Can't freeze movement using Profoto B2

[sam_b.1]

<p>Hello,</p>

<p>I am novice with the Profoto B2 and strobist in general. Today I wanted to try and combine a long exposure with the use of the flash.</p>

<p>The picture below was taken at 1/10s, f8, ISO 200. This is to achieve the blur effect in the windmill. However I wanted myself to be sharp and the profoto head was placed about two meters in front of me, with no modifier, just the bare head at full power. </p>

<p>My question is: why am I completely blurred ? I though the flash should have frozen the movement but it's not the case. Any idea what to change ? <br>

I just want to mention that I've used a ND6 filter to get that low speed, but I don't think that should affect the flash...</p>

<p><img src="https://quvr1g-ch3302.files.1drv.com/y3mQjSCoTHlIrFTI91S79ztkAIvffiCFU_gkj10h_qWQWBnJmFp_W83UB5-52UmR3wzOTbT7E5jguU-hDlDqmlCS6Z4K51X97P3C84cAhjTl_Bv_sTzMl_jzex3yxKKuPcDkSE6Ov556ZaHlfMLdD2v3qkN052p1JolL0bV7czG9FE?width=660&height=440&cropmode=none" alt="" width="660" height="440" /></p>

<p> </p>

[Ken Katz]

It looks like the ambient exposure, at a shutter speed of 1/10, caused the blur. If you want flash to freeze

motion, the ambient exposure needs to be considerably underexposed (like 3+ stops under) in order not to see

ghosting caused by ambient light. You need to come up with a solution whereby the foreground receives

much less ambient light than the windmill. Perhaps at dawn or at dusk where the windmill still receives

sunlight and you, on the ground, do not.

[sam_b.1]

<p>I see. So basically at this time of the day, there is no way to achieve this effect, right ? <br>

Sounds like an impossible shot :) But at least now I know the B2 is not the problem.</p>

<p>Thank you.</p>

[michaelmowery]

<p>Or stay in a static pose for 1/10s and you would have been fine.</p>

[michaelmowery]

<p>also I can hardly see the exposure of the flash. Had the power been up a stop or so more it may have helped a bit more</p>

[mark_schafer1]

You basically have two components to your final exposed image.

The ambient light that's limited but the exposure time, f stop and sentivity and your strobe that's limited but the power of

the strobe, the f stop and the sensitivity.

To illustrate this you could take one exposure without flash and see you ambient "base" exposure. Everything you see

there will be visible in your final image. Adjust as needed.

Now you add the strobe, maybe at the shortest sync time, like at 1/250 or whatever your system lets you. That's your

strobe component.

For your final shot you mix and match those components to get the effect you want.

 

As for your specific image, the only way to do this in camera is to eliminate all ambient exposure on the person, aka build

a dark tent.

In the world of Photoshop, I'd just shoot 2 frames, one proper overall Image with a non blurred person and one, preferably

at the same f stop and focus distance of the blurred windmill (or wait till there's very strong winds).

[sam_b.1]

<p>Thank you for your responses, they were all very useful.<br>

I think combining two exposures in this case and creating a composite is the way to go :)</p>

[felix_wu1]

<p>Just use HSS with your B2 to freeze action outdoor!</p>

[sam_b.1]

<p>sure, but that wouldn't give the wanted effect (blurred windmill) </p>

[bob_bill]

<p>If you use a sekonic meter it would tell you the percentage of light you are getting from flash and ambient. If you have too much ambient, it is allowing the motion to be captured. </p>

[bob_bill]

<p>If you use a sekonic meter it would tell you the percentage of light you are getting from flash and ambient. If you have too much ambient, it is allowing the motion to be captured. </p>

[felix_wu1]

<p>Unfortunately you could never achieve a blurred windmill and a sharp subject at the given lighting condition...not during day time for sure.</p>

[fotografz]

<blockquote>

<p >The picture below was taken at 1/10s, f8, ISO 200. This is to achieve the blur effect in the windmill. However I wanted myself to be sharp and the profoto head was placed about two meters in front of me, with no modifier, just the bare head at full power. </p>

<p >My question is: why am I completely blurred ? I though the flash should have frozen the movement but it's not the case. Any idea what to change ?</p>

</blockquote>

<p > </p>

<p >Set the Mode button on the B2 pack from "Normal" to "Freeze". Then dial down the energy to achieve a faster (shorter) flash duration (at full power, the B2 duration in "Normal" and "Freeze" mode is the same: 1/1000 ... but as the energy setting is decreased, the flash duration gets considerably shorter in "Freeze" Mode: "Normal" mode ranges from 1/9300 @ lowest setting to 1/1000 @ highest, compared to "Freeze" mode which ranges from 1/15,000 to 1/1000 @ highest setting). So dialing approximately 2/3s power should provide about 150+ W/s @ 1/2500 duration (strictly a guess on the duration, but it WILL be faster in "Freeze" mode)</p>

<p > </p>

<p >If you have the Profoto B2 Location kit with 2 heads, use both to light the subject and each will deliver 1/125 W/s for a total of 100% B2 energy capacity (250 W/s,) but the duration will be be the same as one head set to 50% energy in "Freeze" mode.</p>

<blockquote>

<p ><br />I just want to mention that I've used a ND6 filter to get that low speed, but I don't think that should affect the flash...</p>

</blockquote>

<p > </p>

<p >Actually, a ND filter does affect the flash exposure ... NDs cut any light entering the lens, natural or artificial. What NDs do not do is affect the duration of the flash exposure.</p>

<p > </p>

<blockquote>

<p >So basically at this time of the day, there is no way to achieve this effect, right ?</p>

<p > </p>

</blockquote>

<p >All that said, what Bob Bill said is directly dealing with the issue:</p>

<p > </p>

<blockquote>

<p ><em>"If you use a sekonic meter it would tell you the percentage of light you are getting from flash and ambient. If you have too much ambient, it is allowing the motion to be captured". </em></p>

</blockquote>

 

<p >The only way to overcome that issue is to alter the ambient to flash ratio. Remove the ND; Increase the shutter speed to eliminate the ambient "drag"; use the Freeze" mode to get a faster flash duration; and live with the fact that in that ambient light the windmill will not be blurred . So, as suggested by others, you can shoot a second exposure without you in the shot using the ND on the lens to achieve a slower shutter speed leaving aperture and ISO setting the same as the flash image ... then blend the 2 images in PS using layers and the masking or eraser tools.</p>

<p > </p>

- Marc

[jamie_coburn]

<p>The exposure is indeed two separate exposures (flash and ambient) combined into one.<br>

Done correctly the shutter speed is irrelevant. I take night time images where the shutter speed is several seconds and the subject is tack sharp.<br>

You will notice that the center of the subject is sharper while the hands and head are extremely blurry. The sharper areas have almost enough flash....The blurry areas have almost no strobe light. You have to make sure the hands face and all extremities are lit by the strobe. A light meter is handy here....If you set the main light at f8 there should be f8 worth of light on the subject....pay attention to the perimeter of the subject.<br>

When shooting very fast moving subject you want to light from the position that will give you the best chance of sharp frozen images....The subject should be facing and moving into the light. If you have a lot of motion on both sides you need light from both sides or you will get blur.<br>

The image below was set up to wrap light around the subject(s) as they came down the race course. The sun was coming and going so I set up the light on the left 2 stops over the fill light on the right...giving me a dynamic wrap no matter what the sun was doing. Its not perfectly frozen, but the top riders (like this guy) were hitting 60 mph as they came through my lights.<br>

https://500px.com/photo/109957555/dean-by-jamiecoburn?ctx_page=1&from=user&user_id=2400503<br>

<img src="https://500px.com/photo/109957555/dean-by-jamiecoburn?ctx_page=1&from=user&user_id=2400503" alt="" /></p>

<p>Hope that helps!</p>