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

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Archives for 2015

MTF testing of 70-200mm lenses — target distance effects

October 18, 2015 JimK 3 Comments

When using a target made on an inkjet printer, you don’t want to get too close, since the whole idea of slanted edge MTF testing is that the target has much higher resolution than the lens.  For testing at 200mm, I use a target distance of about 20 feet, indicated by a piece of tape… [Read More]

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MTF testing of 70-200mm lenses — fundamental effects, part 2

October 17, 2015 JimK 2 Comments

Taking the exact same data from the previous post and putting into the 16-exposure packets that we’ve been using for MTF testing, we get the following for Nikon equipment manually focused (to keep things simple, I’ll just show you the normalized results): That’s the kind of variation that’s just built into the protocol and the… [Read More]

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MTF testing of 70-200mm lenses — fundamental effects, part 1

October 17, 2015 JimK 2 Comments

In the past few posts on MTF testing, we’ve seen so many things that affect the Imatest MTF50 results that it’s reasonable to look at tests that change very little to find out how much instability there is in the baseline test protocol and the image analysis tools. I made 128 exposures at f/4 with… [Read More]

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MTF testing of 70-200mm lenses — more exposure effects

October 16, 2015 JimK 1 Comment

In this post, found that, with Lightroom (Lr) development, the Imatest MTF50 results were somewhat dependent on exposure. Compensating for actual exposure changes with Lr development Exposure moves mitigated this to a great extent. Is the same thing true with DCRAW development? I developed the raw files from the previous 2-stop range in 1/3 stop… [Read More]

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MTF testing of 70-200mm lenses — Exposure effects

October 15, 2015 JimK 3 Comments

I’ve been reporting on the modulation transfer function results from some lens/sensor testing that I’ve been doing. I few days ago, I show you some work that I’d done with the Nikon 70-200 f/2.8 GII ED on the Nikon D810 to the Sony 70-200 f/4 G OSS FE on a Sony a7RII. I’ve been having… [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
    • 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

Category List

Recent Comments

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