Open Source Digital Cinema Camera based on Elphel

The AXIOM looks cool, but I hope they make the modules... weather sealed.




Tzedekh said:
I was hoping that CMOSIS might do a 16-bit, dual-readout (a la the Alexa sensor or the BMCC's CIS2051), stacked sensor with the global-shutter circuitry on a layer behind the photosites.
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CMOSIS will do whatever you want them to do, if you have the money.
 
Sorry for not supplying this thread with the recent news posts for some time. Its not because there is nothing to report but rather that there is so much to report that its hard for me to find time anymore to write here. :)

Lets recall the most important milestones of the last couple of months:


We finished building our camera prototype: https://www.apertus.org/second-alpha-prototype-ready

We posted the first 4K RAW still: https://www.apertus.org/merry-christmas-2013
AXIOM_ALPHA_APEAKGRADE_thumb.jpg

We extended the open modules camera concept for swappable sensor modules, etc: https://www.apertus.org/extended-open-modules-concept
open-modules-concept-front-V1.jpg

We have moving images from the prototype: https://www.apertus.org/2014-major-breakthrough-axiom-alpha-moving-images

We are now in the final stages of preparing our crowd funding campaign.

More soon, stay tuned!
 
Very nice!

What's that mount in the pic? It seems to be too close to the sensor to be PL, so probably P+S. I was wondering because it seems there's no provision for internal ND filters; a mount with somewhat-longer focal flange distance could allow for that.
 
stefanhuberfilms said:
i suppose this is just for showcasing the function, no 1:1 3D model of the finished product...?
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Exactly, its a proof of concept prototype.

What's that mount in the pic? It seems to be too close to the sensor to be PL, so probably P+S. I was wondering because it seems there's no provision for internal ND filters; a mount with somewhat-longer focal flange distance could allow for that.
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We plan to use the IMS mount from P+S, but with the open design and short FFD native other mounts are also very well possible (PL).
 
We just released an article containing the First Moving Images from Axiom Alpha Prototype!


Alpha03-slider-image-01.jpg



Read more about it and watch the videos on: https://www.apertus.org/2014-first-moving-images-axiom-alpha
 

I think it looks nice, despite the warnings. Filmic even. Maybe you shouldn't calibrate the sensor, lest it turn videotic ;)

Also from the post:

For those of you who may not be aware, our image sensor features an HDR mode called "Piecewise Linear Response (PLR) Mode". This essentially means that you can add two knee-points to the response curve already inside the image sensor, achieving a more logarithmic shaped response curve closer to film negative - with a substantially extended dynamic range in the highlights.
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What's the catch? Wider dynamic range and log gamma? Leave that puppy on all the time.

 
Samuel H said:
That bright parts of the image are exposed with a much shorter shutter speed. It's for highlight recovery, don't let your main subject fall in that area, or you may get the saving-private-Ryan look.
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Yeah, it would've been better had CMOSIS used a dual-readout approach like that used in the BAE/Fairchild CIS2051 and the Arri Alexa sensor. Though it too probably produces image artifacts, they are undoubtedly less objectionable than those associated with the CMV12000's piecewise linear response mode or Red Epic's HDRx.
 
Samuel H said:
Looking good :)

That bright parts of the image are exposed with a much shorter shutter speed. It's for highlight recovery, don't let your main subject fall in that area, or you may get the saving-private-Ryan look.
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Thanks :)

PLR is always a trade to get one thing for another: more dynamic range, more noise, higher shutter speeds. The great thing here though is that you can choose yourself for every shot how much of the highlights you want to retrieve, after all a lot of shots will probably not even require the entire native dynamic range of the sensor so why waste latitude range on them... :)
 
They completely missed the boat. They should have targeted a 2k-2.5k sensor with hig dynamic range like blackmagic did. They are producing a monster with 4k raw format which will much more hardware power and time to develop and at what price... I am always hearing "less than 10k". Who in their right mind would buy this camera above 3k (blackmagic camera)... just because it is open source. I guess, they have missed their window of opportunity with camera from blackmagic and the chinesse camera being much more in line of the spirit of open source than the axion. A good 2k/2,5k camera with apsc sensor and wide dynamic range and low light at a competitive price would have been much better.
 
bright parts of the image are exposed with a much shorter shutter speed. It's for highlight recovery, don't let your main subject fall in that area, or you may get the saving-private-Ryan look.
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From what I've read, Piecewise Linear Response is from some kind of voltaic voodoo, not shifting the shutter speed of the highlights. I get frustrated by my electronic ignorance, but that's the impression I get after sifting the Net for detail:

- Methods to extend the dynamic range of snapshot active pixels sensors
- Increasing Dynamic Range in CMOS image sensors
- CMOSIS CMV300 Data sheet

So the side effect would be a hard-to-reconstruct slope. You'd have to know the exact knee points the camera used and compensate for them in post. Ideally, the sensor's own analog-to-digital converter would have been aware of the kneepoints and adjusted accordingly right then, but I have read nothing of the sort.

A good 2k/2,5k camera with apsc sensor and wide dynamic range and low light at a competitive price would have been much better.
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I agree that a 2K S35 would be interesting. I bet you could get decent, trick-less dynamic range and still keep global shutter. The trouble is, I've seen no such sensor available anywhere from anyone, and I've had my eye out for years (I drew this design in 2008). Blackmagic's 2.5K sensor has rolling shutter and actually is not even Four Thirds format. It has an 18mm diagonal, halfway between Super 16 and 4/3. Throw a SpeedBooster on it, though, and becomes Super 35. Still rolling shutter, though.

For those content with rolling shutter, there probably is already out there a camera that meets their needs and is in their price range. Global shutter aficionados, though, have few to choose from.
 
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