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| Question http://twincitiesrailfan.com/forums/viewtopic.php?f=39&t=1140 |
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| Author: | xrayguy [ Sun Oct 07, 2007 3:34 pm ] |
| Post subject: | Question |
First off I'm not sure if this question is something that belongs on this site, but I've tried RP.net before with some very mixed results so I'll give it a shot. Aaron if this is not something you want here please let me know or just go ahead and remove it. The PIC below is my first attempt at some night photography. I'm wondering if someone could tell me about all the spots. Is this caused by a dirty lens or dirty sensor or something in my settings? Thanks PS Clicking on the "Full Size" function at the site really shows these spots the best. |
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| Author: | Mike B. [ Sun Oct 07, 2007 6:33 pm ] |
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What was your camera set at? It looks like dust, is the lens dusty? |
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| Author: | xrayguy [ Sun Oct 07, 2007 7:11 pm ] |
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Well it doesn't look dusty but that is also the first thing I thought it was. I suppose with the shutter open for sixty seconds any particle might show. |
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| Author: | Mike B. [ Sun Oct 07, 2007 7:51 pm ] |
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Are you using an SLR? What did you shoot the photo at (shutter speed, apeture, etc.)? |
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| Author: | Frederick [ Sun Oct 07, 2007 8:18 pm ] |
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Those look like hot pixels... |
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| Author: | busyemt [ Sun Oct 07, 2007 8:50 pm ] |
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First off, I don't mind the question on photography. I just don't want this to be site to trash other sites... Secondly, it is difficult to tell exactly what that stuff is. Your camera doesn't have interchangable lenses, right? I have some spots on my sensor that show up on slower shutter speeds. I need to have it cleaned. I doubt that it is dust, pollen or bugs, but those could also be problematic on long exposures - for future reference. |
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| Author: | railtalk [ Sun Oct 07, 2007 9:25 pm ] |
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What were the other ISO settings? Single lens cameras (non SLR) have smaller sensors... more pixels in a smaller area. When you get near 7 (+) megapixels in a small sensor, the problem is going to be more significant and noticable. This will cause hot or erroneous pixels. Those are the bright spots. There are many reasons that cause pixels to be hot and show up bright, as in this shot... a couple factors are... higher ISO will cause increased sensor reaction. It means the sensor is taking on more light of the subject, thus making hot pixels brighter. The other is a longer exposure. If a pixel becomes hot and then corrects itself, all the hot pixels that fired up during the exposure will imprint in the shot. My Canon 350D has three hot pixels that show up on pretty much all night shots... I generally just PS these out. When I do really long exposures (1-5 minutes) and raise the ISO, I'll notice more start popping out. Just a digi problem! |
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| Author: | xrayguy [ Sun Oct 07, 2007 10:46 pm ] |
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OK I use a Olympus E500 and it does have interchangable lenses. I have a 40 to 150mm which is what I use most of the time including this shot. Info on the shot Focal lenght was 40mm F 14 60 second exposure ISO was 400. I rechecked the lens tonight and it is pretty clean so I'm ruling out dust. Sounds like "Hot Pixels" is indeed the culprit. So as long as photo discussions are OK I would like to ask if the exposure was perhaps to long and the 400 ISO to high? My thought process was. Click the shutter when the crossing lights begin and hopefully the train has gone by to catch the arms going back up. This incidently did not happen as the exposure ended before the train was gone. Thanks everyone for your input. |
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| Author: | Mike B. [ Sun Oct 07, 2007 11:18 pm ] |
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| Author: | foss0244 [ Mon Oct 08, 2007 1:07 pm ] |
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Maybe somebody here could help you. |
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| Author: | railtalk [ Mon Oct 08, 2007 6:11 pm ] |
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| Author: | xrayguy [ Mon Oct 08, 2007 7:59 pm ] |
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