P-TTL and Pentax Flashes - Pure Frustrations

Started Dec 5, 2007 | Discussions
6x9
6x9 Regular Member • Posts: 274
P-TTL and Pentax Flashes - Pure Frustrations

I had to shoot a corporate event yesterday.

After first 20-30 shots with K10D+ kit lens + AF540FGZ I realized that the output of acceptably exposed shots is only about 50% or even less. Saying this, in order to achieve this result I had to set the exposure compensation at +0.7 EV on the camera and at +0.5 EV on the flash. What is worse, there was no consistency - two consequent shots of the same scene had sometimes difference in exposure of nearly 2 stops.

So, I had to switch the flash into A mode. This old technology was a huge step forward. The shots came out exposed just perfectly. What I did not like however, is that I had to set the zoom position manually. When switching the flash to the A mode the zoom position still shows Auto, but the flash will not zoom. I thought first that something was wrong with my flash. Read the manual today and this mode works as designed. Weird! If I can use A flash mode with my P-TTL capable camera, why the reflector can not be zoomed too?

I noticed also a huge overexposure if I shoot just immediately after switching the [pre-charged] flash on.
--

  • 6x9 -

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wlachan
wlachan Veteran Member • Posts: 6,759
Re: P-TTL and Pentax Flashes - Pure Frustrations

6x9 wrote:

I had to shoot a corporate event yesterday.
After first 20-30 shots with K10D+ kit lens + AF540FGZ I realized
that the output of acceptably exposed shots is only about 50% or even
less. Saying this, in order to achieve this result I had to set the
exposure compensation at +0.7 EV on the camera and at +0.5 EV on the
flash. What is worse, there was no consistency - two consequent shots
of the same scene had sometimes difference in exposure of nearly 2
stops.
So, I had to switch the flash into A mode. This old technology was a
huge step forward. The shots came out exposed just perfectly. What I
did not like however, is that I had to set the zoom position
manually. When switching the flash to the A mode the zoom position
still shows Auto, but the flash will not zoom. I thought first that
something was wrong with my flash. Read the manual today and this
mode works as designed. Weird! If I can use A flash mode with my
P-TTL capable camera, why the reflector can not be zoomed too?
I noticed also a huge overexposure if I shoot just immediately after
switching the [pre-charged] flash on.
--

  • 6x9 -

540FGZ is dumb alright, I had one and was frustrated for the same reasons. I too cannot understand the genius behind the designs.
--
Alan Chan
http://www.pbase.com/wlachan

Duplo Veteran Member • Posts: 6,660
I like it and find it great.

Shot a few events in copenhagen... both with the 540 and the results has been spot on, I usually run the camera in M-mode and flash in Auto... seems to work perfectly. 8 i do dial the Flash EV comp up or down though depending on what look I am after...

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Thomas

Nothing is foolproof to a sufficiently talented fool
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baldeagle21b Contributing Member • Posts: 987
Re: P-TTL and Pentax Flashes - Pure Frustrations

Sounds like it would be helpful for me to learn how the system works before I do something similar. Thanks for the advice.

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Optigrab Regular Member • Posts: 232
Re: P-TTL and Pentax Flashes - Pure Frustrations

Researching which flash to go with, I've read that non-dedicated thyristor flashes meter as reliably as P-TTL. I'm not suggesting that is the consensus, just an impression from reading threads here. That is why I am tempted to save lots of money and go with a modern non-dedicated flash.

Andrew Shirley Contributing Member • Posts: 658
Re: P-TTL and Pentax Flashes - Pure Frustrations

I've seen a lot of hit-and-miss shots from my Sigma flash. I'm not really sold on the P-ttl system. It would seem that the pre-flash should be able to set up a reliable exposure, no?

  • Andrew

Verdict1st Regular Member • Posts: 214
Re: P-TTL and Pentax Flashes - Pure Frustrations

I'm in the market for a couple of flashes. I've been looking at the 540, but after reading this i'm not so sure. Are there any third party lenses (Besides sigma and metz) that you recommend?
--
All that is beautiful is difficult
-Plato

Russell Evans Forum Pro • Posts: 12,617
Re: P-TTL and Pentax Flashes - Pure Frustrations

Optigrab wrote:

Researching which flash to go with, I've read that non-dedicated
thyristor flashes meter as reliably as P-TTL. I'm not suggesting
that is the consensus, just an impression from reading threads here.
That is why I am tempted to save lots of money and go with a modern
non-dedicated flash.

You can go modular so that if you want P-TTL in the future, you can have it. I bought the Quantaray QTB-9550D, the Quantaray QDA P, and the ProMaster 5050DXR P-TTL and can say they work on the K10D. I don't have the experience to say how well they work as a light source, however, as this is my first and only flash. The thing I am hoping for is to be able to afford the Promaster MacroLume TTL Dedicated Digital Macro Flash next year for use with the 5050DXR module.

Quantaray QB-6550D US $50

http://www.ritzcamera.com/product/531660967.htm?bct=t13079503%3Bcidigital-cameras-and-accessories%3Bciflashes

Quantaray QTB-9550D US $85

http://www.ritzcamera.com/product/531660975.htm?bct=t13079503%3Bcidigital-cameras-and-accessories%3Bciflashes

Quantaray QDA P Flash Module for PKR US $15
http://www.ritzcamera.com/product/531660710.htm

ProMaster 5050DXR P-TTL module US $50
http://www.penncamera.com/store/item.asp?ITEM_ID=9236&DEPARTMENT_ID=432

Thank you
Russell

Mig17 Regular Member • Posts: 240
Could you describe more?

Could you elaborate on your shooting conditions? Were you moving around? or set up still on a tripod? What lighting were you shooting under? Shot both horizontal and vertical? Flash orientation?

I find the 540 performs consistently, however being a newbie, what is not consistent is me when I go from hor. to vert., or when I decided to bounce off the walls or ceilings...thats when consistency is off, one side is brighter than the other.

I still practice inside my home, learning how light behaves...trying to get consistent exp. at diff. angles and diff flash gun orientaion, etc...it's pretty hard stuff

I find that shooting Av is the most consistent, vs Manual which is all over the place, for some reason... With Av mode my rear dial is aperture, front dial is Ev compensation to make quick exp. adjustments

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kenyee Senior Member • Posts: 1,522
reflections and P-TTL/e-TTL/i-TTL

Reflections (mirrors, etc.) will totally confuses these systems.

Show us an example or two of your "bad" ones that you didn't expect would be bad...

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John Lai Senior Member • Posts: 2,579
Re: I like it and find it great.

Duplo wrote:

Shot a few events in copenhagen... both with the 540 and the results
has been spot on, I usually run the camera in M-mode and flash in
Auto... seems to work perfectly. 8 i do dial the Flash EV comp up or
down though depending on what look I am after...

Glad I read your post.

I have an old Nikon SB80 DX and I set the flash in auto mode & K100D in Manual mode with speed at 1/180. I then read the flash aperture and manually set this on the camera. Result, most of my pictures are very well exposed.

So I have doubts about purchasing the FZ 540 from what I read in this thread.

John

pictureman Forum Member • Posts: 63
Re: reflections and P-TTL/e-TTL/i-TTL

I have found the same issues with inconsistant flash exposure results under the same conditions and equipment. What happens is that the flash will underexpose if the predominate subject is white (for instance, a wedding gown) and it will overexpose if the subject is mostly black (groom's tux). What happens is that the camera and flash system wants to make everything 18 percent gray (gray card), but it overdoes it. I've never been able to control this during shooting a fast paced event such as a wedding. As a result, I set my Metz 54-MZ 4 in the "A" mode and my camera either on "M" or "Av". It's crazy that we've got to revert back to '80's technology, but this seems to work the best.
--
pictureman

AndrewG NY Regular Member • Posts: 299
Re: reflections and P-TTL/e-TTL/i-TTL

I've been happiest lately with P-TTL + M mode, tweaking only flash comp based on results (chimping). I had also tried A mode and it worked OK too. No doubt that P-TTL can be fooled into marked underexposure by a reflection. I've been meaning to try using CW metering with P-TTL to see if that improves things.

Learning to shoot with the flash is a whole new skill and requires practice and know-how. I think those who approach it expecting it to work perfectly automatically are bound to be disappointed.

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Sytek New Member • Posts: 6
Re: P-TTL and Pentax Flashes - Pure Frustrations

I have the Macrolume TTL Digital unit with both the older 5000DX and the latest 5050DXR modules. The 5000DX module worked with my istD until I upgraded firmware. The flash with the 5050DXR module does work with my D but the exposures are very bright. The flash/module does not work at all with my DS2 nor my K10D. It appears the flash fires its whole output on the preflash, as the images are dark, and show no evidence of the flash firing even though I see it fire with my other eye.

I do forensic photography so I was hoping this flash would be the answer as so far there are no other P-TTL ring flashes for the camera.

Mig17 Regular Member • Posts: 240
Re: P-TTL and Pentax Flashes - Pure Frustrations

Oh yes...I've been meaning to try out spot metering vs matrix as well. I wonder if that will make a big difference in consistency, especially in Manual mode.

What exactly goes on when we take a pic with flash? Does the camera metering system tell the flash how much output to be put out? The flash does have its own metering system right? Does it control the final exposure? What is that thing under the clear red cover on the flash? light meter? and what about that little black circle on the side of it with the pinhole?

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6x9
OP 6x9 Regular Member • Posts: 274
Re: Could you describe more?

Mig17 wrote:

Could you elaborate on your shooting conditions? Were you moving
around? or set up still on a tripod? What lighting were you shooting
under? Shot both horizontal and vertical? Flash orientation?

I was shooting in a restaurant. If I had too shoot without a flash there, I would use 1/15-1/30 s @ f/4 . Not too dark, but a flash was needed.

The flash was mounted on the camera, 90% of shots were horisontal, the zoom reflector was mostly @ 90 degrees (since the ceiling was high and some walls colored). I shot from various locations. No tripod. Shot mostly in Av, M and P modes.

I find that shooting Av is the most consistent, vs Manual which is
all over the place, for some reason... With Av mode my rear dial is
aperture, front dial is Ev compensation to make quick exp. adjustments

Maybe Av is more consistent, but I have not noticed a difference between various modes when shooting with flash.

My P&S S* y camera produces much more predictable results with flash (and without too) in 99% of cases.
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jmacshriver Contributing Member • Posts: 939
Promaster Macrolume

Thanks for your post. I have the DS and 5000 module and have not been able to get the macrolume to work. It works great with my labs KM 7D and 5000dx digital module.

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John
Iowa, USA

nosnoop Senior Member • Posts: 1,694
Re: P-TTL and Pentax Flashes - Satisfaction

I can't explain why my experience is quite different; I am very happy with the P-TTL flash result with good exposure most of the time. I usually do a test shot, dial-in any compensation if needed, and the exposure would be very consistent. I only use bounce flash, and sometimes multiple wireless flash.

The behavior of the flash exposure is the same as non-flash matrix metering - is that it will try to preserve highlight. So if you have reflective object, you have to take that into account. One settings people found useful is to go to Custom Menu, and set the Link AE to AF "On".

Russell Evans Forum Pro • Posts: 12,617
Re: P-TTL and Pentax Flashes - Pure Frustrations

Sytek wrote:

I have the Macrolume TTL Digital unit with both the older 5000DX and
the latest 5050DXR modules. The 5000DX module worked with my istD
until I upgraded firmware. The flash with the 5050DXR module does
work with my D but the exposures are very bright. The flash/module
does not work at all with my DS2 nor my K10D. It appears the flash
fires its whole output on the preflash, as the images are dark, and
show no evidence of the flash firing even though I see it fire with
my other eye.

That is disappointing.

Thank you
Russell

AndrewG NY Regular Member • Posts: 299
Re: P-TTL and Pentax Flashes - Pure Frustrations

Mig17 wrote:

Oh yes...I've been meaning to try out spot metering vs matrix as
well. I wonder if that will make a big difference in consistency,
especially in Manual mode.
What exactly goes on when we take a pic with flash? Does the camera
metering system tell the flash how much output to be put out? The
flash does have its own metering system right? Does it control the
final exposure? What is that thing under the clear red cover on the
flash? light meter? and what about that little black circle on the
side of it with the pinhole?

I personally have doubts about the usefulness of spot here as it is fixed into the center of the frame--I suspect the pre-flash will not fire if you press AE-L...? As I mentioned earlier, I am hoping that CW metering will make the exposure a little less sensitive to sharp highlights (but I haven't tried this yet).

If using P-TTL, it's using the camera's meter during the pre-flash. The camera watches the scene illuminated with the pre-flash and determines how much flash power should be emitted. Then the shutter is opened and the calculated flash burst is fired.

When using the flash's A mode, it uses the flash's built-in pinhole meter which probably operates with some form of center-weighted logic. There's no pre-flash, the flash cuts off power during the burst based on what that sensor sees.

In theory the TTL (through-the-lens) metering should be more accurate as it will exactly match the image composition given the installed lens & zoom. I don't know whether A mode adjusts its exposure evaluation based on installed lens/zoom or not.

The translucent red plastic covers the AF spotbeam illuminator--when the camera tells the flash it needs help with AF it projects a red AF pattern to help AF lock on. Works pretty well in low light.

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