Pre-Flash Issue or Non-Issue -please email KM here.

[Videoguy]

But look, he is ignoring your post too.

I think it's clear enough now .....

Who's ignoring. I'm spending too much time here as it is, so eventually I'm going to have to start ignoring more of the stupid posts.

See if this is clear to you:

KM 5D 129 to 145ms delay
Canon Rebel 68 to 70ms delay
Human blink reflex to light 105 to 135ms delay.

Doesn't get much clearer than that.

 

[RichV]

I've got a feeling KM is investigating lots of issues around flash - I do believe KM SEA when he writes about a new flash unit coming in 2006; the flash line is ready for modernization (if they get it right, it'll be the flash of choice for their cameras). The people that read your input via the KM US web site have no real input to what's developed/fixed - it's Japan that makes the decisions, so write to them if you feel the need. Maybe the best you can hope for is that somebody keeps an eye on forums - this forum must be getting some attention, because it seems to be morphing from a place where the main aim was sharing, evaluating, and appreciating pictures and techniques to something that I won't bother to name, just because it might set off another round. (Okay, this next is a little OT) Although not many will read it, it would probably help to review Ken Rockwell's (satirical) 7 levels of photographers:

http://www.kenrockwell.com/tech/7.htm

Rich

 

[Videoguy]

I've got a feeling KM is investigating lots of issues around flash

• I do believe KM SEA when he writes about a new flash unit coming

in 2006; the flash line is ready for modernization (if they get it
right, it'll be the flash of choice for their cameras).

I hope you are right, and this is what I'm counting on.

this forum must be
getting some attention, because it seems to be morphing from a
place where the main aim was sharing, evaluating, and appreciating
pictures and techniques to something that I won't bother to name,

Exactly, and KM can fix that so we can all get back to sharing the types of info and pictures we had originally intended when we bought the camera.

I dont particularly care if my preflash delay is 90ms or 80ms, I'm not going to nitpick or make a fuss about that. All I care as that it's faster than humans can blink.

Have a great day.

 

[Lawrencew]

of why I and so many others NEVER have the problem.

You can measure all you want.
your "facts" prove nothing to me - because I DONT get the problem.

My proof is hundreds of photos without lazy eye.
Hence there is no lazy eye problem QED
--
Regards
Lawrence

 

[Lawrencew]

You keep saying it is a problem with the 5D/7D - the pre-flash cannot be made shorter because of mirror/AS

So how will a new flash unit help?

BTW, I am not waiting for the new flash - because I DONT have the problem (remember?)
--
Regards
Lawrence

 

[Videoguy]

Lawrence, dont get me wrong. I am happy that you are not experiencing any lazy eyes. You already had troubles with exposure, so I dont wish new troubles onto you or anyone else. If you dont have lazy eyes, that is great. We should all be so fortunate when using the 5D.

If my preflash timings of the KM 5D versus the Canon models compared to the onset blink reflex from light response time doesn't prove anything to you, then there's nothing more I can do at this point. I say keep taking photos with TTL/ADI flash, and you will probably come accross a blinker who blinks faster than 130ms. Until then, consider yourself fortunate for taking photos of so many slow blinkers. They certainly dont live around here.

I hope that's the answer you are wanting.

of why I and so many others NEVER have the problem.

You can measure all you want.
your "facts" prove nothing to me - because I DONT get the problem.

My proof is hundreds of photos without lazy eye.
Hence there is no lazy eye problem QED
--
Regards
Lawrence

 

[Videoguy]

You keep saying it is a problem with the 5D/7D - the pre-flash
cannot be made shorter because of mirror/AS

So how will a new flash unit help?

Lawrance, you are correct as far as the preflash delay lazy eyes issue. The flash unit will NOT help on the existing bodies to prevent lazy eyes, but will have to be combined with a new flash system and/or faster mechanical mirror flip on the BODY itself to correct the issue. As I've mentioned in previous posts, I do NOT expect KM to retrofit an reengineered mechanical assembly into the 5D/7D, so we will need to get a new body to completely solve the problem. This is why I keep referring to the next gen KM body in many of my previous posts on this topic.

 

[Lawrencew]

You keep stating lazy eyes as some kind of "fact" with the 5D.

It isn't.

And you STILL wont answer the question.

If the preflash delay is such a problem according to your measurements and the cause of lazy eye, then why DONT I and others get the problem?

--
Regards
Lawrence

 

[Lawrencew]

Lawrance, you are correct as far as the preflash delay lazy eyes
issue. The flash unit will NOT help on the existing bodies to
prevent lazy eyes, but will have to be combined with a new flash
system and/or faster mechanical mirror flip on the BODY itself to
correct the issue. As I've mentioned in previous posts, I do NOT
expect KM to retrofit an reengineered mechanical assembly into the
5D/7D, so we will need to get a new body to completely solve the
problem. This is why I keep referring to the next gen KM body in
many of my previous posts on this topic.

You never said anything about a new body.

BTW, there isnt a problem. I never get it, nor do many others.
Why can't you understand or explain that simple fact?

--
Regards
Lawrence

 

[Videoguy]

And you STILL wont answer the question.

I think you missed this post. Here it is again:

Lawrence, dont get me wrong. I am happy that you are not experiencing any lazy eyes. You already had troubles with exposure, so I dont wish new troubles onto you or anyone else. If you dont have lazy eyes, that is great. We should all be so fortunate when using the 5D.

If my preflash timings of the KM 5D versus the Canon models compared to the onset blink reflex from light response time doesn't prove anything to you, then there's nothing more I can do at this point. I say keep taking photos with TTL/ADI flash, and you will probably come accross a blinker who blinks faster than 130ms. Until then, consider yourself fortunate for taking photos of so many slow blinkers. They certainly dont live around here. I hope that's the answer you are wanting.

For all of those trying to workaround the issue until a KM new body comes out, please understand it is a serious problem for those users. Keep taking pictures and eventually you will see it.

 

[Videoguy]

Lawrance, you are correct as far as the preflash delay lazy eyes
issue. The flash unit will NOT help on the existing bodies to
prevent lazy eyes, but will have to be combined with a new flash
system and/or faster mechanical mirror flip on the BODY itself to
correct the issue. As I've mentioned in previous posts, I do NOT
expect KM to retrofit an reengineered mechanical assembly into the
5D/7D, so we will need to get a new body to completely solve the
problem. This is why I keep referring to the next gen KM body in
many of my previous posts on this topic.

You never said anything about a new body.

I didnt just before your question, but I have in many of my other posts. And I just did again here. RichW said something about a new flash line, and I assume this means they are working on the flash issues , including preflash delay, and that it will be addressed with the new bodies coupled with the new flashes for the best results. I will gladly shutcan my 3600HS and get a new body to put a permanent end to lazy eyes if the cost is reasonable for what the body presents compared to similarly priced bodies such as D200.

 

[Lawrencew]

You never said anything about a new body.

I didnt just before your question, but I have in many of my other
posts. And I just did again here. RichW said something about a
new flash line, and I assume this means they are working on the
flash issues , including preflash delay, and that it will be
addressed with the new bodies coupled with the new flashes for the
best results. I will gladly shutcan my 3600HS and get a new body
to put a permanent end to lazy eyes if the cost is reasonable for
what the body presents compared to similarly priced bodies such as
D200.

But why dont you just get a Canon? You could do that now. Go on, get one, forget KM. All your problems will be solved. And ours.

 

[Lawrencew]

If my preflash timings of the KM 5D versus the Canon models
compared to the onset blink reflex from light response time doesn't
prove anything to you, then there's nothing more I can do at this
point.

All it proves is that the preflash is longer.
It doesnt prove lazy eye as I and others dont have a problem.

I say keep taking photos with TTL/ADI flash, and you will
probably come accross a blinker who blinks faster than 130ms. Until
then, consider yourself fortunate for taking photos of so many slow
blinkers. They certainly dont live around here.

That's even less proof.
Suddenly all your subjects are slow blinkers and mine are all fast.

I have photographed dozens and dozens of people recently. Not one fast blinker apparently. Doesnt that strike you as strange?
Have you measured the subjects?
No. So we can totally discount that.

For all of those trying to workaround the issue until a KM new body
comes out, please understand it is a serious problem for those
users.

I don't have to workaround it
There isnt a problem.
YOU have a problem.
Many others don't.
Accept it and move on.

Keep taking pictures and eventually you will see it.

I do. And I don't.
--
Regards
Lawrence

 

[Videoguy]

You never said anything about a new body.

I didnt just before your question, but I have in many of my other
posts. And I just did again here. RichW said something about a
new flash line, and I assume this means they are working on the
flash issues , including preflash delay, and that it will be
addressed with the new bodies coupled with the new flashes for the
best results. I will gladly shutcan my 3600HS and get a new body
to put a permanent end to lazy eyes if the cost is reasonable for
what the body presents compared to similarly priced bodies such as
D200.

But why dont you just get a Canon? You could do that now. Go on,
get one, forget KM. All your problems will be solved. And ours.

My lenses, flash, remote release wont' work on a Canon very well will they?

 

[Videoguy]

If my preflash timings of the KM 5D versus the Canon models
compared to the onset blink reflex from light response time doesn't
prove anything to you, then there's nothing more I can do at this
point.

All it proves is that the preflash is longer.
It doesnt prove lazy eye as I and others dont have a problem.

It proves the preflash is longer. So since it's scientific fact that most humans blink closer to 100ms, that should prove something to you. But since it doesn't, there's not much more I can say. That explanation works for most people, but some people dont want to accept it.

That's even less proof.
Suddenly all your subjects are slow blinkers and mine are all fast.

Hard to believe, but if your subjects arent blinking closer to 100ms, they must be blinking pretty quickly.

Yes, I've measured the subjects and confirmed my results against a published scientific study that tested the blink response on a large number of subject.

I don't have to workaround it

Not yet, and that's great for you. I'm not wishing you to have the issue, but I'm convinced that you will eventually be seeing this, and you will not post about it here because you would be too embarassed and in fear of being flamed. So let all the people experiencing this continue working around the issue and discussing their hopes and dreams to a KM solution in the future. And if they want to spend $350 on Metz, let them do it and take nice pictures. Dont get your shorts wadded up in a bunch over it.

 

[Videoguy]

If my preflash timings of the KM 5D versus the Canon models
compared to the onset blink reflex from light response time doesn't
prove anything to you, then there's nothing more I can do at this
point.

All it proves is that the preflash is longer.
It doesnt prove lazy eye as I and others dont have a problem.

It proves the preflash is longer. So since it's scientific fact
that most humans blink closer to 100ms, that should prove something
to you. But since it doesn't, there's not much more I can say.
That explanation works for most people, but some people dont want
to accept it.

That's even less proof.
Suddenly all your subjects are slow blinkers and mine are all fast.

Hard to believe, but if your subjects arent blinking closer to
100ms, they must be blinking pretty quickly.

opps, typo. Should say, they must be blinking pretty slowly, while my blinkers are blinking normally.

 

[jstartin]

Following an explanation of why I was asking the question I asked, politely:

"What several people have asked for is a proper description of the measurement system you used - if it is here somewhere already then I apologise, but I cannot find it with the inadequate search facility on this site. With these details other technical people here can at least decide whether this is a credible way of making measurements, is properly calibrated, unbiased and so on, and whether to believe the numbers or not."

You replied:

"I tested the preflash to flash delay. I did research to compare my
testing of blink responses with published scientific controlled
studies of those blink responses. They support my results."

No, you haven't attempted to answer the question.
..and, as you introduced it..

No, the published work on blink responses don't support your results. Perhaps this is just a wrong choice of words and idiom - if you mean that a comparison of your measurements and the published data on blink responses is consistent with your explanation for a higher prevalence of blinking subjects in 5D/7D flash photographs then I can accept the statement, but your remark, as made, is just wrong. This is not helpful to the message.

Amazing that anyone would dispute this. It's not a complex
experiment that needs a 20 page thesis on. A simple timer test can
be performed by anyone with a reasonable understanding of
electronics.

There is nothing amazing at all. Even the simplest measurement can be made incorrectly if the equipment or the method is faulty. You have been asked several times to explain briefly how the measurements were made. Why do you persist in dodging the question? Something to hide?

Then you said:

"The results speak for themselves. And I have verified
this on other KM bodies, not just mine. And the fact that so many
others see the problem should also make it obvious the the preflash
delay is slower than the human respoinse time."

Here you have something of a circular argument - you have constructed a hypothesis to explain an observation and then use the observation to "prove" the hypothesis. Not good enough I'm afraid.

And then:

"I dont think I need to write a 30 page thesis on this. But in effect, it > feels like I alreadyh have here by answering stupid questions and having > to rehash the same things over and over again."

No, I doesn't need 30 pages. But in response to the clear, direct question you have provided nothing. And it seems you are continuing to rehash that nothing.

 

[Videoguy]

"I tested the preflash to flash delay. I did research to compare my
testing of blink responses with published scientific controlled
studies of those blink responses. They support my results."

Sorry, maybe you didnt see my other post, but I have decided to cease all posting about certain subjects for at least 24 hours. I do not have the time to rehash it all. Perhaps I will create a website which contains all the data and addresses your questions as covered in previous threads in greater detail.

But that is all. Sorry, I refuse to comment further on this topic for now.

Have a good day.

 

[zemes gaoson]

Videoguy wrote:
asons on the rare occassion.

in 60 MS ;-) you usually need 1/60 sec wich is far more than 60 MS
(10x more to be correct).

60ms is NOT 1/60th of a second. And 1/60th of a second is NOT more
than 60ms.

60ms = .060 seconds
1/60 second = .01666 seconds

Right on. I was going to post the same comment. 1/60 sec = 17 ms. Similarly, 100ms is 1/10 sec, and 125mm is 1/8 sec. For some reason, people tend to think it's a very short time whenever a number is giving in milliseconds. 100 ms is a long time. I don't know how accurate Videoguy's measurement is, but if it is true that KM's dSLR cameras have a delay over 100 ms (1/10 or 0.1 sec) between the preflash and the actual flash firing, I would see that as a serious design flaw. Many people, although not all, have a fast enough nerve/muscle reaction time as short as 0.1 sec. This much is science, instead of subjective speculation, and further is scientific fact that is independent of photography and cameras.

My only quarrel is that there is no actual data from a second independent source other than Videoguy as to exactly how much delay there is for KM dSLR cameras. Given this premise, I don't see what we can discuss further, except for each user reporting his or her own experience. This much is personal and subjective, which is never a good subject matter of debating, for at the end people don't even agree on what is the subject of the debate, much less the conclusion. It is time for us to stop bickering over this. It is time to get actual data, both from KM itself and independent testers.

By the way, in the context of the previous post mentioning "1/60 sec", the cited 1/60 sec seems to refer to shutter speed, which has nothing to do with the preflash problem. It does seem many people misunderstand this issue.

 

[Matt Cham]

I didn't want to add to this thread for the longest time,
but I do so only because it's made it back to the surface
of this forum.

About 12 months ago, a KM DSLR forum member
by the name of Geir Ove posted the very first
report of back-focus on the KM 7D. He was mobbed
by dozens of KM 7D owners and flamed like a strip of
bacon. They called him names and humiliated him to
stop posting until I discovered BF myself and started
posting about it as well. I posted several AF tests for
people to perform at home, and to the surprise of
a few critics, Geir Ove was right all along. My camera
was probably the first BF (and certainly not the last!)
ever fixed by KM on the 7D that I am aware of.
It got fixed even before Geir Ove's 7D!

Why was Geir Ove attacked by the mob?
Perhaps they truly thought he was a troll.

See:
http://en.wikipedia.org/wiki/Groupthink

I'm not pointing a finger or placing blame.
I just hope we all get along and stop this
nonsense. This time of year, the only flames
we need are those under the chimney!

Happy Holidays to everyone!

--
Matt Cham

My Gallery: http://mattcham.fotopic.net/