[Phenix]

Update:
Returned to the store already. They will try to fix it first. I only showed them the manual testing off camera. They took it back no problem. Thanks everyone.


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I bought an used af540fgz. Tried it with K5, using both da 18-55wr and da35 2.4.
When camera in AV mode, flash in digital pttl mode, shutter speed never changed no matter where I aimed to meter or what aperture I set.
So I set both camera and flash to manual mode, kept same camera exposure setting and adjusted different flash power output from 1/1 to 1/64, but I always get same extent overexposed images.

Never used Pttl flash before, am I missing sth here or just a defective flash. Luckily I bought from store and can return it.

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Last edited by Phenix; 06-30-2016 at 08:15 AM.

[12345]

I know that the Yongnuo Yn-560 series speedlights had a defect where they would get "stuck" in full power, but I've never heard of it with a Pentax flash. I've never used a Pentax flash, so hopefully some forum members who know more about it will chime in.

[Phenix]

I know that the Yongnuo Yn-560 series speedlights had a defect where they would get "stuck" in full power, but I've never heard of it with a Pentax flash. I've never used a Pentax flash, so hopefully some forum members who know more about it will chime in.

I have Yongnuo 560 III. It has better built and much faster recycle time than the first gen pentax 560fgz. Just all manual sometimes not practical.

[mattt]

You only gave us part of the necessary information to help out..
1) what is your aperture at? When shooting flash photography, your shutter speed controls ambiant / background exposure, while your aperture has most effect on your flash. If you are shooting a flash exposure and want PTTL to do its job, pick an ISO and a moderate aperture, then let the camera control shutter and power.
2) are you shooting dark subject matter ( black suits for example) PTTL will over expose if you do not compensate exposure (yes, you need to dial in a + exposure for wedding dresses, or a - exposure for black tuxedos) - if you adjust exposure compensation on yoru camera body it effects the background exposure
3) are you using a diffuser?
4) is your subject very near your camera? Flash power diminishes by square root of distance.... but if you are shooting something very close, the lowest power might still be too strong.

Post a pic, tell us your exact settings (Camera EXIF and flash settings) we can help you figure it out.

[Phenix]

You only gave us part of the necessary information to help out..
1) what is your aperture at? When shooting flash photography, your shutter speed controls ambiant / background exposure, while your aperture has most effect on your flash. If you are shooting a flash exposure and want PTTL to do its job, pick an ISO and a moderate aperture, then let the camera control shutter and power.
2) are you shooting dark subject matter ( black suits for example) PTTL will over expose if you do not compensate exposure (yes, you need to dial in a + exposure for wedding dresses, or a - exposure for black tuxedos) - if you adjust exposure compensation on yoru camera body it effects the background exposure
3) are you using a diffuser?
4) is your subject very near your camera? Flash power diminishes by square root of distance.... but if you are shooting something very close, the lowest power might still be too strong.

Post a pic, tell us your exact settings (Camera EXIF and flash settings) we can help you figure it out.

uploaded, camera and flash all in manual mode, DA lens, one is full power, another is 1/64, camera setting remain the same, cannot tell any difference.

[Phenix]

flash and camera setting when taken the above two photos

[Phenix]

Flash in PTTL, Camera in AV

different apeture f/2.4 vs f/5

---------- Post added 06-29-16 at 09:54 PM ----------

direct flash, no diffuser. same result when shooting far objects. overexposed in manual mode unless I use f/22 or alike. Power output adjustment seems not working.

in pttl mode, always underexposed compared to no flash shot with ambient light.

Hopefully I am not fundamentally wrong in Flash 101

It must be a broken flash!

---------- Post added 06-29-16 at 10:29 PM ----------

Which is broken? My brain or the flash? Don't wanna be laughed in the face if returning a good flash tomorrow...

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[mcgregni]

In manual flash mode use the flash distance indication to check that your settings are realistic for the flash to subject distance. If you are shooting something very close then even those power adjustments might have no effect. When you half press the shutter then the distance scale will indicate. In your shots here it only shows in one, probably because the meter circuit timed out before you took the shot of the flash displays ... However, it could also indicate a connection problem if that distance scale is not coming on, so worth checking.

As you adjust the aperture, ISO and power then the distance indicated will change. When you have it at a realistic distance then place your subject at the distance .... It should be well exposed.

[Phenix]

In manual flash mode use the flash distance indication to check that your settings are realistic for the flash to subject distance. If you are shooting something very close then even those power adjustments might have no effect. When you half press the shutter then the distance scale will indicate. In your shots here it only shows in one, probably because the meter circuit timed out before you took the shot of the flash displays ... However, it could also indicate a connection problem if that distance scale is not coming on, so worth checking.

As you adjust the aperture, ISO and power then the distance indicated will change. When you have it at a realistic distance then place your subject at the distance .... It should be well exposed.

Thank you. Very helpful guide. I think mine is just broken. I tested again in camera X mode, flash in manual. Camera av f/22, only adjusted power on flash. Full and 1/64 got same results. Target was 7 ft away according to distance reading.

[mcgregni]

Ok , but did you actually PUT the subjects at the indicated distance? The distance scale does not tell you how far away is the target .... It tells YOU how far away to put it ....

I've just checked this with my K7 and AF-540FGZ...

You used F22, so in manual flash mode I set that....

At a zoom setting of 58mm I set mininum power 1/64th .....I had to adjust ISO to 3200 in order to get an indication of 7ft.... These are crazy settings for flash photography. At 1/1 power these settings indicate the subject needs to be around 50ft distance!!!

Did you really move your subject from 7ft to 50ft away? Doing so is the only way you could get proper exposures by the method and settings you say you are using.

I suspect you may be operating the camera and flash way beyond the design limitations....

[Phenix]

Ok , but did you actually PUT the subjects at the indicated distance? The distance scale does not tell you how far away is the target .... It tells YOU how far away to put it ....

I've just checked this with my K7 and AF-540FGZ...

You used F22, so in manual flash mode I set that....

At a zoom setting of 58mm I set mininum power 1/64th .....I had to adjust ISO to 3200 in order to get an indication of 7ft.... These are crazy settings for flash photography. At 1/1 power these settings indicate the subject needs to be around 50ft distance!!!

Did you really move your subject from 7ft to 50ft away? Doing so is the only way you could get proper exposures by the method and settings you say you are using.

I suspect you may be operating the camera and flash way beyond the design limitations....

I posted the pics, full and 1/64, camera X mode, f/22, iso 80. using DA35 lens. I am about 5-6 ft away from target. And it's daytime. I didn't see any exposure difference.

---------- Post added 06-30-16 at 08:14 AM ----------

I also did another shots from 7-8 ft away using the same setting at the same target, similar results.
I had Yongnuo manual flash, full and 1/64 should be totally different for similar settings.

I am not aiming for proper exposure. Just want to check if the power output failed to adjust providing all other settings were the same.

[Flasher]

If you think it is a flash problem then take it off the camera and set it to Manual Full Power. Press the Red button and see how long it takes to recharge. Full power will be very bright and take a few seconds to recharge with the usual squealing involved. Now select 1/64 power and repeat. It should be a quick short flash and there should be no recharge time (ie the red light doesn't go out and no inverter squeal).

---------- Post added 06-30-16 at 10:33 PM ----------

Also try setting the flash to A Mode. Set the aperture to f8 on the flash and the iso to 100. Set you camera to Manual and select 1/160 or 1/180 shutter, f8 aperture and 100 iso. You should get a reasonably exposed shot.

If so then select f4.0 on both flash and camera and repeat. Make the distance to the subject about 6 to 10 feet.

If you get good exposure results then the flash is working as it should.

[Phenix]

If you think it is a flash problem then take it off the camera and set it to Manual Full Power. Press the Red button and see how long it takes to recharge. Full power will be very bright and take a few seconds to recharge with the usual squealing involved. Now select 1/64 power and repeat. It should be a quick short flash and there should be no recharge time (ie the red light doesn't go out and no inverter squeal).

---------- Post added 06-30-16 at 10:33 PM ----------

Also try setting the flash to A Mode. Set the aperture to f8 on the flash and the iso to 100. Set you camera to Manual and select 1/160 or 1/180 shutter, f8 aperture and 100 iso. You should get a reasonably exposed shot.

If so then select f4.0 on both flash and camera and repeat. Make the distance to the subject about 6 to 10 feet.

If you get good exposure results then the flash is working as it should.

I did that, full and 1/64 had same long recharge time when testing, appx 4-5s. also non-visible difference of brightness

[mcgregni]

I think the issue is you are not really assessing the power output in isolation... So many other things are moving around your power settings. ISO 80 at f22 will need a very very small distance to the subject. Try the same manual power test using more sensible settings as suggested by pheniz above.... I'd forget A mode for now, that can open up more confusion. Use those suggested settings in manual mode at the correct distances as indicated.., hold everything in full manual mode apart from the flash power adjustment. You should see a big difference in flash exposures....... Both the previous tests you have made use settings that may make an assessment impossible.

[Flasher]

I did that, full and 1/64 had same long recharge time when testing, appx 4-5s. also non-visible difference of brightness

If it is not mounted to the camera and it does that then you have a faulty unit. Return it to the store.