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09-18-2010, 01:03 PM   #1
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P-ttl-2.0

here have been a few theories as to why Pentax does not sync faster than 1/180th.
The most popular being that its something to do with the SR system.

Here are my theory.
firsly, lets list cameras from Pentax that sync wit P-TTL.
MZ-S 1/180th
Ist D 1/150th
Ist DS 1/180th
Ist DL 1/180th
K100/110D 1/180th
K10D 1/180th
K20D 1/180th
K-7 1/180th
K-x 1/180th
K-r ?
K-5?

The fastest Pentax Sync camera to date is the PZ-1 and PZ-1p that can sync at 1/250th and have a shutter speed of 1/8000th.... They are TTL only and were released in 1990 ish and 1995 ish of the top of my head.

There was a report by someone that the K-5 will also have 1/180th to begin with, but with a firmware update would take NEW flashes with 1/250th.

Someone also said that the K-7 is capable of faster sync but there was something to do with the currant flashes!!! Which is not true as I have a 540 that syncs at 1/250th with my PZ-1p!!!!

It strikes me that 1/180th is an od number to sync to, why was it even this with MZ-S? and the K-7???? and why would someone say its something to do with the flashes itself..... and why would the K-7 be able to sync faster? and why could a firmware be able to make the K-5 sync faster......
Well.
Its P-TTL
P-TTL Version 2.0 around the corner???

If the limitation is in the old flash hardware/software then only a new system will be able to sync faster than 1/180th. I think that Pentax did not allow faster sync with TTL and manual flashes because that would make the P-TTL system look terrible.
Well. I think PTTL2 is near!
Can anyone shed some light.

09-18-2010, 01:31 PM   #2
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I don't buy the SR theory. The first digital SLRs did not have SR, and I doubt Pentax was sure they would add it later on. So, why they should have chosen 1/180th then?
09-18-2010, 01:58 PM   #3
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K-r 1/180 sec
The joke overall is,before the K-7 was in all News and on the homepage,i saw the information bruchure and there was the x time 1/250sec,but it was strikethrough and 1/180sec was above
any suspicion???
09-18-2010, 02:23 PM   #4
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Original Poster
QuoteOriginally posted by zackspeed Quote
K-r 1/180 sec
The joke overall is,before the K-7 was in all News and on the homepage,i saw the information bruchure and there was the x time 1/250sec,but it was strikethrough and 1/180sec was above
any suspicion???
Really.
Could it be a typo. Or was the strykethrough actually printed.
What I am asking is was it original , or did someone change it with a pen?

09-18-2010, 02:35 PM   #5
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when i remember correct....it was changed with a pen.
but,the k-7 had the old firmware for protos in it and there was AF-AUTO and any other different things.......
09-18-2010, 02:37 PM   #6
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My completely WAG is it's always been possible with the HW, it's just been a SW issue. And Pentax sucks at SW. IIRC the old TTL system simply read the strobe light reflected from the film, and at the proper point sent a kill signal to the flash. Very mature technology that they'd perfected over decades. The change to digital required a complete re-engineering of the process, and I'm going to guess that we've been running the "workable" version of the flash control SW ever since. From Pentax's point of view, it wasn't a high priority, and that's probably pretty valid. The only people that need high speed sync are people working with relatively small lights in high ambient conditions. Lots of photo Luddites don't use flash and pros can usually throw watt seconds at the problem. Sports photographers were left in the cold, but if you are a serious sports photog you probably aren't shooting Pentax unless you're an absolute masochist. But then people discovered other neat things you could do with a small strobe, and 1/180 doesn't really cut it, especially when you're selling lots of a)entry level cameras that b) have a higher baseline ISO. So they finally got around to revising the flash control SW.
09-18-2010, 02:58 PM   #7
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flash sync is limited by the speed of the shutter, or by the presence of an -electronic shutter.
the shutter has leading and trailing curtains, the sync speed is the fastest shutter speed that the shutter can do without having to start the trailing curtain before the leading curtain has reached the end of the sensor, ie if that happens then the whole sensor will not be exposed at once and if the flash fires when the whole sensor is not exposed then there will be a dark stripe where the curtain was. This is common knowledge about sync speed and there are many descriptions on this. it wouldnt make sense to not trigger the x sync port and the center hotshoe pin at a faster speed if it was available.
09-18-2010, 02:58 PM   #8
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Well, as far as I am concerned, the sync speed is not the problem (I never felt at a loss for performance with 1/60sec back in the TTL film days, and 1/180 is twice as fast). I can see that there may be some concerns about ghosting at 1/180 still, but I think that would be a rare occurrence, or only a problem for a select group of shooters (the mentioned sports photographers).

The problem I have experienced is exposure errors. I almost always have to dial in -1/3 to -1 flash compensation to get a good exposure, and it seems entirely inconsistent, so I can't just assume a given compensation value for a given shooting situation. I would like to see vastly improved flash metering in P-TTL v 2.0 regardless of the sync speed.

09-18-2010, 03:02 PM   #9
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QuoteOriginally posted by and Quote
flash sync is limited by the speed of the shutter, or by the presence of an -electronic shutter.
the shutter has leading and trailing curtains, the sync speed is the fastest shutter speed that the shutter can do without having to start the trailing curtain before the leading curtain has reached the end of the sensor, ie if that happens then the whole sensor will not be exposed at once and if the flash fires when the whole sensor is not exposed then there will be a dark stripe where the curtain was. This is common knowledge about sync speed and there are many descriptions on this. it wouldnt make sense to not trigger the x sync port and the center hotshoe pin at a faster speed if it was available.
So what you're saying is, Pentax is putting a slower/less capable shutter in the K-7, of 2010, than they were putting in the PZ-1P, of 1999?
09-18-2010, 03:16 PM   #10
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QuoteOriginally posted by junyo Quote
So what you're saying is, Pentax is putting a slower/less capable shutter in the K-7, of 2010, than they were putting in the PZ-1P, of 1999?
Yeah, I really don't get it either. The shutter is definitely the thing that limits sync speed. Flash strobe duration is usually somewhere between something like 1/50,000 sec for preflash and fill flash in some applications to 1/1000 sec for full flash. There is no reason the strobe unit should have an impact on sync speed. The rumored 1/180 or 1/250 sync speed with certain strobes on the K-5 sounds like a firmware trick to force us to buy more expensive P'tax brand strobes if we want the 1/250 sec sync speed.
09-18-2010, 04:32 PM   #11
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QuoteOriginally posted by jon.partsch Quote
Yeah, I really don't get it either. The shutter is definitely the thing that limits sync speed. Flash strobe duration is usually somewhere between something like 1/50,000 sec for preflash and fill flash in some applications to 1/1000 sec for full flash. There is no reason the strobe unit should have an impact on sync speed. The rumored 1/180 or 1/250 sync speed with certain strobes on the K-5 sounds like a firmware trick to force us to buy more expensive P'tax brand strobes if we want the 1/250 sec sync speed.
My conjecture is, shutter speed is one of the things, but not the only thing that limits sync in a modern system. With a TTL flash, you're doing more than simply communicating the sync signal. And while it's a valid point that if higher speed was available why would they make it available, here's just as valid of a question: Why go through the trouble of disabling the center pin above X sync? That's a SW choice, and it makes me think that it works, just not as consistently as they wanted. Maybe some comm or timing issue when they were making the P-TTL system. Maybe that's why it's not super consistent? And rather than fix it initially, they slowed down the com, said, "1/180 is max", giving the system plenty of buffer time, and called it a day. Maybe that why new flashes are required to exploit it? Maybe (probably) this is all wrong.

Pocket Wizard had a chart on their site showing Canon's flash system, and how much slop there was in the timings, even at a higher sync speed, and how they're wringing better efficiency out of FP sync on that system with more precise timings. That also makes me think Pentax can do a lot with SW tweaks.
09-18-2010, 06:18 PM   #12
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QuoteOriginally posted by junyo Quote
Pocket Wizard had a chart on their site showing Canon's flash system, and how much slop there was in the timings, even at a higher sync speed, and how they're wringing better efficiency out of FP sync on that system with more precise timings. That also makes me think Pentax can do a lot with SW tweaks.
okay, I can buy that there is probably some slop in the communication timings between camera and flash, and possibly within the circuitry of each, but I have a hard time with that when third party manufacturers (metz, ect.) can basically make one model of flash and adapt it to each camera manufacturer's digital TTL sync speed. This makes me think that any communication slop must be within the camera, and this should be solvable (is that a word?) with software/firmware - especially in the case of the K-5. If the hardware is there to allow 1/250 sec sync, then I don't see why it can't or shouldn't be made to sync at that speed with ANY existing P-TTL strobe.
09-19-2010, 12:58 AM   #13
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QuoteOriginally posted by jon.partsch Quote
\

The problem I have experienced is exposure errors. I almost always have to dial in -1/3 to -1 flash compensation to get a good exposure, and it seems entirely inconsistent, so I can't just assume a given compensation value for a given shooting situation. I would like to see vastly improved flash metering in P-TTL v 2.0 regardless of the sync speed.
This is my biggest complaint. Clipped highlights are rather annoying. Sometimes -2 doesn't even prevent it and I have to go into manual mode.
09-19-2010, 02:16 AM   #14
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QuoteOriginally posted by jon.partsch Quote
The problem I have experienced is exposure errors. I almost always have to dial in -1/3 to -1 flash compensation to get a good exposure, and it seems entirely inconsistent, so I can't just assume a given compensation value for a given shooting situation. I would like to see vastly improved flash metering in P-TTL v 2.0 regardless of the sync speed.
The situation you describe is with your K110D? If so, I can say the K-7 is whole lot better. It may not be perfect, sure, but a lot better.

The problem isn't really PTTL, that just a flash protocol. The metering is done by the same meter as the non-flash exposure (TTL had its own meter which was Center weighted btw, no multizone). And it worked so-so with their old metering. The 77 zones metering of K7 manage a lot better.

Now PTTL would be improved/tweaked for: higher X-sync and allow Nikon-like features (ratio between flashes etc.) but it would probably make present flashes incompatible or at least incapable of newest features.
09-19-2010, 02:38 AM   #15
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Seriously, sync speed has nothing to do with *TTL. All communication between flashes are done before the camera opens its shutter. If it would send data flashes during the exposure you would have (slight) inaccuracy in the exposure itself. I can't believe Pentax would have made such a weird design in the first place.

And my usual rant: Those who need higher sync speeds use their flashes in manual mode, either hotshoe flashguns or studio strobes. If Pentax would present 1/250 sync as P-TTL only they have effectively killed all potential studio/portrait/strobist buyers.
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