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Under the premise that the 14-bit A-D converter has approximately the range needed to quantize every single photon (<25000 full well capacity, 16K possible values) for low-light shooting raising the ISO is not meaningfully different than adjusting the exposure in Lightroom,

(n.b. I'm taking that as the premise, not asking why that's so or how sensor "gain" really works.) (n.b. This camera does use the Sony Exmor sensor as described in jrista's treatment that this is not a duplicate of. )

Then what is the highest "useful" ISO setting, specifically on the alpha 6000. Has anyone here done experiments and analysis yet?

General reference: Clarkvision's pages (dated camera details).

I don't want to re-discuss theory and misinformation on "gain", so it's not a duplicate. I want to know the specific values of interest for this camera model, to which to apply the "native" and "don't set higher than..." principles to optimize my S/N and (all else being equal) leave one setting alone.

My immediate concern is to get the most out of indoor available light, using a f/1.8 prime lens with OSS. (My ability to handhold long exposure exceeds the ability of subjects to stand still)

  • @mattdm, My question is the specific values for this camera model, not an explanation of the principle in general. – JDługosz May 26 '15 at 13:36
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    @JDługosz do you think this question can have a specific, correct answer? isn't it subjective how much noise you can bear as trade-off for getting more detail/tones in the image? Also asking for a specific camera isn't going to help in general - do we want other questions asking the same thing about 100 other cameras? Maybe a question about how to go about determining the sweet spot for any camera? – MikeW May 26 '15 at 20:48
  • 100 other cameras? Maybe that needs a single database-style listing. A half dozen hot/popular cameras? There is great interest in them. – JDługosz Dec 16 '15 at 1:31
  • Subjective: no. The signal to noise ratio can be measured for both increasing the ISO setting and after upping the exposure in Lightroom. I'm not asking how low of light is ok to shoot (subjective), but how high of a value continues to do something different than just multiplying the numbers after reading the photon count. – JDługosz Dec 16 '15 at 2:25
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JDulogz:

I have been curious about such things as well. Using RawDigger and following the instructions I sought to determine the 'unity gain', which I think is what you are asking. For the a5100, which has the exact same sensor performance as a6000, I found that the unity gain is 200 ISO. At this gain the square of the standard deviation (8172) is higher than the signal (6219). When the sq of the std dev is higher than the signal, raising ISO further has no benefit (there can be a few exceptions). doing the same in post may give better results.

The full well capacity is around 26000+.

I don't know if my result is correct, but on the rawDigger site they do the same test for Canon 5dm2 and come up with ISO 400 for unity gain. so, based on pixel size and accomodating for sensor tech, 200 may be right for a6000.

On the other hand, I tend to go up to iso 1600 or even 3200 in some cases, when I need to get critical focus and framing. If you can't see anything you can't focus can you? Don't get so obsessed with this stuff. ISO 800 is absolutely great, no reason you shouldn't use it to access fater shutter speeds.

  • Please be polite. – Philip Kendall Dec 15 '15 at 17:58
  • @memed when you get more experience points, you can downvote answers. – JDługosz Dec 16 '15 at 2:19
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The purpose of the ISO setting on the A6000 is, as with other cameras, to adjust for lighting conditions. Sensitivity to light is expressed by the ISO number. You can reduce image blurring in lower light (or faster subjects) by increasing the ISO sensitivity. The A6000 (a.k.a. Alpha ILCE-6000) does not capture at all ISO sensitivities simultaneously. You can manually select an ISO from 100 to 25600.

You can see examples of high ISO results in this review: http://www.cnet.com/products/sony-alpha-6000/ At around ISO 800, the noise becomes pronounced. At ISO 25600 small details are no longer recognizable. Correcting a low-ISO image lightroom generally produces less desireable images than choosing an appropriate ISO, most notably in the shadow areas.

Tech Radar has also done a review with signal-to-noise ratio for this and other cameras expressed in a graph. This may help you determine the highest ISO you want to use. http://www.techradar.com/reviews/cameras-and-camcorders/cameras/digital-slrs-hybrids/sony-alpha-a6000-1223772/review/5

However, you can select ISO Auto (the default setting) with sets the ISO sensitivity automatically. If you leave it in the default mode, then you can ignore the ISO setting and let the camera choose one for you.

There is also multi-frame noise reduction, to combine continuous shots to create an image with less noise.

http://docs.esupport.sony.com/dvimag/2014/ILCE6000_guide/en/contents/TP0000386492.html

To help with a handheld shot, you can activate the SteadyShot function by pressing the shutter button halfway down and then shoot images.

http://docs.esupport.sony.com/dvimag/2014/ILCE6000_guide/en/contents/TP0000226772.html

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    The sensitivity of the CMOS does not change. The gain, whether in the A-D stage or computation afterwards, does not change the data present (modulo quantization errors). I think you don't understand what I was asking (see the Clarkvision page and other discussions). I know about (and mentioned stabilization) in the Q, and that I could count on it being available. I know high ISO is noisy, hence my question. I know about Auto, and that is not my question. Other than the third para, I feel that you didn't read/comprehend the question, which is uncomfortable. – JDługosz May 26 '15 at 13:43

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