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11-14-2012, 03:51 PM   #31
HSV
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I think that, probably, is due to the flash metering working separately from exposure metering. I always spot meter and I believe that the camera and/or external flash is metering in matrix when doing p-ttl.

I say this because in the overexposed flash images that I get...while my area of interest is overexposed, the image in average is exposed more or less correctly (following the 18% grey rule). In that regards, I've found that the metering of the AF540 is much more consistent than the K-5's pop-up.

11-15-2012, 02:20 PM   #32
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I did do some testing with wireless PTTL straight/bounced flash, ambient light on/off. There is one setup combination that seems to be more stable (very stable, I did not get any overexposure) than others with wireless flash in K5.

-put flash PTTL mode, inflash exposure correction +-0 AV
-wireless flash mode in camera, flash exposure correction -2 AV (start with this, adjust if needed)
-M exposure mode in camera, exposure correction +-0 AV
-Put fixed ISO
-Underexpose little with adjusting time
-Put in camera menu that camera flash will take part in exposure (sorry can not remember exact words)

This setup looks to work good enough for me, i did not get even one time so much overexposure. I did try wireless PTTL straight flash, bounced wall, bounced roof, ambient light on/off with many different targets. I hope this can help u with K30 also.
11-15-2012, 03:58 PM   #33
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I have a similar setup, except step 5. Seems to work fine enough...sometimes I get overexposure when changing the flash position (shortening the distance to subject) on the 1st frame, but on the 2nd is good. I don't know how the flash adjust power, but the flash output seems to carry over from the previous distance (far) to the new distance (near) therefore giving more output in the 1st frame. On the second one, it will adjust itself to proper power.

Well, this is just a theory of how it works. I see the pro's on video, when they reduce flash power they always have to get the flash to discharge once before the flash adjusts to the newer setting...I think it might be the same in the case of speedlights (I'm not sure).

Just curious...on your step 3, is there any correlation between the exposure compensation and flash output? in other words, can I control flash exposure using the exposure compensation button only?
11-15-2012, 05:26 PM   #34
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QuoteOriginally posted by HSV Quote
Just curious...on your step 3, is there any correlation between the exposure compensation and flash output? in other words, can I control flash exposure using the exposure compensation button only?
Yes, In M-program mode exposure compensation button only adjust flash power. But I do believe myself that exposure compensation is better keep in +-0 value cos it looks like flash results are more stable then.

11-16-2012, 12:03 AM   #35
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QuoteOriginally posted by 123jippo Quote
I did do some testing with wireless PTTL straight/bounced flash, ambient light on/off. There is one setup combination that seems to be more stable (very stable, I did not get any overexposure) than others with wireless flash in K5.

-put flash PTTL mode, inflash exposure correction +-0 AV
-wireless flash mode in camera, flash exposure correction -2 AV (start with this, adjust if needed)
-M exposure mode in camera, exposure correction +-0 AV
-Put fixed ISO
-Underexpose little with adjusting time
-Put in camera menu that camera flash will take part in exposure (sorry can not remember exact words)

This setup looks to work good enough for me, i did not get even one time so much overexposure. I did try wireless PTTL straight flash, bounced wall, bounced roof, ambient light on/off with many different targets. I hope this can help u with K30 also.
I'm glad this is working for you, but here is how P-TTL is supposed to work:

- turn on the camera
- turn on the flash
- take pictures
11-16-2012, 05:10 AM   #36
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Quicksand, you beat me to it.

It's admirable how some users are trying to figure this out. Fact of the matter is, auto flash exposure technology is more or less designed to be plug and play. The bottom line is that the firmware is flawed. Why aren't they fixing this? My guess is that flash performance is at the very bottom of their priority list.
11-16-2012, 06:08 PM   #37
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QuoteOriginally posted by 123jippo Quote
Yes, In M-program mode exposure compensation button only adjust flash power. But I do believe myself that exposure compensation is better keep in +-0 value cos it looks like flash results are more stable then.
Thanks for this trick! I'll be testing it out over the weekend.

I think it's great...saves me the effort of walking up to the flash to change power.
11-19-2012, 05:30 AM   #38
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I did do more testing again...I think my K5 overexposure with flash (with both internal or external flashes) about +2EV always. That is the reason use around -2EV for flash exposure correction. I did give up using buildin wireless flash (i did not get not very stable exposures) totally and use PTTL sync cable instead. Looks like flash exposures are good enough for me now.

I have Nissin universal flash cable and it works fine even its little short. Only thing i do miss little is that can not use both internal or external flashes same time (in contrast mode it was good to take portraits with metz AF 58-2) cos synccable main chord is too big size to open internal flash same time.

11-19-2012, 05:50 AM   #39
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if I had the bucks here is how flash units would work...

install bluetooth.
sell cheap.
release sdk to opensource community for mac, pc, ios and android.

watch Pentax branded flashes outsell everything else on the market.
11-19-2012, 06:36 AM   #40
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I played around a little bit over the weekend with my K-30 and 360FGZ. What I found is that in P mode, if I follow these steps in order, starting with the camera off:

1) mount flash on camera
2) turn on camera
3) turn on flash

... then I would get reliable results with no FEC (and the flash in P-TTL). Bounce or direct -- in fact I think the bounce results were particularly good. In case anyone is wondering, I had the flash set around 75 deg (not quite straight up) for the bounce shots.

The design for P mode flash exposures seems to be:

1) Camera adjusts the shutter for slowest non-blur speed for the detected lens focal length
2) Camera adjusts aperture to capture the most ambient light available
Here's where it gets fuzzy:
3) Camera selects some combination of ISO and flash power for best exposure

(I think the programming tried to keep ISO in the 200 to 500 range regardless of ambient light level but I can't say that with certainty)

Does this correlated with others' experiences?
11-19-2012, 08:08 AM   #41
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QuoteOriginally posted by 123jippo Quote
I did do more testing again...I think my K5 overexposure with flash (with both internal or external flashes) about +2EV always. That is the reason use around -2EV for flash exposure correction. I did give up using buildin wireless flash (i did not get not very stable exposures) totally and use PTTL sync cable instead. Looks like flash exposures are good enough for me now.

I have Nissin universal flash cable and it works fine even its little short. Only thing i do miss little is that can not use both internal or external flashes same time (in contrast mode it was good to take portraits with metz AF 58-2) cos synccable main chord is too big size to open internal flash same time.
Could you explain more about this contrast mode?

(The manual is very, but very vague about how exactly it operates)
11-20-2012, 02:45 AM   #42
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QuoteOriginally posted by IchabodCrane Quote
...
The design for P mode flash exposures seems to be:

1) Camera adjusts the shutter for slowest non-blur speed for the detected lens focal length
2) Camera adjusts aperture to capture the most ambient light available
Here's where it gets fuzzy:
3) Camera selects some combination of ISO and flash power for best exposure

(I think the programming tried to keep ISO in the 200 to 500 range regardless of ambient light level but I can't say that with certainty)
Tnx, looks like P mode is working different than other modes with flash. I will try P mode also with K5 this evenening and report tomorrow.
11-20-2012, 02:57 AM   #43
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QuoteOriginally posted by HSV Quote
Could you explain more about this contrast mode?
(The manual is very, but very vague about how exactly it operates)
Yeah there is not much info in Manual. In contrast mode can use both body buildin and external flash same time. When directing external flash (like in wireless mode and keeping in flash hand) slightly from side to target and there is also buildin flash from front then can take flash photos that have little more light in other side than other side but still have flashlight enough in both sides. Result looks very nice, especially i like contrast mode in quick snapshot style portraits.
11-20-2012, 09:49 AM   #44
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QuoteOriginally posted by 123jippo Quote
Yeah there is not much info in Manual. In contrast mode can use both body buildin and external flash same time. When directing external flash (like in wireless mode and keeping in flash hand) slightly from side to target and there is also buildin flash from front then can take flash photos that have little more light in other side than other side but still have flashlight enough in both sides. Result looks very nice, especially i like contrast mode in quick snapshot style portraits.
Thanks. You're very knowledgeable is this topic.

A few more questions: do you still have to put the -2 compensation on the in-camera flash? or does the in-camera flash automatically underexpose?

On a few post above you have mentioned that you can control the output of the remote flash (when using p-TTL and M mode) using the camera's exposure compensation. Does this mean that the compensation of the camera (as mentioned above) and the compensation of the flash (-3 to +1 dial) are added together? In other words, if I put +2 on the camera's exposure compensation and +1 on the flash output...will I get +3 output?

Another question: why do you put -2 on the in-camera flash output? Is this to reduce power so it contributes less to the overall exposure? can it control the output of the remote flash?

You have stated that you always find the flash overexposed by 2 stops, which is why you put -2. This is on the in-camera flash, right? or both the in-camera and remote flash?
11-21-2012, 01:02 AM   #45
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QuoteOriginally posted by HSV Quote
Thanks. You're very knowledgeable is this topic.
Tnx for ur support also in this discussion. Flash is very important and its nice to talk and share with others and try to find better solutions together. So I do also try to learn here and in this forum has more experienced flash users

QuoteOriginally posted by HSV Quote
do you still have to put the -2 compensation on the in-camera flash? or does the in-camera flash automatically underexpose?
I use -2 flash compensation as a default value both buildin and external flash cos they do both overexposure about same amount in my K5. Normally I use camera program modes Av or M with flash and that -2 has proven to be good starting point that can adjust litle when needed. I did test also yesterday evening flashes in P-mode (actually in all modes) and i did notices that flash exposure is different in separate program modes. In P-mode flash not overexposure same as most program modes, maybe very little if any overexposure in P-mode. But I do not use P-mode myself.

QuoteOriginally posted by HSV Quote
On a few post above you have mentioned that you can control the output of the remote flash (when using p-TTL and M mode) using the camera's exposure compensation. Does this mean that the compensation of the camera (as mentioned above) and the compensation of the flash (-3 to +1 dial) are added together? In other words, if I put +2 on the camera's exposure compensation and +1 on the flash output...will I get +3 output?
For the flash it means +3 yes.

QuoteOriginally posted by HSV Quote
Another question: why do you put -2 on the in-camera flash output? Is this to reduce power so it contributes less to the overall exposure? can it control the output of the remote flash?
I use -2 as a default value for all flash output cos in my K5 in the program modes Av and M that i mostly use with flash that -2 flash exposure compensation gives best results in most cases. In other words my camera flash do overexposure normally about +2 EV (in Av and M) so i need to correct flash exposure. its same with both the in-camera and remote flash. But when bounced and the wall or whatever i use for bouncing then -2 value can be too much correction. But anyway i keep that -2 as default and correct when needed. With external flash i keep that -2 FEC always and use exposure correction in flash unit cos its more easy to use.

If u not have PTTL flash sync cable yet then get one. its really fun and efective way to use flash in one hand and camera in other hand. u will love it.
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