I’ve noticed a few flash problem threads lately, not here particularly, but elsewhere, so I thought I’d start a thread about flash (or not to flash) and ramble on a bit, feel free to interject.
One could say that using high ISO is not a good idea when the distance is close along with a fast f-stop and the ambient light is reasonably bright, I’m not sure if the system can compensate by using very high pulse speeds now, it could be that 1/50000sec interferes with refresh rates and frequencies in the digital age. On the other hand there do seem to be a few question marks over the way the flash system behaves, and some cameras/models seem more prone to irregularities than others.
The problem/challenge with the 3600HS(D) and 5600HS(D) flashes might be related to the fact that they are legacy film FF flashes and I’m not sure if KM or Sony managed to get the guide number and output relationship absolutely nailed for use on APS-C format, I did notice when I began using first my 3600HS(D) and later the HVL-F56AM (same as 5600HS(D)) on the KM5D there were a few initial flaky moments with flash output here and there but they both seemed to ‘settle down’ after a bit of use, maybe because all my lenses happened to be (D) lenses. What made things difficult I think was that OTF was lost in the digital cameras right at the start and the only thing they had to balance that loss with was the use of (D) lenses with ADI in direct fill flash and TTL with 25% pre-flash with just about everything else.
I guess we should be alert to the fact that camera brand marketing is usually happy to announce the advent of some new feature but rather reluctant too keep us informed about features that have been altered/modified or dropped altogether.
As an aside, speaking flash power for a moment, the F56 is actually a more powerful flash than the F58, the bigger the number the more impressive it looks in the brochure or sales cabinet but the GN56 was calculated to cover the angle of view of an 85mm lens on FF at 1/1 power level, the GN58 was calculated on the narrower angle of view of a 105mm lens thus condensing the output and ‘enhancing’ the measurement calculations. One can be misled by numbers on flash units a little unless one has a look past the marketing fluff. Take the old Metz 45 hammerhead with a GN of 45 at 62° of coverage, (= 35mm lens on FF) at first glance one would think that the F56 or F58 would be more powerful but that isn’t the case necessarily, if one were to set the F58 zoom on 62° field of coverage it’s GN drops to around 36 so in reality the F58 has about 2/3rds the power of a Metz45.
Getting back to the F56, one can tell they didn’t manage to get overly much sorted with it for use on APS-C because it still has the legacy ‘wider than 24mm’ flashing symbol when using a focal length shorter than 24mm, meaning for you to deploy the wide angle attachment, the problem with that is even 16mm focal length on APS-C is still no wider than 24mm on FF (give or take a midge) so when using that flash on APS-C with a zoom lens like the 16-80 there should not be any need to deploy the wide attachment at all. On the other hand though if the wide angle attachment is NOT deployed there is a GN output gain so that would have to be compensated for by the camera-flash system. But the bottom line is the flashing wider than 24mm symbol should only occur when using a shorter than 24mm lens on a FF camera (as it does) and also only when using a lens shorter than 16mm on an APS-C camera.
In the back of the handbook for the F58 there is two GN tables that lists variations of output depending on whether the flash is used on a FF camera or an APS-C camera, there isn’t all that much difference in both tables but I assume they basically used the angle of view of most lenses as for FF because then the overlap would be more than enough for use on APS-C, the problem that arises though with zoom head flashes is, is the system smart enough yet to zoom to the correct position and angle of coverage with a particular lens focal length and then get the output correct depending on which FORMAT it’s being used on?
There is also the distinct possibility that various lenses (legacy models and brands) may be incapable of reporting to the camera accurately, or at all.
I think even though they have done some work on the problems it’s basically ‘work in progress,’ there seems to be a few gremlins that still need sorting out…apart, that is, from the contact pin problem (occasional unregulated overexposures, depending on which pin looses contact) and others like incorrect mechanical responses to a particular f-stop or shutter setting.
The old gremlin where there was something reflective in the field of view causing major sudden underexposures seems to have been nipped in the bud from what I’ve seen of late, that one I think was because the on camera flash ‘sent’ a signal to the ‘other’ flash to ‘turn off’ only to receive the signal back in the reflection which caused the camera flash to turn itself off.
ps. I corrected a fopar with the F58 and Metz45 power calculations, I fowled up degrees with mm's when looking up specifications duh! I was tired ok....