Shutter speed override - General Help and Assistance on using CHDK stable releases - CHDK Forum  

Shutter speed override

  • 4 Replies
  • 1799 Views
*

Offline fed

  • *
  • 5
Shutter speed override
« on: 07 / July / 2008, 09:06:47 »
Advertisements
Hi

Perhaps someone would be able to clarify an issue with the shutter override feature on the S3 for me, please.

In the camera feature list (CameraFeatures - CHDK Wiki) it gives the available shutter override potential as

1/40,000" / Flash-Sync 1/60,000" (OEM 1/3,200" & OEM flash-sync to 1/500" only) .

 My problem, (and I am sure it is my problem!) is understanding OEM and when (and how) the highest speeds are available, since 1/3200 seems to be my maximum.

Thanks

*

Offline jetzt

  • ****
  • 316
  • [A710IS,(SD200)]
Re: Shutter speed override
« Reply #1 on: 07 / July / 2008, 09:26:25 »
Don't know it myself now, but it is said here on the forum, that the highest shutter speeds are only available with the highest F-stop numbers.
What's following now, might be completely obvious, but I don't now what you already know about CHDK, so:
*Camera only shows it's own canon values in top most menu. This is irrelevant if you use the chdk extra photo operations.
*In exif there are only the canon values.
*OEM is about canon values

What counts is the Depth of Field in the Picture and the brightness of the frame.

hope I destroyed all clarities
jetzt

*

Offline fed

  • *
  • 5
Re: Shutter speed override
« Reply #2 on: 07 / July / 2008, 09:46:56 »
Thank you for your reply.

Does this mean that the OSD is showing an incorrect value and the camera will infact respond at the highest speed?


*

Offline jetzt

  • ****
  • 316
  • [A710IS,(SD200)]
Re: Shutter speed override
« Reply #3 on: 07 / July / 2008, 10:26:41 »
CHDK osd should show the speed you set with chdk, canon osd shows the one you set with canon. :lol
If you set CHDK speed, the camera is supposed to take chdk speed.
Try it out, set for example 1/3200 with canon and shoot.
Then leave the canon setting like that, only change chdk value to something faster or slower and shoot(Value factor bigger or is one then).
But you don't know if your camera has really done let's say 1/10000 or if it has just done 1/5000,
ok 1/10000 should be accurate but at higher speeds you can never be sure, only by comparing.

Again a bit more confusion for you
jetzt


*

Offline fudgey

  • *****
  • 1705
  • a570is
Re: Shutter speed override
« Reply #4 on: 07 / July / 2008, 14:44:45 »
Yes, what jetzt says. I'll try to say it in other words to make things more complicated.  :D

Canon's OSD says what it thinks is happening, but it doesn't know CHDK is overriding it. So, it can't be trusted.

CHDK override says the override you have set in CHDK settings, but CHDK doesn't know if your camera hardware is actually capable of the things you are requesting. So, CHDK OSD override can't always be trusted either.

You get the highest shutter speeds with the narrowest available aperture (often F/16 using Av override) and (if my memory serves) highest zoom. If you set a Tv override value faster than the camera's limits, the real shutter speed will be slower than what you requested. You can only know the real shutter speed by experimenting to find the limits of your camera, and even then there may be variance between shots; we are working way beyond what Canon's user interface allows, after all.

Values in EXIF tags for shots taken using overrides is another thing to note. Typically the standard tags show what the camera thought was happening, but the override values can be found encoded in the MakerNotes section. Again, even they may be incorrect if the camera wasn't able to perform as requested by the override.
[/quote]

 

Related Topics