[Cascadilla]

I have 2 Pentax K 3 bodies and 2 Pentax 540 FGZ II flash units and a variety of lenses (some Pentax, some Sigma, Tokina, Tamron). No matter how I use them (on camera, with a bracket and TTL connecting cord to the hot shoe, or bounced) exposure is inconsistent, mostly tending to over exposure. Has anybody come up with a work around? I usually wind up dialing in a 1 stop underexposure on the flash, which seems to work reasonably well, but it is annoying that my low tech Vivitar 285's from the early 1990's are more consistent than the $$$$ new Pentax flashes. Any thoughts?

[suraswami]

Which mode are you using?

Full Auto I feel K3 + 540FGZ (version 1) is much better than my K50. But best I feel is set everything to Manual and experiment with the settings, once I get the right numbers, I keep shooting and get 95% of shots right.

And with my testing I feel when used with a Pentax lens the exposure seems much better than other brands.

Sorry I don't have the version 2 flash, I just shared my experience with version 1.

[clackers]

The amount of flash in a scene is like salt and pepper, Cascadilla, a matter of taste.

Just turn the camera dial to give it the amount of FEC you want.

Or even better, go manual power for ultimate control.

[Cascadilla]

I've done a little more testing in my studio and I'm finding that AV mode seems to be working a lot better, although the camera is frequently picking a shutter speed of 1/45 or 1/60 at f/8 with the ISO set to 400, which isn't my first choice of shutter speed for what I use these for--event coverage. That is also why I don't want to go completely manual for settings--I do that all the time in my studio with monolights, but don't have time to constantly adjust when shooting spontaneously. My previous method had been to set the f/stop and shutter speed manually and use the flash automation to determine exposure, which always worked well with my ancient Vivitar 285s. In other respects, the Pentax 540 II is a great flash--a bit more powerful than the Vivitars, more compact and with faster recycling. My tests were with the Sigma 17-50 f/2.8 and a Pentax 18-55 kit lens. Both seemed to be variable in exposure when set manually to shutter speed and f/stop, but seemed to be a lot more consistent in AV mode.

[mcgregni]

Remember that shutter speed does not affect the flash exposure, but rather is a main determinant of the ambient exposure. If all of your illuination is coming from flashes (which is a common situation indoors and in studios) then there's not much point in using any shutter speed other than the max sync (1/180th or 1/200th sec).

When you want to allow ambient light to record also, and mix with the flash lighting, then indoors and in lower light, longer exposures are needed. In Av and P modes, the program line and focal length will limit the shutter speed in order to ensure steady hand-holding The camera system cannot guess what sort of ambient and flash balance you have in mind, so it won't prioritise this aspect. However, if you switch to Slow Speed Sync flash mode on the camera, then the priority becomes a good ambient and flash mixture, and more ambient will be allowed to record via longer exposures.

When using Av mode with flash, I almost always have compensations set for both ambient and flash exposures (when Av is combined with P-TTL) .....often this is minus 0.5 for ambient and plus 0.5 or plus 1.0 for the flash.

[clackers]

I've done a little more testing in my studio and I'm finding that AV mode seems to be working a lot better, although the camera is frequently picking a shutter speed of 1/45 or 1/60 at f/8 with the ISO set to 400, which isn't my first choice of shutter speed for what I use these for--event coverage.

I often manually set the camera exposure indoors so that in Live View or in a test shot I'm happy with the ambient and let P'-TTL do the rest with a -1 FEC. I have a tiny softbox if there isn't much crowd jostling, a Rogue Flashbender otherwise.

Outdoors the shutter speeds are naturally higher and I'm happy to use HSS, often with a bare bulb to get range in sports.

[Cascadilla]

I've tried setting exposure compensation when in manual, but the exposure still varies from shot to shot. I'm hoping that the AV setting will be more consistent. I am quite aware that the flash duration is effectively the shutter speed when working in low light levels, that's why I find it annoying that the automation is trying to drag in some ambient light at the expense of selecting a slow shutter speed on the camera that might result in ghosting or blur.

[mcgregni]

You can download my Guide to the Pentax Flash System from the link in my signature here ..... this contains all the essential information on flash and ambient exposure control and full coverage of the camera and flash modes and how they interact and affect how you control things. There may just be some gaps in your general knowledge or awareness of some Pentax specific features .....I hope the Guide will prove helpful.

[Cascadilla]

Thanks for the flash guide--I've been a working pro for the last 30 years, but have mostly worked with studio flash units and a flash meter. I haven't really taken the time to get totally familiar with the 540's, but was surprised by the difficulty of getting a decent consistent exposure after having a lot of experience with primitive Vivitar 285's and having good results with just setting the shutter speed and f/stop indicated by the calculator dial on the flash. I would have thought that TTL metering would easily do a good job on exposure since the non TTL of the Vivitar usually did. I will spend some time with your guide, a K3 and a 540 flash in the next couple of weeks and see if I can get this figured out. Thanks again.

[mcgregni]

I hope you will find some useful info in the Guide ....I can't guarantee that it will solve all P-TTL exposure issues though. P-TTL has come in for more than it's fair share of stick around here, that's true. The K5 seemed to cause many to have issues, but in terms of exposure consistency generally the K3 onwards have brought good improvements, based on feedback I've read here and on other forums. I am fortunate that my own K7 has been very good with P-TTL and my two Pentax flashes, and no doubt my own positive experience has made me a stronger advocate than many others.