On Sun, 22 Jul 2007 10:48:00 -0700, "Richard H." <(E-Mail Removed)> wrote:

>Doug Jewell wrote:

>> So you mean a "motion blur priority" mode? Kind of like shutter

>> priority, but instead of keeping the shutter fixed, it maintains the

>> shutter speed relative to the FL? so if the camera is at 100mm and I set

>> the shutter to be 1/50, it would move up to 1/150 if I zoomed to 300mm.

>> Can't say I know of any that do it - shutter priority and dialling the

>> shutter speed while you zoom would be the closest. Not all that hard to do.

>

>Bingo!

>

>I tend to shoot in manual mode, so I envision it as a menu option rather

>than a button, akin to "Track shutter speed with focal length". A bit

>of a hybrid between Program and Manual modes, if you will. (An

>alternative might be to allow a manual EV setting with Program mode.)

>

>Certainly this feature would be off by default - it's not the behavior

>anyone would normally expect when manually setting the shutter speed.

>

>Alas, it sounds like this might be a pipedream. Unfortunate, knowing

>that it'd be pretty easily implemented. Maybe one day camera firmware

>will go open source, and we can tweak away.

>

>Cheers,

>Richard
A pipedream? Some camera's have already been "open sourced". If you have a Canon

Powershot S2 or S3 and installed CHDK on it you can just run this simple script

that I just wrote. Save it to your CHDK/SCRIPTS/ folder on your SD card, then

load it up from CHDK's [SET] button menu (when <ALT> is showing).

I wanted to see how simply it can be done. I've not tested it yet, but it should

work. It sets the shutter speed for the 35mm equivalent zoom setting. Using the

old adage of 1/focal-length for shutter-speed. I included a user selectable

variable to lower that limit by 3 stops if you have IS turned on (default).

Just compose your shot, set your zoom where you want it. Then press your <ALT>

toggle-button to put it in script mode and hit the shutter button. The script

will run, set your shutter-speed and take a photo. Then press your <ALT> toggle

button again to exit script-mode to compose another shot. Rinse & repeat.

A similar script can be written for A-Series cameras, but they only have 0-8 or

0-16 zoom steps available (vs. the 0-128 for S-Series). The line:

f=z*3.1+36

would have to be altered a bit. Where f is being calculated to 35mm

focal-length from the lens' hardware and firmware capabilities.

I'll confess minor problem, the zoom on these cameras is not as linear as this

equation calculates. But for all intents and purposes it will get you close to

the 1/focal-length=shutter-speed as is practical. It is afterall just a rough

guideline for the poorest of hand-held photographers.

-------------------------------------------------------------

rem For Canon Powershot S-Series

@title Motion-Blur Priority

param a IS is off=0 on=1

default a 1

if a<0 then a=0

if a>1 then a=1

print "Use in Manual"

print "or Tv mode."

get_zoom z

rem change the following line for A-Series

f=z*3.1+36

s=1/f

if s<=1/3200 then s=35

if s<=1/2500 then s=34

if s<=1/2000 then s=33

if s<=1/1600 then s=32

if s<=1/1250 then s=31

if s<=1/1000 then s=30

if s<=1/800 then s=29

if s<=1/640 then s=28

if s<=1/500 then s=27

if s<=1/400 then s=26

if s<=1/320 then s=25

if s<=1/250 then s=24

if s<=1/200 then s=23

if s<=1/160 then s=22

if s<=1/125 then s=21

if s<=1/100 then s=20

if s<=1/80 then s=19

if s<=1/60 then s=18

if s<=1/50 then s=17

if s<=1/40 then s=16

if s<=1/30 then s=15

if s<=1/25 then s=14

if s<=1/20 then s=13

if s<=1/15 then s=12

if s<=1/13 then s=11

if s<=1/10 then s=10

if s<=1/8 then s=9

if s<=1/6 then s=8

if s<=1/5 then s=7

if s<=1/4 then s=6

if s<=1/3 then s=5

if s<=1/2.5 then s=4

if s<=1/2 then s=3

if s<=1/1.7 then s=2

if s<=1/1.25 then s=1

if s<=1 then s=0

if a=1 then s=s-6

set_tv s

shoot

end