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Re: [OM] hand held telephoto flash

Subject: Re: [OM] hand held telephoto flash
From: Moose <olymoose@xxxxxxxxxxxxx>
Date: Wed, 02 Apr 2003 15:11:38 -0800
It is always OK to hand hold, as there are no Photo Technique Police watching you. On the other hand, if your goal is sharp images, you will want to take some care. I assume from your report that you have been experimenting and still ask this question, that the experiments aren't matching your expectations so far?

The general rule of thumb for reasonable sharpness hand held is 1/lens fl, 1/800 for this lens, so at 1/1000 sec., you are just within the 'rule'. On the other hand, that rule assumes careful technique in holding the camera and releasing the shutter. If you are moving the camera, focusing and jabbing at the shutter all at once at the limit of the flash range, you may not get sharp results. Motorsports photographers like our own Mike and Stephen deal with some of these variables through anticipation, pre-focus and panning, techniques that are less effective with wild creatures than racing vehicles. At 600mm and f8, you also don't have all that much DOF, so accurate focus is important. Even leaving aside Hummingbirds, 1/1000 probably isn't enough to stop motion at teh outer ends of some birds wings.

Are you shooting at night? In daylight with fast film, a significant portion of the exposure may be from ambient light which, at 1/60 sec., will surely be blurry handheld.

There are some good wildlife photography sites on the web. Check 'em out. Check out the birding magazines and sites. Some of those folks use super fast high power flashes for bird pics so they can get some DOF.

Get some more flash power. My first step would be a T32 with the Zoom Adapter. This slightly more than doubles the guide number (from 20 to 42 @ iso100) without a lot of added size and weight. You might even experiment with mounting a plastic fresnel lens (from Edmund or some such) in front (behind? inside?) of the zoom adapter. Even with the Zoom Adapter at it's longest setting, over 900f the light from the flash is illuminating an area outside of the field of view of a 600mm lens. The more light you have and the more effectively you concentrate it, the faster the flash speed and the less blur in the picture.

Moose

Matt BenDaniel wrote:

I've been experimenting with an OM-4Ti, Sigma 600mm/f8, and a T20 flash. The 
T20 is not very powerful and projects a wide beam, but it is still useful for 
subjects at close distances (up to 20 feet if the subject is a light color). 
The specs on the T20 says that the maximum flash duration is 1/1000th second. 
The sync speed of the OM-4Ti is 1/60th second.

Assume the following:
* Photographing at f8.
* Moving subject (e.g. bird) at close range (10 feet). * Ambient light is dim. Even using 400 or 800 speed film, non-flash exposure would have to be 1/4 second.
* With the flash, the OTF meter is "happy" with the flash exposures (blinking 
light in view finder).

Is it OK to hand hold?
After all, isn't the exposure effectively 1/1000th at most?





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