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 / A tale of two cameras, part 6

A tale of two cameras, part 6

January 27, 2013 JimK Leave a Comment

Some people have reported position dependent color casts with the RX-1. I see virtually none. What’s more, I measure very little in the way of cast. Here are my results for the center and the four corners, measured in CIEL*a*b*, using the methodology described here. One unit of distance in the equation D = sqrt(L*^2 + a*^2 + b*^2), or D = sqrt(a*^2 + b*^2) for chroma errors, is usually just barely noticeable, although the eye is more sensitive to chroma errors near the gray axis.

As you can see, there is some lens falloff, but it’s not bad. There are very minor corner chroma casts wide open, but they essentially go away when you stop down a stop or more. It’s interesting that the lens falloff gets better as you stop down, as you would expect, until you get to f/8, where it starts to get worse. Maybe f/8 is where the camera software stops correcting for falloff.

The results are so good, and the camera’s auto white balance so accurate, that these are the raw numbers, with no center zeroing applied.

 

f/2

L* a* b*

C

50

0

1

UR

39

1

1

LR

40

2

1

LL

40

-1

1

UL

38

-2

1

f/2.8

L* a* b*

C

50

0

1

UR

44

0

0

LR

44

1

-1

LL

43

-1

-1

UL

43

-1

-1

f/4

L* a* b*

C

50

0

1

UR

44

0

0

LR

44

0

0

LL

44

0

0

UL

43

-1

0

f/5.6

L* a* b*

C

49

0

1

UR

44

0

0

LR

44

1

0

LL

43

0

0

UL

43

-1

0

f/8

L* a* b*

C

48

1

1

UR

41

0

1

LR

41

0

0

LL

40

-1

0

UL

40

-1

0

Here are the summary results for chroma error, compared with the NEX-7/Zeiss 24mm results. You can see that the RX-1 is even better than the NEX-7/Zeiss 24mm at all but the widest apertures. Both cameras are using software in-camera correction.
RX-1 avg RX-1 WC NEX-7 avg NEX-7 WC
f/2

1.5

2.0

1.3

2

f/2.8

1.9

2.2

1.4

2.6

f/4

1.1

1.4

1.6

3.2

f/5.6

1.2

1.4

2.1

2.8

f/8

1.7

2.2

2.2

2.8

The Last Word

← A tale of two cameras, part 5 A tale of two cameras, part 7 →

Leave a Reply Cancel reply

Your email address will not be published.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

February 2023
S M T W T F S
 1234
567891011
12131415161718
19202122232425
262728  
« Jan    

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

  • Brian Olson on Fuji GFX 100S exposure strategy, M and A modes
  • JimK on Picking a macro lens
  • 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

Archives

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

Unless otherwise noted, all images copyright Jim Kasson.