| inviato il 25 Ottobre 2016 ore 12:58
Come da oggetto,
snapshot.canon-asia.com/article/en/eos-5d-mark-iv-interview-with-devel
non viene menzionato nulla riguardo alla gamma dinamica, ma spiegano alcune delle misure attuate per ottenere un certo livello di rapporto segnale rumore. Tra le altre, hanno utilizzato filtri colore con un livello di trasmittanza maggiore, rispetto a quelli della 5d mark III.
Vengono inoltre discusse le strategie utilizzate per lo smaltimento del calore, lato sensore e processore. Riguardo ai video, hanno deciso di eliminare la possibilità di scattare foto durante la registrazione del filmato per evitare l'interruzione della registrazione, per circa un secondo, che vi sarebbe stata.
Cito un estratto, riguardo al sensore.
"- The new EOS 5D Mark IV saw a significant increase in the number of pixels. What are the technologies that made this possible?
Haraguchi: Where the achievement of a Dual Pixel structure with approximately 30.4 megapixels on the EOS 5D Mark IV is concerned, I believe the main contributing factor is the technology that we have established on the EOS 5DS and EOS 5DS R, which come with an approximately 50.6-megapixel image sensor. As you know, increasing the number of pixels means a smaller area per pixel, which would put a heavier burden on the optical features. However, we managed to resolve most of these issues while we were developing the EOS 5DS, and thus were able to concentrate on achieving a high ISO speed performance at the same time, a quality that is essential to the EOS 5D Mark IV as a traditional model of the 5D series.
- I believe the pixel pitch has become smaller with the increase in the number of pixels to approximately 30.4 megapixels. What measures were taken to prevent deterioration of the S/N ratio?
Haraguchi: The pixel pitch of the EOS 5D Mark IV is 5.36 micron, which is smaller than the pitch of 6.25 micron on the EOS 5D Mark III. Of course, the amount of light absorbed by the sensor decreases the smaller the pixel area sensitive to light. Assuming that the level of noise is constant, the amount of incident light is thus also reduced, which naturally results in a lower S/N (signal-noise) ratio.
To enhance the S/N ratio, we have adopted three measures on the EOS 5D Mark IV. First of all, we reviewed the structure of the photodiodes to secure an area for the photodiode on the pixel more efficiently. Secondly, we improved the transmittance of the colour filters to allow more light to enter the photodiodes. Last but not least, we adopted a new microfabrication process to minimise noise on the sensor.
By combining these technologies, we were able to raise the S/N ratio, which was lowered due to the smaller pixel pitch, to a state that is equivalent to or even higher than before.
- Please explain a little more about this new technology with focus on the transmittance of the colour filter.
Haraguchi: We are unable to disclose the details, but in our efforts to improve the colour filter, one of the approaches we used was to enhance the transmittance so as to raise the proportion of "S" in the S/N ratio.
Let us assume that the amount of light that falls on the micro lenses is 100 units. Out of this, the pixel structure on the EOS 5D Mark III is only able to transmit 80 units. However, with the transmittance of the colour filter improved, the pixel structure of the EOS 5D Mark IV is able to deliver 90 units of the light. Also, we have employed a new material for the colour filter in order to retain its original characteristics. Meanwhile, as for components inside the pixel, other than the photodiodes which are not related to light reception, such as the wiring, we have also changed the layout to boost the basic performance of the CMOS sensor." |
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