[clackers]

While driving to a town to shoot a pro cycling event one year (the Sky team complete with Chris Froome were there), I picked up a hitch-hiker. Seemed like a nice guy. After a few miles, he asked me if I wasn't afraid that he might be a serial killer. I told him the odds of two serial killers being in the same car were extremely unlikely.

After a little diversion, at the venue I went to get my gear out of the back of my car. My K-1 was there beside the usual duct tape, sheet plastic, cable ties and shovel (which now had fresh dirt on it). But I accidentally had left its electronic shutter on from the last time I used it.

The Pentax Q, K-1, KP and K3-III have that available, with increasing levels of sophistication.

A quick primer on shutters.

The old fashioned style 'leaf' shutter built into a lens - my Ricoh GR II has one, and some 645 lenses do too - is like if you form a fist, and open it, with the back of your hand pointing away from you, and close it again. Note that you see your open palm longer than the insides of your fingers. This means the center of the picture gets more exposure than the edges, and this is a practical limit on how fast the shutter can be - perhaps 1/2000s.

The modern focal plane shutter might go to 1/8000s, and it's like two blades (curtains) with a gap between them dropping down over the frame.

I have a K-30, and 1/180s is the smallest amount of time the curtains are apart across the whole frame, so its popup flash is disabled when less than that so we don't get a progressively bigger black band in the picture.
The curtains are of course mechanical, and in combination with certain lighter lenses at certain low shutter speeds (perhaps less than 1/200s) the snap of the mechanism can cause detectable blur when pixel peeping.

The K-1 (which has a bigass, heavy full frame shutter) offered as a firmware upgrade a 'half' electronic shutter for that situation. Only the second curtain drops, meaning most of the shaking never gets recorded by the pixels.

The KP can have purely electronic, which means in Live View it can be silent when it shoots, and the shutter has no wear and tear.

What are the problems? Well, almost no camera has the electronics to switch on, switch off and read all its pixels simultaneously. The reading occurs in rows from top to bottom, so each pixel might be on and off for 1/8000s, but the pixels at the bottom record maybe 1/15s later than the ones at the beginning. If an object is moving, that can be noticed as distortion - see my pic below from that morning. Or if there's lighting that's not constant like fluorescent lamps or flash, there can be weird bands.

Flash is certainly disabled in the Pentax implementation of this technology, but the K-3 III apparently has solved the problem of the sensor moving during that time, and I hear that shake reduction can now be used. Katie got her electronic shutter enabled after about firmware 1.10, IIRC.

From time to time, people have argued that paying a lot extra in a stills camera for a global electronic shutter as used in all high end video bodies will end these limitations, but the truth is that to read every pixel at the same time requires extra electronics around each pixel that increase noise and deliver grainier pictures. Nevertheless, the upcoming Canon EOS R1 may have one for maybe USD $6500 or more.

On the way back to the city from the event, I picked up another hitch hiker. I asked him, "So, where did you think you were going?"

The rest of the series here: Clackers' Beginners Tips (Collected) - PentaxForums.com

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Last edited by clackers; 04-10-2022 at 07:22 PM.

[Paul the Sunman]

For the physicists in the audience: I like to think of the ES as being somewhat akin to being in a different Lorentz frame in Special Relativity. Simultaneity is relative to choice of frame.

[BarryE]

For the physicists in the audience: I like to think of the ES as being somewhat akin to being in a different Lorentz frame in Special Relativity. Simultaneity is relative to choice of frame.

That brings back bad memories and much head scratching ...

---------- Post added 01-07-22 at 09:48 AM ----------

Thanks Clackers. I'd never bothered with ES and consequently never got round to looking at it in more detail.

Got a smile from the jokes too ... I assume they were jokes?

[FozzFoster]

Interesting article Clackers! I really enjoy reading your tips posts

Curious for me...
Every new photographer learns the exposure triangle; ISO, aperture, and shutter speed.
One learns that a faster shutter speed is mainly accessed to 'freeze' the action in your scene.

What's the point of such a fast electronic shutter if it blurs the action at those speeds?
Just cause it's quieter?

[biz-engineer]

There is also motion distortion with the mechanical shutter, it's just less visible, as the actually shutter speed is the flash sync speed, e.g 1/200th for the K1, and eventually slower for medium format (e.g 645 @ 1/100th, more sensitive to camera shake BTW).

[kiwi_jono]

Well thats quite a dramatic affect - makes for an interesting photo!
And think I will avoid hitch hiking in Australia ;-)

[ProfessorBuzz]

IWhat's the point of such a fast electronic shutter if it blurs the action at those speeds?
Just cause it's quieter?

It's about speed - still objects don't exhibit it; rotating the camera 90 degrees changes the effect. High frame rates require high readout speeds - eg faster time between shots = more frames per second.
So for video, it's essential. Some CMOS sensors have global shutters, and don't exhibit this effect; some CCDs have a frame buffer on-chip to help; and equal-exposure window or rotary shutters can help here too.
Mechanical Shutter direction also matters - eg vertical vs horizontal focal plane have a different effect on motion; vs leaf shutters.

[clackers]

Got a smile from the jokes too ... I assume they were jokes?

Come round to my place for dinner to discuss, Barry, I have some chianti ready in the glasses and some fava beans simmering away on the stove!

[clackers]

What's the point of such a fast electronic shutter if it blurs the action at those speeds?

Yeah, pointless in these scenarios, FF. I switched back to mechanical after chimping and seeing my error.

But so much photography is like that ... a technique or method almost necessary for one context is completely inappropriate for another. It's a fascinating hobby we enjoy!

[clackers]

There is also motion distortion with the mechanical shutter, it's just less visible

Yeah, really visible if you shoot rotating aircraft propellors in some situations!

[clackers]

Well thats quite a dramatic affect - makes for an interesting photo!
And think I will avoid hitch hiking in Australia ;-)

(Laughs)

The last one I heard years ago as a grab on radio from a slow talking American ... I've always assumed it was the great Steven Wright.

[clackers]

Just a good point from @UncleVanya for some beginners ... because fractions are fractions, 1/1000s is a smaller amount of time than 1/180s.

If you still struggle with that, the geometric progression that is the f-number system of aperture will blow your minds!

[beholder3]

A quick primer on shutters.

To add:

In consumer cameras cheaper than $6000 (those without at least a stacked sensor) ES (electronic shutter) doesn't work with flashes at all due to those readout times (the brandnew Sony a74 for EUR 2800 still is stuck at sad 1/15 sec).

ES even in the expensive cameras has negative impacts (The Nikon Z9 dynamic range in ISO 100-400 is just on the level of a seven year old APSC D7200).

Due to LEDs and other lights flickering at various frequencies much faster than 1/15 ES risks generating irrepairable images with heavy banding. And you only know this after the fact, since every signle light bulb might be flickering at a different speed.

So avoid silent shutter / ES when:
a) there is low light illuminated with artificial light sources
b) fast moving subjects (bicycles, cars, flapping bird wings...)

c) you need a flash (then you normally simply can not turn ES on)

Obviously that is a lot of limitations.

[reh321]

How well does film work at “stopping motion”??

I got into photography through my other hobby of railroading.

I photographed my first trains in 1967, but quickly got frustrated by the slow shutter speeds of basic point-and-shoot cameras, so I spent some of my ‘college graduation’ money {1969} on a rangefinder camera so I could control shutter speed. I found that 1/250 was usually adequate, but I moved to 1/500 when I got a digital camera. I don’t ‘pixel peek’, so I am completely satisfied by what I get.
I’m not sure how fast they are going; I quit when my reflexes are inadequate to catch something in particular.

I celebrated my “50th year of photographing trains” in Jan 2016 {counting 1967 as “first year”}

[clackers]

How well does film work at “stopping motion”??

Well, it's not about film or digital, Reh, it's about the shutter.

Your film cameras had mechanical shutters, and there wasn't the 1/15s or so sync speed as described above.