• site home
  • blog home
  • galleries
  • contact
  • underwater
  • the bleeding edge

the last word

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

You are here: Home / The Last Word / What’s the fastest shutter speed you should use with EFCS on the a7RII?

What’s the fastest shutter speed you should use with EFCS on the a7RII?

August 11, 2015 JimK 6 Comments

Yesterday I looked at shutter travel time for silent shutter operation on the Sony a7RII. Incidentally, we noted that the electronic first curtain shutter (EFCS) pretty faithfully emulated the acceleration of the mechanical second curtain, at least at 1/500 second.

On the Nikon D810, EFCS stops working at shutter speeds above 1/2000. On the Sony alpha 7 cameras with EFCS, Sony advises against using the capability at fast shutter speeds, but let’s the user decide how far to push it.

So, let’s push it and see what happens when we take pictures of a high-frequency triangle wave on an oscilloscope with the time base set to 500 microseconds (us) per division.

1/1000 second, mechanical shutter
1/1000 second, mechanical shutter
1/1000 second, EFCS
1/1000 second, EFCS

You can see that the EFCS image has a little less exposure at the top of the image, but you probably wouldn’t notice that in a real photograph. The all mechanical image is pretty even.

1/2000 second, mechanical shutter
1/2000 second, mechanical shutter
1/2000 second, EFCS
1/2000 second, EFCS

Now the EFCS exposure is suffering from nonuniformity noticeably, but would probably be fine for many purposes.

1/4000 second, mechanical shutter
1/4000 second, mechanical shutter
1/4000 second, EFCS
1/4000 second, EFCS

The EFCS exposure at the top of the image is about 1/3 of that at the bottom. This should normally be avoided.

1/8000 second, mechanical shutter
1/8000 second, mechanical shutter
1/8000 second, EFCS
1/8000 second, EFCS

There is essentially zero exposure at the top of the EFCS image. Not useful.

The synching of electronic and mechanical behavior over time, temperture, wear, and sample variation is an iffy business.

I used to say that users should avoid a7x EFCS shutter speeds of over 1/2000 second. Based on these results, I’m dropping that to 1/1000.

The Last Word

← Sony a7RII silent shutter speed in APS-C mode 28/2.8 Elmarit-M color casts with a7R & a7RII →

Comments

  1. CarVac says

    August 11, 2015 at 2:30 pm

    That’s absolutely fascinating.

    I had no idea that happened.

    Canons by default use EFCS in live view mode, and it turns out I’ve never once actually used live view with a shutter speed significantly above 1/1000.

    I just tried 1/8000 and the bottom of the image is completely black.

    There’s an option to turn EFCS off, but I never knew why you’d ever do that before.

    Reply
  2. Glenn Barber says

    April 4, 2018 at 4:48 pm

    Are the results on an A&&3 similar?

    When is it particularly valuable to turn EFCS on?

    Reply
    • JimK says

      April 4, 2018 at 5:00 pm

      EFCS is most useful at shutter speeds slower than 1/500 and faster than a second or two, and with longer lenses. The a7RIII EFCS works the same.

      Reply
  3. scott says

    June 11, 2024 at 3:56 am

    have you tested this with lenses that have different exit pupil distances?

    Reply
    • JimK says

      June 11, 2024 at 7:21 am

      It’s been so long I can’t remember, and I don’t have any Sony gear anymore.

      Reply
      • scott says

        June 14, 2024 at 12:45 am

        im more interested in efcs in general, i did some basic testing with a canon r5 (mech and efcs) and canon rp (efcs only) and noticed significant differences between the cameras and also significant differences between different lenses, but only with non electrical lenses.

        Reply

Leave a Reply Cancel reply

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

May 2025
S M T W T F S
 123
45678910
11121314151617
18192021222324
25262728293031
« Apr    

Articles

  • About
    • Patents and papers about color
    • Who am I?
  • How to…
    • Backing up photographic images
    • How to change email providers
    • How to shoot slanted edge images for me
  • 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 35-70 MF 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 Goldilocks and the three flashes
  • DC Wedding Photographer on Goldilocks and the three flashes
  • Wedding Photographer in DC on The 16-Bit Fallacy: Why More Isn’t Always Better in Medium Format Cameras
  • JimK on Fujifilm GFX 100S II precision
  • Renjie Zhu on Fujifilm GFX 100S II precision
  • JimK on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF
  • Ivo de Man on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF
  • JimK on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF
  • JimK on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF
  • Ivo de Man on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF

Archives

Copyright © 2025 · Daily Dish Pro On Genesis Framework · WordPress · Log in

Unless otherwise noted, all images copyright Jim Kasson.