Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-26-2009, 05:45 PM   #1
Pentaxian
K-9's Avatar

Join Date: May 2009
Location: USA
Photos: Albums
Posts: 1,962
K20 P-TTL question

I've never tried an external P-TTL flash but was reading through the manual and it says you set the flash mode to Auto P-TTL and this makes a "pre-flash" fire right before the actual flash? I was wondering if this is like double the flash for every shot you take and is there a slight shutter delay for it to take the exposure? Thanks

07-27-2009, 05:43 AM   #2
Veteran Member
Matjazz's Avatar

Join Date: Sep 2006
Location: EU/Slovenia
Photos: Gallery
Posts: 774
Your built-in flash works in the same manner. The pref lash is usually several stops weaker than exposure flash. So yes it fires twice but it doesn't use even near as much as twice the power. As for the delay, I guess there is some, but I haven't been able to notice it so far.
07-27-2009, 12:43 PM   #3
Senior Member




Join Date: May 2009
Location: Atlanta
Posts: 110
Is that different from the double-flash you get using red-eye reduction?
07-28-2009, 02:58 AM   #4
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,678
Yes, completely separate. Red-eye will activate a separate pupil-constricting flash to limit the red-eye effect.

07-28-2009, 05:07 AM   #5
Loyal Site Supporter




Join Date: Mar 2009
Location: Southern Indiana
Photos: Gallery
Posts: 14,940
You won't actually see the preflash. It is lower power and very brief. It is nothing like the red eye reduction flashes (which are really annoying).
07-28-2009, 05:20 AM   #6
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,678
Although if you look carefully, you'll notice the pre-flash go off in the viewfinder immediately before the mirror flips up to take the exposure.
07-28-2009, 07:51 AM   #7
Senior Member




Join Date: May 2009
Location: Atlanta
Posts: 110
What's the point of the pre-flash?
07-28-2009, 07:58 AM   #8
Veteran Member




Join Date: Dec 2006
Location: Outside of Philly
Posts: 1,564
QuoteOriginally posted by WalterGA Quote
What's the point of the pre-flash?
So the camera's exposure meter can determine what power the main flash needs to fire at during the exposure.

You CAN see the pre-flash if you use rear-curtain sync and a slow-ish shutter speed (~1 second or slower) You'll see the pre-flash, shutter opens, right before the shutter closes you'll see the main flash.

07-28-2009, 04:33 PM   #9
Senior Member




Join Date: May 2009
Location: Atlanta
Posts: 110
Thanks for the info. Couple hours ago, I did what I should have initially done...read about PTLL in my K20 manual!
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, flash, p-ttl, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wireless P-TTL Question Kazy Troubleshooting and Beginner Help 4 01-27-2010 02:59 AM
AF220T and P-TTL question Camera lucida Pentax Camera and Field Accessories 7 08-01-2009 09:49 AM
Question for strobists regarding P-TTL and Slaves konraDarnok Pentax Camera and Field Accessories 8 01-14-2009 04:53 AM
AF360 P-TTL Zoom Question SanDiegoDave Pentax DSLR Discussion 3 03-25-2008 12:22 PM
P-TTL on K10D w/540 question... Duh_Vinci Pentax Camera and Field Accessories 3 03-21-2007 09:01 PM



All times are GMT -7. The time now is 02:04 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top