Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
05-16-2013, 06:04 AM   #1
Site Supporter

Join Date: Nov 2011
Posts: 47
auto focussing with K5 and 300mm DA* f4

I have had a 300mm DA* for a short time, with my K5. I have noticed that the auto focus struggles when shooting birds low overhead (i.e. they fill a substantial portion of the field) against a sky background (with plenty of light). I would have thought that the contrast of the bird's outline profile against the sky is ample for easy AF.Whether it is the angle of elevation of the lens, and whether it's just my lens, I'm not sure. I don't have the same problem with my other AF lens, which is the 18-55mm kit lens.

Has anyone had this problem?

Cheers, Andrew

05-16-2013, 06:36 AM   #2

Join Date: Jan 2012
Location: Slovenia
Photos: Gallery
Posts: 2,180
It might be that the AF sensor can't find contrast in the bird, or mayve the bird is moving too fast for the AF to lock. You did say that it happens when they fly low over you, ie. relatively close to the camera.
05-16-2013, 06:38 AM   #3
Site Supporter
Stone G.'s Avatar

Join Date: Jun 2010
Location: North Zealand, Denmark
Photos: Gallery | Albums
Posts: 1,516
Based upon my experience with the DA* 200 (with a similar AF system):

The narrow field of view provided by telephoto lenses together with the proximity of the bird means that the image will move rapidly over the AF-sensor. That can be a challenge for any AF system. You will have to excersize panning your camera together with the bird (unless you are already doing that?).
05-16-2013, 06:45 AM   #4

Join Date: Sep 2011
Location: Nelson B.C.
Posts: 3,267
Are you using the afc, continuous focussing? Center point focus? With both of them and practice at panning so that the bird stays in the center of the viewfinder, it should focus.

If the bird is low overhead it means that everything is happening quickly, so it may simply be that the lens/body focus mechanism can't react quickly enough.

05-16-2013, 06:56 AM   #5
Veteran Member
steve1307's Avatar

Join Date: Mar 2010
Location: Sydney
Photos: Gallery | Albums
Posts: 1,129
If the bird are low overhead filling the frame of a DA*300 ! What are they doing? Dive-bombing you? I'd get outta there before you get pooped on.

Sounds pretty challenging for any AF system esp if the subject (underside) is in shadow.
05-16-2013, 07:20 AM   #6

Join Date: Jun 2009
Location: GMT +10
Photos: Albums
Posts: 10,845
I usually don't have too many problems with the DA* 300 and the K-5.

Are you using 11 point AF, 5 point or centre-spot? The contrast you describe may only be relevant if there is a AF sensor within the vicinity of a contrasty area, which may not always happen even under 11 point AF if the edge of the bird is right out to the image boundary.

Also I have to add - I hope you aren't using any UV filters, and are always using the hood. Both may play some role in the performance of the lens when shooting into the light as you describe.
05-18-2013, 03:37 AM   #7
Site Supporter

Join Date: Nov 2011
Posts: 47
Original Poster

Thanks All for the tips - I'll do a bit more experimenting and report back.
05-18-2013, 08:26 AM   #8
Site Supporter

Join Date: Jan 2008
Location: Middle of Everywhere
Photos: Gallery
Posts: 1,169
QuoteOriginally posted by Andrew Crouch Quote
Thanks All for the tips - I'll do a bit more experimenting and report back.
Make sure your firmware is up-to-date and consider turning OFF SR (shake reduction).

Also, consider getting a copy and spend a little time learning LR (Lightroom), plus NIK's plug-in collection for LR (NIK offers excellent free on-line tutorials for each module... I use Define for noise reduction, Vivesa to expand dynamic range, Output Sharpening, and Color Efex Pro to adjust lighting.).

A little quick and dirty (I spend no more than 3 minutes on an image ) post-process fine tuning can help a lot.


  • 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!
300mm, 300mm da*, auto, camera, da*, dslr, k-5, k-5 ii, k-5 iis, k5, lens, pentax k-5, sky
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Q v K5 and the Moon with Pentax-A* 645 300mm F4 tootall Pentax Q 4 09-23-2012 10:02 PM
For Sale - Sold: Pentax K5 with extras, warranty, and DA 16-45mm, DA 35mm F2.4, FA 28-70mm F4 AL Jeanick Sold Items 15 08-25-2012 11:26 AM
DA* 300mm F4 with TC vs. Sigma 150-500mm BeerBelly Pentax SLR Lens Discussion 17 10-03-2011 06:35 PM
Nature Butterflies with K5 and DA* 300mm snooked Post Your Photos! 3 06-29-2011 01:14 PM

All times are GMT -7. The time now is 08:39 PM. | 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]