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PhaseOne IQ3 (ES) Electronic Shutter How it works

spassig

Member
Hello
After reading the manual I know the functionality of LS and FPS.
But I don’t understand the functionality of ES.
I „know„ it is not a mechanical system.
Can someone give me a detailed explanation or is a description in www available?
I „know“ LS and FPS must be open by using ES?

Jochen

Edit: I found an explanation in www.
No answer Required
 

Paul2660

Well-known member
As I understand it, ES is a row to row read off the sensor. This is why you see rolling shutter issues with movement when an object moves across the rows of pixels. Which on a phase back is a relatively slow read off. All video cameras are using a ES type shutter. You always see the effect of rolling shutter on airplane propellers. They will show a curved look.

Global shutter would be all pixels capturing light at the same time as a on a piece of film. At least that is my understanding.

What I have never fully understood is why a focal shutter can operate without the issues of rolling shutter especially on longer exposures.

When you really think about all that’s going on behind the scene with a phase back and the ES implementation it’s pretty impressive. Especially with the IQ4 new features like dual exposure and frame averaging both of which need the ES.

Paul C
 

Paul2660

Well-known member
The focal shutter in lenses open 0% to 100 % from the centre inside to the outside.

Jochen

That’s a leaf shutter isn’t it? The focal shutter design varies by camera. I was thinking about the huge focal shutter in the XF body.

I love the ES on all my cameras and use it most of the time as I don’t need the leaf shutter for fast flash sync. Rarely do I see issues with rolling shutter even on windy days.

Paul C
 

med

Active member
What I have never fully understood is why a focal shutter can operate without the issues of rolling shutter especially on longer exposures.
Focal plane shutters can exhibit rolling shutter, but I think you have to work fairly hard to reproduce it with modern shutters. I am by no means an expert, but I believe that faster shutter speeds are more susceptible to it, not longer exposures, as the shutter opening/closing represents more % of the exposure time. In a long exposure, the opening period and closing period represent a mere drop in the bucket of the exposure, similar to why mirror or shutter related vibrations disappear once your exposure is long enough.

Here is an excellent thread on Large Format Photography Forum showing focal plane shutter induced rolling shutter effects, and perhaps the most famous example of it.
 

MGrayson

Subscriber and Workshop Member
Rolling shutters and fans or windmills get along famously! X1D, 90mm, 1/1000 sec electronic shutter:



Matt

:lecture:
Exercise 1) Which blades do the disconnected floating bits belong to?
Exercise 2) What is the equation for the shapes the blades make? (Assume that the blades are just radial line segments. This works well for the giant windmills in wind farms.)
 
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f8orbust

Active member
What I have never fully understood is why a focal shutter can operate without the issues of rolling shutter especially on longer exposures.
With film and a focal plane shutter, an exposure is typically:

Shutter opens (time A) - film is exposed to light (time B) - shutter closes (time C)

A and C are fixed mechanical operations that (on a modern camera) take the same very, very short time whether B is 1/500 second or one hour.

When B is very, very short however (so that A ~ B ~ C) then there is a chance of a limited rolling shutter effect if the subject is moving very, very fast since your exposure is sort of like a thin line of light travelling across the film plane, rather than the entire frame of film being exposed at one and the same time.
 

ErikKaffehr

Well-known member
What I have never fully understood is why a focal shutter can operate without the issues of rolling shutter especially on longer exposures.

Paul C
Hi Paul,

FP shutters have 'rolling shutter effects', it is just that they move much faster. At sync speed and slower the shutter is fully open. So, long times never yield rolling shutter. Short shutter times will have rolling shutter effects, but the subject will not move a lot in say 1/250s or 1/125s.

ES is much slower, more like the 1/20s - 1/1s range in sweep time, so subject movement will have a much greater effect.

Best regards
Erik
 

Boinger

Active member
The simplest way to think about it is.

If the es on the iq3 was able to read each line at 1/500th of a second it would be no different then a 1/500th mechanical fp shutter.

The issue is the slow readout of the iq3 not the nature of the shutter.
 

dougpeterson

Workshop Member
The simplest way to think about it is.

If the es on the iq3 was able to read each line at 1/500th of a second it would be no different then a 1/500th mechanical fp shutter.

The issue is the slow readout of the iq3 not the nature of the shutter.
If I could suggest a minor revision to your otherwise very elegant statement...

An IQ3 or IQ4 with ES can read each line at 1/500th. That is, any individual line can start and end its exposure in 1/500th of a second. It is the time it takes to start the reading of all lines that is the limitation. The last line cannot start reading 1/500th of a second after the first line starts reading, which is the reason for the pronounced rolling shutter effect on objects moving quickly inside of the frame. So to revise your quote slightly:

If the es on the iq3 was able to start all lines reading in 1/500th of a second it would be no different then a 1/500th mechanical fp shutter.
 

Paul2660

Well-known member
Would that not be in effect a global shutter. All lines read at once at 1/500 of a second. Or any selected shutter speed.

Paul C
 

MGrayson

Subscriber and Workshop Member
If I could suggest a minor revision to your otherwise very elegant statement...

An IQ3 or IQ4 with ES can read each line at 1/500th. That is, any individual line can start and end its exposure in 1/500th of a second. It is the time it takes to start the reading of all lines that is the limitation. The last line cannot start reading 1/500th of a second after the first line starts reading, which is the reason for the pronounced rolling shutter effect on objects moving quickly inside of the frame. So to revise your quote slightly:

If the es on the iq3 was able to start all lines reading in 1/500th of a second it would be no different then a 1/500th mechanical fp shutter.
To be precise, it is the shutter flash sync speed - the time it takes one curtain of the shutter to traverse the sensor - say, 1/125 sec - not the exposure time or the time to read out a single line that determines the amount of rolling shutter effect.

--Matt
 

dougpeterson

Workshop Member
To be precise, it is the shutter flash sync speed - the time it takes one curtain of the shutter to traverse the sensor - say, 1/125 sec - not the exposure time or the time to read out a single line that determines the amount of rolling shutter effect.

--Matt
A good way of thinking of it, yes.
 
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