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

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NEX-7 — Zeiss 24 mm autofocus testing

January 20, 2012 JimK 1 Comment

I’ve read a few complaints about the NEX-7’s autofocus performance when used with the Sony/Zeiss 24 mm f/1.8 lens. I don’t think it is that the NEX-7’s autofocus is deficient compared to similar cameras; I think the problem is that the camera body and the lens are both capable of such a high level of… [Read More]

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NEX-7 — Zeiss 24mm f/1.8 performance

January 16, 2012 JimK Leave a Comment

The Zeiss 24mm E-mount lens acquitted itself excellently with a low-contrast subject. Let’s see how it does with a normal tone range. Here’s the overall image, made, like all the images in this post, at the lens’s best aperture of f/5.6 and ISO 100: The center, at two-pixel-for-one magnification, is commendably crisp: The upper left… [Read More]

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NEX-7 — three 24mm lenses compared

January 15, 2012 JimK Leave a Comment

In this and the next few posts I will give you an informal analysis of the performance of the Sony Zeiss 24 mm f/1.8 E-series lens. I will be comparing it to two other 24 mm lenses: the Leica 24 mm f/2.8 Elmarit ASPH, and the Leica 24 mm f/3.8 Elmar ASPH. I thought about… [Read More]

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NEX-7 — Sony/Zeiss 24mm corner errors

January 13, 2012 JimK Leave a Comment

I got my hands on the Sony/Zeiss 24 mm f/1.8 (Official name: Sony Carl Zeiss E 24mm F1.8 ZA). It is a measure of how freaked out I am about the purple corners on the NEX-7 that the first thing I did was test for the effect. The results are good: Avg error WC error… [Read More]

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NEX-7 — measuring how corner color errors vary with aperture

January 7, 2012 JimK Leave a Comment

For the 35mm f/2 M-mount Zeiss Biogon, the aperture-dependence of the corner color errors ceases at apertures smaller (numerically larger) than f/5.6. The average and worst case chromaticity errors by f-stop, measured in CIELab Delta-E: Avg error WC error f/2 5.2 5.8 f/2.8 4.5 5.0 f/4 3.8 5.0 f/5.6 2.8 3.6 f/8 2.8 3.6 f/11… [Read More]

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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
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  • 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
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      • MFT
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      • Full frame
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    • Test instructions — postproduction
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    • Theory of the test
    • What’s wrong with conventional lens screening?
  • Previsualization heresy
  • Privacy Policy
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  • Using in-camera histograms for ETTR
    • Acknowledgments
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    • 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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