====I am casting around for a new flash gun. The choices to date seem to be
an Oly F280 or a Vivitar 285. The F280 has a guide number of only 91
[feet] at 100 ISO whereas the Vivitar 285 has a guide number of 120
[feet] at 100 ISO.
I tested a new-out-of-the-box Vivitar 285 today with a flash meter at 10
feet at 100 ISO and found the output to be only f 5.6! At 5 feet the
reading was f 8 ..... in both instances two full stops of underexposure
or, in other words, only 250f rated output.
I am wondering whether my experience with the flash meter with the 285
was to be expected or whether list members who use, or have used, the
285 can vouch for a better level of performance. Clearly, the loss of
750f output does not speak very highly of what should be a respectable
flash gun.
As far as the F280 is concerned has anyone got any test statistics with
a flash meter to compare actual output with rated output? Any
significant fall off in actual output at GN 91 at 100 ISO would start to
produce underexposed images at relatively close range indeed. Using the
F280 for fill flash at short range might produce satisfactory results
but a fall off in actual versus rated output at full power would produce
seriously underexposed images at the rated distance for any specified f
stop.
John Hudson
Vancouver, BC========
I just did a quick and dirty test of my 285HV Zoom head flash.
Using 10 Charlie feet in a small living room with white walls
I got these results,
Wide = f 8 +1/2
Normal = f 8 + 2/3
Tele = f 11
I haven't calibrated my flash meter in some time but my exposures
are usually right on. I used the test button to fire the unit.
The Vivitar 285 and 283 are in my HO, great units
with consistent accurate results and fit an OM just fine.
The 285 looks a bit large on an OM but it is light weight.
Construction is not all that hefty but they are priced right and last a long
time.
If I had a OM4T I would seriously consider the F 280 for super fp.
I may at times change flash units for full flash exposure though.
If you really need the power shop around for a Vivitar used or
on sale and get both.
If you don't need super fp why bother with the F 280?
Get a T-32 for TTL, manual and auto use.
The same test gave my T-32 an F 8 + 1/3.
Just for the heck of it the T20 gave f 5.6 + 1/3
Charlie L.
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