Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-22-2011, 01:28 PM   #16
Pentaxian
dosdan's Avatar

Join Date: Dec 2007
Location: Brisbane, Australia
Photos: Gallery | Albums
Posts: 1,697
Original Poster
QuoteOriginally posted by Gimbal Quote
Why AF.C paired with a manual focusing lens?
I used a MF lens because I didn't want the speed altered by waiting for focus. Although, with AF the delay should be before the burst starts and hopefully there will not be any further delays during the burst while AF updates. The initial AF delay is not considered here. We're not including the time from when you hold down the shutter release button until the end of the burst, because the initial delay is variable and will change with lens and situation. So I time from peak to peak (the loudest part of the shutter movement - there's a number of peaks).

Normally, I would not use a MF lens with AF.C, but use it here to reduce a variable: any further AF update delay during the burst. If the target is static (I performed the test on a tripod) AF performance should not affect the burst speed once it starts (which is what I'm measuring).

Dan


Last edited by dosdan; 10-23-2011 at 12:16 AM.
10-23-2011, 12:41 AM   #17
Pentaxian
dosdan's Avatar

Join Date: Dec 2007
Location: Brisbane, Australia
Photos: Gallery | Albums
Posts: 1,697
Original Poster
Here's another way of determining the burst speed that should be easier for users. It was suggested by Schmegg in the forums.whirlpool.net.au Photography forum: Photograph a stopwatch program on your PC e.g.

Free stopwatch and countdown timer

Here's how to use this method. It's not as accurate as digital audio (PC timers can be a bit unreliable), but probably good enough for this purpose..

1. Install the timer display program and start it running showing seconds to at least 1 decimal point.
2. Photograph the timer display in a burst until the buffer fills (I suggest a tripod to prevent AF adjusting during the burst (at the start is not a problem).
3. Say the first shot shows the timer (in mm:ss.ddd) at 10:25.100 and the 24th shot shows 10:28:642. The difference is 3.542s over 23 shots (take away 1 for the start). So the burst rate is 3.542/23 = 154ms/shot and 1s/0.154ms = 6.5 fps
4. To ensure that no unexpected stutters occurred, I'd suggest also checking about half-way from the start too. So in this example, at the 13th shot and divide the difference from the first shot by 12. The result should be close to the full burst speed.
5. Send the fps and the other requested camera info to me.

Dan.

Last edited by dosdan; 10-23-2011 at 12:48 AM.
11-11-2011, 09:38 PM   #18
Pentaxian
dosdan's Avatar

Join Date: Dec 2007
Location: Brisbane, Australia
Photos: Gallery | Albums
Posts: 1,697
Original Poster
Some new test results. I put on a AF lens (Sigma 17-70/F2.8-4.5) and compared AF.S vs AF.C. I think you'd be more likely to use AF.C for continuous bursts in action shooting. I also compared Centre-point and Auto focus-point selection. These tests were repeated a number of times and 2 different Class 10 cards tried.

Results with Centre-point focus are:

AF.S 6.8 fps
AF.C 4.8 fps

with Auto-focus point selection approx 0.1 fps slower.

Burst length was usually 20 (AF.S) & 22 shots (AF.C).

The AF.C performance is still considerably better than my K20D which was only about 2.7-2.9 fps.

Dan.

Last edited by dosdan; 11-12-2011 at 03:28 AM.
11-12-2011, 03:24 AM   #19
Pentaxian
RonHendriks1966's Avatar

Join Date: Jan 2009
Photos: Gallery
Posts: 8,714
QuoteOriginally posted by dosdan Quote
Results with Centre-point focus are:

AF.S 6.8 fps
AF.C 4.8 fps

with Auto-focus point selection approx 0.1 fps slower.
Not so bad. I think in the field with a reallife sport it is not so fast as you messured. To my feelings it gets down to just over 3 fps, but when your scene doesn't change to much at a time it does a quicker series of shots and probably gets to those 4.8 fps.

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!
burst, camera, class, db, dslr, k-5, k-5 ii, k-5 iis, k5, max, pentax k-5, shutter
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
slow shutter speed noise reduction simons-photography Pentax DSLR Discussion 15 05-20-2017 10:20 PM
My SD card cannot keep up to speed for Pentax K-X HI Continuous shooting learnphotography Pentax DSLR Discussion 7 04-10-2010 08:28 AM
High speed SDHC cards and K200D's continuous shooting. hahifuheho Pentax Camera and Field Accessories 4 04-02-2010 02:42 PM
K-x & AF360 flash - shutter speed 1/15 or 1/30... always flippedgazelle Flashes, Lighting, and Studio 3 04-02-2010 12:42 AM
K7 High Speed Continuous Shooting tpeace Pentax DSLR Discussion 18 03-15-2010 01:10 PM



All times are GMT -7. The time now is 10:35 PM. | See also: NikonForums.com, CanonForums.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