cash_chew Posted February 16, 2009 Share Posted February 16, 2009 <p>I searched this forum, it is not explicitly mentioned that, so I ask the following:</p><p>1) In M-mode with flash, can you dial in any combination of aperture and shutter speed as long as within the external flash limit, then your foreground subject will be correctly exposed since the flash will vary its power accordingly?</p><p>2) How do you know the above combination will give the correct exposure for the foreground subject since the exposure metering bar only indicate the exposure without flash?</p><p>3) If the above is true, then if you want to over or underexpose a scene, do you use exposure compensation on the camera or flash compensation on the flash?</p><p>4) To capture dim ambient background light with subject in the foreground, you can use slow-sync, or dial-in a slower shutter speed. How low is low enough to prevent the subject in the foreground from mition-blur?</p><p>Hian</p> Link to comment Share on other sites More sharing options...
mike_bisom Posted February 16, 2009 Share Posted February 16, 2009 <p>1) No. In M, manual, you are setting the flash power, it will NOT vary based on your camera settings. In iTTl mode, the flash will vary based on the aperture and distance to subject. The shutter speed should be within the flash sync speed, otherwise you will be using high-speed sync.<br> 2) Since the original above was incorrect this is hard to answer. After the fact, always check the histogram to verify a decent exposure. <br> 3) To underexpose a scene you could do either method, dial in a narrower aperture or lower power (when in M)/ negative flash compensation in iTTL on the flash. It all depends on the look you want to achieve.<br> 4) Depends on how steady you can hold a camera and how fast your subject is moving and how long you focal length is. If indoors, you can try bouncing flash off of walls and ceilings to get some light behind a subject.</p> Link to comment Share on other sites More sharing options...
Matt Laur Posted February 16, 2009 Share Posted February 16, 2009 <p>I think he's referring to putting the CAMERA in [M]anual mode, not the flash.</p> Link to comment Share on other sites More sharing options...
Matt Laur Posted February 16, 2009 Share Posted February 16, 2009 <p>I think he's referring to putting the CAMERA in [M]anual mode, not the flash.</p> Link to comment Share on other sites More sharing options...
hans_janssen Posted February 16, 2009 Share Posted February 16, 2009 <p>The TS stated in M mode with flash and not the flash in M mode.</p> Link to comment Share on other sites More sharing options...
mark_sirota1 Posted February 16, 2009 Share Posted February 16, 2009 <p>Let's assume Matt's right -- the camera is in M mode, and the flash is in TTL or Auto.</p> <p>(1) Yes.<br /> (2) You just have to trust the flash metering system.<br /> (3) Depends what you mean by "scene". Flash compensation will affect the flash-lit portions of the scene. Shutter speed will affect the unlit portions of the scene. Exposure compensation (regular, not flash) has no effect if the camera is in M.<br /> (4) Depends on the movement of the subject and its scale relative to your angle of view, as well as how much ambient light falls on it. There's no way to answer this question.</p> Link to comment Share on other sites More sharing options...
cash_chew Posted February 16, 2009 Author Share Posted February 16, 2009 <p>Thanks for the answer. Yes, the camera is in M-mode, and the flash is in TTL. As for the question number 4, I remember that I saw a pic of a subject jumping in the air with sunset in the background. The subject was well-lit with his action frozen in the air without any motion blurriness, and the ambient sunset was well preserved. I don't know if you can take this kind of shot with just one external flash.</p> Link to comment Share on other sites More sharing options...
mark_sirota1 Posted February 16, 2009 Share Posted February 16, 2009 <p>Sure, if the ambient on the subject is low, the shutter speed is short enough, and you catch the jump at the very top when the motion is slowest.</p> Link to comment Share on other sites More sharing options...
captain_jack Posted February 17, 2009 Share Posted February 17, 2009 <p>The answers above have confused me a little.<br> Someone said - "Exposure compensation (regular, not flash) has no effect if the camera is in M."</p> <p>My initial understanding was:<br> Flash compensation will light up the whole scene (only the front and not the background necessarily) with more light (depending on the compensation entered)</p> <p>Exposure compensation (when used with matrix metering and not spot metering), will add the exposure to even the background. And when used with the flash (even when camera is in M mode), the flash will try to lighten up the background as well.</p> <p>In other words, flash gun has to work harder, if EC is +1 (and no flash compensation) as compare to when flash compensation is dialed +1 (with no EC)</p> <p>Sorry, if I have not come as clear as I wanted to be.</p> Link to comment Share on other sites More sharing options...
captain_jack Posted February 17, 2009 Share Posted February 17, 2009 <p>Tested on my camera. Exposure compensation do work even in Manual mode.</p> Link to comment Share on other sites More sharing options...
dansutton Posted February 17, 2009 Share Posted February 17, 2009 <p>ha. i confused myself so much when, on a whim i adjusted exposure compensation in manual mode on my d90. i expected it to laugh in my face, but for some reason it let me dial the compensation in. i didn't take a picture to see if it adjusted anything, although my settings of shutter speed and aperture remained the same. i have no idea what it does and it seems to be a design flaw to allow exposure omp in this mode.</p> Link to comment Share on other sites More sharing options...
mark_sirota1 Posted February 17, 2009 Share Posted February 17, 2009 <p>Good point, Captain Jack. Sorry about posting misinformation.</p> Link to comment Share on other sites More sharing options...
mike_bisom Posted February 17, 2009 Share Posted February 17, 2009 <p>Dan- in manual, your camera still meters the scene and gives you a reading on your bar graph. This information is still communicated to the flash even. You can dial in a negative compensation in manual and now your graph will show you being underexposed (or more underexposed) or dial in positive EV to show overexposed. While this doesn't affect your shutter/aperture in manual, this information is still comminicated to the flash which will adjust accordingly.</p> Link to comment Share on other sites More sharing options...
captain_jack Posted February 17, 2009 Share Posted February 17, 2009 <p>HI dan,<br> Do this simple test.<br> 1. Put your camera in M mode (0 EC at this time).<br> 2. Select spot metering.<br> 3. Choose and fix an aperture.<br> 4. Now fine-tune your shutter speed till you a balanced exposure. (Look for exposure vertical bar in the viewfinder. It should be in the middle of the scale). Note down the shutter speed.<br> 5. Now dial in +1EC. Repeat step 4. You will notice the shutter speed this time is different. Why?</p> <p>Dialing in +1EC, simply tells the exposure meter of the camera to take in 1 stop of more light to mark it as NORMAL on the exposure scale.</p> Link to comment Share on other sites More sharing options...
cash_chew Posted February 17, 2009 Author Share Posted February 17, 2009 <p>When my camera is in M-mode, without the built-in flash firing, the exposure compensation does not change any outcome of the picture. However, with the flash fired, the flash compensation and exposure compensation yield almost the same histogram. Does that mean that both functions are equivalent?</p> Link to comment Share on other sites More sharing options...
captain_jack Posted February 18, 2009 Share Posted February 18, 2009 <p><em>>>When my camera is in M-mode, without the built-in flash firing, the exposure compensation does not change any outcome of the picture.<<</em><br> Outcome will not change, untill and unless you follow the camera's internal exposure meter and change the aperture or shutter to get the exposure in the middle.<br> <em>>>However, with the flash fired, the flash compensation and exposure compensation yield almost the same histogram. Does that mean that both functions are equivalent?<<</em><br> Both functions are not the same. Look for the change in exposure, especially in the background.</p> Link to comment Share on other sites More sharing options...
mark_sirota1 Posted February 18, 2009 Share Posted February 18, 2009 <p>With the camera in M mode and the flash firing in TTL, yes, they end up being equivalent.</p> Link to comment Share on other sites More sharing options...
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