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BMCC4K? New Fairchild Sensor - Same DR of the Pocket and Cinema, but in 4.5k

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  • Tzedekh
    replied
    Originally posted by Steven Abrams View Post
    The LTN could even be the same sensor with BMD's modifications, but can only be used by another company for a machine vision camera (science/medical/etc) so not a "threat" to BMD's market (digital cinema/video cameras).
    Such a limitation is improbable. The sensors in the BMCC and the Pocket are, like the LTN4625A, scientific/industrial CMOS sensors, yet BMD adapted them for digital-cinema purposes. I seriously doubt BAE/Fairchild will contractually prohibit the LTN's use in a digital-cinema cameramade by a company other than BMD.

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  • Steven Abrams
    replied
    I think a lot can be "guess-worked" from what's been posted and said by BMD already.

    "Fairchild did offer its new Maestro MST4625 exclusive to BlackMagic, which is very similar to LTN4625A for machine vision . . . "

    Combine that with Grant Petty saying BMD spent millions and a couple of years on this new sensor development, and it seems like BMD had input into a sensor design (I've read others saying things like the CFA design by BMD) made by Fairchild that also cost BMD millions to make exclusive to them, but there's the LTN4625A for MACHINE VISION. The LTN could even be the same sensor with BMD's modifications, but can only be used by another company for a machine vision camera (science/medical/etc) so not a "threat" to BMD's market (digital cinema/video cameras).

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  • Somnio
    replied
    New Fairchild Sensor

    Been wondering this myself. But yeah, I think we're being left in the dark on purpose. We're not going to know anything unless Blackmagic (or Fairchild) cough up the information, and that's gonna be a tall order on account of the tens of millions of dollars that are at stake.

    So all we can really say at the present is that what most of us already assume based on Grant's statements: that Blackmagic paid Fairchild to make modifications to the LTN4625A for the purpose of augmenting the sensor's quality and importance to the world of filmmaking.

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  • combatentropy
    replied
    Does anyone know the difference between the LTN4625A and Blackmagic's version of it? I found an intriguing post elsewhere about an MST4625A: "Fairchild did offer its new Maestro MST4625 exclusive to BlackMagic, which is very similar to LTN4625A for machine vision . . . "

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  • Flabasha
    replied
    I work for one of the three "major" TV networks and we just shot some commercials on the URSA for an upcoming show.

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  • Ryan Lightbourn
    replied
    Originally posted by townio View Post
    Sounds like there could be so new BMD camera at NAB. I hope they don't just put it in the URSA because I don't like the form factor. Maybe a pocket 2 ?
    I haven't been keeping up with this, but was Ursa considered a success? I don't know anyone who's shot on one, or even seen one in the field.

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  • combatentropy
    replied
    Put this sensor in something like the Canon XA-10, and my obsolescence is obsolete.

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  • townio
    replied
    Sounds like there could be so new BMD camera at NAB. I hope they don't just put it in the URSA because I don't like the form factor. Maybe a pocket 2 ?

    Leave a comment:


  • Joshua Cadmium
    replied
    Yay for an actual spec sheet!

    While full well capacity is higher, read noise is also higher at 2 e- rms. (The BMCC is 1.5 and the Pocket is 1.2, in comparison).

    So, you have to divide 40,000/2 = 20,000, of which the 20log(20,000) is 86dB or 14.2 stops.

    However, the full well capacity is listed as GREATER THAN 40,000 and read noise is LESS THAN 2, so the difference most likely adds up to the 88dB claimed.

    Also, global shutter mode is listed at less than 5 e- rms. 40,000/5 = 8,000, and 20log(8,000) is 78dB or 12.9 stops. However, like above, we can assume that it's going to be greater than this, so it will most likely be over 13 stops in global.

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  • Steven Abrams
    replied
    http://www.fairchildimaging.com/cata...scmos/ltn4625a

    "> 40,000 e- full well capacity" vs "> 30,000 e- full well capacity" for the Pocket - this should mean more DR than Pocket/BMCC !
    "< 15 e-/pixel/sec at 20C" vs "< 30 e-/pixel/sec at 20C" for the Pocket cam - half the dark current should mean better noise performance which could mean EVEN more useable DR than Pocket/BMCC on top of the gain for more full well capacity !!

    This is looking to be VERY exciting.

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  • Tzedekh
    replied
    Originally posted by combatentropy View Post
    I don't know why Blackmagic didn't offer it in global shutter mode. Worst case, 81.6 dB, that's 13.6 stops.
    Well, no, that's the best case. Maybe tests indicated that noise -- and therefore dynamic range -- were much worse in practice than these figures would predict. Or maybe implementing a global-shutter mode would have raised production costs beyond their targets or significantly delayed release.

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  • combatentropy
    replied
    Thank you. I agree with you about the root mean square.

    Either way, if this is the case, I don't know why Blackmagic didn't offer it in global shutter mode. Worst case, 81.6 dB, that's 13.6 stops.

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  • Tzedekh
    replied
    Originally posted by combatentropy View Post
    Are you saying that you know that the CIS2521 in global-shutter mode loses only about a stop?
    According to pco's pco.edge 5.5 data sheet, the slow-scan rolling-shutter (RS) readout noise is 1.1 e- (median) or 1.5 e- (root mean square [rms]). The equation to derive dynamic range is
    DR, dB = 20 x log(full-well capacity readout noise)

    The stated full-well capacity is 30,000 e-. Using the median readout noise figure 1.1 e- yields an RS DR of 88.7 dB, and using the rms one gives 86.0 dB. So, it looks as if BAE/Fairchild are using the former to calculate DR, probably because it yields the higher figure, whereas they should probably be using the latter noise figure. According to one of Hamamatsu's "Reality Check" articles, "Read noise in CMOS cameras: only rms is meaningful" (here):
    With CCDs there are never any issues regarding which model to use because the typical read noise for all pixels is very similar, thus rms and median are equivalent. With sCMOS, the structure of the sensor inherently has more pixel variation, and the extreme low noise of the sensor makes variation more statistically significant. So when it comes to evaluating camera performance, the truly meaningful spec is rms noise. The rms noise value provides insight into image quality as well as being the appropriate noise variable in quantitative calculations.

    That means 86.0 dB is the more meaningful RS DR figure.

    The median and rms readout noise specs for the fast-scan global-shutter (GS) mode are 2.2 e- and 2.5 e-, respectively, which yield DR figures of 82.7 dB and 81.6 dB. Allowing for rounding, the median-noise GS DR spec is one stop lower than the RS one, but the rms DR spec is less than one stop. Of course, these are theoretical figures -- I've honestly never seen any reports of real-world tests of the CIS2521's global-shutter dynamic range.
    Last edited by Tzedekh; 03-26-2015, 04:17 AM.

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  • Abstrak
    replied
    Originally posted by caleb_camera View Post
    If they implement this to the Ursa and give it a 800 base iso with a decent expanded iso range with little noise the Ursa will sell like hot cakes.
    I'd upgrade my 4K to the URSA if they made the camera smaller and gave us 240 FPS 4K

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  • combatentropy
    replied
    Originally posted by Joshua Cadmium View Post
    "Fairchild imaging is pleased to invite you to visit our booth at the Automate Trade Show, taking place at the McCormick Place Convention Center, Chicago, Illinois, United States, 23-26 March 2015. Come to our booth for a live presentation of the LTN4625A - our 12M pixel, 240 fps, 88dB high dynamic sCMOS Image Sensor! We will have people on hand to answer any questions you may have. Find us at booth# 1196"
    Anyone going?

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