fast shutter speed to isolate motion that would otherwise be a blur to people in real life. By setting a quick shutter speed you can pick out details that otherwise would be invisible to the naked eye. In the case of the waterfall, this would capture every drop as it existed within the frame.

Wikipedia describes shutter speed as:

In photography, shutter speed is a common term used to discuss exposure time, the effective length of time a shutter is open;[1] the total exposure is proportional to this exposure time, or duration of light reaching the film or image sensor.

Exposure time is an important concept to grasp because depending on the available light, increasing or decreasing shutter speed can lighten or darken the photo causing an incorrect exposure. however, in low light, placing the camera on a tripod and increasing the shutter speed can create a clear photo and give the picture a correct exposure.

Ok.....This is a simple concept, longer shutter speeds increase the amount of light collected by the lens and sent to the sensor and creates a blurred motion effect in the photo. A quicker shutter speed collects less light but captures the moment so to speak.

Now get out there right now and experiment with your shutter speed. Turn on the hose or have some one poor a glass of water outside and capture the moment the water leaves the hose or glass with a quick shutter speed. Now set up on a tripod or stabilize the camera on something and decrease the shutter speed. Notice the difference.

I recommend that you shoot for a few minutes or even a day on nothing but Shutter Priority mode. That is indicated by an "s" on my nikon or "Tv" on a canon.

Go do it now.

When you come back we will discuss the final part, ISO.



OK We're back......

Lets now discuss the last item on the exposure triangle, ISO, which is also called Film Speed:

Now Wikipedia defines Film speed as "the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. Relatively insensitive film, with a correspondingly lower speed index requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a slow film. Highly sensitive films are correspondingly termed fast films." (http://en.wikipedia.org/wiki/Film_speed )

Now ISO stands for International Organization for Standardization (ISO), which simply means an international standard for setting film speed.

What you really need to know is that you should select different ISO speeds depending on what situation you are in.

100-200: Outdoors Sunny Day

400-800: Indoors low light

Now shooting outdoors with a high speed of film or high ISO will cause your photos to be to bright and in the same respect, shooting indoors with a ISO 100-200 film might make your pictures to dark because that speed is just not sensitive enough to the light of an indoor situation. Now ISO directly effects what aperture and what shutter speed you can select. The higher the ISO, the faster you can get the shutter speed or the smaller you can get the aperture in order to capture more detail, as we discussed before. This is where you can use ISO to get the correct exposure and depth of field that you want.

Most cameras have an auto ISO mode but we don't want to use this. You get better control and better quality photos by adjusting the ISO yourself. As you experiment with your ISO settings, you will become accustomed to switching the ISO yourself and you will enjoy taking pictures even more.

Now some cameras have effective ISO ranges up 3200 and even above. By effective I mean that the picture maintains its relative sharpness at higher levels. Now the traditional trade off is that the higher the ISO you choose, the grainier the photo, and in most respects that is true. Now some of the newer DSLR's have improved low-light functionality that gives the user more lee-way, but in reality it makes since to try and not go over ISO 800 in order to guarantee a tack-sharp image. If you need to capture the image no matter what, like a scene of your friends in a low-lit restaurant, go ahead and crank up that ISO to get the shot.

Now it's your turn, experiment with your ISO. Find a subject and take a picture on ISO 100 or 200 then start increasing the film speed until you reach the maximum level. Notice how the pictures get brighter and how the picture gets fuzzier as you go along. the scale.

Well that wraps up this podcast.

We discussed Aperture/Shutter Speed and ISO. Go out and focus on each one of these items individually and give yourself time to become familiar with shooting in Aperture and Shutter priority mode.

Next week we are going to put it all together and have you shoot in full manual, giving you the ultimate control over your photos.

Thanks so much for listening.

Remember you can find the show notes at the blog address site http://jebvisionpod.blogspot.com.

You can also find me on Flickr at Jebvision and on Twitter at Jebvision.

Thanks for listening.

Now get out there and shoot!

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