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Old January 28th, 2010, 11:03 AM   #1
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Sensor Discussion

We have been unable to find a 35mm or APS-C sized sensor for the project. The cost of developing such a sensor is too great for the project. As previously described, we have found a sensor with an active area of 19.8mm W x 14.8mm capable of 3k. It is slightly bigger than a typical 4/3" sensor (17.3mm×13.0mm) and much bigger than the 2/3" sensor (8.8mmx6.6mm) found in the RED Scarlet.

In comparison, the Panasonic LUMIX GH1 has a sensor with an approximate width of 18.9 mm. I am interested in hearing everyones thoughts on this sensor. Do you think that this is a good option for the project? If so many people are embracing DSLRs for digital cinema applications would a camera capable of shooting raw with a 19.8mmx14.8mm sensor be a step in the right direction?
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Old January 29th, 2010, 06:54 AM   #2
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I my opinion that sensor should give at least some 'cinematic' feel to the footage. If you look at clips like this
on Vimeo shot with the Lumix and a fast lens, the DOF is quite nice. Of course we have to wait to see some tests of the sensor and find out if CCD will give a nice image. CCD tends to give a harder, less organic image, compared to CMOS.

There is one issue we never discussed when considering a larger sensor. A larger sensor gives a shallower DOF. This is great for cinematography, but there is also another benefit I think. Due the nature of image compression, the more detail an image contains, the more it will suffer with compression. I noticed this with the Elphel too. So the less 'overall' detail we have, by using a larger sensor, the more detail maintained in the sharp areas. Correct me if I'm wrong.
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Old January 29th, 2010, 11:07 AM   #3
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Quote:
Originally Posted by Oscar Spier View Post
I my opinion that sensor should give at least some 'cinematic' feel to the footage.
Very true! In addition, because the sensor is 4:3 with a resolution of 3,300 x 2,475 we can achieve 3K at 16:9 (around 3072x1728) and 3K at 2:1 (3072x1536).However, that is the 3k specifications of RED's proprietary format. I'm not sure what exactly defines a 3k resolution. We could probably go a bit beyond that. In any case, the difference of this and and Lumix should be day and night in comparison.

To be honest, I think a lot of the 'cinematic' feel depends on the lens. Imagine if you shot with this camera using Anamorphic lenses? I have come to see Anamorphics somewhat as a holy grail for achieving a true 'cinematic' feel. Unfortunately, anamorphic lenses cost a fortune and would easily cost double the price of an Apertus camera. We need to explore what options we have with spherical 35mm lenses (maybe using anamorphic adapters) to achieve this look.

Quote:
Originally Posted by Oscar Spier View Post
Of course we have to wait to see some tests of the sensor and find out if CCD will give a nice image. CCD tends to give a harder, less organic image, compared to CMOS.
The sensor is actually a CMOS with global shutter! So no issues with blooming, rolling shutter, etc.

Quote:
Originally Posted by Oscar Spier View Post
There is one issue we never discussed when considering a larger sensor. A larger sensor gives a shallower DOF. This is great for cinematography, but there is also another benefit I think. Due the nature of image compression, the more detail an image contains, the more it will suffer with compression. I noticed this with the Elphel too. So the less 'overall' detail we have, by using a larger sensor, the more detail maintained in the sharp areas. Correct me if I'm wrong.
To add to that point, by stopping down the lens you can get more detail in a shot. So having the capability of shallower DOF doesn't necessarily mean every shot will have shallower DOF. The benefits certainly come in to play when you start to think of what is possible in terms of DOF when you put 35mm lenses in front of the camera.

Hopefully we can find a method of compression that will suit us best. I remember reading about the BloodSimple codec someone was working on. Once the 373s come out and we can swap out the sensor with this one we can start to look at what compression codecs work best with that setup. Of course, we are a long way away from that :(
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Old January 29th, 2010, 05:14 PM   #4
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Originally Posted by Jeremy Cimafonte View Post
The sensor is actually a CMOS with global shutter! So no issues with blooming, rolling shutter, etc.
I meant the sensor for the future Elphel.
As far as I know, the sensor Andrey at Elphel has in mind is a 4/3" CCD.
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Old January 29th, 2010, 09:40 PM   #5
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I meant the sensor for the future Elphel.
As far as I know, the sensor Andrey at Elphel has in mind is a 4/3" CCD.
I wasn't aware Andrey had a sensor in mind. Did you get a chance to talk to him about the Dalsa sensor? I can only assume it is superior in many ways to a CCD. Maybe he could contact Dalsa and get the final word on it. It certainly wouldn't make sense to offer both a 4/3" CCD and the Dalsa (bit bigger than 4/3") CMOS since they are so close in size.
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Old June 18th, 2010, 03:18 AM   #6
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Jeremy what sensor do you mean? and what sensor Andrey means?

what is the diference between CCD interline sensors and CCD full frame sensros?
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Old June 28th, 2010, 07:50 AM   #7
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What about the "new" 35mm 25MP, 53 fps sensor by Cypress ?
Some of the earliest attempt at HD cinema camera used their IBIS sensors...

Image Sensors World: Cypress Introduces 25MP 53fps Global Shutter Sensor
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Old June 29th, 2010, 12:42 AM   #8
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Nice find, thanks!

Please be so kind and add the sensor to the table: Sensors table - ElphelWiki
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Old June 29th, 2010, 12:34 PM   #9
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is "interline" and "full frame" sensor-speak for rolling-shutter and global-shutter?
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Old July 3rd, 2010, 06:40 AM   #10
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As far as I understand it CCDs cannot have a rolling shutter but the terms do refer to the photosite read out method, but wikipedia can explain it much better than my attempts: Charge-coupled device - Wikipedia, the free encyclopedia
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Old July 3rd, 2010, 01:53 PM   #11
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as I read the wikipedia article the "interline" are the ones we are the most interestes since they don't need a mechanical shutter and also because they "reduce smear" no?

another quaestion...
who prints the bayer filter? because of the semi HDR effect elphel proposes (keep one of the green pixels brighter) can such filter be printed for any chip? which ones have such option?
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Old July 4th, 2010, 02:49 PM   #12
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Originally Posted by Biel Bestue View Post
as I read the wikipedia article the "interline" are the ones we are the most interestes since they don't need a mechanical shutter and also because they "reduce smear" no?
Yes, Interline CCD

KAI-02150, KAI-04050, KAI-08050 are pin compatible and therefore should all work with the upcoming Elphel 373.

Quote:
another quaestion...
who prints the bayer filter? because of the semi HDR effect elphel proposes (keep one of the green pixels brighter) can such filter be printed for any chip? which ones have such option?
Sorry, no idea.
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Old August 29th, 2010, 08:03 AM   #13
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look at these test images from KAI-02150 sensor from these thread Any news on Greek HD camera? - Page 72 - DVXuser.com -- The online community for filmmaking they are beautiful! KAI-02150 is a great global shutter cinema sensor even with its 1920 frame size limit. also in that thread there are some tests with red sensors and kodak seems much more usable. really i still can't understand how it will be possible to use different sensor on upcoming elphel. i mean if it will be pin compatible i just can by elphel board without sensor and solid or plug new sensor manually to it and it will be work? or it will req some additional programing?

from other side according KAI-02150 datasheet there is only 64 db of dynamic range in that sensor.
http://www.kodak.com/global/plugins/...uctSummary.pdf
but really don't understand why pictures from elphel current sensor with 70 db dynamic range are looks more more burned than from that camera...

EDIT:
as explain Otis Grapsas:
That spec in sensor datasheets just shows how greater the saturation level is to the noise level. If it's 256x greater, that's a 48dB sensor and a 8 stop sensor. A 64dB sensor vs a 70dB sensor means the 64dB sensor has 1 stop greater noise. If you use the same gamma curves you will get 1 stop of lower dynamic range under the 18% grey but identical dynamic range, behaviour and look over the 18% grey, identical highlight handling. Different gamma, different behaviour. Gamma curves are part of the art of design, they make cameras different and they can even make cameras using identical hardware achieve different performance.

Last edited by Dmytry Shijan; August 29th, 2010 at 02:16 PM.
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Old August 30th, 2010, 05:54 AM   #14
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Creating beautiful images is an art and if you know your stuff you will create beautiful images with a sensors with 64db as well as with 70db, on the other hand if you dont know what you are doing you will fail with both of them.

So a direct image comparison of 2 different cameras/sensors is IMHO only legit if the footage was created by the same DoP or DoPs at the same skill level.
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