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no RAW for Powershot S95?

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Offline martin355113

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no RAW for Powershot S95?
« on: 07 / February / 2012, 03:50:04 »
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Hi

I just started using the CHDK and it looks great. I tried shutter override for the lowlight auto setting and it was fine, but I was not able to get it to save a raw file. I know the low light mode is a bit special employing some kind of binning and normally only providing a jpeg output. Is it not possible to get the raw imge for this settng or am I just fumbling?

My interest is for astrofotography. Having a camera taking pictures at ISO 10.000 for 30 sek should give some interesting pictures.

Best regards


Martin
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Offline tsvstar

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Re: no RAW for Powershot S95?
« Reply #1 on: 07 / February / 2012, 05:49:31 »
Set Av mode, set apperture, set your overrides of time and ISO in CHDK menu.
Set in-camera shoot to raw+jpeg.

I successfully got on this sequence RAW.

For your parameters (ISO=10000) I think you will really get "interesting" picture but not related to real sky. S95 is good camera but not magic. :)
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Offline reyalp

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Re: no RAW for Powershot S95?
« Reply #2 on: 07 / February / 2012, 23:23:59 »
Quote from: martin355113 on 07 / February / 2012, 03:50:04
I just started using the CHDK and it looks great. I tried shutter override for the lowlight auto setting and it was fine, but I was not able to get it to save a raw file. I know the low light mode is a bit special employing some kind of binning and normally only providing a jpeg output. Is it not possible to get the raw imge for this settng or am I just fumbling?
CHDK raw (including DNG) definitely won't work in low light mode, the normal raw buffer isn't available. As far as I can tell, whatever process it is that makes the reduced resolution image happens before the sensor data is available to the part of the system where CHDK runs.

I briefly tried to some sort of "raw" data for D10 in low light mode, without success.

To the best of my knowledge, everyone who has done rigorous testing has found that ISO overrides do not allow you to exceed the limits in the Canon firmware by any significant amount. You might see 10000 display somewhere or in exif, but the actual image values will not change from whatever the highest Canon setting is.
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Offline martin355113

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Re: no RAW for Powershot S95?
« Reply #3 on: 08 / February / 2012, 08:03:20 »
Thanks for the input


I had a hunch raw might be inaccessable in low-light mode, but it would be fun.

Regarding the ISO 10.000 and the "magic", it does work. S95 can actually deliver ISO 12.500 in low-light, and when I compare the results using 2.000, 5.000 etc. and compare with ISO settings in "normal" mode, the S95 delivers effects comparable to the ISO settings.

I suspect the way the S95 handles it is through binning, possibly doing it while developing the jpeg picture from the raw picture. The picture is 1/4 the size (in area) in low-light compared with normal, and the max ISO is 3200, so a 2x2 binning would give ISO 12.800 as max. I will try it and see if lowlight is better than using software binning on normal mode.

I still believe in magic. I am waiting for a less full moon and some clear sky, then I am convinced I will get galaxies captured with the camera. I will report the result.


best regards

Martin
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Offline srsa_4c

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Re: no RAW for Powershot S95?
« Reply #4 on: 08 / February / 2012, 08:41:33 »
Pixel binning is a feature (a readout mode) of the sensor. The S95 has probably the Sony ICX685, there's a short press release available (don't know whether direct linking works): http://www.sony.net/Products/SC-HP/cx_news/vol57/pdf/icx685cqz.pdf
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