Nitnaros Posted December 7, 2007 Share #1 Posted December 7, 2007 Advertisement (gone after registration) Hello Folks, I started using my Canon 580EX (version-I) on my M8 and it works great; I discovered this option on this forum (thanks to Mark Norton's comments on the voltages involved; I also see the comments to insulate the not required pins as a safety measure; and thanks to Jamie Roberts reports). My 580EX has no A-mode for a more automated shooting. Adjusting the flash output via its dial works pretty well (I love the ability to control this in 1/3 steps from full down to 1/128th of full). But working via A-mode would be even more convenient. - So how accurate is the A-mode flash exposure on a Canon 580EX-II or other flashes? - And I guess it works only for flashing the subject straight on, does not work for any bounced flashing - correct? Peter Quote Link to post Share on other sites More sharing options...
Advertisement Posted December 7, 2007 Posted December 7, 2007 Hi Nitnaros, Take a look here How good is A-mode flash exposure (e.g. Canon 580EX-II). I'm sure you'll find what you were looking for!
marknorton Posted December 7, 2007 Share #2 Posted December 7, 2007 I'm not familiar with this flash, but I assume you dial in the ISO, it tells you the aperture to use? The sensor on the flash gun then controls the flash power output, the camera just says "do it" after opening the shutter. The flash sensor reads the light reflected back from the subject, an approximation for TTL metering. One reason why the exposure can be off is because the flash's calibration for a given ISO may be different from the camera's. Sean Reid found the M8 ISO to be a little higher than the selected value, so if your camera is the same, you might find your shots slightly over-exposed, in which case you might want to redice the flash exposure a tad, say 1/3 stop. Quote Link to post Share on other sites More sharing options...
erl Posted December 7, 2007 Share #3 Posted December 7, 2007 I concur with Mark's remarks and add that 'A' mode will work with bounce flash. Just remember that bouncing absorbs a lot of the useful light and thus reduces the effective range for shooting. Also boucing of a coloured surface, such as a green ceiling, will put a green cast over your image. Other than that, bouncing works extremely well. Quick edit: I am assuming you are using a flash with a bounce head, such that the sensor remains facing the subject. That is vital Quote Link to post Share on other sites More sharing options...
Nitnaros Posted December 7, 2007 Author Share #4 Posted December 7, 2007 Regarding the flash exposure: Sounds to me that flashes with A-mode capability have a sensor ("thyristor"?) on it which measures the incoming light and shuts off the flash light depending on chosen aperture and chosen ISO. Light is not measured through the lens, but I guess you folks are right that it measures the light coming back from the subject (flash sitting close to lens), independently whether bounce-flash or not. I am still curious whether anybody has experience with the accuracy of flash exposure with A-mode flashes (does not really matter which camera system). Peter Quote Link to post Share on other sites More sharing options...
gravastar Posted December 7, 2007 Share #5 Posted December 7, 2007 If anyone is thinking of using the new Canon 580MkII flash (the one with the inbuilt auto exposure sensor) with a non Canon camera make sure that this is possible before spending money. I have read somewhere that the auto feature can only be enabled if the flash is mounted and recognises the camera. That may also mean the auto function is only available on the 1DMkIII and 1DsMkIII cameras and not for example the 5D. I have the MKII flash, a 5D, 1DMkIII and an M8 so I will try and verify what works in auto mode this weekend. Bob. Quote Link to post Share on other sites More sharing options...
marknorton Posted December 8, 2007 Share #6 Posted December 8, 2007 I use Nikon flashes (SB28/SB80/SB800) on an M8 in auto mode and they work fine, the flash doing all the work and as erl says, it's vital to keep the flash sensor pointed towards the subject to approximate to TTL metering. As soon as you want to go beyond that, into the Leica/Metz world of GNC or Nikon's iTTL/CLS (or Canon equivalent), there's much greater inter-dependence between camera and flash. Straight-forward auto mode has been around for a long time and is simple - you tell the flash what ISO you are using and it tells you the lens aperture to set (or gives you a number of aperture choices). Quote Link to post Share on other sites More sharing options...
robertwright Posted December 8, 2007 Share #7 Posted December 8, 2007 Advertisement (gone after registration) I have the 580EZ II and it works in auto mode, you set it via a custom function, it works great. It works like any other auto-thyristor type flash, you set the ISO and Aperture you want and bang away. Bonus: if you have another canon flash, like the 580 or 430, the multiple flash master/slave works also, it will fire other units, and you can set ratio. The zoom feature is handy too if you want to use it as a spot. it's heavy but the flash shoe is rugged and has a nice locking feature. For when you need that much power and bounce, it is great. Quote Link to post Share on other sites More sharing options...
lars_bergquist Posted December 8, 2007 Share #8 Posted December 8, 2007 In A-mode with any flash, exposure is controlled by the flash, not the camera. The sensor in the flash cuts off the discharge at the right moment, if you have chosen the right ISO and set the right aperture on the lens. So this will work equally well on any damn camera with a hot shoe, bounce or not bounce. I use A all the time, except on occasion when I use M for bouncing with a small flash without a bounce head, using a shoe-to-shoe cord. In that case of course I do a test exposure and check the histogram – a true benefit of using a digital camera! The old man from the Age of Flashpowder Quote Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted December 8, 2007 Share #9 Posted December 8, 2007 Agree with Lars A mode is controlled by the flash and not the camera , it will preform the same way on any camera. i use the Metz 54 all the time on the M8 in A mode and works perfectly given you know what you are doing also. Remember this stuff can't think you have to control it. Quote Link to post Share on other sites More sharing options...
Jamie Roberts Posted December 8, 2007 Share #10 Posted December 8, 2007 One thing the Canon 580v2 does that the Metz or the Nikons don't--and it bears repeating I think--is give you a very, very wide range of camera settings in the flash controls on A mode (E mode it's called by Canon). You can actually dial in f1.0 on the 580. Since Canon doesn't make an f1.0 lens, it's interesting to me why they did this, other than to give you flash exposure compensation or wiggle room for their f1.2 and f1.4 lenses. But with the Nocti when you need just a weeee bit of fill light, it's great Quote Link to post Share on other sites More sharing options...
thai.charlie Posted December 8, 2007 Share #11 Posted December 8, 2007 I have the 580EZ II and it works in auto mode, you set it via a custom function, it works great. It works like any other auto-thyristor type flash, you set the ISO and Aperture you want and bang away. Am I totally missing something? Can you elaborate where this setting is (I tossed the instruction manual, duh!)? I was under the impression that this flash only works in various TTL modes only (reading reflected flash through the lens). Or is it quasi "A" mode and it is making flash output computations based on what aperture value you dial into it (rather than actually measuring the reflected flash on the unit itself -- ie, no onboard auto-thyristor). Thanks. Quote Link to post Share on other sites More sharing options...
Jamie Roberts Posted December 8, 2007 Share #12 Posted December 8, 2007 Am I totally missing something? Can you elaborate where this setting is (I tossed the instruction manual, duh!)? I was under the impression that this flash only works in various TTL modes only (reading reflected flash through the lens). Or is it quasi "A" mode and it is making flash output computations based on what aperture value you dial into it (rather than actually measuring the reflected flash on the unit itself -- ie, no onboard auto-thyristor). Thanks. You are totally missing this. I did too until the clerk at one of the camera stores here insisted! The 580v2 is not quasi-A anything: the 580v2 *has* a thyristor on the front Have a look and see! LOL!! It's fully A mode capable, in other words. It doesn't just have TTL modes. Having said that, it has two A modes, which they confusingly call E mode. One is AUTO (auto thyristor) mode where the ISO and aperture are read from the camera but the light output is still controlled by the flash. That won't work on the M8, so you want the MANUAL (auto thyristor) mode--E mode with the big M on the display--and then you manually set everything and the light is controlled by the flash. So you jyst set the flash by dialling in Custom Function 5 and setting switch 3, which is Manual E mode on the Canon (doing this by memory folks--someone chime in if I'm really off here). Then you just set your ISO and aperture value and shoot away Quote Link to post Share on other sites More sharing options...
lars_bergquist Posted December 8, 2007 Share #13 Posted December 8, 2007 Jamie, the thyristor is inside. What you are referring to is the small silicon cell on the front of the flash unit, which generates the signal that triggers the thyristor action. The old man from the Age of Flashlamps Quote Link to post Share on other sites More sharing options...
Jamie Roberts Posted December 8, 2007 Share #14 Posted December 8, 2007 Jamie, the thyristor is inside. What you are referring to is the smallsilicon cell on the front of the flash unit, which generates the signal that triggers the thyristor action. The old man from the Age of Flashlamps Yes... that's absolutely true. I knew this, actually, since I've built my share of flash triggers from Radio Shack parts, but all is not always to mind any more on that front. The sensor (light cell) is on the outside--as it is on the 580ex--and the thyristor is the solid state switch that allows current to pass from the capicitors inside the flash to the flash tubes. FWIW, I don't know if they're still using silicon cells as senors, though it seems likely. The young guy from the age of tube (valve, for our UK friends) electronics... Quote Link to post Share on other sites More sharing options...
cliffordjim Posted December 9, 2007 Share #15 Posted December 9, 2007 You can actually dial in f1.0 on the 580. Since Canon doesn't make an f1.0 lens, it's interesting to me why they did this, other than to give you flash exposure compensation or wiggle room for their f1.2 and f1.4 lenses. But with the Nocti when you need just a weeee bit of fill light, it's great Jamie - Does the f1 setting on auto mode work if you are shooting at ISO 640 with the Canon flash? In other words does the flash cut off enough power to not overexpose the image while using the flash with a Noctilux f1 at ISO 640? With my Nikon SB800 set on M @ 1/128 power it is still too hot for f1 at ISO 640 so I am considering the Canon if it can cut the flash enough in Auto mode. thanks! Quote Link to post Share on other sites More sharing options...
robertwright Posted December 9, 2007 Share #16 Posted December 9, 2007 Jamie - Does the f1 setting on auto mode work if you are shooting at ISO 640 with the Canon flash? In other words does the flash cut off enough power to not overexpose the image while using the flash with a Noctilux f1 at ISO 640? With my Nikon SB800 set on M @ 1/128 power it is still too hot for f1 at ISO 640 so I am considering the Canon if it can cut the flash enough in Auto mode. thanks! not sure, but it is easy to put one of those flash diffusers on all the time, the stofen thing, small, doesn't take up much space, and it kills the flash by about a stop. Inside it you could put diffusion or ND which would kill another stop for when you are working at ISO 2500 and F1.0! Quote Link to post Share on other sites More sharing options...
Tom_W Posted December 9, 2007 Share #17 Posted December 9, 2007 This forum is excellent. Tom (an M8 and 1ds3 shooter) Quote Link to post Share on other sites More sharing options...
Jamie Roberts Posted December 9, 2007 Share #18 Posted December 9, 2007 Jamie - Does the f1 setting on auto mode work if you are shooting at ISO 640 with the Canon flash? In other words does the flash cut off enough power to not overexpose the image while using the flash with a Noctilux f1 at ISO 640? With my Nikon SB800 set on M @ 1/128 power it is still too hot for f1 at ISO 640 so I am considering the Canon if it can cut the flash enough in Auto mode. thanks! Hey Jim--in my absolute dark room tests, so just testing the flash output, yes--the 580 does cut enough light for f1.0 at ISO 640, or ISO 1250 for that matter, from about 6 feet away... Two things, though, to bear in mind under these conditions: the Nocti collects so much ambient light at f1 that you really need to decide what's your key and fill--the ambient or the flash. If you're using the flash as fill to get the most out of the Nocti at f1 or 1.2, then you need to cut the flash output even more, and set the ISO on the flash to 1250 or 3200... just like an average light meter, there are many things that can fool the sensor on the flash; white clothing, black clothing (um, like at weddings) can underexpose or over-expose the shot pretty quickly. Fortunately, by playing with the ISO (or the aperture) you can adjust the flash very quickly. Here's a quick shot at 640 and f1.0 // 190s of the father of the groom at a recent wedding (I know it looks posed but actually it wasn't, and I was lucky to have the Nocti pre-focused). There are actually 3 light sources here; the ambient, which was quite bright, but overhead and very 'racoon-eye' inducing; a wireless flash bounced off a very high ceiling to his left and behind him, and my 580V2 bounced on the M8 (on a bracket). If anything, the on-camera flash could have been set a little higher. But you can see it's clamped down enough not to overexpose. This is "out of the camera" except for resizing in PS. It's using the JFI tri-X profile in C1. It's not perfect, but I like where it's going... Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/39779-how-good-is-a-mode-flash-exposure-eg-canon-580ex-ii/?do=findComment&comment=422712'>More sharing options...
temoore Posted December 9, 2007 Share #19 Posted December 9, 2007 Just got the 580EX II and have set custom 5-3 to Auto - manual, so I can set the ISO and Aperture on the flash. When using the M8 in A mode, the camera meters the exposure as if it is taking an available light photo, meaning if it is dark, the shutter will be open for a longer exposure, even though the flash fires. I assume this is the correct way it should operate as my previous DSLR (Canon) did the same in Aperture priority with a flash. Quote Link to post Share on other sites More sharing options...
Jamie Roberts Posted December 9, 2007 Share #20 Posted December 9, 2007 Tom, in A mode the M8 still thinks you're shooting with the ambient light available. So you're still getting what the meter thinks you should regardless of the flash. The fact you're adding flash to that exposure will change the overall exposure. But if you want the ambient to be lower, then you need to switch to manual and set the shutter where you want it to be. When I'm using the flash as the key, I tend to set the ambient a stop or two (or more) below where the meter thinks it should be with the shutter. However, you can't go above the flash synch speed, don't forget (1/200 is what I watch for, though I think the M8 is 1/250). Quote Link to post Share on other sites More sharing options...
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