Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
12-04-2010, 03:21 PM   #1
Forum Member

Join Date: Oct 2008
Location: Croatia
Photos: Gallery
Posts: 64
K-5: behavior with flash in Av

Bit the bullet and got my K-5 this week. Amazing camera, coming from a k200d it's a whole new world to me.

I noticed one thing I haven't seen on the k200d: with flash mounted and a zoom lens (notably the Sigma 17-70) in Av mode, the camera automatically increases the shutter speed as the lens is zoomed to a greater focal length, and decreases it as the lens is zoomed out.

As if it somehow tries to compensate for camera shake - somewhat odd with flash and SR in place, though.

Yet so far, the camera simply leaves me in awe, and such little details only improve on the general picture

12-04-2010, 11:28 PM   #2
Forum Member

Join Date: Nov 2010
Location: Lynchburg, VA
Posts: 57
What shutter speed is it choosing? I can't be sure, but it seems like the K-5 tries to keep the shutter speed no slower than 1/2 the focal length. That would require the shake reduction to "handle" about 1.5 stops. Even with flash, this is a pretty good practice, since ambient light can still contribute to the exposure at slow shutter speeds.
12-05-2010, 12:34 PM   #3
Forum Member

Join Date: Oct 2008
Location: Croatia
Photos: Gallery
Posts: 64
Original Poster
On 17mm, it's 1/50. On 70mm, it's 1/125.
12-07-2010, 03:03 AM   #4
fs999's Avatar

Join Date: Jul 2008
Location: Luxembourg
Photos: Gallery
Posts: 3,745
The Sigma 17-70 opens at f:2.8 at 17mm and at f:4 at 70mm that's why the shutter speed changes...

12-07-2010, 06:12 AM   #5
Site Supporter

Join Date: Feb 2008
Location: Boston MA
Photos: Gallery | Albums
Posts: 279
indeed it chooses a shutter speed according to the 1/focal length rule of thumb to avoid camera shake, since flash is being used anyway. The k7 does the same thing. To turn that feature off, you need to set the camera flash setting to slow sync.

  • 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!
av, camera, dslr, flash, k-5, k-5 ii, k-5 iis, k200d, k5, lens, pentax k-5
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Wierd SD card behavior Hemi345 Pentax Camera and Field Accessories 11 01-05-2011 12:21 PM
Odd behavior THAN THE SWORD Pentax DSLR Discussion 2 09-10-2009 05:36 AM
K-7 vs K100DS Pop Up Flash Behavior ale78 Pentax DSLR Discussion 1 07-24-2009 06:43 PM
Strange *ist ds behavior trd300gt Pentax DSLR Discussion 1 11-14-2008 04:53 AM
K100d built in flash: strange behavior Rafael Pentax DSLR Discussion 5 12-17-2007 03:02 PM

All times are GMT -7. The time now is 12:35 AM. | See also:, 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?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]