Go Back   Steve's Digicams Forums > Digicam Help > Newbie Help

Reply
 
Thread Tools Search this Thread
Old Aug 11, 2009, 7:33 AM   #11
Senior Member
 
VTphotog's Avatar
 
Join Date: Mar 2005
Location: Extreme Northeastern Vermont, USA
Posts: 4,214
Default

Quote:
Originally Posted by spanish_biker79 View Post
My understanding was that the flash duration (whatever that is but around 1/1000? ) is much higher than 1/40,000, hence the shutter closes before it receives all the light it needs to take a proper picture as it would just use 1/40,000 of the flash (whilst the shutter is opened) and all the rest would be wasted.

Not sure if this is right though, it's my understanding so far...
The duration of a Xenon strobe flash (the usual kind) starts at around 1/1000th s, but can be much shorter. The specs I have handy for my Vivitar 285 show a minimum, in auto mode, of 1/30,000. This flash was purchased around 1985. Conceivably, newer, higher powered flashes could be shorter, given the right conditions.
As Peripatetic mentions, speeds in this range are only useful for stopping motion of very fast objects, and are often used with specialized triggering circuits which are sound or light activated.

brian
VTphotog is offline   Reply With Quote
Old Aug 11, 2009, 5:15 PM   #12
Junior Member
 
Join Date: Aug 2009
Posts: 5
Default

Today some pics turned out OK with 1/1600 and ISO 400, the main difference however was the sun!!!! Previously I've tried with daylight but with the typical cloudy British weather, today was really sunny and that made the difference. I suppose some shutter speeds cannot be used in winter


Thanks all guys!
spanish_biker79 is offline   Reply With Quote
Old Aug 14, 2009, 4:08 PM   #13
Senior Member
 
Join Date: Dec 2006
Location: Davenport, IA
Posts: 2,093
Default

I think somethings wrong here. You should be able to use 1/40,000 in full daylight.
See chart below:

Full Daylight Front Lit ISO 1600
f/8 @ 1/6400
f/5.6 @ 1/12800
f/4 @ 1/25600
f/2.8 @ 1/51200*

Cloudy Bright ISO 1600
f/8 @ 1/1600
f/5.6 @ 1/3200
f/4 @ 1/6400

Heavy Overcast ISO 1600
f/5.6 @ 1/1600
f/4 @ 1/3200
f/2.8 @ 1/6400

If the sensor really has ISO 1600 sensitivity you should be able to get a decently exposed photo at something like f/3.5 @ 1/40000 if the subject is front lit in full daylight. Note though that the max aperture at full telephoto for your camera is f/4.6. If you can't get a decently exposed photo under the conditions I've described then I'd think the camera isn't really delivering ISO1600 or there's a shutter problem.

Try this test: full daylight, front lit subject, ISO 1600, f/3.5, shoot a series of starting at 1/40000, 1/20000, 1/10000, 1/5000, 1/2500, 1/1500, 1/750. If the shots lighten up steadily as you reduce the shutter speed then probably the sensor isn't really delivering ISO 1600. If on the other the shots are consistantly dark down to some point and then suddenly jump to correct or over exposure then I'd suspect the high speed electronic shutter is not sync'ed with the mechanical shutter.

A. C.
ac.smith is offline   Reply With Quote
Old Aug 14, 2009, 4:12 PM   #14
Senior Member
 
Join Date: Dec 2006
Location: Davenport, IA
Posts: 2,093
Default

Quote:
Originally Posted by spanish_biker79 View Post
Today some pics turned out OK with 1/1600 and ISO 400, the main difference however was the sun!!!! Previously I've tried with daylight but with the typical cloudy British weather, today was really sunny and that made the difference. I suppose some shutter speeds cannot be used in winter


Thanks all guys!
That's sort of what I suspected. If you want to play with the high speed shutter under your typical conditions you might want to try exposures in this range:
Cloudy Bright ISO 800
f/8 @ 1/800
f/5.6 @ 1/1600
f/4 @ 1/3200
f/2.8 @ 1/6400

A. C.

Last edited by ac.smith; Aug 14, 2009 at 4:17 PM.
ac.smith is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 8:08 PM.