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04-02-2016, 07:49 AM   #1
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K3 (&K1?) flash change/bug

Hello,

I have a Q for all you flash experts out there, which I'm certainly not.

On K7 and K5, if I set camera to Tv and connect a flash on A mode, I can use bracketing to keep the illumination on a foreground object constant but the background changes, ie a range f/4 to f/20 because of the bracketing.

I can't make my K3ii do this. It does work without a flash (bracketing) but if I connect a flash it does photos at the same ev, doesn't change anything. Either I have some obscure setting wrong (although I did default back to factory setting to test), or it's a change, or it's a bug. And, since K1 will use firmware developed on from K-3ii, it'll likely have the same feature/problem.

If flash bracketing like this is something that matters to you, and you have actually made it work like K5 and K7 on a K3/K3ii, please put me out my misery... what's the secret magic setting that'll make it work like I want?

Many thanks

04-02-2016, 08:07 AM   #2
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have to investigate this. thanks for the heads up.

m
04-02-2016, 09:00 AM   #3
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QuoteOriginally posted by Nass Quote
Hello,

I have a Q for all you flash experts out there, which I'm certainly not.

On K7 and K5, if I set camera to Tv and connect a flash on A mode, I can use bracketing to keep the illumination on a foreground object constant but the background changes, ie a range f/4 to f/20 because of the bracketing.

I can't make my K3ii do this. It does work without a flash (bracketing) but if I connect a flash it does photos at the same ev, doesn't change anything. Either I have some obscure setting wrong (although I did default back to factory setting to test), or it's a change, or it's a bug. And, since K1 will use firmware developed on from K-3ii, it'll likely have the same feature/problem.

If flash bracketing like this is something that matters to you, and you have actually made it work like K5 and K7 on a K3/K3ii, please put me out my misery... what's the secret magic setting that'll make it work like I want?

Many thanks
I'm confused. How are you changing the aperture when in Tv mode? How are you achieving bracketing? When the flash is in A mode, its going to try to properly expose the scene the same way everytime.
04-02-2016, 10:02 AM   #4
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I am a bit confused here... As long as I understood flash bracketing, the flash needs to support flash bracketing.

On the other hand as poster above me mention the flash in P-TTL mode will always try to compensate automatically for any changes you do on your camera unless you are in fully manual mode (flash) and then you can do a camera bracketing as usual. If you are using the Flash Exposure Bracketing (FEB) than your flash must support it and it is set on your flash.

You may try to change the exposure mode on your camera to spot and then take it from there. I never tried this but in my logic that tells me that camera will expose for the spot and flash will expose for it as well and that may give you the desired results that will depend of the natural available light.

All the best.

04-02-2016, 10:26 AM   #5
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I'm thinking that in 'A' mode, the flash will continue to output the exact same power each shot, because it doesn't know that the camera is changing the ISO. ..... I'm assuming that Nass is using the ISO changes for the bracketing with aperture and shutter fixed.... ? So it would be the ISO that adjusts the flash exposure recorded for each shot, the flash power remains constant .... ?
04-02-2016, 10:49 AM   #6
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QuoteOriginally posted by enoeske Quote
I'm confused. How are you changing the aperture when in Tv mode? How are you achieving bracketing? When the flash is in A mode, its going to try to properly expose the scene the same way everytime.
Sorry I don't understand the question. On a K5 and K7 as explained I'm on Tv bracketing -4,-3,-2,-1,0 so I get a range of photos like f/4,f/8,f/16 like Tv bracketing is supposed to. The bracketing means the aperture changes.


QuoteOriginally posted by RAART Quote
I am a bit confused here... As long as I understood flash bracketing, the flash needs to support flash bracketing.
No, I'm not talking about Flash Exposure Bracketing. It's camera bracketing but with a flash mounted. If you have a k7 or k5 and flash with A mode you'd see what I mean. I'm not using the flash in PTTL mode either. The behaviour happens in just about any mode on K3ii, the flash seems to override the settings on camera and dictates that the camera can't bracket in the way I have it set to. This is a change from K5/K7.


QuoteOriginally posted by mcgregni Quote
I'm thinking that in 'A' mode, the flash will continue to output the exact same power each shot, because it doesn't know that the camera is changing the ISO. ..... I'm assuming that Nass is using the ISO changes for the bracketing with aperture and shutter fixed.... ? So it would be the ISO that adjusts the flash exposure recorded for each shot, the flash power remains constant .... ?
I think you're closest in terms of getting what's happening but not quite - truth is I'm no flash expert myself so I don't know the ins and outs of this. Yes K7 and K5 are on auto ISO, as is K3ii. But on k5/k7 iso doesn't change in these bracketed sequences, it's just the aperture that changes (which is what I'm after). I don't know how the flash changes but on the images from a k5/k7 sequence the foreground object, lit by a flash, looks the same brightness whereas the background goes from light to dark over the sequence. This is all I'm after, a thing lit at the front by flash and a scale/range of bright to dark backgrounds (it's really k-3ii depth of field bracketing I want, but Pentax doesn't have this although you can make it happen on K5/K7 with that tv/A bodge)

Last edited by Nass; 04-02-2016 at 10:55 AM.
04-02-2016, 11:28 AM   #7
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Nass, we need to confirm the flash mode you're using ... You said 'A' originally ... Do you mean A on the flashgun, as in 'auto-thrystor', which is what I'd assumed .....?. If so, then in fact your flash exposure would 'bracket' using Tav, because the ISO on the camera will change, but the flash doesn't 'know' that's happening.
04-02-2016, 11:35 AM   #8
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I like to know which exact flash you are using? If the flash does not communicate with camera then you will have your answer.

EDIT: btw which lens are you using when you do bracketing on K-3?

04-02-2016, 11:44 AM   #9
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To make this work on k5/k7, I use 'A' mode, on either a Metz 58AFII or Pentax 540FGZ (V1). A is set on the flash
04-02-2016, 12:08 PM   #10
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QuoteOriginally posted by RAART Quote
EDIT: btw which lens are you using when you do bracketing on K-3?
It's actually a tamron 70-200 with extension tubes (full contacts) - which you might think would be a possible cause but it's not - on K5 & K7 the same combo works just fine as I'd like it too...
04-02-2016, 12:27 PM   #11
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Ok, then with 'A' mode flash, BOTH flash and ambient exposures will change with ISO adjustments caused by bracketing in Tav mode .... The flash determines it's own output based on the aperture and ISO settings you make on the flash itself, plus the reflected light returned to the sensor. The flash is not aware of the ISO variations on the camera, so it continues to output the same amount for each exposure .... However, the amount of light recorded by the camera varies with each ISO change.

In theory, P-TTL flash mode should also hold it's output during bracketing, but didn't we recently test this and found that the flash exposures actually bracketed. .... ? Perhaps the K3II simply works differently. I'd like to see a specific flash bracket function for this sort of thing, so we had the choice of bracketing either the flash, or ambient exposure in P-TTL mode.


However, really, 'A' flash mode is not compatible with any auto-exposure modes .... It really needs 'M' manual camera mode . But, if by a clash of technologies and no communications it actually works, then fine!

Last edited by mcgregni; 04-02-2016 at 12:38 PM.
04-02-2016, 01:19 PM   #12
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QuoteOriginally posted by mcgregni Quote
In theory, P-TTL flash mode should also hold it's output during bracketing, but didn't we recently test this and found that the flash exposures actually bracketed. .... ? Perhaps the K3II simply works differently. I'd like to see a specific flash bracket function for this sort of thing, so we had the choice of bracketing either the flash, or ambient exposure in P-TTL mode.
I think maybe this is the crux of the problem, because it looks to me like on K3ii, if you have a flash connected via hotshoe or PTTL lead, then whichever mode you bracket in, I only have the flash light output varying, never ISO, shutter or f/stop.

There seems to be no way to force the camera into a range of outputs using another variable like f/stop, shutter speed or ISO, regardless of what mode you put the camera in or what flash mode you use! Which seems really surprising?

added- with a flash set on PTTL pr PTTL HSS, then when bracketing, in all modes, at least you get a series of dark-light images
but with a flash set on A or M, all images in a bracketed sequence, regardless of camera mode, are the same
Does this seem right to people?

Last edited by Nass; 04-02-2016 at 01:51 PM.
04-02-2016, 01:57 PM   #13
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---------- Post added 02-04-16 at 21:07 ----------

Sorry, I originally read 'Tav' in your opening post, but you're actually using Tv, with he aperture changing. In A flash mode this works the same as I previously described .... both flash and ambient exposures would change for each shot because the aperture is changing, but the flash doesn't know that.

So there's a logic to why it works in A mode ... Check out my Guide, there's a section on A mode and exposure control using it, which involves this offset between the camera and flash settings to control flash power .. The bracketing is just an automated way to do that.

Last edited by mcgregni; 04-02-2016 at 02:08 PM.
04-03-2016, 06:24 AM   #14
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QuoteOriginally posted by mcgregni Quote


---------- Post added 02-04-16 at 21:07 ----------

So there's a logic to why it works in A mode ... Check out my Guide, there's a section on A mode and exposure control using it, which involves this offset between the camera and flash settings to control flash power .. The bracketing is just an automated way to do that.
Yes - I do get the logic. But as I said, there's a change in how a Pentax camera deals with bracketing using a connected flash. Bottom line is on K3ii, bracketing with a flash now only gives you changes in flash power, it doesn't give you changes in aperture, speed or iso anymore. So it's either broken or been changed.
04-03-2016, 01:28 PM   #15
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I'll have another go with the K7 also. Did we not have a recent discussion about bracketing and you pointed out that with a flash connected it was actually the flash output that bracketed, not the ambient exposure ...? I tried it then and that was how it worked. But that was P-TTL mode. In A mode, unless the aperture or ISO varies between the shots, then there's no way for the flash exposure to change .... the flash in A mode does not 'know' the camera settings, it just outputs based on its own settings and the reflected light. So are you saying that with auto-bracketing set, and a flash in 'A' mode, that the aperture and ISO do NOT change for each bracket ?
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