eritho Posted December 21, 2009 Share #1 Posted December 21, 2009 Advertisement (gone after registration) I just got the M9 a few days ago and is now trying to get used to it! Having used M6 and M7 for a long period, but been on DSLR for years, is is a split experience! First shots I completely forgot to focus:o Now, trying to use the SF-20, which I still have, shows a behavior I can't understand. I know the SF-20 will not do TTL with the M9 and therefore set it in"A" mode. The histogram shows approx 2 steps underexposure. As the flash can only be set to give less light I tried to set the camera to EV+2 and, voila, the exposure is dead on. As far as I know, when the flash is working in "A" mode it works independent of the camera and shuts off when enough light has reached the sensor. The Camera is set to "flash" (1/180 sec) and knows nothing about how much light "coming in". Of course there must be an explanation, but I can't figure it out:confused: I love this camera, but I also want to understand it! Anyone on this esteemed forum...........? //Erik Link to post Share on other sites More sharing options...
Advertisement Posted December 21, 2009 Posted December 21, 2009 Hi eritho, Take a look here M9 and SF-20. I'm sure you'll find what you were looking for!
jaapv Posted December 21, 2009 Share #2 Posted December 21, 2009 The amount of light reaching the sensor is determined by the aperture and not by the shutterspeed. Does the aperture setting on your flash correspond to the one on your camera? Link to post Share on other sites More sharing options...
eritho Posted December 21, 2009 Author Share #3 Posted December 21, 2009 The amount of light reaching the sensor is determined by the aperture and not by the shutterspeed. Does the aperture setting on your flash correspond to the one on your camera? Yes, I have extra checked this. I really don't understand how this is possible! //Erik Link to post Share on other sites More sharing options...
Nicoleica Posted December 21, 2009 Share #4 Posted December 21, 2009 Is the ISO setting the same on both camera and flash? I'm not sure the SF-20 will obtain this from the camera or not. Link to post Share on other sites More sharing options...
jaapv Posted December 21, 2009 Share #5 Posted December 21, 2009 Do you have the camera set to Auto-Iso? That will play havoc with manual operation. Link to post Share on other sites More sharing options...
AlanJW Posted December 21, 2009 Share #6 Posted December 21, 2009 SF20: No auto ISO Flash should pick up set ISO from camera Set f/stops same on camera and flash Where is your shutter speed set? 1/125? Link to post Share on other sites More sharing options...
eritho Posted December 21, 2009 Author Share #7 Posted December 21, 2009 Advertisement (gone after registration) SF20:No auto ISO Flash should pick up set ISO from camera Set f/stops same on camera and flash Where is your shutter speed set? 1/125? I have just checked again to be sure: No auto ISO. Flash will pick ISO from camera. f/stop 5,6 on camera and flash. Shutter 1/180. 2 stops underexposure. Dial in EV+2 on camera. Exposure dead on. Can't figure out what is going on:( I'm happy it works, but I would like to know why! Anybody having M8 or M9 and SF-20 and willing to check out? //Erik Link to post Share on other sites More sharing options...
Nicoleica Posted December 21, 2009 Share #8 Posted December 21, 2009 Have you tried manually setting the ISO on the flash? And also have you double-checked that there is no minus compensation set on the flash? (Just a thought.) Link to post Share on other sites More sharing options...
jaapv Posted December 21, 2009 Share #9 Posted December 21, 2009 Yes, but how could exposure comp on the camera affect the flash, Nicole? If auto- ISO is switched off, the speed set manually and the aperture is the same, the only variable must be the flash - and it cannot read exposure compensation off the camera, especially in A mode.:confused:. The only explanation I can come up with is that auto-ISO, despite being switched off as far as the camera is concerned still is active in the circuit that controls the flash ISO setting....Which would be a newly-discovered bug. Link to post Share on other sites More sharing options...
eritho Posted December 21, 2009 Author Share #10 Posted December 21, 2009 Have you tried manually setting the ISO on the flash? And also have you double-checked that there is no minus compensation set on the flash? (Just a thought.) Yes, I have tried this also. Actually, I think I have tried everything, because now I'm pretty upset, that I can't understand this. What happens in the camera, when you dial EV+2? If it is not changing shutter time or f/stop, could it be that it just adjusts ISO from say 160 to 640 without noticing flash, or operator? Could this really be an explanation? I hope not! If so, is it same procedure when using EV adjusting without using flash? In the days of using film you had three options to do EV+2. Change shutter time, aperture, or set an ISO value differing from the film used. //Erik Link to post Share on other sites More sharing options...
eritho Posted December 21, 2009 Author Share #11 Posted December 21, 2009 Yes, but how could exposure comp on the camera affect the flash, Nicole? If auto- ISO is switched off, the speed set manually and the aperture is the same, the only variable must be the flash - and it cannot read exposure compensation off the camera, especially in A mode.:confused:. The only explanation I can come up with is that auto-ISO, despite being switched off as far as the camera is concerned still is active in the circuit that controls the flash ISO setting....Which would be a newly-discovered bug. Jaap, it looks like we are on same line if I understand your post right! How is exposure compensation possible at all if you don't chance shutter speed, aperture, or ISO? //Erik Link to post Share on other sites More sharing options...
250swb Posted December 21, 2009 Share #12 Posted December 21, 2009 I have just tried this with my SF20 and yes, you dial in +2 EV in the camera, keep aperture, ISO and shutter speed the same and get a correct exposure (as opposed to a couple of stops under in Auto mode). It seems like the camera is increasing the flash intensity while that can't be programmed directly into the flash itself. Info in review says 180 sec and 160 ISO on all photos both under and over exposed. Steve Steve Link to post Share on other sites More sharing options...
Nicoleica Posted December 21, 2009 Share #13 Posted December 21, 2009 Yes, but how could exposure comp on the camera affect the flash, Nicole? If auto- ISO is switched off, the speed set manually and the aperture is the same, the only variable must be the flash - and it cannot read exposure compensation off the camera, especially in A mode.:confused:. The only explanation I can come up with is that auto-ISO, despite being switched off as far as the camera is concerned still is active in the circuit that controls the flash ISO setting....Which would be a newly-discovered bug. My thinking was that if compensation was set on the flash, effectively telling the flash to output less light, then a positive compensation on the camera (Effectively increasing the ISO setting as aperture and shutter speed are fixed.) would compensate for this. It's easy enough to set unintended compensation on an SF20/SF24D by pressing the P button twice in error. 'Twas just a thought. Link to post Share on other sites More sharing options...
eritho Posted December 21, 2009 Author Share #14 Posted December 21, 2009 I have been thinking:rolleyes: As aperture is fixed when set on the lens, there are only three parameters which could be changed by dialing in EV +2. Quadruple the output from the flash. Change shutter speed from 1/180 to 1/45 sec. Change ISO from 160 to 640. My best guess is the last, changing ISO setting. Which by digital of course is nonsense, but then amplify the signal correspondent to this. This must then be the same procedure used when using exposure compensation using no flash! In this case only the two last parameters are variable, changing shutter speed or ISO. What do you think? Link to post Share on other sites More sharing options...
250swb Posted December 21, 2009 Share #15 Posted December 21, 2009 My thinking was that if compensation was set on the flash, effectively telling the flash to output less light, then a positive compensation on the camera (Effectively increasing the ISO setting as aperture and shutter speed are fixed.) would compensate for this. It's easy enough to set unintended compensation on an SF20/SF24D by pressing the P button twice in error. 'Twas just a thought. Except if you do not set 'unintended' compensation the camera still tells you two test images images are both 160 ISO at 180th, and comparing those two images side by side, one +2EV(camera indused), and one 0EV there is no difference in noise (160 to 640 ISO difference). So it would seem the camera is not telling lies, the ISO and shutter speed stay the same (for instance dialing in -3EV you cannot hear the shutter opening for longer). Which means the camera is adjusting the flash power when setting + or - EV, and there is a native 2 stop underexposure (or thereabouts) when set on base uncompensated Auto settings? No? I have just tried the same thing with an Olympus FL50 on 'Auto', and the camera cannot adjust the exposure by dialing in + or - EV. Steve Link to post Share on other sites More sharing options...
eritho Posted December 25, 2009 Author Share #16 Posted December 25, 2009 Having now used the SF-20 on the M9 for approx. 100 shots yesterday I'm still puzzled: Why is it underexposing 2 stops on a M9 and not on a M6 or M7? When the flash is set to "A" and adjusted to same aperture and ISO value as camera it should also give same amount of light and thus same exposure. By setting camera to +2EV the exposure is alright. But why? What is changed by setting +2EV on camera, shutter time or ISO? Is anybody able to give a correct, understandable answer to these three questions? Link to post Share on other sites More sharing options...
Guest mc_k Posted December 26, 2009 Share #17 Posted December 26, 2009 Having now used the SF-20 on the M9 for approx. 100 shots yesterday I'm still puzzled: Why is it underexposing 2 stops on a M9 and not on a M6 or M7? When the flash is set to "A" and adjusted to same aperture and ISO value as camera it should also give same amount of light and thus same exposure. By setting camera to +2EV the exposure is alright. But why? What is changed by setting +2EV on camera, shutter time or ISO? Is anybody able to give a correct, understandable answer to these three questions? I don't think Auto will work perfectly in all size rooms with all different kinds of light. At least it doesn't with the SF24. The camera compensation controls the ambient exposure. Try dragging the shutter two stops with the compensation off and see if that gets the exposure you want as well. I assume the camera compensation controls the exposure time, but maybe I am wrong. Link to post Share on other sites More sharing options...
eritho Posted December 26, 2009 Author Share #18 Posted December 26, 2009 I don't think Auto will work perfectly in all size rooms with all different kinds of light. At least it doesn't with the SF24. The camera compensation controls the ambient exposure. Try dragging the shutter two stops with the compensation off and see if that gets the exposure you want as well. I assume the camera compensation controls the exposure time, but maybe I am wrong. Auto works alright in different rooms, at least as constant as on a M6 or M7, but always around two stops underexposed! No problem to set shutter two steps 1/45 instead of 1/180. But, as the time of the flashlight is so short it doesn't matter if you set 1/180 or longer. A longer shutter time will allow more more influence of ambient light but not from the flash. Or am I wrong here? Link to post Share on other sites More sharing options...
Guest mc_k Posted December 26, 2009 Share #19 Posted December 26, 2009 yes, you're right. Link to post Share on other sites More sharing options...
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