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the last word

Photography meets digital computer technology. Photography wins -- most of the time.

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Is the Sony a7 ISOless?

February 19, 2014 JimK 3 Comments

With the noise floor and self-heating testing out of the way, we’re ready to tackle the question, “Is the a7 ISOless?” If that question makes no sense to you, hang in there. Explanations follow. If you’ve read this or a similar explanation before, skip to the graphs. Let’s talk a bit about how your camera… [Read More]

The Bleeding Edge, The Last Word

Sony a7 noise floor in continuous mode

February 19, 2014 JimK 4 Comments

All of the histograms in the preceding post were made with the drive mode in single shot. When you put it in continuous, you get something different: ISO 100: ISO 200: ISO 400: In each case, only every fourth bucket has data. The pattern is the same at other shutter speeds and ISOs. In single… [Read More]

The Last Word

Sony a7 noise floor

February 18, 2014 JimK Leave a Comment

Here’s the average value of the standard deviation of noise floor in the central 90% of the image vs ISO at 1/30th second: If the amplifiers and the analog to digital converters in the a7 were perfect, and all the read noise came from the sensor array itself, then the read noise would double every… [Read More]

The Last Word

Testing the Sony a7, part 1

February 18, 2014 JimK 4 Comments

Well, it’s not really part 1, since I did some shutter shock testing earlier. But now I know that the camera’s vibration is no problem, I’ll give it my regular testing regime. [Added later: If you’re interested in the a7 noise floor in single shot mode, look here. If you care that the a7 becomes… [Read More]

The Last Word

Can you see the Sony raw compression artifacts?

February 17, 2014 JimK 1 Comment

In the previous few days’ posts, I’ve established that: The Sony raw compression algorithm generates artifacts that can be made visible by subtracting an uncompressed image chosen to stress the algorithm from one that has been compressed and decompressed and subjecting the result to amplification by a factor of 20 or 30. If the delta… [Read More]

The Last Word

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Articles

  • About
    • Patents and papers about color
    • Who am I?
  • How to…
    • Backing up photographic images
    • How to change email providers
    • How to shoot slanted edge images for me
  • Lens screening testing
    • Equipment and Software
    • Examples
      • Bad and OK 200-600 at 600
      • Excellent 180-400 zoom
      • Fair 14-30mm zoom
      • Good 100-200 mm MF zoom
      • Good 100-400 zoom
      • Good 100mm lens on P1 P45+
      • Good 120mm MF lens
      • Good 18mm FF lens
      • Good 24-105 mm FF lens
      • Good 24-70 FF zoom
      • Good 35 mm FF lens
      • Good 35-70 MF lens
      • Good 60 mm lens on IQ3-100
      • Good 63 mm MF lens
      • Good 65 mm FF lens
      • Good 85 mm FF lens
      • Good and bad 25mm FF lenses
      • Good zoom at 24 mm
      • Marginal 18mm lens
      • Marginal 35mm FF lens
      • Mildly problematic 55 mm FF lens
      • OK 16-35mm zoom
      • OK 60mm lens on P1 P45+
      • OK Sony 600mm f/4
      • Pretty good 16-35 FF zoom
      • Pretty good 90mm FF lens
      • Problematic 400 mm FF lens
      • Tilted 20 mm f/1.8 FF lens
      • Tilted 30 mm MF lens
      • Tilted 50 mm FF lens
      • Two 15mm FF lenses
    • Found a problem – now what?
    • Goals for this test
    • Minimum target distances
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Printable Siemens Star targets
    • Target size on sensor
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Test instructions — postproduction
    • Test instructions — reading the images
    • Test instructions – capture
    • Theory of the test
    • What’s wrong with conventional lens screening?
  • Previsualization heresy
  • Privacy Policy
  • Recommended photographic web sites
  • Using in-camera histograms for ETTR
    • Acknowledgments
    • Why ETTR?
    • Normal in-camera histograms
    • Image processing for in-camera histograms
    • Making the in-camera histogram closely represent the raw histogram
    • Shortcuts to UniWB
    • Preparing for monitor-based UniWB
    • A one-step UniWB procedure
    • The math behind the one-step method
    • Iteration using Newton’s Method

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