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 / Sharpness testing, part 11

Sharpness testing, part 11

November 19, 2013 JimK Leave a Comment

I came up with a way to explore the camera vibration that is degrading the images in the previous post. I set up an oscilloscope about 30 feet away from the D800E, mounted as before on the StackShot rail and the RRS TVC-34L Versa Series 3 tripod with RRS BH-55 ball head. I turned down the intensity to minimize CRT blooming, and I set the horizontal time base to 100 milliseconds per division. I focused the Zeiss 100mm f/2 ZF lens with live view, and set the shutter speed to ½ second, which would give me five divisions of exposure. I made ten images with each shutter tripping regime so that I could find images for each where the trace started on the left side of the oscilloscope screen.

Here’s a full frame sample image:

_8E04382

 

I brought the images into Lightroom, converted them to black and white, then exported then to Photoshop as layers. In Photoshop, I cropped the images and boosted the contrast, then res’d them up 300% horizontally and 1000% vertically, so you can see the individual D800E pixels.

First, hand release with the camera in a horizontal (landscape) orientation:

Horo man

And in a vertical (portrait) orientation:

Vert man

In the horizontal orientation, there is a damped sinusoidal oscillation at about 20 Hz, superimposed on an exponential. There is about a two or three pixel peak-to-peak oscillation at the end of the ½ second shutter opening. In the vertical orientation, there are a couple of cycles of a 5 Hz vibration, followed by a two or three pixel peak-to-peak signal.  Clearly, hand release is pretty bad if you want sharp images.

Using a remote release looks like this with the camera oriented horizontally:

Horo rem

and like this with the camera oriented vertically:

vert rem

The 20 Hertz vibration in the horizontal mode (that means it’s a vertical vibration) remains. It’s just smaller. There’s a similar horizontal vibration of slightly less amplitude.

 

Releasing the mirror, waiting three seconds, and manually tripping the shutter looks like this with the camera oriented horizontally:

Horo man mu

And like this with the camera oriented vertically:

vert man mu

It’s better than with the mirror down – the 20 Hz vibration is smaller – but there’s evidence of vibration induced by my hand.

 

Releasing the mirror, waiting three seconds, and remotely tripping the shutter looks like this with the camera oriented horizontally:

horo rem mu

And like this with the camera oriented vertically:

vert rem mu

There are vertical vibrations of two or three pixels peak-to-peak in the 20 to 50 Hz region, and horizontal vibrations of one or two pixels peak-to-peak in the 20 to 50 Hz region.

Using the three-second shutter delay with the wired remote release looks like this with the camera oriented horizontally:

horo 3sec rem

And like this with the camera oriented vertically:

vert 3sec rem

There’s a two to three pixel peak-to-peak 20 to 60 Hz vertical vibration, and a somewhat smaller, but similar, horizontal vibration. There is almost no evidence of vibration from the opening of the shutter.

Using the three-second shutter delay with a manual release looks like this with the camera oriented horizontally:

horo 3sec man

And like this with the camera oriented vertically:

vert 3sec man

The results are similar to those with the remote release.

So, it appears that there are several ways to release the shutter without introducing much vibration, with the 3-second shutter delay being the most convenient. However, there also appears to be some residual vibration that is independent of the shutter opening. Is that the oscilloscope spot moving up and down slightly? Is it 60-Hz electrical vibration coupling through the concrete floor to the tripod? Is the focused spot really about the same size as a pixel? Or am I looking at sub-pixel vibration broadened by demosaicing interpolation?

All good questions.

The Last Word

← Sharpness testing, part 10 Sharpness testing, part 12 →

Leave a Reply Cancel reply

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

March 2023
S M T W T F S
 1234
567891011
12131415161718
19202122232425
262728293031  
« 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

  • JimK on Sony 135 STF on GFX-50R, sharpness
  • K on Sony 135 STF on GFX-50R, sharpness
  • Mal Paso on Christmas tree light bokeh with the XCD 38V on the X2D
  • Sebastian on More on tilted adapters
  • JimK on On microlens size in the GFX 100 and GFX 50R/S
  • Kyle Krug on On microlens size in the GFX 100 and GFX 50R/S
  • JimK on Hasselblad X2D electronic shutter scan time
  • Jake on Hasselblad X2D electronic shutter scan time
  • Piotr Chylarecki on Who am I?
  • JimK on Who am I?

Archives

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

Unless otherwise noted, all images copyright Jim Kasson.