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Old Jan 27, 2003, 9:31 AM   #21
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I'm not sure using long exposures is reasonable to test for "hot" pixels. With long enough exposures, using an uncooled sensor, noise will always produce some pixels turned on in a perfectly black scene. Even if those are always in the same place, that could indicate a "warm" pixel which shouldn't cause much problem in normal use.

Max Lyons' Thumber's (http://www.tawbaware.com/index.html - shareware) noise analysis report is worth looking at.

It is well worth doing some tests with long exposures just to find the limit of your camera, but noise is a different issue than hot pixels.
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Old Jan 27, 2003, 10:59 AM   #22
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BillDrew
Thanks for your input.The story so far is I am a real newbie coming from a mechanical slant.Fenlander opened my eyes away from P setting and that started me thinking in photo terms.Then Inoticed 1or maybe2 white dots in indoor images not necessary inthe same spot.That brought the mechanics back to find why ccd was doing this in a 4 month old camera.MentorRon then introduced me to black image analysis which on three black images shows no white dots and says there are no dead or hot pixels.So is ccd pruducing the spot because it is charging up an indoor image of some dark areas.Is this the accepted standard of these cameras or does it have a fault?
jasm
ps these spot spots are rarely visible in normal zoom 100%
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Old Jan 27, 2003, 11:08 AM   #23
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If HOTPIXELTEST program says there are none, then there are none. Maybe I missed something in your description of the problem. Where are you "zooming in" to see these white dots? On your PC's monitor or on your camera's LCD? Make sure you are not trying to "create" a problem by zooming to 200% or higher.
You should never zoom in past 100% or full original size to check for damaged pixels. It's self-defeating: you then become disenchanted with your camera, and the "problem" is really non-existant in the "real world". Most people view pictures at 100% or smaller: that is, people who are interested in pictures, not in being overcritical of the technology which is really in it's infancy compared to film. If your camera is a 2MP or greater, and you print the full image, you are printing it with smaller dimensions than it has at 100% on a monitor. When printing 1.3MP pictures which had one or two hot pixels (value: 255) which were easily visible on my monitor, they were really unnoticeable on the 8x10 prints. As most hot pixels are not at the full 255 value (like my FinePix 2300 with one pixel at value 141), they should not be a problem. I wouldn't have even noticed the 2300's pixel without the HOTPIXELTEST program. Only two of the FinePix 1300's seven hot pixels was noticeable on my monitor.
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Old Jan 27, 2003, 3:27 PM   #24
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MentorRon
This all started by me seeing a white dot in the background of an image at 100% on monitor and it prompted me therefor to go looking in consequent images taken inside I took the view ,with no experiance that olympus should be able to produce quality that woul be better. I must say i am learning fast that my original plan to have a computer add on might be right and if photography is my new leaning a film camera would be more appropriate.Thanks again for your help it is really appreciated.
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Old Jan 27, 2003, 5:32 PM   #25
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Quote:
I must say i am learning fast that my original plan to have a computer add on might be right and if photography is my new leaning a film camera would be more appropriate.
jasm
I'm not sure I fully understand this sentence. But they imply that you might not go with digital photography and move back to film. If I am missunderstanding you, then ignore the rest of my post!

If this is because of the pixel related problems please reconsider. There are many benefits of using/switching to digital that this problem is easily outweighed.

I'm not going to list them all, but the ones which matter to me. As a beginner myself, the biggest ones for me are the ability to take tons of pictures and experiment without worrying about cost of the developing. (Ya, this is partially a falacy because the cost of the camera is so much more.) Also the immedate feedback from being able to review my pictures in the LCD and not having to wait for the developing. The EXIF (sp?) data is also great in learing what settings were used for what pictures and learning the settings effects (especially if you take the same picture many times with different settings. Then you'll learn what the effect is of changing what settings.)

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Old Jan 27, 2003, 6:02 PM   #26
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EricS I completely agree with all you say when I bought a digital camera I saw it as an extension of the computer and then Fenlander pointed me in the better photographic route and now I suppose it is a case of being hypercritical.I will continue to use digital I will have to i just bought a second hand c700 to save messing about with c4000 zoom lens addons.I think what I was saying that my increased interest in photography would be better served by a film camera of which I have no real experience either.

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Old Jan 27, 2003, 6:48 PM   #27
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Then again, I know many who want lens add-ons to their C-700 whether it's closeup, wide-angle, or tele!

For instance, here's a site of someone who's added to their C-2100 (same amount of zoom as C-700) to turn their 380mm optical zoom to 1900mm:

http://jimsphotopage.com/UZI/index.html

and here's a site where someone is comparing wide angle lenses for that same camera:

http://members.aol.com/pixbydg/waweb/wa.html

No matter how much you may have, you'll want more!
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Old Jan 28, 2003, 4:45 AM   #28
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Thats called human nature.
jasm
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Old Feb 3, 2003, 2:32 PM   #29
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Jasm:

When you ran the HotPixelTest (if you did), how many pixels were at or above a 200 value (which appear as white)? If they are closer to or smaller than a 150 value (which appear as grey), they should only be noticeable when doing night shots or pictures of black objects that are located where the hot pixels are. If you PRINT these images at 8x10 or less, they should not be visible.
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Old Feb 3, 2003, 4:46 PM   #30
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Mentor Ron,
I ran tests at default settings they generally have occurred in flash images in dark parts.I ran 10 shq images and 6 tif all at 4secs before test and showed o dead o hot i will put image which is under lit of my youngest grandaughter without post processing on pbase with link.
jasm
http://pbase.com/jasm/jasm
gdaughter gdaughter2 two seperate images above about knee top .diag. above top lh corner quite definate but do not show on test?

Thanks again for interest tried to run on dpreview without much success.Wonder if i should give in and run pixel mapping.
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