Monday, June 14, 2010

Photography Tips-How an Image is Recorded

This post will go back to the very basic idea of photography. It will essentially answer the question of "what it means to take a photograph."

Since most of my posts deal with setting such as aperture, ISO, and shutter speeds, we're going to talk about Photography through the use of a Pinhole camera, so we can ignore the fancy terminology and technique of a traditional SLR camera.

What is a pinhole camera? Well it's essentially a light tight container of some sort which has a pinhole on the opposite side of your film or photographic paper. Here is an example of a pinhole camera you can make yourself:

So essentially you poke a tiny hole in some sort of container (give the hole a cover, like a piece of tape to keep light from getting in), and you make sure the container is light tight, and you have the camera.

What about film? For a camera like the one to the left, you wouldn't buy normal 35mm film. Instead, you would go out and buy photographic paper (Ilford, Kodak) and you would cut a piece big enough to cover the opposite end of your camera.

CAREFUL! though, because this paper can NOT be opened in the light. So essentially you would go into a dark room, block all the light, and place a sheet of paper in the container on the opposite end from the pinhole, so that when you remove the piece of tape, or cover, the light is being let in towards the back of the camera, where your paper is.

What is photographic paper? Photographic paper, or film, is paper that has been coated with light sensitive chemicals. In traditional black and white photography, these chemicals are silver-halide crystals. They are light sensitive, meaning when light touches these crystals, they begin turning black. An image is created by really bright, white things reflecting more light than dark or black objects, so you get a negative image. So if you have a white cabinet with a black vase on it, the white cabinet will reflect more light into your camera, turning the halide-crystals black, creating a black cabinet, and the black vase will reflect hardly any light, and your image will have a sort of vase-outline that wasn't affected by light, leaving it white.

So we place this paper into our camera, and then we are ready to use it. Because light is what makes the image appear, the more light you have, the darker your negative (meaning when the negative is processed the BRIGHTER your positive image), the less light, the whiter the negative (or the darker the image). Some pinholes take a looong time (at least 30 seconds) to create even a faint image, so it's all about trial and error. So you'll take your camera out and remove the cover to your pinhole, and let the light start pouring into the hole, slowly creating an image on the back of your camera where your paper is.

This is essentially how a photograph is ALWAYS taken, but with an SLR you have a lens, so you have different options as to how you let the light come in, and how that makes your image look.

After you take the photo you will have to develop the paper or film in a darkroom (walgreens won't be able to do anything with photographic paper), so this is only feasible if you build a pinhole that can use 35mm film, or if you have a way of processing your own paper/film. But a pinhole camera is really just a good introduction for how an image is captured on camera.

Let's Recap:
-a pinhole camera is a light tight container that has a tiny hole on the opposite side of your photographic paper/film.
-photographic paper is light sensitive, meaning it's coated with chemicals which change shades/colors when light hits it, creating your image.
-White objects reflect the most light, altering the chemicals the most, and dark objects reflect the least light, hardly affecting the chemicals at all, creating a negative image.
-The amount of light let in to affect your image, is directly related to the amount of time you leave the "shutter open" or the cover off.
-you must place the paper in the camera in a dark room, and remove it in a dark room, and process it in a dark room, or your image will turn completely black from overstimulation to light.
-The pinhole, and the lens are similar, and time is the main factor in creating any image through any camera.

-learn how to make a 35mm film pinhole camera:
(scroll down toward the text)
-People have made their rooms pinhole cameras, lots of times!

Saturday, June 12, 2010

Photography Tips-Nikon D300

So I just want to say that the Nikon D300 is my baby. This is mainly because I can't afford a Nikon D3 at the moment, or else I'd have that. However, if you're on a lower budget and you are interested in stop motion, or action photography, the Nikon D300 has a great ability to take a lot of shots in a short amount of time. It also gives AMAZING image quality, if set on RAW. I will add a blog in the future about why RAW files are important, but it's mainly about high quality editing.

The D300 is HEAVY, but not the heaviest I've lifted. It's definitely a good deal for the money. I haven't used a D700 but in my opinion, I'd like to skip from the D300 to the D3, as I've read that the D700 is like an in between, and if I'm going to spend that kind of money, I may as well go all the way.

A reason you would go for the D700 is if you really really really can't afford the D3, but can the D700, AND you want a Full Frame Sensor. The Nikon D300 is still considered consumer-professional, because it's sensor is of normal proportions.

Great camera though, all the images that were taken by me on this site and on were taken with the Nikon D300, but I use photoshop extensively on some of my images as well, though Photoshop can't help a bad root image, unless you're hiding its bad qualities with a bunch of filters, which I don't recommend.

But the D300 is quite affordable, and a terrific little piece of equipment. But BUY a GOOD lens!!!

Friday, June 11, 2010

Photography Tips- Amanda Peppers Photography

I’m not here to promote myself as an artist, however I thought some of you might be interested in seeing what kind of work I make as an artist.

Here is my portfolio site and an example photo:

Photography Tips- Photoshop Actions

Ok so I’m taking a little detour, but I really enjoy this tool in Photoshop. The Actions tool in photoshop can be found at the top by going to Window-> Actions. An Action is a set of processes you want applied to a photograph. So let’s say you opened up a photo in photoshop you went through nearly 100 steps to edit it, and you want to apply all those steps to your next 50 photographs.

A great place to learn about creating your own actions is:

There are millions of saved actions available for download on the internet. A lot of popular ones give your photos that vintage, edgy feel. If you’re curious about browsing a few of these, and are a good places to start.

Photography Tips- Natural Light

Let’s first talk about why lighting is important. As you’re beginning to learn here, photography is all about light. Photography is the act of picking an aperture setting, opening a shutter for a length of time, and letting the light that reflects off the subject, bounce through the camera and towards the sensor or film in the back. So what gives an image a harsh contrast or that soft romantic feel? It’s not just photoshop or post-process editing. Most of the quality of a photograph comes from what kind of light was being bounced toward the sensor. The photos in this post I took around 7 30 pm near the end of Spring, I think the sun was setting around 8 or 8:15. At this point the sun in the sky was behind the trees, and I find this is the best time for photos. When the sun is just hiding, it still illuminates the sky enough to illuminate the ground, and if you’re using your shutter speeds properly, and perhaps a tripod (though the images above were handheld), you can pick up some really good detail from this. When sunlight is hitting an object directly it causes harsh shadows and bright highlights, and though to the human eye this can look fantastic, the camera will over-record those highlights, and under-record the shadows, meaning you see no detail in either area.

Sometimes you may want this strong contrast, but to the traditional classic photographers (and to your professors when you’re receiving an education), the goal of a good exposure is to capture details in the highlights as well as the shadows.

When people refer to the “quality” of light, they usually mean its degree of diffusion, which can range from contrasty and hard-edged to soft and diffused. Direct light creates hard-edged, dark shadows. The smaller the light (relative to the size of the subject) or the further away, the shaper and darker the shadows will be. An example of direct light is a spotlight, or the sun on a clear day. Diffused light scatters onto the subject from many directions. Shadows, if present, are very light. An overcast day, dusk, or the shade will diffuse and soften light. This can be really nice lighting for portraits, gently modeling the planes of the face.

If you plan on shooting outdoors a lot, here is a very useful tip: Light changes as the time of day changes.

Daylight has a natural blue cast to it, so the more sun that’s available, the cooler your photograph will feel. So for that warmer tone, sunrise and sunset is best, or a bit of photoshop!

Photography Tips- Lensbaby Composer

Lensbaby The Composer for Canon EF mount Digital SLR Cameras
I love the Lensbaby. Lensbaby is a lens that creates a tilt/shift effect (something similar to what you would get with a view camera), so it essentially has a sweet spot of sharp focus and it blurs the edges. You can move the Lensbaby’s sharp area around, and it creates a very romantic feel. It also comes with Lensbaby accessories that mimic a pinhole camera and a zoneplate. It’s just all around fun!

Here’s one Lensbaby photo I took:

Photography Tips- Top 10 SLRs

I know I always found Top 10 Digital Cameras lists useful when I wasn’t sure about camera quality. I recently added an amazon store via the “Photography Genius Recommends:” link at the top of this page, and now you can search for (and purchase) any of these Top 10 Digital Cameras or other camera accessories, without having to leave the page. You can also click here.

Top 10 Digital Cameras:

1.) Nikon D3

  • 12.1-megapixel FX-format (23.9 x 36mm) CMOS sensor
  • 3.0-inch, super density 920,000-dot VGA color monitor; 170-degree wide-angle viewing and tempered-glass protection
  • Continuous shooting at up to 9 frames-per-second at full FX resolution
  • Fast, accurate 51-point AF with 3D Focus Tracking
  • Capture images to CF I/II cards

    Amazon Price: $7,400

    2.) Canon EOS 1D MarkIII

  • 10.1-megapixel CMOS sensor captures enough detail for photo-quality 18 x 24-inch prints
  • Shoot up to 10fps; burst rate up to 110 full-resolution JPEG images
  • High-precision AF system with 19 user-selectable AF points
  • New DIGIC III Image Processor provides fast, accurate image processing
  • Large 3.0-inch LCD display

    Amazon price: $3,500

    3.) Canon EOS 5D MarkII

  • 21.1-megapixel full-frame CMOS sensor, 14-bit A/D conversion, wide range ISO setting 100-6400
  • Body only; lenses sold separately
  • DIGIC 4 Image Processor; high-performance 3.9 fps continuous shooting; Live View Function for stills
  • Full HD video capture at 1920×1080 resolution for up to 4GB per clip ; HDMI output
  • Updated EOS Integrated Cleaning System specifically designed to work with a full-frame sensor

    Amazon price: $3,300

    4.) Nikon D700

  • 12.1-megapixel FX-format (23.9 x 36mm) CMOS sensor; body only
  • 3.0-inch, 920,000-dot VGA color monitor; 170-degree wide-angle viewing and tempered-glass protection
  • Fast, accurate 51-point AF system; 3D Focus Tracking and two Live View shooting modes
  • Base ISO range from 200-6400 can be expanded to range from ISO 100 (Lo-1) to 25,600 (Hi-2); 0.12-second start-up speed
  • Capture images to CF I/II cards; compliant high-speed UDMA CF cards that will enable recording speeds up to 35 megabytes/second

    Amazon price: $2,400

    5.) Canon EOS 1D MarkIV (only number 5 because it’s so expensive)

  • 21.1-megapixel full-frame CMOS sensor
  • Large 3.0-inch LCD display with Live View and seven brightness settings
  • 5 fps at shutter speeds 1/500 second or faster (for bursts of up to 45 Large/Fine JPEGs or 15 RAW images)
  • sRAW mode; 35-zone metering system; 45-point AF; integrated Self-Cleaning Sensor Unit
  • Powered by LP-E4 lithium-ion battery pack; stores images on CF, SD, or some SDHC memory cardsAmazon price: $6,200

    6.) Nikon D300 DX (my top camera!)

  • 12.3-megapixel captures enough detail for poster-size photo-quality prints
  • 3.0-inch LiveView LCD display; new 51-point AF system
  • In burst mode, shoots up to 100 shots at full 12.3-megapixel resolution
  • EXPEED Image Processing System and similar Scene Recognition System to that found in the D3
  • Self-cleaning sensor unit; magnesium alloy construction with rubber gaskets and sealsAmazon Price: $1,450

    7.) Canon EOS 5D

  • 12.8-megapixel CCD captures images up to 4,368 x 2,912 pixels
  • World’s smallest and lightest full-frame digital SLR as of August 2005–the sensor operates without a conversion factor
  • New larger 2.5-inch LCD screen can be viewed even at extreme angles of up to 170 degrees
  • Consecutive shooting allows the capture of 3.0 frames per second for up to 60 consecutive JPEG or 17 RAW frames in a burst
  • Captures images on CompactFlash Type I and Type II cards, compatible with cards of 2 GB capacity and largerAmazon price: $2,800

    8.) Olympus E-volt E-3

  • 10-megapixel Live MOS image sensor captures enough detail for photo-quality 18 x 24-inch prints
  • 2.5-inch Live View LCD display; magnify directly on the LCD by 5, 7, or 10x
  • Mechanical Image Stabilization with Supersonic Wave Drive
  • Exclusive dust-free technology for spot-free photos
  • Capture images to CompactFlash Type I/II, Microdrive, xD-Picture Card (Dual-Slot)

    Amazon price: not sold by Amazon

    9.) Sony Alpha A-900

  • 35mm full-frame 24.6-megapixel Exmor CMOS image sensor
  • Body only; lenses sold separately
  • SteadyShot INSIDE in-camera image stabilization; Dual BIONZ processors for up to fast 5 fps performance
  • 3.0-inch Xtra Fine LCD photo-quality display; Intelligent Preview Function reduces trial-and-error
  • Accepts CompactFlash and Memory Stick Duo Media memory cards

    Amazon price: $2,600

    10.) Nikon D90

  • 12.3-megapixel DX-format CMOS imaging sensor
  • Body only; lenses sold separately
  • D-Movie Mode; Cinematic 24fps HD with sound
  • 3-inch super-density 920,000-dot color LCD monitor
  • Capture images to SD/SDHC memory cards (not included)

    (also MY camera!)

    Amazon price: $780

  • Photography Tips- What is Aperture?

    The Aperture and Light:

    If you look at your SLR camera lens you will most likely see two sets of numbers. The particular set we’re going to be talking about here in regards to aperture will have numbers in the sequence 2.8, 4, 5.6, 8, 11, 16, 22, etc. These numbers are called your F-stops. If you’ve read my article on shutter speeds, I defined the term stop as a measure of exposure. Stop is more accurately used in regards to aperture, as it describes aperture size. Aperture is essentially the size of your lens opening. If you think about the pupil of your eye, you’ll recall that it expands and contracts in order to let in more or less light. The aperture is actually a ring within your lens that widens or contracts depending on the settings you choose (i.e. the ring with the f-stop numbers I mentioned). When you remove your lens from your SLR camera, you can actually see the ring that adjusts. If you like, you can adjust those numbers I mentioned while the lens is removed from your camera, and you will see the ring open and close. Here is an idea of what aperture looks like:

    Copyright 2006-2008 © i Digital Photo

    What do the F-Stop numbers mean?

    If you remember my article on shutter speeds, I explained that the shutter speed measurements (100, 200, 400) are actually fractions of seconds (i.e. 1/100s, 1/200s, 1/400s), which means the higher the number, the FASTER the shutter. The same applies to F-Stops. F/22 is actually a measurement of 1/22 , which means the lens opening is going to be SMALLER. F/4 will actually be ¼ and therefore be a wider opening.

    Why is aperture important?

    Aperture controls two things: exposure and Depth of Field. Depth of Field is how much of your photograph is in focus, from foreground to background. With f-stops you can soften that background in a portrait or make that landscape you love in almost complete focus, but you have to know how to adjust aperture to your desired effect. Aperture controls exposure by allowing MORE light in on a lower f-stop setting, i.e. f/2.8. This is because the f-stop is actually a wider opening, since it’s a larger fraction. Makes sense, right? Well here’s where it can get backwards and confusing. This same setting of f/2.8, when compared to f/22, is actually going to give you a smaller depth of field, meaning only a small portion of your photograph is in focus. I will discuss Depth of field more, later. For now, here examples of how aperture affects depth of field:



    So let’s recap:

    -Aperture is a ring in your lens that contracts or widens based on the f-stop settings you choose.
    -F-stop is a fraction that represents how large the opening is in your lens, which directly affects how much light is reaching the film/digital sensor.
    - Aperture also controls depth of field, which is the area of your photograph that is in “acceptable” focus. “Acceptable” is a loose term, but essentially means how much of your photograph (from foreground to background) is in focus.

    Photography Tips- what are shutter speeds?

    Photography Tips: What are shutter speeds?

    The Shutter and Light:

    Photography is defined as writing with light. When photography was first invented, people recorded images onto a material that was coated with chemical emulsion which reacted to light. The most common emulsion today in film photography is Silver Halide. This silver halide reacts to light in such a way that bright objects are recorded dark, because the chemical turns dark when exposed to light. Bright objects reflect the most light, and end up dark in the negative image. The dark objects don’t reflect enough light to alter the chemical, and it appears white in the negative. This is the basis for how photography works.

    So if Photography is about recording light, then light is the single most important factor in recording a good image. There are three factors that contribute to a good exposure, Shutter Speed, Aperture, and ISO. In addition to the exposure of the image, each of these functions also controls other details in image making, that I will go further into in a second. For now we will just discuss shutter speeds, but I have other articles which explain Aperture and ISO.

    The shutter in a camera is the only thing in the camera that physically allows light to enter and be recorded on the film or digital sensor. The other two settings help decide how much light gets in. When you press the button to take a photograph, you are telling the camera to open its shutter and close it again. Shutter settings decide how long the shutter stays open before it closes again. This is known as shutter speed.

    How do I control Shutter speed?

    If you’re using a film camera there’s a dial that has numbers ranging probably from 1 to 1000, or maybe higher. It will double in increments such as 1, 2, 4, 8, 15, 30, 60, 125, 250, 500, 1000. If you’re using digital, there will most likely be an LCD screen that has these numbers in sequence when you rotate one of your dials. You will want to refer to your SLR camera manual to understand which dial controls shutter speed. These numbers are actually FRACTIONS, not whole measurements. This means 1 stands for 1 second. 2 is actually ½ second, 4 is ¼ seconds. That means the higher the number, the least amount of time the shutter is staying open. The faster a shutter moves (like 1/1000) the LEAST amount of light is allowed to reach the film/digital sensor. This comes into play when deciding what a good exposure would be. If you’re images are too dark, your shutter speed is most likely too FAST, and you will want to pick a small number (i.e. a longer period of time) to get the correct exposure. Likewise, if your picture is too bright, you are letting in too much light and you will want to make the shutter speed faster. There are also numbers representing whole seconds, 1, 2, 4, 8, 15, and 30. The difference between these numbers and the previous ones is they will always be accompanied by a “. So instead of just 2, it will look like 2”. So if you’re looking at 2, it’s really ½ second and if you’re looking at 2” it’s 2 seconds. This means the shutter will be open for a whole two seconds, and you will be able to count it between the initial click and the final click.

    What else should I know about Shutter speeds?

    Shutter speed does NOT only control exposure! It also controls camera blur. There are many different types of camera blur. For example there’s camera shake and there is motion blur. Camera shake is when your hand is unsteady and the image is blurred, whereas motion blur is from your subject being in motion. Shutter speed can eliminate BOTH types of blur if it’s fast enough. This is because the speed of the shutter doesn’t allow enough time for the image to be recorded in motion. If the shutter is open for 2 seconds, however, your hand would definitely shake in that two seconds, and it records the starting point and the finishing point of an image in an overlap. With motion blur, it’s the same. It records the starting point and all movements being made in that two seconds. Also keep in mind that a subject moving towards you creates less blur that a subject moving parallel to the camera. This allows for you to use slower shutter speeds while still stopping the motion. This is where shutter speeds get creative. If you want the cool motion blur effect, I recommend using a tripod and leaving the shutter open longer. If you want a crisp, clear image, you’ll want a faster shutter speed. A really fun technique for motion blur is panning. Panning is when you move the camera in the same direction as the subject when the subject is in motion. So imagine you are photographing your friend on a bicycle and he is riding from the right side of the frame to the left side. Instead of letting him ride across the frame of your viewfinder, follow him with your camera, like you would a video, to blur the background and focus your friend. So he will essentially look frozen in a moving world.

    What does the term stop mean?

    A stop is just a measurement of exposure control. You will hear this term again when we go over aperture. All the numbers I listed earlier represent one stop of change. Most digital cameras will actually allow you to change the shutter in increments of 1/3 stops. This means you can be even more precise in determining exposure and speed.

    A beginner’s field guide to Shutter speeds:

    Type of motion Speed Camera-to-Subject Distance
    25 ft 50 ft 100ft
    Very fast walker (5 mph) 1/125 1/60 1/30
    Child running (10mph) 1/250 1/125 1/60
    Good sprinter (20mph) 1/500 1/250 1/125
    Speeding car (50mph) 1/1000 1/500 1/250

    A really cool example of panning:

    Photography Tips- Nikon D90

    One of my favorite cameras is the Nikon D90. One of the more economical choices, it offers amazing picture quality and a video option. I use this as my back-up camera and I love the video on it. The most fun thing about having video on an SLR is you can switch out the lenses, so you can shoot video with a lensbaby or even a crazy fisheye!

    Photography Tips- Manual vs Automatic

    Manual vs Automatic?

    Most people I come across who are asking “manual vs automatic?” are the people who don’t understand what functions of a camera make it manual vs automatic settings. So I will touch on what each one means.


    Automatic setting for any camera just mean the camera is picking average shutter speed settings and average aperture settings to give you an average (but usually decent) exposure every time. All you have to do is press the button. The only criticism you will ever hear about using your camera in automatic mode is that you can’t truly be creative with it. This leads to the typical consumer thinking that professional photographers are only good because they’re using manual, and then when the consumer tries manual they end up with worse pictures than automatic and don’t fully understand why.


    Manual settings mean you tell the camera what to do for every little thing. You tell it how fast to open its shutter, what aperture setting to use, and if you’re using digital, even what ISO to use. If you’ve ever owned a film camera, when you load the film there’s a black rectangle that the film slides over, this is its shutter, and it opens up to allow light to hit the film and record an image. If you have only owned a digital camera, just imagine the lens opening and closing really fast. In Manual mode, you can tell it how fast to open and how long to stay open before it closes again. (To learn more about different shutter speeds and what they do, click here.) Also in Manual mode, you can tell the camera how much light to let in through the aperture setting. Have you ever seen a portrait done by a professional where the person is in clear focus, and the background is blurred, and it really makes the person pop? This was a choice of aperture. With aperture you can choose how much of the photograph you would like in focus. (To learn more about aperture settings, click here).

    Manual is MORE work!

    You can definitely be more creative in Manual mode, but it is a lot more work and time that you have to think about what you are doing. When first learning Manual it will take practice and several tries to get a good exposure every time. I’ve been shooting in Manual mode for 5 years and I still mess up every now and then because I forget to adjust something. If you change the shutter speed you have to change the aperture and if you change the aperture you have to change the shutter speed, and if you forget to, you will get a really bright or really dark exposure. Fortunately with digital you can see your mistake right away and try again, unless the crucial moment was missed. If you’re just taking photos at your child’s birthday party and you don’t care what the background looks like or about using artistic lighting, you will be just fine in automatic. It is not always better to be in manual, and I take pride in using a point and shoot in automatic for simple things that I just want the memories for.

    Your colors, clarity, and composition will NOT be better just because you switched to manual. All these things are factors determined by you and Manual is not a setting like portrait or landscape on your point and shoot camera. Your camera becomes completely dependent on your decisions when it’s on manual, and you will need to know what shutter speed and aperture have to do with each other, as well as ISO before you can really get anywhere in Manual mode.

    I will teach you the relationship between aperture and shutter speeds, and more about how to use your camera in manual mode, in my next article.

    Photography Tips- What is ISO?

    What does ISO stand for?

    What ISO really is:
    the term ISO stands for International Standards Organization. Every time you buy film it has a number like 200 or 400 or 800 on it and the Kodak boxes will usually let you know if it’s good for indoor or outdoor lighting. This description is a direct result of the film’s ISO. Now digital cameras have ISO settings because ISO also affects the exposure of your images. I will touch on this bit in a minute.

    So what is the ISO number?
    The ISO number of film indicates how sensitive that film is to light. Film is produced differently so that some is more sensitive than others to light. This is why some film is good for outdoors while some films have ISO’s that make it better for indoor or night photography. Since ISO stands for the International Standards Organization, all this really means is they determine what sensitivity gets what number indication, so that when you purchase a roll of film that says 400 on it, it will react the same to light as the last roll of film you bought, no matter what brand you bought from.

    ISO numbers:
    So which ISO numbers are used for which types of light? The lower the ISO number, the LEAST sensitive it is to light. So an ISO of 100 or lower is going to be ideal for outdoors on a sunny day because the light is very strong. The higher the ISO the MORE sensitive it is to light, which means it takes very little light to create a good exposure. So an ISO of 800 or more would be ideal at night, so that if you’re recording moving subjects in dim lighting, you can get a decent exposure while stopping the motion of those subjects.

    Why ISO is important:
    ISO is very important for manual users. If you ever use your camera on manual then you probably know the relationship between shutter speed and aperture to make a good exposure. If you don’t know this, don’t worry, I have an article that explains it in more detail. Shutter speed is used to stop or blur motion, while aperture is used mostly to determine how much of a photograph will be in focus. But when you change either the shutter speed or the aperture you directly affect the exposure and must compensate to get a good one. But let’s say I want a small aperture opening so that I can get everything in focus, well this opening lets in a small amount of light, so we compensate by leaving the shutter open longer. Well what if I’m taking a photograph of my dog who is running around in my dimly lit apartment, but I want everything in focus. I would use a small aperture and I’d use a slower shutter speed. But then my dog would be blurred and I wouldn’t get a good photograph. By changing my ISO from something like 400 to 1000 it allows me to use a faster shutter speed, because the film or digital sensor is now more sensitive to light, and doesn’t need as much light let in to make a good exposure. Now I can stop the motion of my dog running, have a smaller aperture, and still make a good exposure.

    Why not use 800+ ISO all the time?
    Although this seems like a good strategy for all lighting situations, the higher the ISO is the grainier the image is. If you are working digitally then this translates to how much noise will be in your photograph. To get a really nice clean photo, you want to use a lower ISO. It can be an artistic choice, however, to give an image noise or grain and in that case you may choose a higher ISO. But for most people, we want to use the lowest number possible for our subject matter.
    So a quick recap:

    Low ISO (ex 100) is good for outdoor, strong lights, and still subjects. It also produces a very crisp clean image.

    High ISO (ex 800 or 1600) is good for low light or night photography and moving subjects. However it also produces more noise and grain in the image.