Posted: 1/16/2008 6:45:31 AM EDT
|
A person selling a used Canon 20D sent me this reply to a question I had about shutter actuations. "The count on the meter is 954-5401" So is the actuation count 954? Or 5401? Thanks guys. |
|
Neither. The only way to know the actual shutter count is to have it sent to Canon. Either that, or on the Canon DSLR make sure that your file numbering is "continuous" from the day the box is opened, and that you always reformat the card each time you insert it. That way, each file will be labeled with the current shutter actuation at the time the picture was taken. If you ever set the file numbering to overwrite, insert an old CF card with out of sysnch numbered files, or if you insert a card from another camera without formatting it, you are screwed. For a used camera, you really can't trust that the owner has done this. There is an urban legand that there is a utility that can read shutter counts from the file. The 20D does NOT store shutter actuation info in the exif, or anywhere else within the file beyond the file name. The above paragraph explains why that isn't a reliable method to know shutter count. |
|
I would be fairly certain that the shutter count is at LEAST 5,401. This assumes that a card with a lot of files wasn't inserted when the camera was relatively new. You can't count on the image number for shutter actuation though. The number could very well be 15,401 or 25,401, and you wouldn't know. When buying a piece of used electronics, you must assume some risk that the item will fail sooner than you think. Unless the guy is a pro, or a dedicated amateur, I wouldn't think that there are enough clicks to put the camera at the end of it's life. Chances are, you'll get plenty of life out of it, as long as it works properly. Part of buying used, is the fact that you'll get older stuff, and it may have less useful life. 20-30 thousand clicks on a 20D isn't going to put it on the verge of failure. Nikon does store the total shutter actuations in the EXIF, so were you considering a D70s or something, you could know for sure. Good luck! If you buy, put the money you saved towards a future upgrade, then keep saving... |
|
Thanks for the replies, I purchased another one that the gentleman said had roughly 6,000 clicks on it. The shutters on the 20D supposedly last to 100,000, so it's safe to say I'll have a new camera well before this comes close to that. Now I just need to find a good lense for this, going to be doing some portrait work, but mainly wild-life and landscapes. Trying to keep the lense below $550. |
It's on rebate right now, and a great lens for landscapes: Canon EF 17-40mm f/4L USM Ultra Wide Angle Zoom $629 on rebate For wildlife, you'll want a telephoto, which is the opposite of what you want for landscapes!  :Canon EF 70-200mm f/4L USM Autofocus Telephoto Zoom Lens. $538 on rebate. This is probably the lowest end telephoto lens you should consider. Lots of magnification + wide open apertures = boatloads of $$$! Image Stabilization or IS is valuable for wildlife, but add $450 to the price. Adding an f/stop of light ability to the lens will also add about $550 - 600 to the price as well. |
|
An f/ stop refers to the maximum aperture size available. Each f/ stop doubles the amount of light taken in, so an f/4 lens takes in half the light at it's maximum aperture as an f/2.8 lens does at it's maximum aperture. From f/2.8 to f/5.6 you have a quarter of the incoming light. Lenses of f/2.8 and higher (f/2, f/1.4) are called "fast" because the more light allowed in, the faster the shutter speed can be. |
I'll try to explain but for further reading, go and read about f/stops on Wikipedia. Basically a stop is a halving or doubling of the light. Your lens has a mechanism that consists of 5-9 or so little plastic or metal blades. These are arranged in a circle and when they all move together, they form a hole for light to pass through. Picture some futuristic hatchway and you'll be picturing how an Aperture mechanism works. This aperture mechanism is responsible for allowing certain amounts of light through the lens. The larger the opening, the more light can pass, and the smaller the opening, the less light will pass. Your camera needs to have the correct amount of light on film (or sensor) to record a nice image. The aperture can be opened or closed, in concert with the shutter speed, to allow the photographer or the camera to permit the correct amount of light to get to the sensor. Shutter speeds are thought of as fractions of a second. 1/60th or 1/250th and so on. Since we think of a one "stop" increase as a doubling of the light, adding a "stop" to 1/60th of a second would mean changing to 1/30th of a second instead. Apertures can be adjusted in "stops" as well. Their numbers are not linear however and are expressed as values that are related by the square root of 2. (This is because we are talking about a circular opening). Aperture numbers should probably be memorized. The most common ones are 2, 2.8, 4, 5.6, 8, 11, 16, 22. f/8 is twice as small as f/5.6 for example. The higher numbers mean that the hole in the lens, or the aperture is smaller. Smaller numbers mean that the hole is larger. Why does it seem backwards? Well, because "f" refers to the focal length, and the aperture size is a ratio of the focal length to a fixed f-number. f/2 means that the light hole is 1/2 the size of the focal length. f/4 is 1/4 the size and so on. Dividing a number by an ever increasing number yields a smaller and smaller quotient, right? As one approaches f/22 on a lens, the light hole is down to 1/22nd the size of the focal length. On a 50mm lens, f/22 is only 2.3 millimeters wide, so you can see why it doesn't pass much light. By contrast, a f/2 setting on a 50mm lens has a large 25mm light hole. Larger light hole = more light available for the camera. Lower f/number = more light available for the camera. f/4 allows twice as much light to hit the sensor as does f/5.6, but only HALF the light that f/2.8 allows. Since f/2.8 allows double the light through compared to f/4, you can use a twice as fast a shutter speed at f/2.8 to get the same amount of light. This allows the photographer to freeze action more, and get more subject isolation. (lower f/numbers have a narrower depth of field). That is why we consider lenses that open as wide as f/2.8 or even wider, as "fast" lenses. They can use faster shutter speeds in less than ideal light conditions as the slower lenses, like the ones that can only open to f/5.6. I did a pretty lengthy post on basic camera settings here. This one is geared towards Nikon, but the principles apply to every digital camera on the market. Edited to change a comma to a period. |
