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03-12-2016, 02:17 PM   #1
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K-S2 + kit 18-50 + AF201FG/Metz 44-AF2 => overexposed pictures.

I've been testing the camera with the flash. I've noticed, that when I try to take pictures with external flash in TTL mode, with the kit lens set to 18mm, I have to add -2EV flash compensation and -5EV exposure compensation to get decent pictures. With no compensation everything is almost completely white.
When I zoom to 50mm, only -3.5EV (and -2EV for flash) is enough.
When I take a 55-300 zoom and zoom it all the way, only -2EV for flash is enough.
It did not depend on the flash (Pentax or Metz behaved the same).

I bounce from the white ceiling and take a picture of a wall/window 3 meters away, in almost complete darkness. The mode is set to "P", the metering is set to default.
Camera firmware version: 1.11.

Is it me doing something wrong, or is it the camera?

03-12-2016, 02:36 PM   #2
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I suspect that the K-S2 does not provide Wireless slave functioning .... ? (Will try and verify this from a manual as soon as possible). Certainly the AF201 does not offer that, so you can't use it to trigger an off-camera flash using the Wireless P-TTL system.......

A quick look at the K-S2 manual shows no Wireless mode in its Flash Modes menu. I can only assume that your Metz 'Slave' flash is being triggered optically and is not set to manual mode? P-TTL mode won't work at all, and may explain the extreme erratic behaviour you're getting. There may be away to trigger it using a 'dumb slave' optical method, plus setting its output in manual mode, but you will still be getting illumination from your on-camera flashes.

Last edited by mcgregni; 03-12-2016 at 02:44 PM.
03-12-2016, 02:48 PM   #3
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I was testing with one flash at a time - either Pentax or Metz.
03-12-2016, 03:03 PM   #4
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Tell us how you are setting things up ..... the flash modes on the camera and the Metz flash, plus any slave settings on the Metz. I was assuming you were using the Metz off-camera and either the built-in or the AF201 to trigger the Metz?

Unfortunately with your camera and flashes you don't have Wireless P-TTL automatic flash functioning. You may be able to get a workable Manual flash exposure though.

03-13-2016, 03:11 AM   #5
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I've made 2 tests with the simplest possible external flash set-ups:
Test 1: AF201FG on the hot shoe, set to Auto mode, camera set to default flash settings. There is no other flash there. No remote firing, no master/slave.
Test 2: Metz on the hot shoe, set to ttl, camera to default. No other flash, no remote, no master/slave.
The only thing that might, I think, have influenced the exposure, is "link ae and af point" (menu C5). I will test this evening again to see, if this was it.
Otherwise - all metering- or flash- wise is set to default/auto.
03-13-2016, 03:24 AM   #6
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Sorry, I thought you were using off camera flash. P-TTL flash exposures should work with both accessary flashes. Check the flash mode on the camera is set to the first one, 'Auto flash'. Check that your ISO is fixed at a sensible level, say. ISO 400, set manual camera exposure mode, set aperture at F5.6, shutter to 1/180th ..... With these settings your automatic flash exposures should be good at distances within an average sized house room, including bounce. Try it and see ... You'll be wiping out any ambient light indoors, but you'll be able to assess how the flash performs without any other variables .
03-13-2016, 12:07 PM   #7
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"token timeout", so I have to write everything again . Well, I'll be quicker this time.

It seems K-S2 has a firmware bug, that sets the ISO in P + auto ISO mode with external flash to maximum value and so overexposing the picture, by 5-7 stops. I can set the ISO by hand and I admire all who want to set the exposure manually, but it is not me, and probably never will. The P-TTL was created to make the settings automatic, and here, unlike on my Nikon, it simply does not work. I can see pre-flashes, but the metering system seems to be fooled by otherwise complete darkness, sets the ISO to max and overexposes. Annoying.

Of course it might be I missed something, there is a setting that will make it work, but so far I have not found it.
03-13-2016, 01:19 PM   #8
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Well, I have heard of people having problems using auto-ISO with flash, even without any bugs. My own recommendation would be to use a fixed ISO for flash working ...auto is asking for trouble I feel. P-TTL is about automatic flash exposure .... How the ambient exposure is controlled from the camera is really for the user to decide and take control. There are different ways to do it, but you need to be in control. It is unrealistic to expect a camera and flash system to make the right choices and ' correctly' balance flash and ambient light, and pick the optimum settings for each situation and physical environment.

I hope the bug can be fixed and it improves the automation for you, which can be very handy in quick situations ..... But if you are interested in taking control, then I invite you to download my Pentax flash Guide (in my sig below my posts) which deals with a lot of these matters.

03-23-2016, 05:45 AM   #9
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I am finding that I need on my K-S2 in average -0.5 EV compensation for all pictures and -1 on built in flash compensation in addition.
03-23-2016, 11:30 AM   #10
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I believe that every P-TTL flash exposure needs the user to take control and make flash compensation adjustments .... Flash exposure has so many ' correct' possibilities that it is unrealistic to expect the camera to pitch it correctly for each situation, even more so than for ambient exposures. That would be to expect the camera to understand your creative intentions as well.

One common factor that affects automatic flash exposures is the size of the flash-lit subject in relation to the surrounds .... If the subject is small in the frame then minus compensation is likely ... If subject is large in the frame, like a head and shoulders portrait, then plus compensation is likely.

andymat, how are you getting on with the K-S2 and flashes now, after the various bits of advice here ... You went quiet ....
03-23-2016, 02:02 PM   #11
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mcgregni,

Thanks for the support. I still think this is a bug of the firmware, so I am trying to resolve the the issue, also in discussion with Pentax. They have said that in P+auto-ISO "some areas of the picture might be overexposed" (at +5 stops it redefines "some"), and that I should go to manual ISO mode. After my protest they went quiet, and so have I. In official newspeak it is called "your issue has been escalated"... So I wait.

My findings so far:
Setup: dark room at night, taking picture of a beige wall and white window frame. No ambient light.
Actors:
I) K-S2 +
1) internal flash,
2) external flash
a) AF201FG,
b) Metz 44-AF2.
II) D5300 + SB-300

Results:
I.1: The internal flash behaves as I expect it - the ISO in the P+auto-ISO mode is reduced to sensible value, and the picture is more-or-less properly exposed. Exactly the same way my Nikon does it.
I.2.a: The camera sets the ISO to the max. value, overexposing the picture,
I.2.b: as in I.2.a
II: camera sets the ISO to something sensible, no overexposure.

I will keep the forum posted of any new developments.
03-24-2016, 07:09 AM   #12
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I understand that you are motivated to try and fix any firmware bug.... But if your ultimate aim is to get good, reliable flash exposures, balanced with the ambient light if you want, and for your creative aims with flash to be realised, then I truly feel that focusing on a camera auto-ISO issue is pointless.


I really would advise to forget auto-iso for flash work and fix ISO instead. IMO ISO is an aspect that needs a positive consideration and decision on by the photographer for every flash situation.....

Perhaps the Pentax guys didn't test that configuration and flash specifically, and you've caught them out ? But, I don't think it matters at all.
03-24-2016, 08:27 AM   #13
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I will try later today. I have the afg? 360 but I like my nikon sb-28s much better so I have to shoot manual.
03-24-2016, 10:47 AM   #14
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I just tried to reproduce your results with the k-s2 and the AF-360FGZ. On board flash set to A and auto zoom. Camera in both P and auto mode with ISO set to auto 100-12800. 18-50 set at 35mm. I had the camera set both on auto flash discharge and flash on. It took a perfectly lit picture every time at 1/90 F4.5 ISO 400. Maybe there is a parameter I didn't try. Does flash have auto ISO?

Any suggestions as to what I might try to get this over exposure? Maybe its the flash? Maybe a contact not sending info between the camera and flash? If it were firmware it seems I would have that problem unless its specific to the newer flash you have (you have the new one?).
03-24-2016, 12:02 PM   #15
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'A' Flash Mode on the AF-360FGZ (and AF-540FGZ) is not compatible with any camera automatic exposure mode (P, Av Tav etc). You should use Manual exposure mode on the camera with 'A' Flash Mode. There is no settings information communicated between the camera and flash in 'A' Flash Mode, and auto-zoom does not work.


If you wanted to test the automatic functioning of the camera and flash, including auto-ISO, you'd need to use P-TTL flash mode.


But, I guess its clear enough by now , I don't recommend using auto-ISO with flash at all
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