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10-26-2013, 12:53 AM   #46
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QuoteOriginally posted by GeneV Quote
Exactly. In my experience, the difference in the ability to freeze action between 1/180 and 1/250 is seldom significant nor is the half stop, but I suppose in that instance... Neither of those speeds would really freeze serious movement, and both would do a pretty good job on a subject which wasn't exactly standing still, so we are really talking about a pretty narrow window of subjects needing a flash, but with ambient light, where 1/180 is not enough but 1/250 really hits the spot.

Now, if we get into sync speeds like the older Nikons which are in leaf shutter territory (1/500), then we have a real action-stopping capability. (IMO) For some reason, even Nikon is dialing those speeds back in newer models.
That technology (switching sensor off rather than 2nd curtain )belong in PS and CCD large CMOS sensors will not switch off cleanly.

So you get jello effect and why Nikon dropped it once CMOS became the preferred tech.

10-26-2013, 02:03 AM   #47
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QuoteOriginally posted by awaldram Quote
The 58 has a bug so is not usable for HSS controller/master so unless you have a Pentax flash as well you cannot do HSS off camera, seem harsh to blame Pentax for a Metz bug ?
I was only describing the use of p-TTL HSS with the Metz as itself mounted on the hotshoe, not as a master/controller, so nothing to do with the bug.

QuoteOriginally posted by awaldram Quote
This image has nothing to-do with HSS or even shutter, It's a straight flash shot so is about Power and T.1 of the flash, answering you followup question
t.1 is directly proportional to the power required and depends on model you Metz manual will have a table to show .
but here is a couple
Metz 58 1:1 1/125
pentax 540 1:1 1/750
Once either flash is not powering flat out you into 1/10,000 or better .
Thanks for the explanation. Also, what do you mean by straight flash shot? Mounted on the cam, or fired with regular sync? In my earlier post, I meant that it was mounted on cam, with the flash head locked facing forward

I have a friend who has the AF360, Will try that out though I am not sure if the Pentax (as master) and Metz flashes can communicate (since you said the Metz won't work as master I'll try it the other way around).
10-26-2013, 02:31 AM - 2 Likes   #48
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The X speed of any DSLR camera is the fastest shutter speed you can use when all the sensor is exposed, on a Pentax it's 1/180th of a second. Other cameras can manage 1/250th of a second, and it matters. Faster shutter speeds than that are by releasing the second curtain before the first curtain has reached the bottom of the frame. At high speeds you have a 'slit' of light travelling over the sensor, if you fire a flash during these faster shutter speeds you will get a 'slit' of light across just part of the image.

One limited answer to this is High Speed Sync, here the flash fires multiple times as the second curtain traverses the sensor. Unfortunately you have to reduce flash power to 'strobe' the flash this way so the effective range of the flash is reduced, the faster the shutter speed selected, the more times the flash has to fire, the lower the light output per flash.

As the need for a faster shutter speed is usually in bright light when you want the flash to fill in the shadows cast by a bright Sun the last thing you want is reduced flash power especially if you want to use a wide aperture for DOF reasons. So it's only a limited answer.

The only way around this is to use ND filters reducing the light entering the camera, so the camera will have to use a slower shutter speed, I use a variable ND filter adjusted so the ambient will give me 1/180th of a second then take the shot as normal, but it is a workaround not really a solution. Outdoor fashion photography or portraiture the 1/180th of a second X speed is a real limitation.

The shot of the rugby player is a 'red herring'. Here the photographer is using the very fast flash duration to 'freeze' the action in totally dark conditions (no ambient). Xenon tubes always fire at full power, correct exposure is achieved by altering the duration of the flash by 'quenching' the flash tube. Even on full power the flash duration is only around 1/800th to 1/1000th of a second, on lower powers it's even faster, on my Metz at 1/128th power it's only around 1/30,000th of a second, on my manual ring flash at 1/256th power it's 1/50,000 of a second, measured on my oscilloscope. Fast enough to freeze a bullet passing through an apple. It's the way high speed photography works.

Chris
10-26-2013, 03:52 AM   #49
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QuoteOriginally posted by ChrisJ Quote
Even on full power the flash duration is only around 1/800th to 1/1000th of a second, on lower powers it's even faster, on my Metz at 1/128th power it's only around 1/30,000th of a second, on my manual ring flash at 1/256th power it's 1/50,000 of a second, measured on my oscilloscope
This is correct if you're talking about speedlights or other flashes where the output is controlled by IGBT. If you use typical variable voltage controlled studio monoblocks, you're gonna get the shortest flash at full power (how short it is depends on the combination of capacitor size, flash tube speed and the quality of both elements) which gets longer as the power goes down.
My hybrid Bowens monoblocks, which use the capacitor switching method combined with voltage varying have three main settings with three different flash durations (t.5) at 1/1:
1/3250s (250w/s)
1/2240s (500w/s)
1/1700s (750w/s)
On each setting the flash duration gets longer as the power goes down.
There are flash systems (power pack and heads) where the flash output is controlled completely by the capacitor switching.

10-26-2013, 04:22 AM   #50
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QuoteOriginally posted by jaad75 Quote
This is correct if you're talking about speedlights or other flashes where the output is controlled by IGBT. If you use typical variable voltage controlled studio monoblocks, you're gonna get the shortest flash at full power (how short it is depends on the combination of capacitor size, flash tube speed and the quality of both elements) which gets longer as the power goes down.
My hybrid Bowens monoblocks, which use the capacitor switching method combined with voltage varying have three main settings with three different flash durations (t.5) at 1/1:
1/3250s (250w/s)
1/2240s (500w/s)
1/1700s (750w/s)
On each setting the flash duration gets longer as the power goes down.
There are flash systems (power pack and heads) where the flash output is controlled completely by the capacitor switching.
Studio strobes are different, they alter output by altering the charge in the capacitor, and, as you say, have the longest flash duration at lower powers, I've known them to go down to as slow as 1/60th of a second flash duration (older models), the more powerful the flash the longer flash duration at low powers tends to be, then the Pentax X speed of 1/180th is too fast and the shutter will close before the exposure from the strobe is finished. They work the opposite way to flashguns (UK), speedlights (US).

Chris

Last edited by ChrisJ; 10-26-2013 at 04:29 AM.
10-27-2013, 05:10 PM   #51
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QuoteOriginally posted by ChrisJ Quote
The X speed of any DSLR camera is the fastest shutter speed you can use when all the sensor is exposed, on a Pentax it's 1/180th of a second. Other cameras can manage 1/250th of a second, and it matters. Faster shutter speeds than that are by releasing the second curtain before the first curtain has reached the bottom of the frame. At high speeds you have a 'slit' of light travelling over the sensor, if you fire a flash during these faster shutter speeds you will get a 'slit' of light across just part of the image.

One limited answer to this is High Speed Sync, here the flash fires multiple times as the second curtain traverses the sensor. Unfortunately you have to reduce flash power to 'strobe' the flash this way so the effective range of the flash is reduced, the faster the shutter speed selected, the more times the flash has to fire, the lower the light output per flash.

As the need for a faster shutter speed is usually in bright light when you want the flash to fill in the shadows cast by a bright Sun the last thing you want is reduced flash power especially if you want to use a wide aperture for DOF reasons. So it's only a limited answer.

The only way around this is to use ND filters reducing the light entering the camera, so the camera will have to use a slower shutter speed, I use a variable ND filter adjusted so the ambient will give me 1/180th of a second then take the shot as normal, but it is a workaround not really a solution. Outdoor fashion photography or portraiture the 1/180th of a second X speed is a real limitation.

The shot of the rugby player is a 'red herring'. Here the photographer is using the very fast flash duration to 'freeze' the action in totally dark conditions (no ambient). Xenon tubes always fire at full power, correct exposure is achieved by altering the duration of the flash by 'quenching' the flash tube. Even on full power the flash duration is only around 1/800th to 1/1000th of a second, on lower powers it's even faster, on my Metz at 1/128th power it's only around 1/30,000th of a second, on my manual ring flash at 1/256th power it's 1/50,000 of a second, measured on my oscilloscope. Fast enough to freeze a bullet passing through an apple. It's the way high speed photography works.

Chris
Excellent explanation, thank you. I don't use flash outside so this issue has never affected me. I still have one question though. The issue seems to be that Pentax only allows 1/180 but other cameras allow 1/250. Is that difference really going to make a difference in most shots? I can see if it was 1/500 or 1/1000 we are asking for to stop motion but the increase of just a partial stop? Not my area of experience so I'm just asking.
10-28-2013, 06:06 AM - 1 Like   #52
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QuoteOriginally posted by jatrax Quote
Excellent explanation, thank you. I don't use flash outside so this issue has never affected me. I still have one question though. The issue seems to be that Pentax only allows 1/180 but other cameras allow 1/250. Is that difference really going to make a difference in most shots? I can see if it was 1/500 or 1/1000 we are asking for to stop motion but the increase of just a partial stop? Not my area of experience so I'm just asking.
When taking pictures with flash you (usually) have two light sources so your taking two exposures simultaneously, the exposure for the ambient component and the exposure for the flash component. How you blend the two is the Art of flash. photography.

In a studio there's no problem because the ambient component is usually low, so the shutter speed for correct exposure for the ambient will be below the 1/180th of a second 'X' speed, all is well. But out of doors when the ambient light level is high and the exposure for the ambient light is faster than 1/180th we have a problem, often the 1/3rd stop faster shutter that 1/250th gives you makes all the difference especially if you want to use a wide aperture for DOF reasons, the low Pentax X speed limits the f stop you can use and therefore the DOF.

In the K5 there is 80 ISO which, I believe, was included for this reason, 80 ISO is noisy, a lot noisier than 1600 ISO (try it), but it's the equivalent of fitting an ND1.5 (approx) filter, so the ambient exposure shutter speed is that little bit slower from the exposure shooting 100 ISO, it's the difference between 1/180th and 1/250th, no accident I think. The new K3 doesn't have this.

I know it sounds like splitting hairs, but to a Pro shooting fashion shots out doors day in and day out it really does matter, it does (slightly) compromise your shots.

Chris
10-28-2013, 06:12 AM   #53
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Er, ISO 80 is noisier than ISO 1600? I don't own a k-5, but everyone else I've read on the forum have said that ISO 80 is less noisy than ISO 100...

Also, I don't think we know for sure if the k-3 doesn't have ISO 80? The only confirmed ISO values are the non-expanded ISO, from what I've seen on the reveals.

10-28-2013, 06:32 AM   #54
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QuoteOriginally posted by ChrisJ Quote
I know it sounds like splitting hairs, but to a Pro shooting fashion shots out doors day in and day out it really does matter, it does (slightly) compromise your shots.
Do we know anyone like that? Why would a pro shooting fashion shots day in day out be using a $1300 camera. Is there even enough outdoor fashion venues to shoot fashion outdoors day in day out? Who is the magical photographer who has to have this 1/3 of a stop?
10-28-2013, 06:40 AM   #55
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So, the Pentax photo might be overexposed by 1/3 of a stop vis-s-vis some camera with a 1/250 sync speed? I'm sorry, but that may have made a discernible difference in the days of colour slide film, but I'm not convinced it would be much of a problem with a RAW file. I accept that the difference in speed may make be helpful when the subject is moving, and there is a need to freeze the action somewhat, but a fashion shoot? I can't believe that any photographer worth their salt couldn't work around a 1/3 of a stop difference in shutter speed.
10-28-2013, 06:46 AM   #56
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QuoteOriginally posted by Cynog Ap Brychan Quote
So, the Pentax photo might be overexposed by 1/3 of a stop vis-s-vis some camera with a 1/250 sync speed? I'm sorry, but that may have made a discernible difference in the days of colour slide film, but I'm not convinced it would be much of a problem with a RAW file. I accept that the difference in speed may make be helpful when the subject is moving, and there is a need to freeze the action somewhat, but a fashion shoot? I can't believe that any photographer worth their salt couldn't work around a 1/3 of a stop difference in shutter speed.
I can't believe any photographer worth his salt couldn't underexpose a full stop and get away with it...I here what the guy is saying, but like the famous one stop difference in noise between ISO 200 and 400, I want to see some images that illustrate what he's talking about. I suspect this is more a case of 1/250 is available so i have to have it more than 1/180 doesn't work... but hey, I hardly ever use flash, so no one should care what I think.

But folks need to ask themselves, if 1/250 flash sync didn't exist, would that affect my work? Or even can I tell the difference between a photo taken at 1/180 and one taken at /250? I suspect an honest answer might be hard to come by though.

SO if you can, post an example. I'd love to see it.
10-28-2013, 07:19 AM - 1 Like   #57
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I wouldn't go that far. If you are working at the limits of light and your equipment, 1/3rd of a stop would make a difference. I don't, so it isn't important to me.

When Pentax announced their WR flash units someone said that they couldn't imagine a situation where a WR flash unit would be required. I was in one yesterday. So to not see a situation where that faster sync speed would make a difference may be a lack of imagination.

And yes, it can be worked around. Photography is in large part working around the limitations of the device we have in our hand.
10-28-2013, 08:09 AM - 2 Likes   #58
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QuoteOriginally posted by normhead Quote
Do we know anyone like that? Why would a pro shooting fashion shots day in day out be using a $1300 camera. Is there even enough outdoor fashion venues to shoot fashion outdoors day in day out? Who is the magical photographer who has to have this 1/3 of a stop?
Well me for one. But the lower X speed of Pentax cameras is a disincentive for Pro's to use them as I'm sure Pentax is well aware of, hence the inclusion of 80 ISO in the K5 (possibly?), what other reason is there for 80 ISO?

Pro's put up with the unreliability of Canon, the expense of Nikon, why they aren't using a $1300 camera that has great image quality, lower noise, is far more reliable, weather resistant etc. etc. is another question you'll have to ask them.

I suggest one answer could be depth of field, if you want full frame and the narrow DOF that goes with it, you have to go with Canikon. The slower X speed limits the narrowness of the DOF as you have to use a (slightly) smaller f stop when using flash, along with the APS sized sensor which widens DOF, it all adds up for people who have to sell their images where narrow DOF can make a difference between your shot being chosen for publication and the next guy's. There are no image quality reasons for full frame anymore, but there are DOF reasons which is why I would love to see a Pentax FF camera. Combine all those things and you can see why Pro's tend to go for Canikons with all their faults and cost. If Canon can manage of 1/500th of a second X speed on their full frame cameras why can't Pentax on their APS cameras, don't they both use Seiko shutter mechanisms?

The opportunity for closing the gap between Canikon and Pentax has been missed - again, it's a small thing, but a few small things add up to a big difference. I hear time and time again from colleagues in the industry that Pentax doesn't cater for the needs of Pro photographers and, to be honest, I have to agree with them, having a few Canikons of my own. That's why Pentaxians on here and in other forums are pulling their hair out year after year, because we know that Pentax make great cameras, good enough to fill the number one slot as they did a few decades ago.

Amateurs want the camera the Pro's use in the mistaken belief that they will be able to take Pro images, wrong we know, but that's how it is, that's why a Pro level camera is necessary in the Pentax line up, the K3, great as it, innovative as it is, is not it, it's these little things like the slow X speed that limit market share for Pentax especially where it counts, in the Pro arena, camera market share is a top down thing, and it's a shame, I'll still buy one though.

Sorry, this turned into quite a rant.

Chris
10-28-2013, 08:25 AM   #59
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QuoteOriginally posted by ChrisJ Quote
When taking pictures with flash you (usually) have two light sources so your taking two exposures simultaneously, the exposure for the ambient component and the exposure for the flash component. How you blend the two is the Art of flash. photography.

In a studio there's no problem because the ambient component is usually low, so the shutter speed for correct exposure for the ambient will be below the 1/180th of a second 'X' speed, all is well. But out of doors when the ambient light level is high and the exposure for the ambient light is faster than 1/180th we have a problem, often the 1/3rd stop faster shutter that 1/250th gives you makes all the difference especially if you want to use a wide aperture for DOF reasons, the low Pentax X speed limits the f stop you can use and therefore the DOF.

In the K5 there is 80 ISO which, I believe, was included for this reason, 80 ISO is noisy, a lot noisier than 1600 ISO (try it), but it's the equivalent of fitting an ND1.5 (approx) filter, so the ambient exposure shutter speed is that little bit slower from the exposure shooting 100 ISO, it's the difference between 1/180th and 1/250th, no accident I think. The new K3 doesn't have this.

I know it sounds like splitting hairs, but to a Pro shooting fashion shots out doors day in and day out it really does matter, it does (slightly) compromise your shots.

Chris
number of errors here
iso80 is the lowest noise setting on the k5 its the point you reach that elusive 14.1 bit DR it the highest Signal to Noise ratio.
Secondly no pro is going to be using a single pocket flashgun , the whole idea is preposterous to my mind.

But even the keen outdoor flash shooter would have it covered considerably better than relying on a 1/3 of a stop

3 x fgz360z will deliver more power @1/1000 in HSS than a single one @1/180

I Metz45Digital will deliver a lot more power in HSS mode than that 1/3rd of a stop in mechanical shutter would gain you Vs fgz540.

I take my flash shooting moderately seriously I can bring a lot of hss flashes into play if I need or indeed want that 'automated' flash approach.!

I'd suggest you have a look at Strobist: Lighting 101 As I think that will go a long way to fixing you 1/250 woes.
10-28-2013, 08:36 AM   #60
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QuoteOriginally posted by normhead Quote
But folks need to ask themselves, if 1/250 flash sync didn't exist, would that affect my work? Or even can I tell the difference between a photo taken at 1/180 and one taken at /250? I suspect an honest answer might be hard to come by though.
I'll give you an honest answer two letters NO

Nobody AFAIN can detect 1/3 or less in exposure variance without side by side comparison.
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