"Martin Doppelbauer" <Martin.Doppelbauer@t-online.de> wrote in message news:bjl6im$sts$01$1@news.t-online.com...

> I own a GL2 and was wondering why the smallest aperture value was only

> f/8.0.

>

> However recently I noticed a strange behaviour: when you press exposure lock

> in bright lightning conditions and than adjust manually to make the picture

> darker

> you can actually get aperture values well below f/8.0 !

> This even works fine when the camera indicated an overexposure it could not

> handle in Auto mode (blinking ND ON).

> Lock the exposure and reduce brightness. When playing the tape back use the

> DATA CODE button on your remote to display camera data and you'll find

> values well below f/8.0 (for example f/22).

> To bad these values are never used in Auto Exposure nor can they be

> activated

> directly in Manual or Av mode.

>

> Anybody else noticed this ? Any reasons ? Workarounds ?

All lenses suffer the softening effects of diffraction at smaller stops,

and smaller formats suffer these at wider stops than larger (as in,

for 35mm, f22 may be barely acceptable for optimum sharpness,

but for 2 1/4 square it is OK, and for 4x5 it is no problem at

all - and f64 may be the first "too small" stop for that format [but

it would be OK for 8x10, etc.]). For 1/3rd inch CCDs, f11

may be the limit (see VX2000 stills at each stop at

www.David-Ruether-Photography.com/diffraction.htm), and for 1/4", it may

be f8. Since the optical demands of this medium are relatively

low, smaller stops can give acceptable results (one of my Mini-DV

cameras would go to f32 and look OK[!]). At least with the Sony

VX2000 with the ND warning blinking (and for others without the

warning indicator) with the "auto shutter" enabled, overexposure

would not occur (the shutter speed rises to compensate - but it

can go quite high in bright light, risking "strobing"). Use of the

proper ND filter (the VX2000 has two built in) permits using

an optimum stop for good resolution and a low enough shutter

speed to prevent strobing effects in bright light...--

David Ruether

d_ruether@hotmail.com

http://www.David-Ruether-Photography.com