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05-06-2008, 04:55 PM   #1
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Flash photography, SR on or off?

Just out of curiousity, who shuts SR off when using the flash? The reason I ask is, I was taking a couple test shots with my horse show set-up (k10d, da70mm, af540, power pack, bracket, etc.), Just making sure everything is working properly. I was shooting at my inlaws farm inside thier small arena. I was shooting 1/180, flash on full power manual, f6.3, iso 400 and noticed the hooves on the horse looked a little blurry, like motion blur. Most of the time the horses are pretty froze due to the fact that using the flash is like shooting 1/1000 shutter speed or so. Am I too far away from the subject, or is this SR? The body of the horse is sharp. Its a little strange but maybe I just havent noticed this before. Maybe the sync of 1/180 is just a touch slow?


Last edited by reknelb; 05-07-2008 at 02:55 PM.
05-06-2008, 06:32 PM   #2
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I don't think SR would cause a blur to just one portion of the picture.

Also depends on the amount of ambient light. The flash itself is very fast indeed, but if there is enough available light the camera can pick up a slight motion blur.

The horse itself may not be moving fast, but the tips of the hooves could be, even at a slow trot.
05-08-2008, 07:55 AM   #3
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SR is always OFF when shooting with Flash. Even if it is switched ON.
I think that you get a blur because of low amount of flash light and long focal length of lens.
05-08-2008, 08:11 AM   #4
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If there is enough ambiant light, you might get "secondary" exposure that would look like blur. When there is not enough difference between the ambiant light and the flash, you get such a problem with moving subject (I,m sure the hooves were moving).

05-08-2008, 08:13 AM   #5
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QuoteOriginally posted by Zebooka Quote
SR is always OFF when shooting with Flash. Even if it is switched ON.
Hmmm, I don't think so, at least not with a flash connected to the body. You are right in the case of wireless flash, however.
05-08-2008, 04:12 PM   #6
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There definitly wasn't enough light for ambient to be an issue. The comments about the SR is interesting as I was also panning with the subject. I think I'll turn it off and give it another shot this weekend just out of curiousity. I was off camera with the flash but on a bracket with a sync cord.
05-09-2008, 03:19 AM   #7
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QuoteOriginally posted by RBellavance Quote
Hmmm, I don't think so, at least not with a flash connected to the body. You are right in the case of wireless flash, however.
I read the manual last night and all I could find was that SR will NOT work with wireless flash. They did mention leaving the SR on for slow shutter flash shots so the SR does work with the flash.
05-09-2008, 05:22 AM   #8
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Dumb question time

You said the hooves were blurry, what about the rest of the image?

Let's decide first whether this is motion blur, lack of depth of field, or what ever.

As far as flash and being set to full power, I believe you will find the duration is quite long at full power and will not perfectly freeze an object that is moving through a narrow field of view. Remember that flash power is really not changing the intensity of the flash, but the length of time the flash is operating. for example 1/16 power is really nothing but a very short burst roughly 1/16 the duration of the full power burst.

Ambient lighting would play more of an impact with slower shutter speeds, or marginal power settings, where the time the shutter is fully open is much longer than the flash duration, BUT at full power, the two are about the same, There is a post somewhere in the forums where someone has noted a slight darking of the bottom of the frame at full power, stating this goes away when the duration is cut to 1/125 or 1/150 as opposed to 1/180 indicating that the AF 540 might have a duration at full power slightly longer than the time the shutter is fully open.

05-09-2008, 05:41 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
There is a post somewhere in the forums where someone has noted a slight darking of the bottom of the frame at full power, stating this goes away when the duration is cut to 1/125 or 1/150 as opposed to 1/180 indicating that the AF 540 might have a duration at full power slightly longer than the time the shutter is fully open.
And I believe Metz states this directly in the manual somewhere for their flash units. (Which has led to some negative comments towards that brand, but maybe they're just documenting better. It's too bad no one does in-depth geeky tech reviews of flashes.)
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