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Old Feb 29, 2016, 2:40 PM   #21
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Thanks Mike. I am surprised I did not already have that one.

With the flash set in the manual mode utilizing HSS are the recharge times for the flash going to be the same regardless of where I have the power set for the flash?

If I have the flash set to the full power 1/1 will the recharge time be longer than if the flash were set to half power? I did some practice shots outside last night trying to approximate the ranges I shoot from at the track and noticed a few things.

Here is what I was trying. I am going to list everything just so someone does not have to reread the entire thread for the specifics.

Sony A-550 with my Sigma 50-150 f/2.8 APO
shooting in full manual mode with aperture at f/2.8
I varied the shutter speed between 1/600th to 1/1000
I also varied the ISO to gauge effect

Not that all of that is out of the way here are a few of my observations. From a range of 25 to 30 feet (my range at the track) even with the ISO set at 200 the 1/1 setting (full power) overpowers the subject giving quite bright and even washed out images.

Other than to just start dropping the power level on the flash until the lighting is suitable are there other changes I could be making?
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Old Feb 29, 2016, 10:07 PM   #22
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Shooting at 1/1 uses more power and does take longer to recharge.
HSS uses even more power and will wear out batteries much quicker.
I would never attempt to shoot burst with an onboard flash.

To adjust flash power with the camera there's the flash +/-EV scale right under the +/-EV scale for exposure. I find that a quicker way to adjust flash power then adjusting the flash depending on the A550s adjustment buttons. I haven't owned that camera for a number of years and it may have a different quick navi layout then the A900 I currently use. I can't remember. With the 58 flash it is quick to adjust power with the left/right side of the round dial when in manual. At night you may need to push the illumination button to see what level your power is at.
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Old Mar 2, 2016, 11:55 PM   #23
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You would not shoot in burst with an on board flash? Is it because the flash is on the camera body or just not with a flash in general? JohnG gave examples of his football shots with the flash on the monopod below the camera. He shot in burst with the flash firing as fast as it would recharge but not necessarily at the frame rate of the camera.
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Old Mar 3, 2016, 10:39 AM   #24
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If your flash power is low enough, it may retain sufficient charge to fire to or three times in burst mode, but after that it won't be able to keep up. (in my somewhat limited experience). Off-camera flashes may have enough power, either with AC or with heavy duty batteries, to do it, though. I recall one photographer who used several flashes and a sequencer to be able to shoot flash shots continuously (at full power). Don't recall if it was a commercial unit or something he built himself.
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Old Mar 3, 2016, 1:12 PM   #25
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Quote:
Originally Posted by Old Boat Guy View Post
You would not shoot in burst with an on board flash? Is it because the flash is on the camera body or just not with a flash in general? JohnG gave examples of his football shots with the flash on the monopod below the camera. He shot in burst with the flash firing as fast as it would recharge but not necessarily at the frame rate of the camera.
A 9 second car can cover the first 60 feet in 1.2 seconds from a standstill.
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Old Mar 4, 2016, 9:45 AM   #26
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What you may want to do is forget trying to use HSS at all and let the flash provide most of the light.

The idea is that even if you're using relatively slow shutter speeds, with other settings like aperture and ISO speed lower than needed for ambient light exposure (where you'd normally end up with a very underexposed image), is to let the flash itself freeze the action.

A typical flash burst (without using HSS to pulse the light), is around 1/1000 second or faster. So. the flash itself (single burst. not using HSS) can freeze the action, since the subject is only properly exposed during the very fast flash burst. The lower the flash burst length needed, the faster the recharge times (and HSS increases recharge times because of the way it pulses the light).

IOW, if using something like 1/200 second (so that HSS is not needed), at around f/2.8 and ISO 800 in night conditions in poor liighting, that should give you enough flash range from what it sounds like from your distance with fairly fast recharge times, while leaving the subject several stops underexposed if you were not using the flash. The trick is making sure that the photo would normaly be very dark if using the same settings without a flash. Then, when the flash is used, ypu get a photo with the subject frozen without any blur (since the flash burst is around 1/1000 second and the subject is only properly exposed during that short flash burst).

Without knowing the exact lighting, it's hard to give you exact settings to use. But. try to keep the camera settings so that you're a few stops underexposed without the flash, using settings that give you enough flash range. Then, the flash will freeze the action if it is the primary light source, with no HSS or fast shutter speeds needed.
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Old Mar 4, 2016, 9:45 AM   #27
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Quote:
Originally Posted by VTphotog View Post
If your flash power is low enough, it may retain sufficient charge to fire to or three times in burst mode, but after that it won't be able to keep up. (in my somewhat limited experience). Off-camera flashes may have enough power, either with AC or with heavy duty batteries, to do it, though. I recall one photographer who used several flashes and a sequencer to be able to shoot flash shots continuously (at full power). Don't recall if it was a commercial unit or something he built himself.
Thanks Brian. I will find out tomorrow evening how well this may work. Or not work as the case might be. At this point I have a much better understanding of how everything interacts so should be able to make adjustments on the fly.

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A 9 second car can cover the first 60 feet in 1.2 seconds from a standstill.
They can get up and go in a hurry. With most of these guys being amateurs it can also be a natural disaster. I shot three sequences of one cars launch all on the same run. The guy stalled the car twice with his third try seeing him finally get off the marks. Everything I have shot thus far has been all test and tune so very informal.

During the day I can afford to waste the first few shots and start shooting early. Anyone with a camera capable of keeping up with the autofocus during burst shooting can learn to do this during the day. It is all about finding the rhythm.

I am just guessing but I think at night my flash should fire twice during the launch sequence so my timing will be critical. The Sigma lens I use has shown itself to be very fast when it comes to finding focus and then making the minor adjustments to keep things in focus during the sequence of shots so that makes life much easier as well.

If I get the timing right I should get some decent shots. If not then we can all have a good laugh at my expense when I post some of the results.

Thanks again for all of the advice
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Old Mar 5, 2016, 11:46 AM   #28
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We must have posted at the same time Jim as I missed your reply.

I am definitely going to try different methods to see what works the best. I have however found that you and VTphotog are correct about the shutter speed not being as critical at night. I played around with this last night and did find that not using HSS and setting the power output of the flash at a lower level did give me enough light with faster refresh time for the flash.

Thanks Jim and I will be trying yours and Brian's suggestions.
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Old Mar 5, 2016, 6:57 PM   #29
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As a quick aside:

HSS is usually used when you have *too much* ambient light but still want the flash to fire. For example, if I were shooting a portrait on a sunny day and wanted a wide aperture for DOF reasons, I'd be forced to use high shutter speeds. If I now wanted to add a flash to fill foreground shadows and increase contrast with the background, I'd require high-speed sync. Once the amount of ambient light becomes negligible compared to the amount of light provided by the flash, HSS serves little to no purpose.

As ambient light decreases, the shutter speed effectively becomes the flash duration, regardless of actual shutter speed. An extreme example of would be a 5 second exposure in a pitch-dark room. Camera on a tripod, flash in hand, trigger the shutter, point the flash at the subject, and hit the test button. Move the subject and flash them again. The result is a nearly-dark room with two copies of the same person.

Last edited by conor; Mar 5, 2016 at 7:09 PM.
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