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08-27-2011, 10:02 PM   #31
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QuoteOriginally posted by Philoslothical Quote
rather than just develop one that can illuminate longer at peak luminousity
It may interest you to know that that technology already exists and has for decades. They're called "flashbulbs".

08-28-2011, 10:08 AM   #32
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QuoteOriginally posted by Philoslothical Quote
Brilliant, thanks! So my problem was that I was grossly overestimating the duration of the flash, during any length of exposure.

It's a wonder that they would need to strobe a high speed sync flash rather than just develop one that can illuminate longer at peak luminousity. I gather heat issues and filament longevity would both come into play, but it sounds like it would drastically simplify everything else.

Thanks for your patience on this.
Electronic flashes do not have a filament. They are gas filled tubes that are fired from an electrode in the bulb.
08-28-2011, 01:20 PM   #33
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QuoteOriginally posted by dlacouture Quote
Now I could see a use for an electronic shutter option allowing sync speed up to 1/8000... Say, in the Flash menu, having a new option : normal, HSS, Wireless, and Electronic Shutter.
The new Ricoh GXR Mount actually has the option of electronic shutter up to 1/8000. Yet to see how it will work.
08-30-2011, 05:48 PM   #34
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why they can't make the shutter wait for 1/180s? Problem solved. Sync Speed: 0 second.

08-30-2011, 07:08 PM   #35
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QuoteOriginally posted by feishui Quote
why they can't make the shutter wait for 1/180s? Problem solved. Sync Speed: 0 second.
What?
08-30-2011, 07:10 PM   #36
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QuoteOriginally posted by FullertonImages Quote
Not true at all.

Not all strobe photography is done in a dark room. When shooting action sports outside, you are typically mixing strobes with the constant ambient light. Let's say you're shooting BMX people do backflips, since this is a situation that's I've particularly had trouble with. It's the golden hour and sunset looks good. You want to drop down the ambient light a stop or two, so everything get nice and rich, but not so far that everything goes black. Then you want to add light back in on the BMXer. Problem is, they're moving really fast while they're doing that backflip, and since the constant, ambient light is still part of the exposure, the BMXer is going too fast for 1/180th.

What you end up with is almost a double frame, two seperate exposures. You get a nice sharp image of the BMXer from the flash, but you also have a blurry, ghosted image of the BMXer underneath the sharp one, and makes the whole BMXer look soft. The difference in motion blur from 1/180th to 1/250th is more than you would think, and it makes a big difference in these situations. The only thing you can do otherwise is stop down the ambient light so much that it's not a factor, which a) kills the ambience of the sunset and the golden hour scene, and b) requires huge amounts of watt/seconds.
Absolutely! There must be many of us using external flashes crying out for Ricoh to improve the sync speed of the next Pentax DSLR... If there is a K3 (or whatever) on the way it needs to compete with CaNikon on EVERY level...
08-30-2011, 07:14 PM   #37
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QuoteOriginally posted by feishui Quote
Problem solved. Sync Speed: 0 second
What?!

Drugs much?!
09-01-2011, 12:56 PM   #38
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QuoteOriginally posted by DaveHolmes Quote
What?!

Drugs much?!

I am sorry if it is too confusing for you guys. My understanding is that right now after you click the button, the shutter opens almost at 0s, but the flash can't be activated until 1/180s later. Am I correct?
If this is correct, why they can't let the shutter be released 1/180s after your click? Then the sync speed will be 0s.

Of course you will get a little bit delay for your shot, but 1/180s delay is nothing for a regular shot.

09-01-2011, 01:10 PM   #39
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QuoteOriginally posted by feishui Quote
I am sorry if it is too confusing for you guys. My understanding is that right now after you click the button, the shutter opens almost at 0s, but the flash can't be activated until 1/180s later. Am I correct?
If this is correct, why they can't let the shutter be released 1/180s after your click? Then the sync speed will be 0s.

Of course you will get a little bit delay for your shot, but 1/180s delay is nothing for a regular shot.

You misunderstand how sync speed works.

It does not take 1/180 of a second for the shutter to actuate. The time it takes for the shutter to start actuating is already accounted for in the timing chain.

1/180 is the shortest time that the entire sensor is uncovered. The flash can fire at that speed and not be blocked at all by the shutter curtains. Above 1/180, the shutters move in synchronization to make a slit that moves across the sensor face. If you fire a normal flash when you have a moving slit, you are only going to get a band of the frame that is lit, with the rest of the frame dark.

The shutters that Pentax uses work at 1/180, other camera brands and models have different shutters that have different operating speeds. In addition, many non-Pentax cameras will still trigger the flash above 1/180 so you can use the flash above your sync speed if you want to. Pentax cameras do not do this.
09-01-2011, 01:32 PM   #40
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Sorry guys. Thank you for the excellent explanation.

QuoteOriginally posted by alohadave Quote
You misunderstand how sync speed works.

It does not take 1/180 of a second for the shutter to actuate. The time it takes for the shutter to start actuating is already accounted for in the timing chain.

1/180 is the shortest time that the entire sensor is uncovered. The flash can fire at that speed and not be blocked at all by the shutter curtains. Above 1/180, the shutters move in synchronization to make a slit that moves across the sensor face. If you fire a normal flash when you have a moving slit, you are only going to get a band of the frame that is lit, with the rest of the frame dark.

The shutters that Pentax uses work at 1/180, other camera brands and models have different shutters that have different operating speeds. In addition, many non-Pentax cameras will still trigger the flash above 1/180 so you can use the flash above your sync speed if you want to. Pentax cameras do not do this.
09-02-2011, 10:34 AM   #41
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QuoteOriginally posted by richard balonglong Quote
Man! annoying 1/180sec sync speed! tsk tsk... Yeah, there's the High Speed Sync, but only available on Pentax flash, not available to all external flashes out there. And yeah, we can use an ND filter to stop down. But 1/180sec still isn't enough speed especially with subjects that are fast-moving. Some times, a lot of photographers want to shoot at f/2.8 or larger aperture then wanted to use a flash to lit those unwanted dark shadows and at the same time to eliminate motion blur. Other brands has a sync speed of 1/250sec., but still not enough. A 1/500sec. would be a great sync speed like the old Nikon D70s has. :ugh:
Anyway, I hope that Ricoh would improve the sync speed of Pentax cameras, if not, at least give more adjustment of the flash's power like from 1/1 down to 1/128 (for built-in flash)...
Flash sync is a function of 2 things, the shutter, and also the flash. I have a PZ-1 which has a 1/250 sync shutter so I have always wondered why the DSLRs have a slower sync, when you consider that the shutter does not have to move as far, so that even the same blade speed could and should result in an increase in sync speed.

However, I have also noticed that some flash shots taken with my *istD and AF500FTZ in TTL mode are much crisper and show less blurr than the AF540FGZ (also in TTL mode when using the same lens and shooting conditions.

this leads me to think that the AF540 FGZ has a much longer flash duration for the same power output. I.e. not as bright a flash but longer to get the exposure.

This is somewhat confirmed by the fact that in full power at 1/180 the AF540FGZ produces a slight dark band across the bottom of the image on a K10D suggesting that the flash duration at full power is actually a little longer than the full frame open time of the camera.

What I suspect is really happening, is that because photos are free (relitively) with a DSLR, pentax is being a little conservative on shutter speed, and flash power because people will take morephotos than they did on film.

In my case, with film, I took about 21K images spread over 3 cameras, in a 22 year period. In digital, in not quite 8 years I am at a little over 40K images.

I am not by many standards a high volume shooter, and my current shooting rate is about 7K per year, and is 5 K per year average since going digital. on film, my average shooting rate over 22 years was about 900 shots per year.
09-03-2011, 08:35 PM   #42
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QuoteOriginally posted by feishui Quote
I am sorry if it is too confusing for you guys. My understanding is that right now after you click the button, the shutter opens almost at 0s, but the flash can't be activated until 1/180s later. Am I correct?
Although it's been explained above, I'd also suggest you go back to page 1 of the thread and have a look at the Youtube video I posted; it does a really good job at explaining flash and shutter synchronisation.
09-04-2011, 06:04 AM   #43
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QuoteOriginally posted by feishui Quote
I am sorry if it is too confusing for you guys. My understanding is that right now after you click the button, the shutter opens almost at 0s, but the flash can't be activated until 1/180s later. Am I correct?
If this is correct, why they can't let the shutter be released 1/180s after your click? Then the sync speed will be 0s.

Of course you will get a little bit delay for your shot, but 1/180s delay is nothing for a regular shot.
No, the way the shutter works is as follows, relitive to flash.

the leading curtain moves, and opens fully, at this instant in time, the flash triggers when the sensor is fuly un covered. a short time later, the trailing curtain moves and begins covering the frame.

the travel time of the leading and trailing curtains are the same, so that no difference in exposure occurres on the frame, but the total 1/180th of a second is actually the travel time of the curtain, plus the time the frame is fully open.

1/200 (i use this because it gives round numbers) means that any one point of the sensor is uncovered fully for 5mS, in simple terms this could be split 2.5 mS transit time and 2.5mS full open time.

Above sync speed, the full frame is never completely uncovered at any time, the trailing curtain begins moving before the leading curtain reaches the other side of the frame, As a result, you get a "slit" that moves across the frame, travelling at the speed of the curtain, but getting narrower as shutter speed increases further.
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