rbaron Posted August 27, 2009 Share #1 Posted August 27, 2009 Advertisement (gone after registration) New SF 58 user here. The Instruction manual is less than completely clear but I think I'm getting it figured out. But I do have this question: With an M8 or M8.2, why or in what circumstances would one choose the 'A' mode over the 'TTL' mode? Thanks, --Bob Link to post Share on other sites More sharing options...
Advertisement Posted August 27, 2009 Posted August 27, 2009 Hi rbaron, Take a look here SF 58: Why Use 'A' Versus 'TTL'?. I'm sure you'll find what you were looking for!
marknorton Posted August 27, 2009 Share #2 Posted August 27, 2009 When the flash is used in TTL mode, it has to emit a series of preliminary flashes which the camera then meters and tells the flash what exposure it wants. This all takes time and the initial flashes can be distracting. The camera is better than it used to be - the pre-flashes take much less time. The advantage of TTL mode is that the metering takes the working aperture of the lens into account. In A mode, the camera simply tells the flash what ISO is selected and the flash tells you what aperture to set. When the flash is fired, it's the flash itself which does the metering and it shuts the flash off when the correct exposure has been achieved. The other advantage of TTL flash metering is that the camera can take account of the contribution which any available light is going to make to the exposure because it knows the selected shutter speed. In A mode, the flash does not know this. Link to post Share on other sites More sharing options...
rbaron Posted August 27, 2009 Author Share #3 Posted August 27, 2009 When the flash is used in TTL mode, it has to emit a series of preliminary flashes which the camera then meters and tells the flash what exposure it wants. This all takes time and the initial flashes can be distracting. The camera is better than it used to be - the pre-flashes take much less time. The advantage of TTL mode is that the metering takes the working aperture of the lens into account. I understand this, and based on my limited testing I agree with you the pre-flashing seems to be much improved and less distracting. In A mode, the camera simply tells the flash what ISO is selected and the flash tells you what aperture to set. When the flash is fired, it's the flash itself which does the metering and it shuts the flash off when the correct exposure has been achieved.In this connection, I was very surprised to read in a fine print footnote (p55 of the Instructions for those who are following along) "Aperture values set on the lens are not transmitted by the Leica M8/M8.2. As a result, they must be entered manually on the flash unit." It took me a while to find this. I wonder if this will be corrected by future firmware updates to the camera and/or flash. The other advantage of TTL flash metering is that the camera can take account of the contribution which any available light is going to make to the exposure because it knows the selected shutter speed. In A mode, the flash does not know this.So with the M8/M8.2, the only reason not to use TTL under most ordinary circumstances would be to avoid the pre-flashing, correct? Link to post Share on other sites More sharing options...
Guest roey Posted August 27, 2009 Share #4 Posted August 27, 2009 In this connection, I was very surprised to read in a fine print footnote (p55 of the Instructions for those who are following along) "Aperture values set on the lens are not transmitted by the Leica M8/M8.2. As a result, they must be entered manually on the flash unit." It took me a while to find this. I wonder if this will be corrected by future firmware updates to the camera and/or flash. The camera can't transmit the aperture value because it doesn't know it. Even in TTL mode the aperture value is not known, however it automatically becomes part of the equation because the camera measures the pre-flashes through the lens. Link to post Share on other sites More sharing options...
adli Posted August 27, 2009 Share #5 Posted August 27, 2009 In this connection, I was very surprised to read in a fine print footnote (p55 of the Instructions for those who are following along) "Aperture values set on the lens are not transmitted by the Leica M8/M8.2. As a result, they must be entered manually on the flash unit." It took me a while to find this. I wonder if this will be corrected by future firmware updates to the camera and/or flash. It's not an firmware issue. As oposed to modern DSLRs, there are no means of transmitting the aperture value from a Leica M lens to the camera body. Neither electronically nor mechanically. Link to post Share on other sites More sharing options...
rbaron Posted August 27, 2009 Author Share #6 Posted August 27, 2009 It's not an firmware issue. As oposed to modern DSLRs, there are no means of transmitting the aperture value from a Leica M lens to the camera body. Neither electronically nor mechanically. I knew that. Just a little brain fade this morning.... So back to my original question, as modified: Other than to avoid a slight delay for and the possible intrusive effect of pre-flashing, is there any reason to select 'A' mode over 'TTL'? --Bob Link to post Share on other sites More sharing options...
marknorton Posted August 27, 2009 Share #7 Posted August 27, 2009 Advertisement (gone after registration) No, I don't think so, TTL flash metering is much to be preferred, especially in availble light situations. Link to post Share on other sites More sharing options...
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