Canon EOS M6.2 Does it produce shutter shock ? Yes it does. 5 September 2020

 

This photo has nothing to do with the test described in this post but it's  more interesting than  test charts. EOS M50, EF-M 18-150mm lens

You can read more about Canon EOS mirrorless RF and EF-M cameras and lenses here

Canon’s first foray into the mirrorless interchangeable lens camera (MILC) market was with the EOS M in 2012.  This and every subsequent Canon MILC using either the EF-M mount or the more recently introduced RF mount uses electronic first curtain shutter (EFCS) by default………..

until the EOS M6.2  which was introduced in 2019 without any option to use EFCS.  

This seems passing strange to me as the EOS 90D DSLR released at the same time and using the same sensor, does offer an EFCS option.

The first digital MILCs were introduced in 2008 by Panasonic and Olympus using the Micro Four Thirds (MFT) sensor format. I bought and used a series of  Panasonic MFT cameras over the next ten years and became very familiar with their many idiosyncrasies.

I noticed that with some lenses at some focal lengths and some shutter speeds there was marked image blurring, often with a double image appearance.

I called this shutter shock and reported it on this blog.

Imaging Resource also noted and reported the phenomenon around the same time.

A long, drawn out saga of denials and claims by users ensued.

This was accompanied by Panasonic and Olympus refusing to admit there was any kind of problem at all, until they fixed it by introducing EFCS by default (and re-designing the shutter ) then they proudly announced this as a feature of their new cameras which did not have the problem.

I thought at the time that all the camera makers had this issue sorted and that we would never see the dreaded shutter shock again.

Unfortunately I was wrong. Canon, after making a string of models without shutter shock has produced one which does have shutter shock due to the absence of EFCS.

So it seems we, the long suffering camera users have to go through this whole sorry saga yet again.

So what is shutter shock ?

In a MILC the focal plane shutter is open when you are viewing the subject to be photographed. I has to be thus to enable the image from the lens to reach the sensor.

With a standard mechanical shutter when you press the shutter button a sequence of events occurs very quickly thus:

Shutter closes > shutter opens to start the exposure > exposure occurs > shutter closes to end the exposure > shutter opens again ready for the next shot.

That initial shutter close/shutter open action does not happen with a DSLR with optical viewfinder operation as the shutter is closed while the mirror is down.

That initial shutter close/open action in a MILC causes a little shockwave to pass through the camera and lens immediately before the exposure.

With some lenses at some focal lengths and some shutter speeds this can jiggle the autofocus and/or image stabiliser elements in the lens enough to blur the image.

The problem is more likely to occur with spring loaded shutters and less likely with electromagnetically controlled shutters which have been specifically designed to have a soft close type of operation.

When I operate the camera with my ear right on the camera body the EOS-M6.2 shutter makes a hard, snappy sound which I suspect indicates a spring loaded shutter type.

The M50 also has a hard snappy shutter sound but that camera does have EFCS and no issues with shutter shock that I have detected or that I have heard reported.

On my Panasonic G95 camera (now gone) the shutter had a soft-shuffle sound. Panasonic indicates this camera has an electromagnetically controlled, soft close shutter type. The G95 also has EFCS and no shutter shock.

The Canon EOS M6.2

I was happy enough with my EOS M50 but the grass is always potentially greener in the next paddock.

I read many favourable reviews and user reports of the M6.2 some of which mentioned the shutter shock issue in passing as being of no practical significance in use.

The M6.2 is clearly an upgrade over the M50 in many respects with a better sensor, performance and controls.

So with some trepidation I bought one and forthwith tested it for shutter shock, of which I found plenty.

This is the test chart, full size. I am only looking at the lettering close to the center of the frame.

Test procedure

This is dreary boring, time consuming  stuff which I guess is why many owners don’t do it. They would presumably much rather go out and make photos which I totally understand.

I tested all the current model native Canon EF-M lenses except the 28mm which I have on order but which is held up somewhere presumably a victim of Covid-19 slowdown issues.

I also tested the Canon EF 70-300mm Mk2 with the required adapter.

I photographed a test target, hand held, with stabiliser on where available, at the wide and long end of the zooms and at a series of shutter speeds from about 1/20 sec to 1/640 sec. I ran one sequence with E-shutter and another sequence with M-Shutter.

I also checked some shutter speeds on/off tripod to determine whether this had an effect on the results which it did not.

I then compared the resulting frames with the E-Sh and M-Sh versions side by side at 100% on screen.

This gave me the information I sought.

Crop of test chart, E-Shutter typical appearance. EF-M 18-150mm lens at 122mm 1/60 sec

Crop of test chart. Typical appearance with M-Shutter at affected shutter speeds.
Same lens, focal length and shutter speed as the frame above this

Results

Primes:

* EF-M 22mm f2, no problem. No difference in sharpness between M-Sh and E-Sh.

* EF-M 32mm f1.4, no problem.

Both these primes can be used with the M-Shutter at any shutter speed with no detriment to image quality.

Update 4 November 2020

* EF-M 28mm f3.5 macro:  This is the only EF-M prime with IS. I tested it the same way as the other lenses and found no definite problem. I did see some slight loss of acutance at 1/100 and 1/125 second on my test subject. I suggest users run their own tests to see if they can detect any problem.

Zooms:

All the zooms showed evidence of some impairment to image sharpness at some focal lengths and shutter speeds.

* EF-M 11-22mm

At 11mm I found no problems.

At 22mm I found a slight but detectable reduction in sharpness with the M-Sh in the range of shutter speeds from 1/60-1/200 second.

* EF-M 15-45mm

At 15mm I found no problems.

At 45mm there was evident softening with the M-Sh from 1/80 – 1/200 sec.

* EF-M 18-150mm

At 18mm I found no problems

At 59mm I found softening with the M-Sh  from 1/60  - 1/160 second.

At 122mm I found softening at all shutter speeds up to 1/320 sec.

* EF-M 55-200mm

At 55mm I found no problems.

At 90mm There was softness from 1/60 – 1/125 second.

At 200mm This was the worst performer with softness and double imaging from 1/60 – 1/125sec.

* Canon EF 70-300mm (on tripod)

At 70mm, no problems.

At 300mm I found blurring from 1/40 – 1/100 second.

Discussion

You can see a pattern here.

The 22mm and 32mm primes are OK.

The zooms were OK at their shortest focal length but showed evidence of softening at the longer focal lengths with some shutter speeds.

The affected shutter speeds were generally in the range from 1/60-1/200sec.

I found no problems with faster or slower shutter speeds.

 Stabiliser ON vs stabiliser OFF

I attempted to test whether shutter shock is affected by stabiliser status but with inconclusive results. 

When hand held with the stabiliser off, I got unsharp results due to camera shake making it impossible to figure out which unsharp frame might have been due to shutter shock and which to camera shake.

On tripod all the camera makers including Canon recommend switching the stabiliser off as leaving it on could impair sharpness. So I could not devise a meaningful comparison for this situation. 

Thoughts about management strategies

1. Use the E-Shutter all the time with all lenses.

This solves the shutter shock problem and on my tests does not appear to result in any loss of image quality at high ISO settings or when shadows are lifted in post processing Raw files. 

I also see no difference in dynamic range (ability to capture highlight and shadow detail when subject brightness range is high) between M-Sh and E-Sh.

The problems with this approach are the well known issues which E-Sh brings to the process.

These include banding with discontinuous artificial light sources and image skew with panning.

The E-Sh on the EOS-M6.2 scans the frame in about 1/20 second. 

By the way a quick way to confirm this is to photograph a relatively featureless scene like a white wall under fluorescent light. At a shutter speed of around 1/200 sec (it's not critical) I see 5 big green bands on each frame. The power supply in Australia operates at 50 hz (cycles per second).

The formula is  (number of lines) divided by (hz x 2), so in this case we have 

5 divided by 50x2 = 1/20 second.

2. Just use primes and M-Sh with the M6.2.

3. Work out a system to use M-Sh but avoid the affected shutter speeds.  I have not yet figured out anything along these lines which works for me.

4. Pretend there is no problem and never understand why some shots are not as sharp as expected.

5. Pray that Canon can come up with a firmware based solution of some kind.

For the record I am using a combination of these strategies.

For still subjects and landscapes I use the E-shutter. For action I use a fast shutter speed and the M-shutter.

The 22mm f2 and 32mm f1.4 can be used with M-shutter at any shutter speed.

What I really want

Is a camera with an auto shutter function thus:

* EFCS from the slowest shutter speed up to about 1/500sec.

* Mechanical shutter from 1/500 sec up to the fastest available mechanical shutter speed. This varies with different cameras but is often around 1/2000-1/4000sec.

* E-Shutter for the fastest speeds.

The rationale of not using EFCS in the shutter speed range around 1/500-1/4000 is that EFCS has been reported to cause possible impairment of  image quality in out of focus areas and  reduced exposure in highlights  in this shutter speed range.