I suspect this is because of the way it is being taught. You see, ISO started out as a property of film, and it was much easier to visualise it in terms of the old technology. So that's where I want to start my explanation, before bringing you into the 21st century with ISO today.
ISO actually started out as ASA, which stands for American Standards Association. Decades ago, a commercial film manufacturer came up with a set of numbers to define the sensitivity of different types of film. That set of numbers was accepted by the American Standards Association, so all American manufacturers could use the same system. Later, the American standard was adopted by the International Standards Organization, so ASA became ISO.
What does all that mean? Well, it means that the letters ISO didn't really stand for anything except for the name of an organization.
What is important is what ISO referred to, which was the sensitivity of the film. The emulsion on some films reacted quite slowly to light, and on other films much faster. Slower films had a smaller ISO number, like 25, 64, 100. Faster films had a higher number, like 200, 400, 800.
A slow film needed a relatively high level of light to create a well-exposed photo. That meant that to take a photo in darker conditions, you would need to use a fairly wide aperture and/or a fairly slow shutter speed to get a result. On the other hand, a faster film reacted to light a lot more quickly, so it needed much less exposure to light to take a photo.
Fast film sounds pretty good, doesn't it? A chance to take a photo in any conditions without a tripod, and to freeze moving subjects with very fast shutter speeds. So why didn't everyone just use fast films all the time?
The answer is that the advantages of fast films came with a trade-off; loss of image quality. The grains of emulsion on a fast film were larger, so a photo taken on a film with ISO 400 or 800 had a rougher, 'grainier' look. This may not have been a problem in a small print, but became quite apparent with big enlargements. Consequently, most professional photographers preferred to use slower films of 100 or 64 ISO for most of their work.
So is this just a lesson in ancient history? After all, you have a digital camera, so what does all this have to do with you. Well, it may surprise you to know that despite the huge revolution in technology, the essentials of ISO have not changed one bit.
Your camera should allow you the option of adjusting your ISO setting. Just like in the days of film, if you set your ISO to a low number like 100, you will need more light to create a correct exposure. That means that you may need to keep a tripod handy for cloudy days, and in certain low-light situations you may not always get the aperture and shutter speed settings you want. If you set your ISO to 400 or 800, your camera will become much more sensitive to light; you will be able to shoot in exactly the same conditions without a tripod, and with greater flexibility to choose the aperture and shutter speeds you want.
But here is the amazing part. Higher ISO settings still come with the same trade-off that once existed with film. Along with the speedier sensitivity to light, you can also expect the image to have a grainier finish. I don't know if it is pixellation, or digital noise, or a combination of both, but it is generally understood that for all their advantages, high ISO photos come with a reduction of image quality that becomes more obvious the more you enlarge the image.
So there you have a quick introduction to what ISO is all about. Perhaps I am just showing my age, but I find this subject easier to explain in old-technology terms. For many people it is easier to visualise when related to something solid like film, rather than something that happens on a computer chip. Anyway, I hope this helps you if you have had trouble understanding what ISO is all about.
Digital Photography Pocket Guide
The camera consumer trend over the past five years has been to go digital. The development and use of Single Lens Reflex [SLR] digital cameras has grown dramatically. The marked drop in use of large format film cameras and enlarging lenses reflects the decreasing market demand for those historically traditional film cameras. While one reputable manufacturer is still producing their flagship film cameras, most have discontinued a large number of their film lenses. While many remain faithful to the advantages of film technology, it is obvious that digital photography is going to capture the mainstream market. The increased quality in digital capture and memory capacity has been one alluring factor. For the first generation digital cameras, there was the challenging question of whether to store the digital data files in RAW or in JPEG or TIFF. Now many companies provide instant storage of a RAW image at the same time a full-color JPEG is displayed for the photographer's immediate use.
You may want to choose your low-end camera as much by what kind of storage cards it uses as by its features, especially if you're trying to save money. Even if you don't buy your storage cards on eBay, it can be a great place to compare prices and get an idea which types of cards (and capacities) are currently less expensive. Most low-end cameras use standard (or rechargeable) AA or AAA batteries, which are inexpensive for casual use and found just about everywhere. A very few cameras in this class use 6-volt lithium batteries, which have become fairly common. The lithium batteries reduce the size and weight of the camera. Obviously, flash usage reduces battery life, but many cameras allow you to turn off the LCD display, which also saves considerable battery life. You may have to think a little more about how you use the tool (many low-end cameras are slow to power-up, so that fleeting moment may not be captured, and automatic shut-off to save battery life may be as short as 30 seconds), but good photographic habits include knowing the limitations of the tool. Within those limits, a low-end digital camera is the most efficient way to get the job done.
It is commonly believed that cold weather can damage a camera - and it also happens to be true. Condensation can form inside a camera, as it grows cooler, and not just in the lens. Moisture can cause a number of intermittent or permanent problems with the camera's electronics. Condensation inside the camera can freeze and cause damage if it is in the cold for too long. Warm the camera up slowly after it's been out in the cold, but do your best to keep it from getting cold in the first place! Many cold-weather photographers carry their cameras inside their jacket to keep them from getting cold enough for condensation to form. Lastly, consider storing the camera in a plastic bag - the condensation will form first on the bag before it forms in the camera.
The great debate about how many mega pixels a digital camera must have for quality photographs rages on. Of course the answers depends primarily on how large you want your print to be and what the characteristics of the camera's sensor is. Just like traditional silver-based analog prints digital photographs begin to pixilate as enlargements increase in size. To get the best use of your camera and investment, it is best to explore the many facets that affect the quality of digital photography. What is the sensor and how does it affect digital photo quality? No matter how many mega pixels the camera you are looking at may boast, a photograph can still lack field of depth and true colors due to other features you may have overlooked in digital cameras. What is even worse, you may have splurged on an 8 to 10 mega pixel camera, but not have it set up to optimize performance. On the other hand, if you went for a 4 or 5 mega pixel camera there are features that you may be unaware of that could dramatically affect the quality of your photographs. We want you to get the most out of the camera you choose.
You will want to get familiar with a term called the "Focal Length". This term explains just how far out a shot can be taken, and still be in focus. There are a couple of different categories of focal lengths, including telephoto (perfect narrow sized photos) and wide-angle (best for wider shots). It is noted that most of the digital cameras are built with telephoto lenses, and not the wide-angle. If you are looking to take pictures of wide spaces, then you may need an additional lens.
Night photos can be extremely beautiful, but very challenging to take. Just like many other parts of life, though, if you practice, you will get better and more natural at it. The beauty of digital photography, too, is that if you don't like a shot, you can just erase it and do it over, without having to develop the film and wait another day to retake the photo! Many people find delight in the daylight hours, enjoying sunlight, people walking and so on. However, some of us see more attractions during the night hours, and few of us will bring those attractions to attention through digital photography. Some of the best pictures taken where during the night hours, especially at what time the lighting is in check.
Probably the easiest and most popular method of sharing a digital photo is to print it out. You can either print it out yourself, on your own printer and paper at home, or you can have a professional do it for you. In either case, you will need to store the images onto a CD or DVD and use that to print out your copies. (It's a little like when you have regular file processed, in the fact that the hard copy of your pictures will be used to pick out the photos you would like to print out.) You will then pick out the photo(s) you want to print and they will be printed out onto a glossy photo paper. It's easy as pie and very inexpensive, especially if you can do it at home! If you are comfortable with using your computer and the Internet, you can also send your pictures with an email. This is a quick and convenient alternative to the old "snail mail" way to send mail to another person. The recipients can also print them out; if they decide they would like to, or use them as a wallpaper background for their computer. You can learn to download the photo and send it right on the Internet, and your computer's user manual should also have a section explaining it. It is not hard to learn, so don't let the technology overwhelm and intimidate you.
Both Andrew Goodall & Dan Feildman are contributors for EditorialToday. The above articles have been edited for relevancy and timeliness. All write-ups, reviews, tips and guides published by EditorialToday.com and its partners or affiliates are for informational purposes only. They should not be used for any legal or any other type of advice. We do not endorse any author, contributor, writer or article posted by our team.
Andrew Goodall has sinced written about articles on various topics from Digital Photography, Photography and Digital Photography. ISO, aperture, shutter speed, depth of field...all the essentials of good photography seem simple when they are explained in terms you can understand. Visit . Andrew Goodall's top article generates over 40500 views. Bookmark Andrew Goodall to your Favourites.
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