Olympus-OM
[Top] [All Lists]

Re: [OM] F 280 Fill in Flash Range

Subject: Re: [OM] F 280 Fill in Flash Range
From: "John A. Lind" <jlind@xxxxxxxxxxxx>
Date: Mon, 07 Jul 2003 01:00:39 -0500
The F280 has a GN less than the T-32 and it plummets in Super FP mode. The faster the shutter speed, the more it plummets . . . dramatically. This greatly reduces the working distance of the flash.

Not unique to the F280, the plummeting GN issue dates to the days of long duration FP flash bulbs (e.g., 26 and 26B, the long duration version of the Press 25). When you set the shutter speed above the X-Sync, you get a slit moving across the film plane. The shutter curtains *always* travel at the same speed, regardless of shutter speed. Thus, shutter speed is controlled by the delay between releasing the first and second shutter curtains, not their speed of travel. As shutter speed increases, the delay decreases and the slit narrows. Each time the shutter speed doubles (e.g. from 1/125th to 1/250th) the width of the slit is cut in half, and this cuts in half the light reaching the film from a flash in FP mode, or long duration flash bulb for that matter.

Look at the table for the flash on the eSIF site. With the OM-3ti or OM-4T in FP mode, the flash GN drops from 28m/92ft (ISO 100, meters/feet) to:

            ISO 100
Shutter   GN(m)  GN(ft)
1/60th    14.7    48.2
1/125th   10.4    34.1
1/250th    7.3    23.9
1/500th    5.2    17.1
1/1000th   3.7    12.1
1/2000th   2.6     8.5

Even at f/4 to maintain a decent depth of field with human subjects, at 1/125th second shutter speed in Super FP mode, the maximum working distance is very short:

GN for 1/125th @ f/4
ISO 100:  2.6m / 8.5 ft
ISO 200:  3.7m / 12 ft
ISO 400:  5.2m / 17 ft

Consider the severe maximum working distance limitation amd compare it to the working distance and film speed you normally use with fill flash before buying the F280.

-- John


< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz