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01-03-2008, 05:49 AM   #1
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P-ttl

I'm a recent convert from Canon to Pentax. I've been shooting 2 K10Ds for a few weeks now. My main lenses are the 18-50 2.8 and the 50-135 2.8.

Shooting a Canon 30D with the 580 I got very consistent exposures and beautiful results. With the 540 Pentax set to P-TTL my results were all over the place. 2-3 stops underexposed even dialing in +1 in the strobe and the body for flash exposure comp. I was very very disappointed. Then I tried using the 540 in "A" mode instead of P-TTL. Vola! Beautiful, consistent, predictable strobe output and no need for exposure comp. Strange but here are some examples:

These we're shot back-to-back in continuous mode. 1/50 @ 2.8 Manual 400 ISO K10D 50-135 2.8 DA* @ 135 540FGZ in A mode. Converted to JPEG from DNG otherwise unadjusted.





01-03-2008, 07:04 AM   #2
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Hey there.First off, nice pictures :-) Made me smile! How have you been experiencing the other things about your swap to Pentax? With 18-50 do you mean the sigma lens?

Let's see. I own a 360, and presuming the P-TTL is the same as the 540, I have to say I agree on the P-TTL system being off quite some times. I use it on-camera with +0.5 dialed in and tend to get more consistent results that way, otherwise it's always half a stop to a full stop underexposed. I actually use my flashes off-camera most of the time, so for me the whole P-TTL system is not really an issue... But I agree it could be more consistent.

B.T.W., did you consider that the zoom of the 540 is only up unto 105mm (is that correct?), and using the flash with a lens at a focal lenght further away (135) should logically lead to some underexposure since the flash covers more then the frame you are covering with your lens? I do think that P-TTL should correct for this anyhow. Did you try at other focal lengths? Was the 540 even autozoomed to match your lens?
01-03-2008, 07:59 AM   #3
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It would be useful to see shots of your problem, not shots that seemed to work.

Also, what metering did you have for the P-TTL mode?

I suspect your problem is more related to settings than flash.

I have used a K10D and AF540FGZ for over a year and never had shots 2-3 stops off on exposure.

The only issue I have with the K10D and flash metering is that I would prefer TTL as the *istD, so that older lenses could be used with other than "auto mode" that use the flash's sensor.


Edit note. You state "manual mode.

How did you set apature? note that if you used the apature ring, P-TTL won't work. You must use the thumbwheel to set apature
01-03-2008, 09:12 AM   #4
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I've experienced inconsistent flash results with the camera on green or P, but since I moved to using Tv and setting the shutter speed, results are much more consistent, even leaving the flash (540) on P-TTL. I bounce the flash most of the time and still get pretty consistent results, so I'm much happier.

Cheers

01-03-2008, 09:27 AM   #5
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I should have added that I always set the camera to manual mode, and 1/180 second for flash.

usually I deliberately set apature to give at least -3 stops for natural lighting
01-03-2008, 09:47 AM   #6
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Glad you like the shots!

QuoteOriginally posted by barendvl Quote
With 18-50 do you mean the sigma lens?
Yup that would be the one.

QuoteOriginally posted by barendvl Quote
B.T.W., did you consider that the zoom of the 540 is only up unto 105mm (is that correct?), and using the flash with a lens at a focal lenght further away (135) should logically lead to some underexposure since the flash covers more then the frame you are covering with your lens? I do think that P-TTL should correct for this anyhow. Did you try at other focal lengths? Was the 540 even autozoomed to match your lens?
These shots (as are many of mine) were bounced at an angle over my shoulder so zoom head position is not the issue.

QuoteQuote:
It would be useful to see shots of your problem, not shots that seemed to work.
Trashed all of those!]

QuoteQuote:
Also, what metering did you have for the P-TTL mode?
Multi segment metering (which I have found to be pretty inaccurate)

QuoteQuote:
Edit note. You state "manual mode.

How did you set apature? note that if you used the apature ring, P-TTL won't work. You must use the thumbwheel to set apature
I ALWAYS shoot in manual exposure (10,000 frames a month on average) none of my lenses have an aperture ring so it's always set with the thumbwheel.

QuoteQuote:
I should have added that I always set the camera to manual mode, and 1/180 second for flash.

usually I deliberately set apature to give at least -3 stops for natural lighting
I tend to shoot slower shutter speeds to let in more ambient light and balance the strobe. I'm very rarely above 1/60 when shooting indoors and usually around 2.8 to 5.6
01-03-2008, 10:18 AM   #7
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QuoteOriginally posted by nikonic Quote
Trashed all of those!
Sounds like it'd be easy enough to take more crappy ones to attach ;-)
01-03-2008, 01:36 PM   #8
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I had similar problems until....

In the Custom Settings, set the Link AF Point and AE to on or 2

This ensures that the flash exposure is on the focal area and not on some reflective bright spot somewhere else in the frame, or even from jewellery or the reflection from an eye.

Worked for me, and I went from a 1 in 10 success rate to 9 out of 10, I was close to tossing the camera and flash, that was a year ago.

EG.

Before this setting



After the setting



Phil

01-03-2008, 06:39 PM   #9
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It took me a long time to learn my 360 flash...When I first got it, I was more frustrated than anything else, but perseverance paid off...I don't really have any tips because I use mine with two lenses only. My Tamron 28-75 f/2.8 and my 16-50* lens. The reason I mention the two lenses is because they both require different flash settings. Why? I have no clue.
01-03-2008, 08:39 PM   #10
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QuoteOriginally posted by matix Quote
In the Custom Settings, set the Link AF Point and AE to on or 2

This ensures that the flash exposure is on the focal area and not on some reflective bright spot somewhere else in the frame, or even from jewellery or the reflection from an eye.

Worked for me, and I went from a 1 in 10 success rate to 9 out of 10, I was close to tossing the camera and flash, that was a year ago.
Never helped me and my 540.

From what I have heard, the 360 is much more accurate.

The 540 seems to be quite consistent for everyone, but for MANY people (including myself), it consistently underexposes even in situations that should result in gross over exposure (spot metering on a matte black object, for example.)

I wound up keeping my 540 because mail-order returns and exhanges are a pain and most of its deficiencies can be worked around, but more often than not I wind up using it as a manual optical slave for a Vivitar 285HV. Knowing what I know now, I would have bought multiple (extra) 285HVs and triggering equipment instead of the 540.
01-03-2008, 08:43 PM   #11
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I also encounter the same problem. A mode of my 360 will give me better result. P-TTL is currently sucks.
But i also found the 16 segments metering (the top one, above center weighted metering) plus +1.0 EV on 360 gave me the same result in P-TTL.

I think you should try this. Hope it helps.
01-03-2008, 09:59 PM   #12
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what are your camera settings? i found that setting the body to -3ev with the flash at 0 generally solved any issue i had. mind you, i've only used it once but the results were great.

mine are the following:
4
2
2
4
2
1
2
2
1
1
1
1
1
1
1
2
1
1
1
1
1
2
1
1
1
1
1
2
1
1
1
2
1

Last edited by attack11; 01-03-2008 at 10:05 PM.
01-04-2008, 06:12 AM   #13
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Found metz 58 AF-1 to be much better. He was sure the metz has consistency both P-TTL and A mode.

FBA - Metz 58-AF1
01-04-2008, 06:34 AM   #14
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Original Poster
Overall I'm very happy with the 540. I love the range of swivel on the head with its 1 button operation. The speed and ease of the controls is great. The wireless operation is MUCH MUCH better than Canon's.

When operating in the A mode the results are accurate, consistent, and exactly what I want it to be. It's just interesting that the P-TTL mode has been so problematic for me. I'm glad that the A mode works so well because the prospect of using the strobe in full manual mode all the time would have made me switch companies (metz,etc.)

Is there a way to have the strobe default to the A mode on start up? I always have to change it when starting the strobe from P-TTL to A and thats a bit of a pain.
01-04-2008, 06:35 AM   #15
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QuoteOriginally posted by kyrios Quote
Found metz 58 AF-1 to be much better. He was sure the metz has consistency both P-TTL and A mode.

FBA - Metz 58-AF1
Is the metz 58 af-1 better than the cheaper sigma ef-530 dg super? If yes, why?
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