AF360 FGZ or Sigma 500 DG Super in P-TTL/TTL?

I have problems getting a proper exposure with *ist DS using onboard flash (severe underexposure with close distance to the subject and long focal length, see my other thread "*istDS underexposure with onboard flash'" in this forum) and wonder whether this is a limitation of P-TTL metering.

Once hooked up to a P-TTL-supporting body with appropriate lens (in my case, *istDS with kit lens), can AF360FGZ or Sigma 500 DG Super work in regular TTL or the only option is P-TTL? I would like to have a possibility to choose between both modes.

How do these flashes perform in P-TTL?

Could you please perform a similar experiment I described in the other thread with these flashes?

tomaszmatys said:

I have problems getting a proper exposure with *ist DS using
onboard flash (severe underexposure with close distance to the
subject and long focal length, see my other thread "*istDS
underexposure with onboard flash'" in this forum) and wonder
whether this is a limitation of P-TTL metering.

Once hooked up to a P-TTL-supporting body with appropriate lens (in
my case, *istDS with kit lens), can AF360FGZ or Sigma 500 DG Super
work in regular TTL or the only option is P-TTL? I would like to
have a possibility to choose between both modes.

How do these flashes perform in P-TTL?
Could you please perform a similar experiment I described in the
other thread with these flashes?

Click to expand...

When you mount the AF360FGZ (and the Sigma should be the same) on a P-TTL compatible Pentax (of course) camera it switches to P-TTL. What was the test you wanted? P-TTL is considered superior to TTL.
--
John Power
Racehorse in the Desert

'Life is too short to miss out on photography.'

Not quite what you asked, but since I own both flashes (for different cameras) I might add a little note. The Pentax unit seems a bit better built and is a little easier to use. The Sigma has both tilt and swivel.

Either way you won't be disapointed.

The test and problem description was in my other post, let me paste it below. I would be very grateful if you could do something similar with external AF360FGZ or Sigma 500 in P-TTL.

"Thanks to encouragement from this excellent forum I have recently purchased *istDS with the kit lens (18-55). The camera performs great outdoors, but I have serious problems getting proper exposure using onboard flash. While the photographs taken with wide zoom look decent, zooming in results in underexposure reaching -2 to -3 EV in extreme cases with the right side of the histogram being virtually empty.

I did the following experiments: I photographed an off-white wall from various distances (1-3 m) using 18, 35 and 55 mm focal length and ISO 400 in M program with constant aperture 5.6 and exposure time 1/30 without ambient light (so the exposure should only depend on the onboard flash duration).

At 18 mm all photographs are exposed OK and the peak of the histogram is more or less in the center.

At 55 mm, the closer to the wall, the more underexposed the photos are (by about -2.5 EV at 1m, -1EV at 1.5-2 m and the exposure starts to be OK and the histogram is centered at distances more than 2.5-3m).

At 35 mm the distance at which histogram gets centered is shorter (about 2m).

So, to summarize, photos taken with onboard flash are underexposed while shooting from close distance with long focal length. The underexposure gets worse if you zoom in or get closer to the subject.

At the same time photos taken with my friend’s Pentax AF 500 FTZ flash working in TTL are well exposed.

Could you try to do similar experiment and report the results? Do you think this behavior is normal or is my camera defective? If this is a normal behavior with P-TTL, why is it?

All these makes me consider getting an external TTL flash instead of AF360FGZ or Sigma 500 DG Super with P-TTL, unless they can work in both P-TTL and TTL modes."

racehorse in the desert said:

When you mount the AF360FGZ (and the Sigma should be the same) on a
P-TTL compatible Pentax (of course) camera it switches to P-TTL.
What was the test you wanted? P-TTL is considered superior to TTL.
--
John Power
Racehorse in the Desert

'Life is too short to miss out on photography.'

Click to expand...

How does the Pentax 500FTZ compare to the newer Pentax 360FGZ?

Which one is better for the DS?

-Ed

Edwood said:

How does the Pentax 500FTZ compare to the newer Pentax 360FGZ?

Which one is better for the DS?

-Ed

Click to expand...

The 500FTZ is the older unit and does not have the wireless flash, etc., features of the 360FGZ, but it has a little more power.
--
John Power
Racehorse in the Desert

'Life is too short to miss out on photography.'

OK, I'll bite.

Just took a few minutes to repeat what you did but using the D with DA16-45 (flat of-white wall and range about 2.5m

I must say right up front that I consider onboard flash a waste of time (others have pointed out that I am missing the convenience factor of easy portrait fill flash "on location"!) due to the v.modest power and low position.

Know problem with the DA16-45 and onboard flash is the shadow caste by the extended lens at wide angles.

I found the opposite to you:

(1) with onboard flash the wide angle shots had a tendancy towards under exposure. At 20mm the peak of the histogram was Level 81. At 28mm it was Level 82 and at 45mm Level 91. Generally a tendancy towards under exposure as you would expect of the 'token' onboard flash camera makers provide (and most a worse than Pentax in my experience)

(2) With Sigma EF 500 DG Super the results were far better exposed, more even over the focal ranges and the histogram was broader and less 'peaky'.

At 16mm (with wide angle diffuser activated the histogram peak was at Level 111 and this gradually increased as I zoomed through 20, 28 to 45mm where the peak was up at Level 148.

Ultimately what this confirms is that no matter what the camera's P-TTL capability the onboard flash low power can't be made up for amd shouldn't be considered for anything other than occassional use and then at quite close ranges.

--
Brett



The Journey is the Thing

Brett, thanks for giving it a try.
Maybe D measures better than DS?
Anyway, external flash is the way to go.

Tomasz

Brett St Pierre said:

OK, I'll bite.

Just took a few minutes to repeat what you did but using the D with
DA16-45 (flat of-white wall and range about 2.5m

I must say right up front that I consider onboard flash a waste of
time (others have pointed out that I am missing the convenience
factor of easy portrait fill flash "on location"!) due to the
v.modest power and low position.

Know problem with the DA16-45 and onboard flash is the shadow caste
by the extended lens at wide angles.

I found the opposite to you:

(1) with onboard flash the wide angle shots had a tendancy towards
under exposure. At 20mm the peak of the histogram was Level 81. At
28mm it was Level 82 and at 45mm Level 91. Generally a tendancy
towards under exposure as you would expect of the 'token' onboard
flash camera makers provide (and most a worse than Pentax in my
experience)

(2) With Sigma EF 500 DG Super the results were far better
exposed, more even over the focal ranges and the histogram was
broader and less 'peaky'.
At 16mm (with wide angle diffuser activated the histogram peak was
at Level 111 and this gradually increased as I zoomed through 20,
28 to 45mm where the peak was up at Level 148.

Ultimately what this confirms is that no matter what the camera's
P-TTL capability the onboard flash low power can't be made up for
amd shouldn't be considered for anything other than occassional use
and then at quite close ranges.

--
Brett



The Journey is the Thing

Click to expand...

tomaszmatys said:

Brett, thanks for giving it a try.
Maybe D measures better than DS?

Click to expand...

D shouldn't be better with P-TTL as I think that would have just trasferred over. The DS flash is more powerful (I think) so that would give DS an advantage that I didn't think about before.

tomaszmatys said:

Anyway, external flash is the way to go.

Click to expand...

I agree if flash must be used.

Regards

--
Brett



The Journey is the Thing