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12-09-2014, 02:10 PM   #16
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QuoteOriginally posted by philbaum Quote
Well, you and emacs know more about this stuff than i do. But if there is not much difference in QE between sensors - how did Sony come out with the A7S sensor, and secondly, isn't it likely that 1 or 2 more companies will follow Sony's tack on this low light sensor?
The differences between cameras are a lot less SIGNIFICANT than the numbers imply.

The truth is - most cameras take a pretty decent picture these days, even in low light. Yes, even phone cameras.

Even 1-2 stops of difference is not really a big deal.

Yes there is a difference between full frame and 1" sensor, and a difference between an APS-C and a phone camera, but other than extremes the differences will be masked by the skill of the photographer. Shooting in low light is really about understanding how light works and composition more than camera performance.

12-09-2014, 02:48 PM   #17
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QuoteOriginally posted by Christine Tham Quote
The differences between cameras are a lot less SIGNIFICANT than the numbers imply.

The truth is - most cameras take a pretty decent picture these days, even in low light. Yes, even phone cameras.

Even 1-2 stops of difference is not really a big deal.

Yes there is a difference between full frame and 1" sensor, and a difference between an APS-C and a phone camera, but other than extremes the differences will be masked by the skill of the photographer. Shooting in low light is really about understanding how light works and composition more than camera performance.
It depends on what the photographer is doing or wants to do. If you don't know where you are going, than any road is good enough to get you there. Same thing applies to cameras. If one is new to the craft, than i agree. Thing is, i know what i want to do with a camera and my current cameras are not entirely getting it done. Time for me to try a different format
12-09-2014, 03:00 PM   #18
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QuoteOriginally posted by philbaum Quote
It depends on what the photographer is doing or wants to do. If you don't know where you are going, than any road is good enough to get you there. Same thing applies to cameras. If one is new to the craft, than i agree. Thing is, i know what i want to do with a camera and my current cameras are not entirely getting it done. Time for me to try a different format
Phil. Sony A7s, Nikon D4s, Pentax 645z... quit wasting your time...
12-09-2014, 03:19 PM - 2 Likes   #19
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QuoteOriginally posted by philbaum Quote
But if there is not much difference in QE between sensors - how did Sony come out with the A7S sensor, and secondly, isn't it likely that 1 or 2 more companies will follow Sony's tack on this low light sensor?
The way that Sony has got such the step in performance here is that they switch the sensitivity of the sensor part-way through the ISO sequence. Normally a sensor design is a compromise. It can be optimised either for high sensitivity, with its concomitant, low read-out noise, or for a high saturation level (a large FWC), but not both. See this tread for an overview of the problem: Question about the Floating Diffusion (FD) node in image sensors: Photographic Science and Technology Forum: Digital Photography Review.

Aptina came up with a way to switch the sensor from one mode to the other. This is called "DR-Pix". Sony has licensed this, as has Nikon in their "1" series.

Here, Aptina explains the technology:

In more detail: http://www.aptina.com/products/technology/DR-Pix_WhitePaper.pdf

See also: Re: A7s DxoMark results out: Photographic Science and Technology Forum: Digital Photography Review

I expect this technology to appear in more models.

As regards QE, most cameras should have a constant effective QE as the ISO varies, but not the A7s. See the first graph in this message:
http://www.dpreview.com/forums/post/54512169

Dan.


Last edited by dosdan; 12-09-2014 at 04:03 PM.
12-09-2014, 04:46 PM   #20
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For example, let's compare the Sony A7 (24MP), A7R (36MP) & A7S (12MP). They all have the same sized-FF sensor.

Sony A7S versus Sony A7 versus Sony A7R - Side by side camera comparison - DxOMark

  1. From the ISO curve you can see that ISO50 is fudged.
  2. Notice that the A7S has the lowest Landscape Score. This is because, while the DR-Pix technology can switch the sensor between high sensitivity & low noise modes, it can't be both at the same time. And the Landscape sport is the DR in stops (EV) at base ISO: the ratio between the FWC & the noise floor. Notice how the A7S DR Curve follows a different slope from the other 2 cameras.
  3. Look how much better the A7S Sports Score is than the other two cameras: +0.7 stops compared to the A7 & + 0.4 stops compared to A7R.
  4. Look at the SNR (18%) performance. The A7S show better mid-to-high ISO performance due to DR-Pix. Eventually all curves so a slight change/slep on the right as raw NR kicks in.

Last edited by dosdan; 12-09-2014 at 05:08 PM.
12-09-2014, 05:17 PM   #21
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QuoteOriginally posted by philbaum Quote
Thing is, i know what i want to do with a camera and my current cameras are not entirely getting it done. Time for me to try a different format
If you do know what you want to do and if your current camera can't do it, then my point is that the differences between cameras are *probably* not going to be significant enough to make a difference.

I don't know your specific need, and maybe buying an A7S will solve your problem - the only way to find out is to try one out. If you were based in Australia, I could probably arrange something through my contacts but not sure what the options are where you live.

I have a different approach in that I understand what the limitations of whatever camera I am using, and I find subjects and compositions that work within those limitations. I don't dream of things that are not possible. But we are now getting into a discussion about our individual creative approach and processes, and I certainly don't want to "lecture" you on how you approach your "art."

Anyway, I hope you find an answer to what you want.
12-10-2014, 12:53 AM   #22
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QuoteOriginally posted by normhead Quote
Phil. Sony A7s, Nikon D4s, Pentax 645z... quit wasting your time...
Best laugh i've had all year, but you're right - as usual :-)

12-10-2014, 02:50 AM   #23
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QuoteOriginally posted by dosdan Quote
The way that Sony has got such the step in performance here is that they switch the sensitivity of the sensor part-way through the ISO sequence. Normally a sensor design is a compromise. It can be optimised either for high sensitivity, with its concomitant, low read-out noise, or for a high saturation level (a large FWC), but not both. See this tread for an overview of the problem: Question about the Floating Diffusion (FD) node in image sensors: Photographic Science and Technology Forum: Digital Photography Review.

Aptina came up with a way to switch the sensor from one mode to the other. This is called "DR-Pix". Sony has licensed this, as has Nikon in their "1" series.

Here, Aptina explains the technology: Aptina DR-Pix Technology - YouTube

In more detail: http://www.aptina.com/products/technology/DR-Pix_WhitePaper.pdf

See also: Re: A7s DxoMark results out: Photographic Science and Technology Forum: Digital Photography Review

I expect this technology to appear in more models.

As regards QE, most cameras should have a constant effective QE as the ISO varies, but not the A7s. See the first graph in this message:
The A7s' Climbing Effective QE and PRNU: Photographic Science and Technology Forum: Digital Photography Review

Dan.
Thanks Dan, thats an incredible development, i very much appreciate your explanation!
12-10-2014, 10:58 AM   #24
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QuoteOriginally posted by Christine Tham Quote
If you do know what you want to do and if your current camera can't do it, then my point is that the differences between cameras are *probably* not going to be significant enough to make a difference.

I don't know your specific need, and maybe buying an A7S will solve your problem - the only way to find out is to try one out. If you were based in Australia, I could probably arrange something through my contacts but not sure what the options are where you live.

I have a different approach in that I understand what the limitations of whatever camera I am using, and I find subjects and compositions that work within those limitations. I don't dream of things that are not possible. But we are now getting into a discussion about our individual creative approach and processes, and I certainly don't want to "lecture" you on how you approach your "art."

Anyway, I hope you find an answer to what you want.
Christine, thanks for your offer, and if i was fortunate to live in Australia, i would be sure to travel to Sydney to meet you :-)

A friend in a photo club has the A7S and allowed me to shoot it so i have some familiarity with it. As to my art, my dream was always to sell prints, and i've been doing that for 5 years. One can't always tell what dreams are impossible - unless you try them.

Last edited by philbaum; 12-10-2014 at 12:56 PM.
12-10-2014, 12:49 PM   #25
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QuoteOriginally posted by philbaum Quote
One can't always tell what dreams are impossible - unless you try them.
That's certainly true - and great art have been created because someone refused to believe it was impossible.

Differences in performance in cameras may or may not be a factor whether something is "impossible" or not. By all means, if you believe (or can verify) that it DOES make a difference in your case, then buy the right camera. But if it does not make a difference, find another way to achieve your goal.

I tend to find with all equipment incremental benefits stop being significant beyond a certain price point and individual skill/experience/usage becomes a more significant factor. When I started riding a bicycle, I went from zero to an A group rider on a ten year old bike rescued from someone's garage that I rebuilt. These days I am a C group rider on a $4k bicycle, and I doubt buying a $12k bicycle will significantly improve my performance. Yes, I can get back to the A group (and they keep asking me when I will return) but it will have nothing to do with the bicycle. Similarly we invested over $100k on our home theatre, but with my ears I can barely hear above 12kHz.

There is no real reason for me to buy new cameras or upgrade to a better model - there hasn't been for many years. I do it because well, there is a certain joy from buying a higher performance model, and frankly I can't take my money to the grave so I may as well spend it. But I am realistic enough to understand that in my case it will do nothing to my photography, regardless of the supposed improvement in specs.
12-14-2014, 07:04 PM   #26
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QuoteOriginally posted by dosdan Quote
The way that Sony has got such the step in performance here is that they switch the sensitivity of the sensor part-way through the ISO sequence.
Here's a new article that goes a bit deeper into the Sony A7S imaging system's performance: Sony A7S DR-Pix Read Noise

Dan.
12-15-2014, 02:06 AM   #27
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QuoteOriginally posted by dosdan Quote
Here's a new article that goes a bit deeper into the Sony A7S imaging system's performance: Sony A7S DR-Pix Read Noise

Dan.
Thanks Dan for the additional article. I think i read from other links you provided that Sony had licensed the technology from Aptina, but perhaps i'm mistaken. It seems that photographers have larger sensitivity ranges to look forward to. It just gets better and better :-)

phil
12-15-2014, 07:35 AM   #28
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When looking at what camera is best suited to a particular use, it is equally important to consider resolution. With the same high performing lens:
  • a larger sensor will show higher resolution
  • a higher pixel count will increase resolution

Check this DXOMark comparison of three Nikon cameras using the same Sigma lens:
  • The 16mp full frame Df resolves 15 megapixels
  • The 24mp APS-C D7100 resolves 16 megapixels
  • The 36 mm full-frame D810 resolves 30 megapixels
The 12mp Sony would score lower than all of the above (11 or 12mp maximum). It is a specialty camera, intended for best in class low light shooting, but maybe slightly inferior to a 24mp APS-C for landscape work, and definitely inferior to an A7R.

Last edited by audiobomber; 12-15-2014 at 10:22 AM.
12-15-2014, 10:31 AM   #29
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QuoteOriginally posted by audiobomber Quote
When looking at what camera is best suited to a particular use, it is equally important to consider resolution. With the same high performing lens:
  • a larger sensor will show higher resolution
  • a higher pixel count will increase resolution

Check this DXOMark comparison of three Nikon cameras using the same Sigma lens:
  • The 16mp full frame Df resolves 15 megapixels
  • The 24mp APS-C D7100 resolves 16 megapixels
  • The 36 mm full-frame D810 resolves 30 megapixels

The 12mp Sony would score lower than all of the above (11 or 12mp maximum). It is a specialty camera, intended for best in class low light shooting, but slightly inferior to a 24mp APS-C for landscape work.
I've had more pictures ruined by low light conditions than a lack of pixels. This is an entirely subjective comment, but it seems to me that mfr emphasize mp more than low light capability. I shoot theatre dress rehearsals a lot and frequently run out of adequate lighting to maintain optimum sharpness while handheld. I have a friend, co-owner of a gallery, who is getting rid of his D800 because of blurry pictures. Megapixels aren't everything. There needs to be a better balance between mp and low light performance by mfr, IMO.

The good news is that the technology made use of by Sony, licensed in part from Aptina, should eventually improve the range of low light performance in most digital cameras. Depending on patents, etc :-(
12-15-2014, 11:34 AM   #30
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QuoteOriginally posted by philbaum Quote
I've had more pictures ruined by low light conditions than a lack of pixels. This is an entirely subjective comment, but it seems to me that mfr emphasize mp more than low light capability.
Sounds like an A7S would be a good camera for you. I would be very unhappy if I had to go back to a lower pixel count. I frequently crop 24mp images down to 4mp or even less. Noise is not my problem, my problem is filling the frame with the bird.

The "fewer pixels is better" argument doesn't hold water when comparing current 16mp and 24mp APS-C sensors. No significant penalty in noise or DR came with the extra resolution. Maybe they could do a low noise 6mp APS-C sensor, and it would make some people happy, but would there be enough interest to sustain the idea? I think it was brilliant of Sony to fill that niche in FF. It will probably be a great idea for APS-C down the road. The ideal scenario would be a camera that can be optimized for either low noise or high resolution.

QuoteOriginally posted by philbaum Quote
The good news is that the technology made use of by Sony, licensed in part from Aptina, should eventually improve the range of low light performance in most digital cameras. Depending on patents, etc :-(
It does seem an exciting technology.

PS Your friend needs to improve his technique or stop pixel peeping at 36mp, or maybe get a better lens.
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