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| G7 Even with E-Shutter the camera manages high subject brightness range well. There is direct sun on the skylights and very little light at all on the legs of the diners at the bottom of the frame. Pulling up the dark tones in Adobe Camera Raw does increase noise but not to an objectionable level in my view. |
The Panasonic Lumix G7 is a mirrorless interchangeable lens camera (MILC).
MILCs are, or may be, prone to degradation of image quality with some lenses at some focal lengths and some shutter speeds due to vibration produced by the mechanical focal plane shutter.
Below is an excerpt from the Digital Photography Review G7 Review of July 2015 by Richard Butler and Samuel Spencer.
However, the camera's shutter appears to shake (and soften) the image, especially at shutter speeds of around 1/160th of a second. This can be eliminated (and its imapact assessed) by using the camera'selectonic shutter mode - either by specifying electronic shutter or by engaging 'silent mode.' The resultant images are sharper but risk exhibiting rolling shutter, if used with fast-moving subjects, and come at some cost to dynamic range and a slight increase in noise at the highest ISO settings.
I can confirm from my own tests that DPR is correct about the Mechanical Shutter causing image softness, particularly on tripod, at least with the 14-42mm zoom lens which I used.
I also ran my own tests to discover how much of an issue is the loss of dynamic range and increased noise at high ISO settings with the E-Shutter. See E-Shutter Noise Tests, below.
I am now starting to read reports of the same problem in the new ultra high Pixel count full frame DSLRs. Even with mirror lock up and tripod mounting the disturbance caused by the focal plane shutter opening to commence exposure can be enough to impair the resolution of fine detail.
I mention this to clarify that this is not a Panasonic or M43 problem but potentially an issue for any camera with a mirror and/or focal plane shutter which moves then stops suddenly immediately prior to exposure. I have not heard of any case where an in lens diaphragm type leaf shutter has caused sufficient vibration to impair image detail but I guess it could be possible.
From my perspective as a consumer, Panasonic’s solution to this problem appears to be
a) Pretend it is not happening and refuse to acknowledge the issue but simultaneously
b) provide a solution in the form of E-Shutter.
For reasons unknown to me Panasonic provides Electronic First Curtain Shutter (EFCS) on some models but not others. The G7 does not have it.
As far as I am aware the only Lumix ILCs to have EFCS are the GM1, GM5 and GF7. These cameras use a small, light focal plane shutter driven by stepper motor giving a fastest speed of only 1/500 second.
In addition Panasonic provides no help or indeed any information at all about when and why the user might use one or the other shutter type.
So here is some:
Mechanical Shutter (M-Shutter)
Advantages of M-Shutter
* Compatible with flash.
* Enables shutter speeds slower than 1 second.
* No banding with fluorescent light.
* No rolling shutter effect with movement.
Disadvantages of M-Shutter
* Image degradation due to shutter shock with some lenses, focal lengths and shutter speeds. Every lens has to be tested separately for shutter shock image degradation.
* Audible noise of operation.
* Super fast shutter speeds not available.
Electronic Shutter (E-Shutter)
Note:E-Shutter is always used for motion picture (video) capture.
Advantages of E-Shutter
* No shutter shock problem with any lens.
* Silent operation if required (switch electronic beeps off).
* Very high shutter speeds available.
Disadvantages of E-Shutter
* No shutter speeds longer than 1 second at low ISO, 1/8 second at high ISO.
* Not compatible with flash.
* Banding in fluorescent light.
* Rolling shutter effect (distortion) with movement.
* Potential for increased digital noise and reduced dynamic range at high ISO settings.
Notes:
* Before using the M-Shutter with any lens, test to find whether there is a shutter shock issue with that lens. The procedurewhich I use is described here.
* You must use the M-Shutter when the E-Shutter is inoperative.
This is when using flash and with shutter speeds longer than 1 second. With long shutter speeds on tripod or other support utilise the [Shutter Delay] feature to prevent camera and/or shutter shake and set 2 second timer delay or activate the shutter remotely.
* On the G7 the fastest M-Shutter speed is 1/4000, E-Shutter goes up to 1/16000 sec.
* Burst rate varies with shutter type. For the Panasonic G7 see Page 182 of the Owners Manual for advanced features.
E-Shutter noise tests, Lumix G7
In order to increase scanning speed camera makers may use reduced bit rate capture with E-Shutter.
With Panasonic M43 the standard bit rate is 12. Bit rate for E-shutter may be 10. I say “may be” because manufacturers including Panasonic adopt an obscurantist position on such things.
Update, December 2015 The G7 outputs 10 bit files with E-Shutter. The GX8 outputs 12 bit files with E-Shutter. If RAW images made with the G7 E-Shutter require much lifting of dark tones in adobe Camera Raw or Lightroom, a blotchy green mottled appearance can be seen in those lifted tones. This does not occur with the GX8.
Update, December 2015 The G7 outputs 10 bit files with E-Shutter. The GX8 outputs 12 bit files with E-Shutter. If RAW images made with the G7 E-Shutter require much lifting of dark tones in adobe Camera Raw or Lightroom, a blotchy green mottled appearance can be seen in those lifted tones. This does not occur with the GX8.
I photographed a subject with plenty of highlight and shadow at ISO settings from 100 to 25600, using the M-Shutter then the E-Shutter.
I compared the resulting files in adobe Camera Raw both at ACR default settings and adjusted for best result in my subjective judgement trying to achieve a balance of noise reduction, sharpness, color and contrast.
I found no significant difference between the E-Shutter and M-Shutter results at Low and medium ISO settings.
At very high ISO settings I noticed the M-Shutter files had
a) Darker near black dark tones and
b) Less noise in the near black dark tones.
This was noticeable at ISO 12800 and 25600 and evident only on pixel peeping at 100% on screen.
Conclusion
For general photography without flash the G7 E-Shutter does the job quietly, without the risk of shutter shock and without noticeable adverse effects on picture quality.
Historical note
I compared my recent ISO 12800 photos made with the G7 camera with my scans of 15 year old photos made with ISO 400 black and white and color film.
The G7 12800 RAW pictures have more detail and less grain after processing in ACR.
Minor quibbles about dark tone noise levels at very high ISO settings are of little significance in the greater scheme of things.
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