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06-28-2009, 09:46 AM   #1
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Sync speed and tech question.

Pentax have sync speed at 1/180sec. The old Nikon D70 have a hybrid mech./electronic shutter that syncs up to 1/500sec with TTL flash and higher with flashes connected with PW.

Is it possible to modify a Pentax K100D to do the same as the Nikon D70?

06-28-2009, 10:24 AM   #2
and
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Nope. The k100d has the same sensor but they didnt use the electronic shutter, they are just using a mechanical one. Shouldnt be possible to modify the camera to use it.
06-28-2009, 10:44 AM   #3
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Shouldn't it be possible to use higher sync speed with dSLRs with LV? Both the mirror and the shutter are up.
06-28-2009, 11:12 AM   #4
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Probably not. The new Nikons don't have that feature and that's certainly for a reason.

06-28-2009, 02:40 PM   #5
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Not possible with my K100D super as I tried.
I just stops tripping the flash at over 180.
Unlike in the film cameras, the flash will fire even if you rack up the shutter speed beyond the sync speed.
The only problem with the film cameras is the flash will fire but it won't be caught in the picture or half of the picture/image will be with flash and the other half will not have it as the mechanical shutter either becomes delayed or too fast (mechanical limitation).
The problem with the K100D super, I think, is that it has been programmed into its system not to fire the flash above the 180 speed.
06-28-2009, 08:13 PM   #6
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If you need to take a flash shot with a shutter speed greater than 1/180 secs :-

Use an AF360/AF540 or other P-TTL compatible flash with High-Speed Synch capability (e.g. Metz AF48 or Sigma 530 DG ST Super).
Set the flash to HS (High-Speed Synch) - only works in P-TTL mode.
Set the camera to Tv (shutter priority) or Manual.
Set the Shutter speed to whatever speed you need e.g. 1/1000 s or 1/500s.

Try it - it works.

One caveat is the flash will not fire at full power. At 1/500s shutter speed, I think you are left with only 1/3 of the full flash power. At 1/1000s, only 1/4 of full flash power. So you have to keep well within the range of the flash.

Last edited by kittykat46; 06-28-2009 at 09:26 PM.
06-28-2009, 08:47 PM   #7
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QuoteOriginally posted by kittykat46 Quote
Set the flash to HS (High-Speed Synch) - only works in P-TTL mode.
.
Flash newbie question:

do you have different "mode" in the same flash? If yes, what are the reasons to change mode?
Thanks
06-28-2009, 09:23 PM   #8
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QuoteOriginally posted by soalle Quote
Flash newbie question:

do you have different "mode" in the same flash? If yes, what are the reasons to change mode?
Thanks
My answers refer to Pentax AF360/AF540 flash, 3rd party flashes will differ slightly in implementation, even if they have all these modes.

The default mode is P-TTL, which uses the Pentax through-the-lens exposure system. Fully automatic . Quite a lot of feedback that it tends to underexpose, but there are ways around this. I usually set +0.5 and set "link AF point to AE" in the menu.

Other settings are "Auto" flash, which uses the Flash unit's own sensor. Seems to work for most people.
Manual flash, where you manually set the flash power.

You can also set the flash to be a Master or Slave flash (off-camera, even multiple slaves, like what you may see in photo studios).

Other P-TTL settings include High-Speed Synch (explained above), Trailing Curtain flash (where the flash fires at the End of a long shutter exposure) which helps give a "speed" flavour to the photo (like Superman advertisements :-) )

06-28-2009, 09:25 PM   #9
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QuoteOriginally posted by soalle Quote
Flash newbie question:

do you have different "mode" in the same flash? If yes, what are the reasons to change mode?
Thanks
Yes, a flash can have more than one mode of operation. The AF 540 FGZ that I have allows
  • P-TTL - the camera uses a pre-exposure flash to read the light returning and expose accordingly
  • Auto - the flash has a sensor in it that reads the light coming back to the flash. There is no pre-flash with this.
  • Manual - you figure out yourself what f/stop to use to get the exposure you want from the flash, using the guide numbers and the fractional power settings.
There are valid reasons for use of any one of these.
06-29-2009, 01:51 AM   #10
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Thanks for your input.

I don't have AF-540 flash, sold both of them. Only have manual flashes.

I'm thinking about buying a P&S with hot-shoe that syncs on all shutter speeds.
My Cactus V4 triggers is good for 1/320sec. Maybe 1/400sec.
When I get my PW I can sync at 1/640sec. Maybe 1/1000sec if I'm lucky.
06-29-2009, 05:56 PM   #11
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QuoteOriginally posted by Canada_Rockies Quote
Yes, a flash can have more than one mode of operation. The AF 540 FGZ that I have allows
  • P-TTL - the camera uses a pre-exposure flash to read the light returning and expose accordingly
  • Auto - the flash has a sensor in it that reads the light coming back to the flash. There is no pre-flash with this.
  • Manual - you figure out yourself what f/stop to use to get the exposure you want from the flash, using the guide numbers and the fractional power settings.
There are valid reasons for use of any one of these.

Thanks very much for the answer...

the thing I do not get is: what does P-TTL that the Auto cannot do? And the other way around?
06-29-2009, 06:57 PM   #12
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QuoteOriginally posted by soalle Quote
......

the thing I do not get is: what does P-TTL that the Auto cannot do? And the other way around?
Some flash features which only function with P-TTL and not on Auto

a. High Speed Synch
b. Rear Curtain Flash
c. Automatic flash zoom adjustment as you change the attached zoom lens focal length. Not much of an issue if you mainly use fixed primes - just set once when you turn on the flash.
d. Automatic ISO adjustment as the ISO sensitivity on your camera changes - this is especially useful if your ISO setting is on "Automatic", which means the camera may change it at any moment without your realising it.

What Auto does, which P-TTL doesn't

a. Manual exposure mode
b. Non-"A" manual exposure lenses
c. Auto seems to expose more accurately than P-TTL, based on many user's feedback.

I usually use P-TTL because of the advantages listed above, with +1.0 E/V flash compensation, and set "Link AF point to AE" on the menu.

Not great compared to some other system's flash performance , but I get to keep most of my flash shots.

Last edited by kittykat46; 06-29-2009 at 07:02 PM.
06-29-2009, 07:56 PM   #13
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QuoteOriginally posted by soalle Quote
Thanks very much for the answer...

the thing I do not get is: what does P-TTL that the Auto cannot do? And the other way around?
P-TTL has some modes that you only can get with P-TTL. High speed sync, trailing curtains sync, contrast control for example. I am not saying anything about if these things are worth having only that you only get them with P-TTL.

From the point of view of metering there is also a differents. They may not be of interest to some but they are there. P-TTL is from the camera and flash to the subject. If the distance changes P-TTL metering can pick up the change, even if the flash is off camera. Auto is from the subject to the flash. If the flash is on the camera no differents, but if it is off camera it may not see the change. If there is nothing changing then manual gives more control and is probably the better option. Now that P-TTL see these changes may not be all that significant but the point of view of the metering system may be relevant. If the flash is to one side and the subject has a light background or is back lit the metering may see this as the subject has more light on it them it really has. From the cameras point of view the subject may have a dark background but subject will look dark because the flash sees to much light. You could also reverse this and auto would be the better option.

Some never use their flash in anything but manual. Some never use their camera in anything but manual too. But more options are more tools to solve a problem.

DAZ
06-29-2009, 09:23 PM   #14
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Thanks kittykat46 and DAZ, you answered perfectly my questions
06-29-2009, 09:50 PM   #15
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QuoteOriginally posted by GerryL Quote
Not possible with my K100D super as I tried.
I just stops tripping the flash at over 180.
Unlike in the film cameras, the flash will fire even if you rack up the shutter speed beyond the sync speed.
The only problem with the film cameras is the flash will fire but it won't be caught in the picture or half of the picture/image will be with flash and the other half will not have it as the mechanical shutter either becomes delayed or too fast (mechanical limitation).
The problem with the K100D super, I think, is that it has been programmed into its system not to fire the flash above the 180 speed.
You are so correct.
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