A7/A7R Light leaks reported + White Orbs issue?

Started Feb 8, 2014 | Discussions thread
_sem_ Veteran Member • Posts: 5,023
Re: A7 No White Orbs issue?

blue_skies wrote:

captura wrote:

Well this guy reported it with his A7, and the question is, was the only one, or are there others, and how many? Strangely the thread was cut short after less than 100 messages: What's going on?


Steve, that thread is at 150 messaage (149 responses). Threads auto-lock at 150 messages.

Read ProfHandD's response in that thread, as it supports my comments in that same thread:


The problem manifests itself by:

  1. High dynamic range of the sensor, making reflections perceptible if
  2. Highlights are dramatic (bright lights on a dark background, sun in frame)
  3. The shot is over-exposed (highlight at, or close to blow-out)
  4. Using a stopped down aperture
  5. Use of short-flange lens (typically WA RF lens)

Remove one or two of these variables and the problem goes away,

The patterned flares are not an innovation of A7/R, although they indeed look prominent.

When shining a flashlight straight to the sensor through the open mount at a certain angle, one can see that the sensor indeed acts like a diffraction grating:

Diffraction-intereference on the GH2 sensor from a LED flashlight

It appears that certain lenses, particularly some of those with short flange distances, are likely to reflect the magnified pattern (maybe just a spectral part of it) back onto the sensor. Particularly when provoked with strong directed beams of light, and when the rest of the image is relatively dark. Patterns of red, green or purple dots have been noticed with many cameras: some mFT cameras with certain lenses; many advanced compacts like RX100, XZ-2, certain Sigmas. The intensity and shape of the pattern varies with both the sensor and the lens (probably different sensor reflectivity at certain wavelengths, different lens coatings). The more expensive the gear involved, the louder the complaints. Though worst cases with huge blobs are found on cellphone cameras. Sample SGS2 flare dance movie:


I first thought DSLRs were immune. But with enough torture with a small LED flashlight in a dark room, cross-shaped flares can be noticed sometimes (showing overall interference pattern rather than individual dots), and some lenses (for example Tamron 60/2 macro) show patterns in "regular" flares (maybe from some of the front lens elements, not the rear ones?).



I think the White Orbs of the Fuji X10 are a different phenomenon related to "sensor bleeding" (recall the horrible vertical bleeding of CCD sensors?).

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