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Tom_Kline

Member Since 07 Nov 2004
Offline Last Active Today, 04:35 AM
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In Topic: blurry fish shutter speed advice

16 September 2016 - 11:13 AM

I don't understand. If you use aperture priority, how do you also set the shutter speed? Doesn't the camera just pick one to give you the correct exposure?

Roger that. The camera selected the 1/640 s. It also varied the ISO since I was using auto ISO - I use this a lot for ambient light pix. I set 1/500 s. as the minimum shutter speed and ISO 800 and 12800 as the, respectively, minimum and maximum ISO (in the auto ISO menu). Fixed at f/13 due to aperture priority. This is with a 1Dx, auto ISO functionality varies with camera model. If I run out of ISO, i.e. at 12800 and more exposure is needed then the camera will go to longer than 1/500 s. (this happens later in the day as well as when a cloud passes between the sun and the camera - the sun is weaker in Alaska at 60 degrees N compared to the tropics- so exposures may be different from you are used to).


In Topic: blurry fish shutter speed advice

16 September 2016 - 10:21 AM

Please post examples, can't really help without.  1/250 should be more than enough to freeze the action so seems a bit strange to be honest

 

Some fish are capable of very quick movement that may not involve traveling. Family Antennaridae feeding comes to mind.

 

I was editing pix I took a few weeks ago yesterday and marked this one to use here in case this got asked. This is an ambient light exposure at 1/640 s. I was using aperture priority with auto ISO. Note the blur at the front and tail ends of this female Pink Salmon in the process of excavating her redd. The large dorsal spots just posterior of her head are not blurred. Rocks on the bottom closer than the fish are in focus so this is not a DOF issue. One pic is a blow-up of the other.


In Topic: blurry fish shutter speed advice

15 September 2016 - 02:42 PM

1/1000 s for a strobe duration is really long.....10 times shorter than that is more likely. Any blur is almost certainly due to ambient light and camera settings that allow that ambient light to get to the sensor. Use small apertures, low ISO, strobes on high power, and avoid any camera automatic exposure settings like P or A or S.

I don't think so.

To get to near 1/10000 of a second one has to turn down the power. For example-

This site has some actual measurements:

http://gock.net/2012...-small-strobes/

 

The first strobe listed is a Canon 580EX

At full power the duration is just 1/250 s.

At half power it is close to 1/1000 s.

To get to near 1/10000 s. one has to go to 1/32 power.

Other strobes are not as quick.

Both Broncolors had longer than 1/1000 s. duration at all settings tested.

It would be cool if we had data like this for underwater strobes!

I typically use my underwater strobes at 1/2 to 1/4 power so I expect the flash to be closer to 1/1000 s. rather than 1/10000 s. 


In Topic: blurry fish shutter speed advice

14 September 2016 - 04:47 PM

i wondered about lowering iso to isolate strobe as exposure source or raising shutter speed???


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i guess partly depends if you care about the background, suggestions?


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You can only go as far as the synch speed is a limit. Lower ISO might help to reduce the ambient part. Still, the strobe may not be able to stop the fish movement. I think I have come across this issue as well while photographing salmon. The female flicks her body several times in one second when she digs her redd (salmon nest). The speed at the tip of her snout is extremely fast (head moves in opposite direction to the tail). I have had to toss out numerous flash shots due to blurring. Ambient exposure was almost nil in many shots so I think it is due to the flash exposure being too long - 1/1000 sec. (I have heard of this as being an example of flash duration) may not be short enough for some movement.


In Topic: blurry fish shutter speed advice

14 September 2016 - 04:37 PM

You should post some examples.  A couple of possibilities: 1. The blur is coming from the ambient light part of the exposure. 2. It is coming from the flash part and the flash duration is too long for the fish movement. Few if any of the strobe manufacturers provide info on the duration of their flashes. They should do for given fractions of flash output: full, half, quarter and so on. The duration goes down as power is reduced. If you are going TTL this will be an unknown unless your strobe provides a readout of the output.