Electronic 'Shutter' - Why not?

[FlyingPete]

I was reading a rant from an N**** user who was singing their praise over our faithful Canons singly due to the higher flash sync speed available (he says that FE is a waste of time and space for a number of reasons).

Anyway in order to achieve this, apparently N**** uses a 'electronic shutter' at higher speeds that effectively opens the mechanical shutter, then takes a snap of the data from the sensor for a given period of time (eg 1/500s). Now this is how I understood the non SLR digicams worked as well.

Why can't they do this all the time, and why does Canon not to this. The net result as I see it, the removal of a mechanical component, and higher potential shutter speeds and flash sync.

[Longwatcher]

Just guessing off the top of my head that they are using a Sony P&S sensor instead of a DSLR sensor so don't have a choice.

I can't remember the reason but I am pretty sure there is a real reason why a mechanical shutter covering the Sensor is better, but I could be remembering wrong.

[CyberDyneSystems]

The original 1D used a combination of a "real" shutter and electronic one.. (in this case when we say electronic shutter we don't mean a shutter at all.. we mean "blacking out" the CCD) ...this is why the 1D was as fast as any Nikon ever was at flash synch speeds.

This is also why any current Nikon CCD eqipped camera boasting a 1/500th flash synch is using technology and Ideas borrowed from 5 year old Canon technology found in the 1D.

The argument for faster flash synch speeds from the Nikon owners is essentially a funny way of making an inherently bad feature into a good one...

How so? you ask....

The answer lies in WHY an electronic shutter is not an option in the more recent Canon pro DSLR offerings.

CMOS... is not currently fast enough to be up to the task of behaving like a shutter with it's own strobing effect like the CCD was...

What? this sounds like more bad news for Canon to you?

well read on...

CCD,.. which does have it's advantages.. is conducive to being used to strobe on and off creating this shutter effect,.

Again.. sounds better for Nikon?

Well here's the rub.

CCD Does NOT scale to as large a sensor or as high a pixel density with the robustness that a CMOS does..

You'll note that Nikon's high speed CCD/shutter offering was the D2H at only 4MP (like the 1D) when the 1D MkII released at the same time was double that at 8MP+...

To acheive an affordable,reliable 1.3Crop 8.2MO sensor.. Canon literally HAD to use CMOS as opposed to CCD.

So Nikon owners may brag that there CCD equipped cameras have faster flash synch.. but they gain this faster synch speed by sacrificing CMOS technology,. larger sensor sizes,.. and more MP.

Essentially there gain in Flash synch is a result of using the less scalable tech of the CCD... a sacrifice that most Sports shooters were not willling to go along with.. hence even more Nikon owners switching to the 1D MkII for sports as opposed to going digital with the D2H.

In a nutshell,. Nikon has been behind the curve in Sensor development,. they have been stuck using CCD which limits them to smaller sensor sizes and lower resolution. (you will note Nikon has no full frame sensors and there new high MP D2X will be equipped with there first CMOS sensor as a CCD was not viable for 12MP)

A pleasant side effect in retaining dedication to the old CCD has been the ability to maintain the higher synch rate of the D2H.

Is higher flash synch worht remaining limited to 4 or 6MP at fractional frame sensor sizes?


Not to me.. ;)

[scottbergerphoto]

Very interesting CDS! Thanks.
Scott

[PacAce]

Just one question. What's the big deal about a higher sync speed anyway? It's only twice faster than the Canon's. What am I missing? ???

[FlyingPete]

Hey CDS, nice explanation! I suppose the fact that the CMOS sensor cannot 'strobe' at high speed, is one of the many reasons you will never see a movie mode in a Canon DSLR!

Just one question. What's the big deal about a higher sync speed anyway? It's only twice faster than the Canon's. What am I missing? ???

Here is the blurb from the article I read:

Sync speed is the only important shutter specification. Top (unsynced) speeds are irrelevant; no one ever shoots above 1/2,000; pros just shoot slower film for better color when we get that much light. On the other hand, flash sync speed is the fastest shutter speed you can use with flash, period. 1/250 is not what we want and 1/125 is out of the question. 1/500 to 1/1,000 is where we want to be able to shoot since we use fill flash all the time, especially in daylight. The need for speed is obvious to action shooters. Less obvious is that fast sync speeds enable more efficient use of flash power and are often required for successful fill flash use in direct sunlight. Ever wonder why you see a flash mounted on every pro's camera in broad daylight? It's because fill flash improves most daylight photos and a fast sync speed is usually required to balance successfully with direct sunlight.

Later on, on FP Flash:

Marketing departments like to push the "FP" trick flash modes that seem to let you sync at any speed, even 1/8,000. This doesn't count as far as I'm concerned. I explain FP modes here. Canon calls this "High Speed Sync" and I forget what Sigma and others call it. It is not a substitute for genuine fast sync speeds.

Any finally why:

Stopping Motion
Depth of Field Flexibility
Maximum Flash Range
Flash Battery Life
Flash Recycle Time
Maximum Frame Rate
Buffer Depth
Allows Use of Smaller Flashes


The whole article can be found here:
http://www.kenrockwell.com/tech/syncspeed.htm

[pradeep1]

Go figure it was a Ken Rockwell quote that started this thread. Good ol' Ken. He can rile up Canon users pretty well with his "observations". :rolleyes:

My personal opinion of him is halfway between "makes sense" and "full of sh*t". :p

[CyberDyneSystems]

I could go on for hours.. but I'll just tackle the first statement to illustrate the point;;

Sync speed is the only important shutter specification.

er.. not to the many thousands of photographers how don't use or care about flash at all,. never mind high speed synch....
On the very rare occasions that I use flash.. I can get my 550EX to synch WAAAAAAY past 1/500th on the MkII with HS synch option.. but you know what? I have never used it for faster than 1/125th

Anyway.. pretty much everything he says is a blatant generalisation based on his own SPECIFIC taste and use,.. that he somehow has mistaken for the only way anything and everything in photography should be done.

A "My way or the Highway" kind of guy.

I suppose it would make sense if there was only one road to chose...

[timmyquest]

Shooting at 1/500 is fairly worthless.

Perhaps not worthless, but rarely used.

[DaveG]

Shooting at 1/500 is fairly worthless.

Perhaps not worthless, but rarely used.


If you do a lot of work where you are trying to fill flash then a high synch speed is extremely useful from the perspective that you get much more control. With 1/60 of a second synch I would be forced to use 1/60 @ f22 if the subject was in bright daylight and I was using ISO400. With a synch speed of 1/500 I have the choice of f22 to f8. I could also use the lens at f11 and then control how bight the background could be, making the sky behind a bride and groom deep blue rather than a washed out blue.

Now 1/250 synch gets me there. It'd be nice to have 1/500 but I'm not going to die without it.

[Belmondo]

This is a very interesting thread. For me, flash photography remains in the realm of 'black art.'

[Andy_T]

With 1/60 of a second synch I would be forced to use 1/60 @ f22 if the subject was in bright daylight and I was using ISO400. With a synch speed of 1/500 I have the choice of f22 to f8.


Why would you not just set your ISO to 100 ???

Best regards,
Andy

[DaveG]

Why would you not just set your ISO to 100 ???

Best regards,
Andy

I would in most cases. That's why 1/250 is fine.

[alan sh]

Ken said "1/500 to 1/1,000 is where we want to be able to shoot since we use fill flash all the time, especially in daylight"

Sorry - but if we are using fill flash, the assumption is the light is low(ish), so shutter speed will not be that fast. 1/250th is plenty.

If you are using fill flash on a nice sunny day, why ?

[robertwgross]

If you are using fill flash on a nice sunny day, why ?

To reduce the harshness of shadows.

---Bob Gross---

[timmyquest]

I cant imagine high speed sync ever causing problems for using a flash to fill the shadows. Maybe i'm wrong as i've not really done it. But uhh...yeah

[Jim Larson]

I use high speed sync.

Try an outdoor portrait with a 50/1.8 set at F1.8 and ISO 100. . . .If the subject is wearing a hat, you will need the flash to fill in the face.

Shutter speed will move right up to 1000 or 2000 because you are shooting wide open and trying to blur out the background. This is where high speed sync comes in. The unfortuante part is that high speed sync reduces flash output. . so your subject needs to be relatively close. . . .

[FlyingPete]

I use high speed sync.

Try an outdoor portrait with a 50/1.8 set at F1.8 and ISO 100. . . .If the subject is wearing a hat, you will need the flash to fill in the face.

Shutter speed will move right up to 1000 or 2000 because you are shooting wide open and trying to blur out the background. This is where high speed sync comes in. The unfortuante part is that high speed sync reduces flash output. . so your subject needs to be relatively close. . . .


The flash has to also do a surprising lot of hard work doing fill on a bright day, considering how bright the sun is! I know most of the time my internal barely does the job and usually only really close up.