the last word

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

  • site home
  • blog home
  • galleries
  • contact
  • underwater
  • the bleeding edge
You are here: Home / The Last Word / MTF testing of 70-200mm lenses — target distance effects

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 on the floor. I can’t position the camera to within an inch, but I can get it to within two or three inches. Is that good enough?

I ran the usual test with 16-image sets with the target distance between sets changing downwards from 20 feet (I can’t change it upwards very far) in one foot increments. Here’s what resulted:

Nikon distance

Normalized to the mean of the first set of sixteen images:

Nikon distance norm

We can see that the variation across the chart is significantly  larger than the Nikon autofocusing error that we measured in the previous post. The point at one in from the right end is suspect, because the mean is odd compared to the point to its right, and because the spread is so large. We can also wee that a few inches either way is not going to be a deal breaker.

The Last Word

← MTF testing of 70-200mm lenses — fundamental effects, part 2 How big do I print? →

Comments

  1. Jack Hogan says

    October 18, 2015 at 5:14 am

    Good stuff, did you refocus at each distance? I am surprised at how quickly it falls off : after all 16ft is still 24X200mm.

    Reply
    • Jim says

      October 18, 2015 at 6:21 am

      I used autofocus, so I refocused for each image. Eventually, I can do a test with a die-cut slanted edge.

      Reply
      • CarVac says

        October 19, 2015 at 4:58 am

        Wouldn’t a razor blade be the simplest way to do that?

        Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

January 2023
S M T W T F S
1234567
891011121314
15161718192021
22232425262728
293031  
« Dec    

Articles

  • About
    • Patents and papers about color
    • Who am I?
  • Good 35-70 MF lens
  • How to…
    • Backing up photographic images
    • How to change email providers
  • 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 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

  • JimK on Picking a macro lens
  • Glenn Whorrall on Picking a macro lens
  • JimK on What pitch do you need to scan 6×6 TMax 100?
  • Hatzipavlis Peter on What pitch do you need to scan 6×6 TMax 100?
  • JeyB on Internal focusing 100ish macro lenses
  • JimK on How focus-bracketing systems work
  • Garry George on How focus-bracketing systems work
  • Rhonald on Format size and image quality
  • JimK on Internal focusing 100ish macro lenses
  • Darrel Crilley on Fuji 100-200/5.6 on GFX, Nikon 70-200/@2.8E, Apo-Sonnar 135 on Z7, revisited

Archives

Copyright © 2023 · Daily Dish Pro On Genesis Framework · WordPress · Log in

Unless otherwise noted, all images copyright Jim Kasson.