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-   -   EX1R IR handling: really hardware? (https://www.dvinfo.net/forum/sony-xdcam-ex-pro-handhelds/470103-ex1r-ir-handling-really-hardware.html)

Piotr Wozniacki December 28th, 2009 10:38 AM

EX1R IR handling: really hardware?
 
Having seen the early comparison pics (showing better blacks, and higher low-light sensitivity), and now reading the actual users' testimonies (like Marty's) - I' starting to wonder:

- is the EX1R supposedly better handling of IR problem (or feature?) really achieved by hardware changes alone? If it were, how come the overall sensitivity has been reported HIGHER than that of the original EX1?

If my suspicions are well-grounded, and the less IR contamination is due to some SOFTWARE processing rather than HARDWARE -

- can we, the original EX1/EX3 users, count on the next firmware release to take care of this?

Just wondering...

Nick Wilson December 28th, 2009 11:20 AM

My understanding of this issue, without any specific knowledge of how Sony have designed the EX1 is:

- As we know, a colour camera works by filtering the incoming light into red, green and blue. Each of these filtered images is recorded by an imager chip, which records the luminance of that colour. The display shows the output from each imager in the appropriate colour, and we are back to a colour image. This works because our eyes resolve colour by means of retinal cones that are sensitive to either red, green or blue light.

- The spectrum is continuous, and there is no hard cut-offs between the colours. The camera maker has to judge what filters to use to achieve the goal, which is fidelity (the scene reproduced electronically matches what the eye perceives).

- With any sensors, but particularly CMOS, they are sensitive to red and infrared light with wavelengths which cannot be seen by the eye. If the scene reflects these wavelengths, the red channel will show luminance where the eye would see none. As we know, there are fabrics in particular which reflect far red - this is not a concern to the fabric or dye manufacturers because they are designing for the human eye.

- To overcome this, the red channel filtering needs to cut off at the point that the eye ceases to be sensitive. With the EX cameras, it appears that the cut-off wavelength is too long so the sensor reports far (invisible) red in just the same way as it picks up visible red. Brown is dark red, so black objects appear brown. This is an optical problem needing an optical solution such as the Tiffen T1 or an internal equivalent. There is no software fix, as software could do nothing apart from reducing the overall, visible and far red sensitivity.

Cheers

Piotr Wozniacki December 28th, 2009 11:37 AM

I absolutely agree with the theory you describe, Nick. However -

What makes me wonder is that - even though cutting the FR (far red) more aggressively than with EX1 - the EX1R is still reported to have higher overall brightness (or low-light sensitivity).

Considering that the (already lower) sensitivity of the original EX1 is further reduced (by 1/3 - 1 full stop, reports vary) with the Tiffen T1 filter on - how is it achieved with the EX1R that the FR is reduced WHILE the low light sensitivity is increased?

Alister Chapman December 28th, 2009 03:56 PM

When I compared my EX1 with the pre-production EX1R I did not notice any difference in sensitivity.

Piotr Wozniacki December 28th, 2009 04:17 PM

Well, Andy of Abel Cine Tech has posted some grabs on this forum indicating the opposite...

But I guess his tests might have not been very scientific.

On the other hand, if all that has changed is a stronger FR filtration, the EX1R should in fact be a little *less* sensitive - more like the original EX1 with the T1 filter!

John Poipie December 28th, 2009 05:05 PM

The ND filters are on a wheel with 3 "glasses". It would be very simple just to replace these
"glasses" with filter glasses that correct the problem.

Nick Wilson December 28th, 2009 05:14 PM

Quote:

Originally Posted by Piotr Wozniacki (Post 1465352)
Considering that the (already lower) sensitivity of the original EX1 is further reduced (by 1/3 - 1 full stop, reports vary) with the Tiffen T1 filter on - how is it achieved with the EX1R that the FR is reduced WHILE the low light sensitivity is increased?

Again without inside info, I guess

- the EX1 has its own filter - this plus a T1 is going to reduce light by more than just a T1 equivalent on its own.

- in the 2 years since the EX1 was released, experience/improvements in DSP chips has enabled them to push the gain a little whilst keeping the same S/N

Maybe!


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