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Old Sep 11, 2010, 1:15 PM   #11
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I wasn't aware of the P mode issue on some cameras and 2nd curtain and wouldn't be using P mode anyway for this kind of shot so the curtain used won't hurt at all.
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Old Sep 11, 2010, 3:32 PM   #12
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Sorry, go M mode. ;-)

You should never use Aperture Priority with a flash, and that goes for any camera. The reason is because the camera will expose for ambient light, using the flash for fill only.
If the flash is a dedicated unit, and communicates with the camera properly, it will set to flash sync speed (usually high enough to avoid motion blur problems), and adjust the flash power for proper exposure for the aperture selected. At least it works this way with my Minolta and Pentax.
Manual mode with flash is useful if the lighting and subject distance don't change, or you have time to make adjustments. The Minolta system (and I suppose Sony, now) is particularly good, since it integrates subject distance into the flash exposure, which helps compensate for over-or under-reflection when checking the pre-flash.
Using an auto-thyristor flash, Aperture priority is the correct way to go, since this is what the flash is considering when it controls power.

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Old Sep 11, 2010, 6:28 PM   #13
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I'm not talking about using manual power settings for the flash. I'm talking about using manual exposure mode on the camera, where you set both the aperture and shutter speed.

Now, it does look like you may be right about Sony models (although they don't use the sync speed in low light, they will set the shutter speed to 1/60 second with flash if using Aperture Priority mode in low light). I just tested it with a Sony A700 to find out. I learn something new every day, and never bothered to test that with a Sony dSLR. Thanks. :-)

So, that might work OK. But, many dSLR models will not do that using Aperture Priority.

If you use Aperture Priority, many cameras are going to set the shutter speed for ambient light, not to the flash sync speed.

That can cause blur from subject movement from shutter speeds that are too slow, since ambient light is contributing too much to the exposure for the flash to freeze the action in many indoor conditions.

I see that type of problem on a regular basis in the forums (blurry photos because someone was using Aperture Priority with flash, and shutter speeds were too slow to prevent blur from subject movement with the amount of ambient light contributing the exposure).

I always stick with manual exposure instead, so I'm controlling both variables, with very rare exceptions.

As for using a non-dedicated Auto thyristor type flash, I would definitely not use Aperture Priority, since that could result in issues in low light (since the camera would not be aware of the flash being there, and would try to expose for ambient light). I use non-dedicated Auto Thyristor flash models on a regular basis with my A700, and it does not know the flash is there at all for exposure purposes.

With that type of flash, I'd definitely stick with manual exposure and set the flash and camera to match for ISO speed and aperture, selecting a shutter speed that lets in the desired amount of ambient light (and let the flash control the flash burst length by measuring reflected light during the exposure, terminating it when it sees enough reflected light for your ISO speed and aperture setting).

There's no real "up" side to using Aperture Priority from my perspective, with either a dedicated or non-dedicated flash, and with many camera models, there is a down side to that approach (where the camera may try to expose for ambient light, leading to blur and/or ghosting issues).

You can just as easily use manual exposure, selecting both the desired aperture and shutter speed. Then, if you're using a dSLR with a dedicated flash, it still controls the length of the flash burst, based on your aperture and and ISO speed settings and the amount of reflected light it sees from the metering pre-flash (also taking subject distance into consideration with some models). Or, if you're using a non-dedicated auto thyristor type flash, the flash is doing the work instead.

I don't see any up side to using Aperture Priority with either type of system. From my perspective, Manual Exposure is easier and gives you more control.
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Old Sep 11, 2010, 8:03 PM   #14
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Oops! My typing got ahead of my brain on that one. What I was intending to say was that it is the aperture which is the primary setting when using the non-dedicated flash, and yes, it does require manual exposure mode. Definitely my bad.

I haven't used a lot of Dslrs with dedicated flash, but of those I have, they will all set to a shutter speed of about 1/60 or so as a default. I think it is mostly due to the flash units being backward compatible with older film cameras. The ones with the horizontal run shutter curtains used to use 1/60th as the x-sync speed. Wasn't sure if the newer flash/camera combinations had increased that, so I just mentioned sync speed.
Using direct flash with a dedicated flash head shouldn't be problem with motion blur, but bounced flash reduces the light enough that that could crop up.

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Old Sep 11, 2010, 9:20 PM   #15
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OK. Job done. Lessons learned.
1. blur shows up at less than 1/125
2. don't forget to set wb to flash
3. bounce works well with 10 foot ceilings
4. spot focus is touchy
5. it all "just works"

Thanks for the suggestions. I messed up and adjusted the shutter speed down to 1/60 by mistake. A couple of times I didn't wait for the flash to recharge. Mostly, everything worked out as well as I could expect. I got a couple of other folk to take some pics (of me) and they came out too. Attached are a few samples. They could be sharper but for these purposes they will serve.

Valuable to know about that P and Rear curtain scenario. Wouldn't want to ruin a set of photos doing that.
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Old Sep 11, 2010, 10:01 PM   #16
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Quote:
blur shows up at less than 1/125
When you have a lot of ambient light coming in through windows in the daytime, you may need to use a bit faster shutter speeds.

I notice your aperture was at f/4.5, too. That allows in more ambient light compared to the suggested settings (f/5.6 to f/6.3), making it less likely that the flash is going to freeze the action at ISO 400 with shutter speeds as slow as 1/60 second if you have a lot of ambient light coming in through windows (as you did with some of those images). Using f/5.6 or f/6.3 also gives you a bit more depth of field, making it easier to get more of the subjects in focus for people type gatherings.

I usually start with around f/5.6 to f/6.3 at ISO 400, with a shutter speed of around 1/100 second. In most indoor lighting, that works fine. But, in brighter conditions (subjects next to Windows with light shining in), you may need a faster shutter speeds at times. In darker conditions (i.e., typical indoor lighting at night), you can usually use slower shutter speeds and/or wider apertures and/or higher ISO speeds to let in more ambient light without any blur.

The idea is to make sure your subjects are a couple of stops or so underexposed using the same settings without the flash. That way, the subject is only illuminated properly during the very short flash burst (usually around 1/1000 second or faster), so that the flash can freeze any subject movement.

Or, if you don't want that much difference so that the exposure leans more towards ambient light, make sure your shutter speeds are a bit faster with that much light coming in through Windows using apertures that wide at ISO 400.

There's no single right way to do it, and different users will use different techniques.
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Old Sep 17, 2010, 2:16 PM   #17
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Originally Posted by JimC View Post
When you have a lot of ambient light coming in through windows in the daytime, you may need to use a bit faster shutter speeds.

I notice your aperture was at f/4.5, too. That allows in more ambient light compared to the suggested settings (f/5.6 to f/6.3), making it less likely that the flash is going to freeze the action at ISO 400 with shutter speeds as slow as 1/60 second if you have a lot of ambient light coming in through windows (as you did with some of those images). Using f/5.6 or f/6.3 also gives you a bit more depth of field, making it easier to get more of the subjects in focus for people type gatherings.

I usually start with around f/5.6 to f/6.3 at ISO 400, with a shutter speed of around 1/100 second. In most indoor lighting, that works fine. But, in brighter conditions (subjects next to Windows with light shining in), you may need a faster shutter speeds at times. In darker conditions (i.e., typical indoor lighting at night), you can usually use slower shutter speeds and/or wider apertures and/or higher ISO speeds to let in more ambient light without any blur.

The idea is to make sure your subjects are a couple of stops or so underexposed using the same settings without the flash. That way, the subject is only illuminated properly during the very short flash burst (usually around 1/1000 second or faster), so that the flash can freeze any subject movement.

Or, if you don't want that much difference so that the exposure leans more towards ambient light, make sure your shutter speeds are a bit faster with that much light coming in through Windows using apertures that wide at ISO 400.

There's no single right way to do it, and different users will use different techniques.
One question you say use Manual mode on camera i get that, but what do you set the flash to like on the Canon 580 EX II ETTL II? I am new to flash and when I did try Manual and ETTL in low light at 1/100th my exposure compensation was way to low, and I needed 1/5th sec to get it close to 0, am I doing something wrong in my flash settings? thanks
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Old Sep 17, 2010, 2:33 PM   #18
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One question you say use Manual mode on camera i get that, but what do you set the flash to like on the Canon 580 EX II ETTL II? I am new to flash and when I did try Manual and ETTL in low light at 1/100th my exposure compensation was way to low, and I needed 1/5th sec to get it close to 0, am I doing something wrong in my flash settings? thanks
What do you mean "your exposure compensation was way too low"? Not sure I understand that comment. Exposure compensation is you telling the camera/flash to output more or less flash power than the system thinks is necessary.

Note - with canon cameras you'll see two notches on the meter in the viewfinder - one representing the camera's exposure and one representing the flash' . So, when you took a photo at 1/100 what exactly happened in the photo? Was the photo underexposed? Overexposed? Motion blur? what?
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Old Sep 17, 2010, 2:38 PM   #19
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What do you mean "your exposure compensation was way too low"? Not sure I understand that comment. Exposure compensation is you telling the camera/flash to output more or less flash power than the system thinks is necessary.

Note - with canon cameras you'll see two notches on the meter in the viewfinder - one representing the camera's exposure and one representing the flash' . So, when you took a photo at 1/100 what exactly happened in the photo? Was the photo underexposed? Overexposed? Motion blur? what?
Sorry John what I meant is my 5D II compensation not the flash
at 1/100th I just it just was a little underexposed.
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Old Sep 17, 2010, 2:42 PM   #20
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Hercules - do you have the shot? Here's why. Assuming distance is short you should have plenty of flash power to properly illuminate a subject at 1/100 - but the devil is in the details. If you were 50 feet away and had aperture of f32 and ISO 100 - well, no, that wouldn't work well. Now, if you're saying you needed 1/5 so your camera metered at zero, that makes sense in many low light situations. You're not going to get it near zero, which is why you want to use flash. But I think it will be easier to help if we see a picture with the problem you're encountering.
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