shutter Mechanical & Electronic Shutter

[kentishrev]

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I have a general question, that I guess will apply to CL, TL and others.  I know from experience on the CL that the mechanical shutter produces far better images than the elecronic shutter (there is a demonstrable banding issue indoors, and generally mechanical just 'looks' better).  This view seems to be supported by many other posts.  However, I'd simply welcome an explanation of 'why' this is the case.  In a digital camera, what advantage does the mechanical shutter provide?  I'm just intrigued.  Many thanks.

[lct]

3 hours ago, kentishrev said:

I know from experience on the CL that the mechanical shutter produces far better images than the elecronic shutter (there is a demonstrable banding issue indoors, and generally mechanical just 'looks' better).  This view seems to be supported by many other posts.  However, I'd simply welcome an explanation of 'why' this is the case.

It is the case only in some special circumstances in my own experience with the CL and other digital cameras. Typically under some non-tungsten artificial light, also on some moving subjects i've been told. But mechanical shutter producing "far better images", i've seen that only in flash photography because it needs a mechanical shutter to work so far.

[kentishrev]

3 minutes ago, lct said:

It is the case only in some special circumstances in my own experience with the CL and other digital cameras. Typically under some non-tungsten artificial light, also on some moving subjects i've been told. But mechanical shutter producing "far better images", i've seen that only in flash photography because it needs a mechanical shutter to work so far.

I’ve certainly noticed a difference, particularly under artificial light. Terrible banding with electronic shutter. But don’t know the actual reason for it.

[lct]

You will find a lot of explanations on the web. Here for instance: https://www.dpreview.com/forums/post/56291766

[LocalHero1953]

The banding is only with some articifial light where the colour varies (imperceptibly to the eye) with mains frequency (50 Hz in the UK). Electronic shutters 'read' the sensor line by line, typically over a total period of 1/30s. If your shutter speed is set at, say, 1/1000sec, each line will 'see', for 1/1000sec, light of a colour that depends on the part of the mains frequency cycle the light source is in. Thus, as the sensor is read over 1/30sec, each line will 'see' a different colour - hence the banding.

But not all light sources vary much with mains frequency: tungsten light bulbs that work by heating a filament up to a glowing temperature don't cool down quickly - the buffering effect keeps their colour constant. I don't know enough about different light sources to say which ones do cause banding an which don't. I believe that more expensive light sources have a buffering built in to keep the colour constant.

I normally take a number of test shots to see if banding is a problem or not - I try to shoot a person lit by just one light source as a test. In venues with high quality modern lighting it is becoming less of a problem. Last week I shot a music performance in a modern rehearsal room brightly lit, paid with scant regard to cost - no visible banding at all.

Eventually we will have truly 'global' shutters that 'read' all the lines on a sensor in one go. Then we will have no banding, but we may have a lot of colour variation from frame to frame, because the light colour will still vary with mains frequency in cheaper lights.

Edited October 20, 2018 by LocalHero1953

[hoppyman]

I have observed the banding issue under specific artificial light, however I don’t follow the remark that the mechanical shutter results are “better” apart from that situation. I am not aware of that being mentioned previously?

i took the CL on a trip for casual travel photography and quite a big share of my shots were low light high ISO large aperture inside museums and the like. I haven’t observed any problem in my shots there as I start my editing. I do appreciate the complete silence of operation. Shall be interested to see if others are reporting the better results with the mechanical shutter (apart from that specific issue with some artificial light)

[kentishrev]

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1 hour ago, hoppyman said:

I have observed the banding issue under specific artificial light, however I don’t follow the remark that the mechanical shutter results are “better” apart from that situation. I am not aware of that being mentioned previously?

i took the CL on a trip for casual travel photography and quite a big share of my shots were low light high ISO large aperture inside museums and the like. I haven’t observed any problem in my shots there as I start my editing. I do appreciate the complete silence of operation. Shall be interested to see if others are reporting the better results with the mechanical shutter (apart from that specific issue with some artificial light)

I've noticed the banding quite often - but in the same room at home (I guess our lights are cheap).  But outside I've also noticed slightly less sharp pictures of crowds and general street pictures (having left the electronic shutter on 'always' in error on a trip last month).  Having seen the helpful explanations about the 'roll' of the electronic shutter, that would explain why I haven't seen it in still shots. 

[lct]

Never seen such a lack of sharpness so far. Most of my CL pics are taken in silent mode but i have a "shutter" profile for indoor photography and moving subjects if needed. FWIW.

[kentishrev]

1 hour ago, lct said:

Never seen such a lack of sharpness so far. Most of my CL pics are taken in silent mode but i have a "shutter" profile for indoor photography and moving subjects if needed. FWIW.

As I said, it was only in particular shots and may have been a shutter speed issue (my error) given nature of shot. But I hadn’t expected it and then later saw others saying similar. It doesn’t however detract from this amazing camera.

[FrozenInTime]

Rolling shutter and flicker aside, it’s my general understanding than the SNR should be higher from a mechanical shutter, as in the dark,  the sensor wells/capacitors can be discharged to a lower state before exposure begins.