Blur/double image at high speed

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Blur/double image at high speed

Postby Paqart » Tue Nov 06, 2018 5:13 am

Before I get to my question, where are drafts saved? My session timed out on me the first time I wrote this, so I lost the draft. Then I wrote it again and clicked the "save drafts" button so that I wouldn't lose the draft. However, after I did that, the message disappeared and I don't see where it could be. So now I will write this a third time.

When shooting athletes in motion with my DF+ and IQ250 or my newer XF and IQ3-100, I get image artifacts that look a bit like a double exposure. This only happens when flash is used. I have used ProFoto B1 units and the Pro-8 and Pro-10 power packs with pro heads. At first I thought it was motion blur, but on closer inspection, it is more like two images that are just slightly off-registered. This happens at any shutter speed up to and including the maximum speed of 1/1600s.

I thought this happened because the ambient daylight was sufficient to light the subject at 1/1600s but the flash had a shorter duration, thus creating a second exposure within the 1/1600s main exposure. However, this also happens in dark rooms lit entirely by flash, and I have since discovered that the B1 units I used outside are slower at full power than 1/1600s.

Any ideas how to stop this from happening?

Attached is a tiny full-size crop from one of these images.

Image
Paqart
 
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Re: Blur/double image at high speed

Postby Paqart » Tue Nov 06, 2018 5:15 am

Broken link error in OP. Here is another link.

Image

If the inline link doesn't work, cut and paste this and it will: https://drive.google.com/open?id=15bluQ ... C5Q4ek7iCj
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Re: Blur/double image at high speed

Postby DouglasHarwinCamera » Thu Jan 31, 2019 7:39 pm

This a technical question that has lots of variables. I assume

First, DF+ and XF bodies - The XF shutter speeds are much faster and allow you to set the flash curtain timing.
Second, Lens - AF lens or LS lens? I am assuming LS. In that case, there should not be an issue.
Third, ProFoto B1, Pro-8 and Pro-10 - all have a different flash durations and without getting too technical. The higher the power output the slower the flash duration. You are using 3 different units all at full power, I assume. Each unit will output a different flash duration. Like you said, "B1 units I used outside are slower at full power than 1/1600s."
Another consideration is Pocket Wizards vs Profoto Air. Air units are able to match a sync cable speed and sync up to 1/1600s.

If you can use one set of units, I suggest Pro-10's cause of the Freeze mode (shortest flash duration) with Profoto Air and you should have this issue.


Friendly,
Douglas
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