Karl Guttag
Veteran Member
Below I am proposing a couple of simple experiments for those with a SD9 to try. I think they would help get things onto a more objective basis.
There are a couple of problems that most everybody agrees on seeing in the SD9 images, one is “Dust” and the other is Vanishing saturated Reds/Oranges/Magentas.
EXPERIMENT 1: WHERE IS THE DUST?
There is a simple experiment to run to determine approximately where the dust is located. Basically all you have to do is go into Aperture Preferred mode and set the Exposure for +1 (since you will be shooting at the sky). Then point toward the sky and shoot a picture at F2.8, F5.6, F11, and F22. Then (optional), if the camera will support it, take off the lens and at a high shutter speed (this may take some trial and error to get the shutter speed high enough to no overexpose).
The “shadow” caste by dust is a function of the distance from the sensor and the F-number. The more you stop down (higher F-number) the sharper the dust will become. If the dust is more than a centimeter from the Sensor it will not cast a discernable shadow at F2.8, but if it is about a centimeter away it will cast one at say F11. Basically you can figure out how far the dust is away from the sensor by what F-number it appears at. The smaller the F-number for it to appear, the closer the dust is to the sensor.
BTW, dust in the lens or even on the "dust protector" is way to far away from the sensor to image sharply. The fact that dust is showing up on F8 shots, suggests that it is near or in the sensor.
IF without a lens at all the camera Dust is “sharp,” then this suggests that the dust in either on the surface of the sensor (permanently encapsulated with the device) OR the pixel is dead. Even at F2.8, if the dust is sharp it suggests a dead or permanently blocked pixel.
The “take a picture of the sky at F16” is something that everyone that is checking their camera for Dust does, because it is known that stopping down the lens makes the dust stand out. This is something any DSLR owner (of any brand) should do regularly to check for the accumulation of dust. It would also be interesting to see if the "Dust" gets worse or stays the same over time.
EXPERIMENT 2: Do Saturated Colors Blow Out Worse than other Cameras?
I think most everyone agrees that the SD9 has some strange problems with light sources, but there is also evidence (say the “horse track picture” with the blown out traffic cone) that it has problems with brightly lit saturated colors. What may some times thought to be “specular reflections” (white due to light refection) may in fact be color blow outs. This experiment is designed to see how sensitive the SD9 is to blowing out colors. A simple way to get a variety of intensities is to take a Curve or Spherical object (either bright red or bright orange, we know that traffic cones “work”) and illuminated it primarily from one side. This will cause a gradient type of shading. Take a close up picture of the object over a range of exposures (exposure bracketing. If possible, do the same with another brand of camera so that people can compare the results.
It would be nice to run the experiment with different colors. Red/Orange/Magenta seems to be a particular problem for the SD9, it would be interesting to see what other colors do.
I tried to “construct” tests that would be quick and easy to run and has a good chance of giving some objective results. The “Where is the Dust?” test is particularly easy to run and I am surprised nobody has done it yet.
Karl
There are a couple of problems that most everybody agrees on seeing in the SD9 images, one is “Dust” and the other is Vanishing saturated Reds/Oranges/Magentas.
EXPERIMENT 1: WHERE IS THE DUST?
There is a simple experiment to run to determine approximately where the dust is located. Basically all you have to do is go into Aperture Preferred mode and set the Exposure for +1 (since you will be shooting at the sky). Then point toward the sky and shoot a picture at F2.8, F5.6, F11, and F22. Then (optional), if the camera will support it, take off the lens and at a high shutter speed (this may take some trial and error to get the shutter speed high enough to no overexpose).
The “shadow” caste by dust is a function of the distance from the sensor and the F-number. The more you stop down (higher F-number) the sharper the dust will become. If the dust is more than a centimeter from the Sensor it will not cast a discernable shadow at F2.8, but if it is about a centimeter away it will cast one at say F11. Basically you can figure out how far the dust is away from the sensor by what F-number it appears at. The smaller the F-number for it to appear, the closer the dust is to the sensor.
BTW, dust in the lens or even on the "dust protector" is way to far away from the sensor to image sharply. The fact that dust is showing up on F8 shots, suggests that it is near or in the sensor.
IF without a lens at all the camera Dust is “sharp,” then this suggests that the dust in either on the surface of the sensor (permanently encapsulated with the device) OR the pixel is dead. Even at F2.8, if the dust is sharp it suggests a dead or permanently blocked pixel.
The “take a picture of the sky at F16” is something that everyone that is checking their camera for Dust does, because it is known that stopping down the lens makes the dust stand out. This is something any DSLR owner (of any brand) should do regularly to check for the accumulation of dust. It would also be interesting to see if the "Dust" gets worse or stays the same over time.
EXPERIMENT 2: Do Saturated Colors Blow Out Worse than other Cameras?
I think most everyone agrees that the SD9 has some strange problems with light sources, but there is also evidence (say the “horse track picture” with the blown out traffic cone) that it has problems with brightly lit saturated colors. What may some times thought to be “specular reflections” (white due to light refection) may in fact be color blow outs. This experiment is designed to see how sensitive the SD9 is to blowing out colors. A simple way to get a variety of intensities is to take a Curve or Spherical object (either bright red or bright orange, we know that traffic cones “work”) and illuminated it primarily from one side. This will cause a gradient type of shading. Take a close up picture of the object over a range of exposures (exposure bracketing. If possible, do the same with another brand of camera so that people can compare the results.
It would be nice to run the experiment with different colors. Red/Orange/Magenta seems to be a particular problem for the SD9, it would be interesting to see what other colors do.
I tried to “construct” tests that would be quick and easy to run and has a good chance of giving some objective results. The “Where is the Dust?” test is particularly easy to run and I am surprised nobody has done it yet.
Karl
