I agree the P-TTL doesn't seem to do much. But that could still mean you're having trouble from being outside the metering range of the preflash. What happens if you open the aperture all the way? If that makes the preflash register with the camera, you should get underexposure. :-)
lørdag 30. april 2011 skrev Leon Altoff <leon.alt...@gmail.com> følgende: > Close, you may have missed my message to Paul about the change in > behavior if I actually feed in a focal length for the set up. This > now stops it firing at full power, but does not get the exposure > correct. > > I can now dial in an exposure adjustment on the camera camera and have > it affect the output, but then opening the aperture 2 stop results in > a 2 stop variation in exposure (brighter) rather than the P-TTL > adjusting for it. Closing the aperture makes it dimmer. It seems > that the P-TTL is just not doing much of anything. > > Using 2 differently powered flashes can only lead to trouble (unless > you want 2 different power outputs of course). > > Leon > > On 29 April 2011 23:55, AlunFoto <alunf...@gmail.com> wrote: >> Leon, >> Combining the info from this thread and another, you have a setup with >> two AF-360FGZ flashes, a 30mm (or thereabouts) lens on bellows with up >> to 25mm extension. The lens is stopped down to f/16, and the >> flash-to-subject distance is about 10 cm for both flashes. I assume >> both flashes are in the same mode, "green" P-TTL. >> >> My guess is that the extension and stopped-down aperture combined >> makes the preflash too weak for the camera to gauge the right >> exposure. It then assumes that the motif is at least 70 cm away and >> just about pitch dark, blasting it with all flash power available. If >> this is a correct guess, I believe you will continue to see >> overexposures as you decrease extension, until you reach a point where >> the preflash registers with the camera's light meter. I'm curious to >> see what happens then. Judging from my experience with the 540 earlier >> today, you should drop very rapidly into underexposure. Assuming >> constant flash to subject distance for all exposures. >> >> It might be a good idea to try one flash at a time too, just to rule >> out that the dual flash setup mess up anything. I'm very confused by >> my own dual flash setup, but I suspect that's down to different power >> rating (GN 54 vs GN 16), so it might not apply to you at all. :-) >> >> >> Jostein >> >> 2011/4/24 Leon Altoff <leon.alt...@gmail.com>: >>> I need to find out more about this, because it doesn't work for me. >>> At least, not with the lens I use. >>> >>> I'll admit it's not your normal A lens, but this set up worked on the >>> MZ-S and the *istD and I'd love to have it work on the K7 (or the next >>> camera upgrade). I have added A contacts to a set of bellows. With >>> the camera set to fully open aperture (f2 in this case), and the lens >>> on the bellows closed down when the prefire happens, the camera >>> calculates the correct exposure and the flash fires correctly - using >>> the *istD and 2 AF360 flashes. The K10D and K7 fire the flash at full >>> output. >>> >>> Both the newer cameras behave as if there is an A lens connected to >>> the camera. The camera recognises the aperture range I set the mount >>> to and I can select the aperture accordingly. It even meters >>> correctly for changes in the aperture set on the camera in P mode. >>> Everything except the flash output. >>> >>> If someone has a simple A lens (maximum of 6 contacts on the lens), a >>> K7 and an AF360 flash can you conduct an experiment to see if you get >>> correct P-TTL exposure out of the setup? That will at least let me >>> know if it's just me or a design issue. I'll have to try high speed >>> sync mode to see if that makes a difference since it works for Paul. >>> >>> Leon >>> >>> On 18 April 2011 23:26, Paul Stenquist <pnstenqu...@comcast.net> wrote: >>>> >>>> On Apr 18, 2011, at 9:12 AM, Thibouille wrote: >>>> >>>>> AFAIK the A lenses do PTTL with K7. >>>> >>>> And with the K5 as well. I frequently use it with my A400/5.6 in >>>> high-speed synch mode. >>>> Paul >>>> >>>> >>>>> >>>>> 2011/4/18 Leon Altoff <leon.alt...@gmail.com>: >>>>>> Hi Tim, >>>>>> >>>>>> I've considered this same thing, though Pentax normally do manage to >>>>>> make a nice improvement between models. Personally I've decided to >>>>>> upgrade every second major upgrade - bought a K10D, skipped the K20D, >>>>>> bought the K7, skipped the K5, buy the K3?. >>>>>> >>>>>> I'll admit I'd like the improved low light capability of the K5 over >>>>>> the K7, but as I'm expecting the K3 (for want of a better model number >>>>>> to apply) to be improved I can wait. For a while. If it's not >>>>>> improved then I will probably go out and buy a K5 simply to keep the >>>>>> control layou-- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. > -- http://www.alunfoto.no/galleri/ http://alunfoto.blogspot.com -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
