Pentax P-TTL Flash Comparison - Page 2

felix68 · 01-20-2009, 03:14 PM

Matt,

Thanks for putting together this great reference. One note that you may want to make is to add that the 540 does synch with the camera body in "A" mode. If the camera is in P or Tv mode, you just set the apeture that you want on the flash and the camera syncs to that value. You have a comment that the Metz 58 reads the apeture from the camera but I thought the 540 was going to be completely manual.
I considered the Metz becuase of this synch function in "A" mode but didn't want to pay that much. I was very suprised when I got the 540 and found that there is communication between the body and flash, just the flash controlling the body.

mattdm · 01-20-2009, 03:18 PM

Originally Posted by felix68

Matt,

Thanks for putting together this great reference. One note that you may want to make is to add that the 540 does synch with the camera body in "A" mode. If the camera is in P or Tv mode, you just set the apeture that you want on the flash and the camera syncs to that value. You have a comment that the Metz 58 reads the apeture from the camera but I thought the 540 was going to be completely manual.
I considered the Metz becuase of this synch function in "A" mode but didn't want to pay that much. I was very suprised when I got the 540 and found that there is communication between the body and flash, just the flash controlling the body.

Oh, interesting — I don't have that flash, so I'm relying on what people tell me. What about ISO?

felix68 · 01-20-2009, 03:58 PM

Originally Posted by mattdm

Oh, interesting — I don't have that flash, so I'm relying on what people tell me. What about ISO?

No, the ISO has to be set manually and the flash only controls the body in P or Tv mode. It is on page 29 of the manual but not very well worded:

"The camera's aperture value is synchronized with that of the flash unit when then camera exposure mode is set to Programmed AE or Shutter Priority AE."

I took that to mean that the body was controlling the flash in these exposure modes but it is the other way around. Its better than no automation in the "A" mode.
The zoom is also manual in the "A" mode according to the manual so all you get is the flash controlling the aperture.

mattdm · 01-20-2009, 06:07 PM

Originally Posted by felix68

No, the ISO has to be set manually and the flash only controls the body in P or Tv mode.

Hmmm. Does the flash do the wrong thing if you set ISO incorrectly?

felix68 · 01-20-2009, 07:41 PM

Originally Posted by mattdm

Hmmm. Does the flash do the wrong thing if you set ISO incorrectly?

I was amazed to find out upon testing that the flash and camera do the right thing and adjust the lens aperture if your camera ISO doesn't match the flash. Not only that but the flash adjusts automatically to the correct ISO when you turn the flash on so if you have ISO 400 set, the flash comes up with ISO 400 the first time. If you adjust ISO after that, the flash compensates with aperture.

mattdm · 01-20-2009, 08:46 PM

Originally Posted by felix68

I was amazed to find out upon testing that the flash and camera do the right thing and adjust the lens aperture if your camera ISO doesn't match the flash. Not only that but the flash adjusts automatically to the correct ISO when you turn the flash on so if you have ISO 400 set, the flash comes up with ISO 400 the first time. If you adjust ISO after that, the flash compensates with aperture.

Cool — thanks for testing. Given that the Metz flash can get the ISO information, it'd be crazy if the Pentax version couldn't do something with it.

So, how exactly does it behave in Auto mode in Av or Sv?

Oh, and what does it do in Tv or P if you're using Auto ISO?

felix68 · 01-20-2009, 09:54 PM

Originally Posted by mattdm

Cool — thanks for testing. Given that the Metz flash can get the ISO information, it'd be crazy if the Pentax version couldn't do something with it.

So, how exactly does it behave in Auto mode in Av or Sv?

Oh, and what does it do in Tv or P if you're using Auto ISO?

It looks like in Av nothing is automated. You can set aperture and the camera still picks shutter speed up to 1/180th but nothing changes on the flash and it will expose incorrectly. I don't have Sv on my K100D so I can't test that but the manual says only P and Tv in A mode. Auto Pict mode and all of the scene modes seem to work the same as P on my camera. You can use them but the camera defaults to what the flash is set to.
I tried to shoot with very small apertures to see if it would bump up ISO in Auto ISO but all I could get are shots at ISO 200. Looks like the K100D at least defaults to the lowest ISO for Auto ISO shots in A mode.

*Ofer Hadas* · 02-02-2009, 01:43 PM

Hi all
I was wondering about the right way to overcome the problem of a darker picture when taking a picture with a flash when a bright object is in the frame - like a white shirt or white table cloth

Thanks.
BTW changing the metering (center/ave/spot) on the camera wount help

felix68 · 02-03-2009, 05:31 PM

Originally Posted by Ofer Hadas

Hi all
I was wondering about the right way to overcome the problem of a darker picture when taking a picture with a flash when a bright object is in the frame - like a white shirt or white table cloth

Thanks.
BTW changing the metering (center/ave/spot) on the camera wount help

The easiest way is to switch to A Mode on the flash, if your flash has it. The A Mode uses a sensor on the flash itself to meter and gives an average reading of the entire scene.

*Ofer Hadas* · 02-05-2009, 12:48 PM

thanks.
I have af360 - it happands in TTL . I will try the A mode. I tried to set the bias to +1 which helped But I was wondering if my flash setting was wrong

K200D 18-250, MX Vivitar 285 and sets of "analog" lencs 70-200mm 50mm 1.4 28mm

Marcus · 02-12-2009, 01:28 PM

I don't have the 360 but I think it's the same sort of thing.

In Av mode on the 540FGZ, I usually set the EV compensation on my camera to +1.0 and set the flash exposure compensation on my camera to +1.0. And you're good to go.

Auto does the trick sometimes. But P-TTL works just fine. Just make sure that you have enough juice in your flash. I'm not 100% sure but it seems like weak batteries can cause you problems with P-TTL.

dopeytree · 03-13-2009, 10:13 AM

Does nikons wireless flash system flash the built in flash as a commander (like pentax's wireless system) or does it use radio waves? I just want to know because im finding it a tad annoying having to have my 540 flash in line of sight of the k10d.

mattdm · 03-13-2009, 11:26 AM

Originally Posted by dopeytree

Does nikons wireless flash system flash the built in flash as a commander (like pentax's wireless system) or does it use radio waves? I just want to know because im finding it a tad annoying having to have my 540 flash in line of sight of the k10d.

Same optical preflash wireless.

dopeytree · 03-14-2009, 10:43 AM

so it is basically the same as pentax's system? Minus having flash's in different groups etc

mattdm · 03-14-2009, 04:12 PM

Originally Posted by dopeytree

so it is basically the same as pentax's system? Minus having flash's in different groups etc

Right — a little more sophisticated, but in essence the same.