Author Topic: Sensor checkup?  (Read 6293 times)

ToniX

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Sensor checkup?
« on: April 02, 2014, 11:06:25 PM »
Do someone know about any method, to check whether the  performances of a sensor falls within the standard parameters?  ::)
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Audionut

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Re: Sensor checkup?
« Reply #1 on: April 03, 2014, 01:39:57 AM »
Analyze the raw data.

ToniX

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Re: Sensor checkup?
« Reply #2 on: April 03, 2014, 09:46:22 AM »
 any SW suggestion? I wish to check if I have a faulty sensor. I found Raw image analyzer but
it seem to me  it is not intended for such use, and it is quite complex to learn how to use it.
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a1ex

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Re: Sensor checkup?
« Reply #3 on: April 03, 2014, 09:58:05 AM »
raw_diag module from here: www.magiclantern.fm/forum/index.php?topic=10111 (compare the results with those from another camera, same model).

What faults do you suspect?

ToniX

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Re: Sensor checkup?
« Reply #4 on: April 03, 2014, 11:12:48 PM »
it is difficult to explain exactly, two symptoms mainly: a lot of grain especially in dark areas, even at low Iso and bright lighting conditions, and the settings that doesn't match... ??? (taking photos in ML, no video)
Thanks for the link, I will give it a try.
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reddeercity

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Re: Sensor checkup?
« Reply #5 on: April 04, 2014, 01:15:06 AM »
a1ex  just had a look at the link, and seem that the 5D2 has a little more DR at ISO 81. Dose it drop off like the 5D3 , or it stops there?

Audionut

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Re: Sensor checkup?
« Reply #6 on: April 04, 2014, 03:29:51 AM »
and it is quite complex to learn how to use it.

It's a complex subject ;)

Are you aware of things such as, dynamic range, and how to interpret the results?  Shot noise, the various forms of electronic noise?

a1ex

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Re: Sensor checkup?
« Reply #7 on: April 04, 2014, 07:38:41 AM »
a1ex  just had a look at the link, and seem that the 5D2 has a little more DR at ISO 81. Dose it drop off like the 5D3 , or it stops there?

Not sure I understand the question (what do you mean by drop off?), but that's the lowest ISO I could get on 5D2.

Note: I used the DxO definition for ISO, that is, the clipping point, and I assumed Canon's ISO 100 200 400 and so on are exact.

Canon's ISO 50 has the same clipping point as ISO 100, so it is actually ISO 100.

reddeercity

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Re: Sensor checkup?
« Reply #8 on: April 04, 2014, 08:21:20 AM »
Not sure I understand the question (what do you mean by drop off?), but that's the lowest ISO I could get on 5D2.

Note: I used the DxO definition for ISO, that is, the clipping point, and I assumed Canon's ISO 100 200 400 and so on are exact.

Canon's ISO 50 has the same clipping point as ISO 100, so it is actually ISO 100.
I was referring to the graph, I notice on the 5d3 at ISO 115 the DR was at it's maximum then DR started decreasing when the ISO reach 66, where as the 5d2
kept a steady increase in DR to ISO 81. A very nice increase over factor DR well worth the effect.   

a1ex

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Re: Sensor checkup?
« Reply #9 on: April 04, 2014, 08:33:14 AM »
Ah, on 5D3 I was able to re-implement ISO 100 from Canon ISO 200. That is, I'm using a signal twice as hot in the internal electronics (where most of the noise comes from). The signal is pre-amplified by 1 stop before leaving the CMOS and I've turned down the post-CMOS amps to get the same amount of highlights as with ISO 100 (but with CMOS amp set as if it were for ISO 200).

For ISO 66 I can no longer do this trick (I can't get from Canon ISO 200 down to ISO 66, it stops at just a little above 100).

On 5D2/50D I don't know how to do this trick; the registers are different. On 60D I know how to do it, and I believe most newer cameras will be similar. 550D... don't remember, but I believe it's more like 60D.

ToniX

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Re: Sensor checkup?
« Reply #10 on: April 04, 2014, 09:30:15 AM »
A1ex, I visited the link, I knew that thread from before I posted my question..

sorry I don't understand the other replies...  are related in some way to my question?

any more simple, empiric test?


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a1ex

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Re: Sensor checkup?
« Reply #11 on: April 04, 2014, 09:55:12 AM »
That thread contains a module which you can use to analyze the noise.