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 / Testing a scanning camera with the ISO 12233 target

Testing a scanning camera with the ISO 12233 target

February 9, 2014 By JimK Leave a Comment

Based on the testing that I’ve done so far, I have identified two possible cameras for the firehouse series.

  • The Sony alpha 7R with electronic flash lighting, using rear-curtain synch at 1/25 second or longer to mitigate the effects of that camera’s shutter vibration.
  • The Nikon D800E with available light.

I’d use Nikon F-mount lenses on both bodies, although I’m a little worried about the weight of the Zeiss 135mm APO Sonnar on the Sony. I’m pretty sure each would give me good results. It’s a lot easier to focus the Sony, but dragging studio lighting equipment around wouldn’t be much fun.

However, the idea of working with ancillary equipment gave me another idea: a scanning back. It probably would be less hassle to shoot on location with a back and a tethered computer than it would be to set up light stands, reflectors, and diffusers. I have a scanning back that I used for the Timescapes series, so I gave it a try on the ISO 12233 target.

I set up this gear: Nikkor 120mm f/5.6 AM ED macro lens with a IR/UV cut filter on a Linhof Master Technika, RRS plate, RRS clamp, Arca Swiss C1 Cube, RRS TVC-44 legs. ISO 200, lens set at f/11. Betterlight Super 6K back, set for a 6000×7998 (48 megapixel) image. ISO 12233 target with the camera at a distance to yield an active area about 550 pixels high. Thus, the lines between those labeled “5” and “6” represent 1 line pair per pixel pair. The 120mm lens is the equivalent of a 38mm lens on a 35mm camera, and is marginal at covering a 4×5 negative when focused at infinity, but does just fine with the Betterlight imaging area. Target illumination for the images was provided by a single Fotodiox LED-200WA-56 lamp using the supplied reflector. The camera was set to 1/60 second per scan line with the Fotodiox at maximum output.

I focused manually, wide open using the ground glass and the 14-diopter loupe that I was born with. There is no question that this is a less accurate way to focus than using live view on the a7R, or even on the D800E. I used the standard Betterlight tone curves, brought the TIFF into Photoshop, and did a minor white balance adjustment.

Here’s a crop from the upper right-hand corner, enlarged 3x using nearest neighbor, and JPEG’d:

Betterlight_0335 cr

Several things are worth noting.

  • The horizontal and vertical lines are both resolved to the sensel level, even though the lens is 25 years old and was not constructed with the high resolution of digital sensors in mind. However, the contrast at that resolution is not quite up to the best of today’s lenses.
  • There is no false color in the horizontal lines, in spite of the lack of an antialiasing filter. This is because the red, green, and blue color planes each have their own line sensor one horizontal pixel apart, and the Betterlight firmware de-skews the column data so that the RGB values in any column are those of one pixel location. If there’s no subject motion and sufficiently low camera vibration, as there is here, it works perfectly.
  • There is a small amount on false color in the vertical lines. Those near the “2” have red or green tinges to their edges. I believe this is due to camera vibration. The Betterlight line sensor is driven by a motor, which introduces some vibration, and we have seen that the tripod/head assembly that I’m using is less resistant to horizontal vibration than vertical vibration. The level of vibration is, however, small enough to be only of academic interest.

These results are better than they appear, since the camera as tested has 48 megapixels of resolution, and we’re looking at (blown up) individual pixels. In similar-sized prints, the sensor pixels from the Betterlight back will be smaller on the paper than those from the a7R or D800E.

This is worth a little more exploration. More later.

← D800E shutter shock with a Cognisys rail More BetterLight testing with the ISO 12233 target →

Leave a Reply Cancel reply

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

April 2021
S M T W T F S
 123
45678910
11121314151617
18192021222324
252627282930  
« Mar    

Articles

  • About
    • Patents and papers about color
    • Who am I?
  • 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 Relative sensitivity of Sony a7RIV and GFX 100S
  • Ilya Zakharevich on Pixel shift with the Fujifilm GFX 100S
  • Ilya Zakharevich on Relative sensitivity of Sony a7RIV and GFX 100S
  • JimK on GFX 100S sensor is a 4-shot stitch
  • John Leathwick on GFX 100S sensor is a 4-shot stitch
  • Christer Almqvist on GFX 100S sensor is a 4-shot stitch
  • JimK on Three dimensionality and sensor format
  • Tom Hegeman on Three dimensionality and sensor format
  • Bjoern on Three dimensionality and sensor format
  • JimK on Shutter shock in the GFX 100s

Archives

Unless otherwise noted, all images copyright Jim Kasson.