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 / Sony a7 EFCS: how much difference does it make? Part 4

Sony a7 EFCS: how much difference does it make? Part 4

March 29, 2014 JimK 4 Comments

When I presented this post to show how much the a7 suffers from shutter shock with and without the electronic first curtain shutter using the Zony 55, I wondered aloud why the a7’s mechanical first curtain shutter seemed to affect the sharpness less than the a7R’s mechanical FCS. In order to explore that issue in more detail, I used a Nikon AF Nikkor 180mm f2.8 ED instead of the Zony 55.

With both the a7 and the a7R, I mounted the lens to a Novaflex adapter, attached the Novoflex QR foot to the adapter in landscape orientation, added the camera, and attached the whole thing to an Arca Swiss C1 head which was attached to a set of RRS TVC-44 legs. Before you castigate me for using the a7R with an adapter collar, something that I and others have demonstrated is a bad idea, consider my motivations in this test. I’m not trying to find out the best way to mount the a7R when used with a smallish 180mm lens, I’m trying to find out if there’s something inherently different between the vibration of the a7 and a7R FCS, and this is a handy way to construct a fairly sensitive test setup.  An adapter collar foot, while not a good way to mount a camera/lens assembly to the tripod with the a7R, works very well with the a7, as long as you use EFCS.

I mounted a Heliopan variable ND filter on the lens. I lit an Imatest SFRPlus target with a Fotodiox 5500K variable output LED source. I set the ISO to 400, focused wide open, and set the aperture to f/5.6. Using the ND filter and the light together to control the, and made a series of exposures of durations from 1/800 second through ¼ second at 1/3 stop intervals. With the light on full and shutter speed set to 1/800 at the start, I controlled the number of photons hitting the sensor with the ND filter until I got to 1/60 second, put the filter back to minimum absorption and set the light level with the Fotodiox control until I got to 1/50 second, then continued on attenuating the light with the ND filter.

I processed the images in Lightroom 5.3 with default settings except for cropping and white balance, then I processed them in Imatest, measuring the MTF30 and MTF50 for both vertical and horizontal edges. I converted the Imatest cycles/pixel data to cycles/picture height, and made plots.

Here’s the MTF50 for horizontal edges (the a7 curve with the EFCS on is indicated by the E suffix, and the a7R curve is identified in the prefix, the other two curves being for the a7):

mtf50ha7a7r180

The a7 and a7R are affected to about the same degree in this orientation, which has the shutter moving in the direction that blurs the (horizontal) lines the most. The a7R, having higher resolution to begin with, starts from a better position. The shutter speeds that are the most affected are somewhat different between the two cameras. These curves are slightly surprising to me; I would have expected the point of maximum blurring to occur at about the same resolution for both cameras.

For vertical edges, the main shutter vibrations are in the same direction as the edge, and thus the shutter’s effect is reduced:

mtf50va7a7r180

This is a similar result to that obtained for horizontal lines with the Zony 55. The mechanical FCS of the a7 seems to have little effect, while the FCS on the a7R shows more variation with shutter speed. I believe that the reason is that the a7R is more sensitive to shutter vibration simply because of its higher resolution.

MTF30 for horizontal edges:

mtf30ha7a7r180

Except for the absolute values, and some minor variations, these are virtually the same as the MTF50 curves.

MTF30 for vertical edges:

mtf30va7a7r180

Again, essentially the same information as in the MTF50 curves.

While the total magnitude of the two camera’s mechanical first curtain shutters vibration appears to be similar, the a7R appears to be of higher frequency, as it affects the faster shutter speeds relatively more. I’ve observed that the a7R shutter has an unusually large amount of high-frequency vibration before.

The Last Word

← Sony a7 EFCS: how much difference does it make? Part 3 Rolling my own autohalftoning →

Comments

  1. Jack Hogan says

    April 5, 2014 at 11:47 am

    Good work Jim. That’s probably why Sony just came out with a firmware update that allows the use of the electronic shutter on the A7r as well. Here is some more reading on it
    http://www.dpreview.com/forums/thread/3583280

    and for a different take on the difference between horizontal and vertical readings:
    http://www.dpreview.com/forums/thread/3606692

    Reply
    • Jim says

      April 5, 2014 at 1:57 pm

      Jack, I’ve upgraded the firmware on my a7R, but I can’t find an electronic FCS setting like there is on the a7. Wouldn’t the a7R need a sensor change for this?

      Jim

      Reply
  2. Jack Hogan says

    April 5, 2014 at 2:09 pm

    Apologies Jim, I got my wires crossed. The recent firmware update that introduces an electronic first shutter is for the Olympus E-M1, not the A7r – my mistake.

    Reply

Trackbacks

  1. Some thoughts on long-lens photography | The Last Word says:
    May 21, 2015 at 12:19 pm

    […] Before electronic first-curtain shutter (EFCS), long-lens (which I’ll define as 300mm and over on a full-frame 35mm camera) photography was usually about wildlife and sports. For those activities ultimate sharpness wasn’t the prime concern. Those who attempted SLR landscape photos were usually frustrated by camera motion, even with the mirror locked up. With mirrorless cameras without EFCS, problems came in two flavors. Those that allowed live view to be turned off, like the Leica M240, suffered the same kind of camera vibration as those who used SLRs with the mirror up. The mirrorless cameras that didn’t allow live view to be turned off, like the Sony alpha 7R (a7R), had the considerable additional vibration of winding the shutter just before it was fired. […]

    Reply

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 Fujifilm GFX 100S pixel shift, visuals
  • Sarmed Mirza on Fujifilm GFX 100S pixel shift, visuals
  • lancej on Two ways to improve the Q2 handling
  • 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

Archives

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

Unless otherwise noted, all images copyright Jim Kasson.