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01-11-2010, 08:29 PM   #1
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K20D Long exposures bright white

Hello, I am new to photography and have been trying to do long exposures with my K20D. I know about the problem with the sensor that makes it impossible to turn of the noise reduction in buld mode, but as I understand it that only means it will take twice as long to take a picture. I have been taking exposures for 45-60 minutes of star trails near streetlamps about 30 miles from the city, and all of the pictures have turned out either very bright white or totally white. I have been using buld mode on tripod ISO100 f 3.5 28mm manual autofocus. Is there a setting I am leaving out that is making all of these exposures so unaturally bright? I also tried to take a picture of the sun setting today with only about a 3 second exposure in bulb mode and it turned out completely white. Please let me know if there is something I am doing wrong, or if there may be something wrong with the camera. Thank you.


Last edited by Jacho; 01-11-2010 at 08:42 PM.
01-11-2010, 08:38 PM   #2
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Set aperture to f/16- f/22 to get desired result?
01-11-2010, 08:44 PM   #3
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Both scenarios sound as though the exposure is simply far too long, resulting in completely blown out photos. A photo of a sunset should not require bulb mode - the camera will accurately meter the scene (you can apply some exposure compensation based on the result, but exposure times should be quite far under 1 second).

The second scenario is alittle more difficult. Digital is fortunately good for experimenting and learning from your mistakes. Did you mean 45-60 minutes or seconds? If minutes, well start by changing that time to seconds! If an image turns out under-exposed, then double the shutter time. If over exposed as you have indicated, then halve the exposure time until you get it right. Like I said, experiment with the shutter time, aperture and ISO (generally lower values are better in this case), to see what makes an appealing image to you. Good luck!
01-11-2010, 09:04 PM   #4
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Welcome to the forum Jacho.
Experience will tell you what settings work where.
Even the faintest ambient lighting other than the stars will record on the sensor in all long exposure shots, so this will affect whether you will be able to get star trails or not.
Most effective setting is the pitch-black scene with moonless or near-moonless sky. Foreground can be creatively lit with a manually-fired flashgun from different aspects (ensuring no part of the flashgun head points anywhere within 180 degrees of the camera lens).

Then as for settings, I have a starting point for dark scenes of f/5.6 at ISO 100, testing the exposure for 3-5 minutes to see what records, then tweak from there.

Hope this helps.

01-12-2010, 05:30 AM   #5
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QuoteOriginally posted by Jacho Quote
I have been taking exposures for 45-60 minutes of star trails near streetlamps about 30 miles from the city, and all of the pictures have turned out either very bright white or totally white.
If you are near street lamps, you won't be able to record star trail properly. There will always be some light coming from the street lights to "screw up" everything. And f:3.5 is going to let way too much light for star trails.
01-12-2010, 11:40 PM   #6
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If you're not familiar with the basics of exposure - how aperture, shutter speed, and ISO relate - then that's the place to start. Googling those three terms together will turns up tons of info, as will most books on photography. But the bottom line is, if you want a darker exposure for a given shutter speed you need a smaller aperture and/or a lower ISO.
01-12-2010, 11:58 PM   #7
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Agreeing with above....if you are trying for star trails or any other astrophotography, you need to be fart far away from streetlamps of any kind. The darker the better. Everything else about shutter speed, aperture and exposure is crucial, but your setting is just as important. In this case, your setting is most important and is leading to poor results.

Jason
01-13-2010, 06:06 AM   #8
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Regardless of what you're shooting, you can't just pick any random combination of shutter, aperture and iso that strikes your fancy; there is a balance that must be struck to get a proper exposure. Any time you leave the auto modes it is up to you to understand and implement the basics of exposure settings. Fortunately, the basics are not difficult to learn.

01-13-2010, 12:29 PM   #9
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QuoteOriginally posted by Jasvox Quote
you need to be fart far away from streetlamps of any kind. The darker the better.
Perhaps you meant 'to fart far away from streetlamps'.
God only knows what would happen if the light were to shine on a fart...

OK, silly joke... carry on with the farting star trails...
01-13-2010, 04:06 PM   #10
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Like they said, too much time/open f stop, for ambient light.

Cheers, Mike.
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