Hi Gerard - Thank you, that's very helpful. From what you're saying, I'm gathering that Vari-Power is only available when the /flash/ is in manual mode, and that it can be so even when the camera is some other mode. This is a new possibilty to me, and I'll try to do some EOS flash reading (I know there are Web resoiurces) on what the relationship is - under ETTL - between the camera and the flash under these conditions - say body on P or Av, flash on M. It may be as simple as "they're independent," like the situation on my older cameras when I put the flash on manual, but even there I think (not sure about this) the thyristor is still reading the flash and extinguishing it according to conditions, however just conditions set by the power setting (1/4, 1/16 etc) on the flash. I told you my flash theory was rusty. <g>
One other question, not having dealt with slaving before: how much control is there over main/slave power ratios? best Ken E-TTL(II) uses the evaluative exposure circuits of the camera to >determine the exposure. E-TTL-II takes also distance information (if >available) into account. >With (M)anual mode, you set a fixed power and the flash will ALWAYS >fire at that specific power setting. >Flash exposure depends on f/stop (lens aperture) and distance. If you >set FEC to -1, the ETTL system will expose the subject at -1 stop even >if you walk to it, get further away or open-up/close-down the >diafragma (within the limits of the flash power). With Manual, first >of all, you will need a flash meter (or the digital histogram method) >to determine the correct exposure. Let's say that (like in your >example) that you set 1/2 power to get the subject with -1 stop flash >exposure; now, if you get closer and want to maintain the same >exposure you have to dial down the flash power or increase the f/stop >to compensate for the variation in distance. > > >My limited understanding of E-TTL also causes me to > > wonder how much this changes in various exposure modes, especially Av. > >In (M)anual mode, the flash will output the given amount of power >(1/1,1/2,1/4,1/8...) independently of the camera mode used. I hope >that's also clear from the previous paragraph. > > > > With my current 420EX/30D or Elan 7 setup I can get 2 stops of > > negative FEC, so one advantage of the 580EX would be the ability to > > go all the way down to 1/128 for macro fill and the like, if these > > two are really related. >1/128 = Nope. That's just minumum manual power, but in E-TTL the flash >can output even less power than that! > >With the 580EX you can get -3 stops FEC, but I don't know how that >helps in macro situations (-3 would be only for some catchlights) > > > > Any other comments on what real-world, noticeable, pluses there would > > be to the upgrade also welcome. I do realize the 580 has a higher > > GN, of course. But the 420EX is an amazing little unit, I've never > > been disappointed in it. But now that I have a DSLR I'm wanting to > > experiment a lot more - what would the 580 do that the 420 can't? > >I don't have a 420EX so I can't answer to that question. I upgraded >from a 550EX and I'm very satisfied with the 580EX. Main 'highlights' >(pun intended :-) are: 14mm diffusion panel, white catchlight panel, >very fast recycle times, a friendly user interface (the wheel behind >is the best thing that Canon could do!) I can even set one slave with >1 hand instead of needing two hands for the 550EX. the 580EX can be a >wireless master controller. > > >what would the 580 do that the 420 can't? >The obvious: putting out more light >-Wireless master >- 14mm coverage >- manual mode >- stroboscopic mode >- automatic zoom compensation for DSRL cropping >- wanting another 580EX >- a hole in your pocket > >:-) * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
