Purple fringing with D800

Started Jan 5, 2013 | Discussions thread
moony16 Regular Member • Posts: 469
Re: A sensor can contribute to purple fringing

TOF guy wrote:

moony16 wrote:

TOF guy wrote:

To be exact: the microlens in front of each pixel can cause purple fringing. It can be differentiated from lens CA but the fact that it uniformly affects the frame. Often it is associated with blooming and is therefore more prevalent in CCDs, and is much more likely to affect sensors with small pixel pitch. A description can be found following this link (scroll to the paragraph entitled "Photography" and start reading beginning with the sentence "Another cause of this fringing is chromatic aberration in the very small microlenses used to collect more light for each CCD pixel").

To give an example, the Sony 828 was notorious for its propensity to purple fringing in part caused by the microlens, see these examples .

However the D800 appears to be immune from this problem. Your answer is perfectly correct in this regard

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Thierry - posted as regular forum member

Agreed, sensors can, indeed, contribute to the problem &, when they do, the word used is "blooming."

Not exactly: it's a separate problem. Blooming comes from the leak of charges from one pixel (the pixell well to be exact) to the next. It's an electronic issue. Purple fringing induced by microlens is an optical issue.

Purple fringing is more readily seen near lines of high contrast. Blooming will occur if the bright area adjacent to the line of is overexposed. Hence the two are often associated but not necesarily. There are other differences. Blooming may create white streaks. PF induced by microlens does not.

CCD sensors are very prone to blooming issues, whereas Cmos sensors (which the D800 has) are known for being resistant to blooming.


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Thierry - posted as regular forum member

Here is an introductory sentence from your provided link above:

We'll call it 'purple fringing' but it's clearly a combination of chromatic aberrations caused by the interaction of the lens and the microlenses on the sensor and enhanced by a certain amount of blooming which carries the color out further than the original artifact.

My original claim stands: the role the sensor palys in the distortion is called blooming. I never associated blooming with PFing--please re-read for clarity. I know it's a separate problem and designated it as such with the word "blooming." I also know CCDs are prone to blooming, whereas CMOS is resistant, which is why I wrote it. I did not need you confirmation of this.


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