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Old Nov 20, 2004, 9:10 PM   #1
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Im new to digital photography and have been researching cameras. I thought the S7000Z fujifilm was a good camera for a beginner, but just now i was on a tutorial website and reading about star trails.

http://www.danheller.com/star-trails.html

I figured out that i need a camera with long exposure time to do these time of shots, after a quick google search it seems the S7000 only has a 15 second exposure time. So is it not possible to get star trails with the S7000? If its the wrong camera for this type of shot, can someone recomend alternatives that have teh same features as the S7k but a longer exposure time, im guessing upto 3 hours?1?!?

Thank You, and yes im a noob and i want to take up photography as a hobby, because its sexy!
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Old Nov 20, 2004, 10:11 PM   #2
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Thanks for the link... sorry I can't help you with your camera. I thought only dSLR's could have indefinite exposure (since I don't think any camera is gonna have a programmed 3-hours exposure time) but I might be wrong about it.
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Old Nov 20, 2004, 10:20 PM   #3
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Kubera wrote:
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If its the wrong camera for this type of shot, can someone recomend alternatives that have teh same features as the S7k but a longer exposure time, im guessing upto 3 hours?1?!?
Well, I hate to burst your bubble. But, you're not going to find a digital camera thatis realisticallycapable of exposures that long. Yes, some models do have longer exposures (and even have a bulb mode, so that the exposure can be as long as desired). But, this will impact quality. I'd forget abouta 3 hour exposure with a digital camera.

This is one area that film still has an advantage. The sensors used in Digital Cameras have a problem with noise and hot pixels (where a pixel turns on to it's maximum brightness) when exposure times get long. As a result, sophisticated "dark frame subtraction" noise reduction systems need to be incorporated. These systems are designed to replace the hot pixels with values from adjacent pixels as they occur (and the longer the exposure, the greater the number of hot pixels).

It's not uncommon for the image to have hundreds of hot pixels on a relatively short exposure (15 seconds or so). But, you just don't see them because of the noise reduction system. However, the longer the exposure, the greater the chance of error (hot pixels that won't be mapped out via interpolation), and the more of the image that is being modified via interpolation (you're actually losing real pixels as the noise reduction replaces them).

Now, a DSLR model is much better in this area. But even these are likely to have alot of hot pixels on exposures over 30 seconds or so (you just may not see most of them after noise reduction is applied). But, they're better suited for this type of photography since their much larger image sensors are less prone to noise and hot pixels, compared to the smaller sensors used in non-DSLR models.

The lowest priced DSLR model right now is the Digital Rebel (but it will be a larger and heavier solution, especially when you factor in the cost of the lenses you may want/need (and brighter lenses are more expensive and heavier). You'll probably want more than one lens for the shooting conditions you'll use it in, too.

This modelwill allow you to set exposure times up to 30 seconds. Or, you can use Bulb mode with an optional RS-60E3 wired remote switch (to hold the shutter open as long as desired).

Now, you don't *have* to take star trails with a single long exposure. There are software products designed to let you combine multiple images taken over a longer period of time for this purpose. One of them is Image Stacker:

http://www.tawbaware.com/imgstack.htm

Here are examples of Star Trail images combined using it:

http://www.tawbaware.com/maxlyons/cg...e.pl?gallery=8


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Old Nov 20, 2004, 10:39 PM   #4
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Thanks for your reply, ima download that program and hopefully experiment with it soon, and your right, film > digital when it comes to exposure times.
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Old Nov 21, 2004, 2:15 AM   #5
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The S-7000 is one of the rare digital cameras with a Multiple Exposure setting. I know it's not what you're talking about, but it's something you could fool around with for diferent types of effect.
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