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05-19-2009, 02:57 PM   #1
danielchtong's Avatar

Join Date: Jul 2007
Location: Toronto
Posts: 851
Suggested MF practice for BIF fast shots

This is an extension of another thread on picking AF focus point

QuoteOriginally posted by hinman Quote

I went back to same location to shoot the Forster's terns a 2nd time, the foul up on AF is nailed this time. It comes from AF not picking up any spot when I pan the bird flying over sky that has low contrast as in partially white bird over white clouds. The problem is less when I pan the bird over water. The foul up happens so often that I have to switch from AF.C to MF.
It is very disappointing because when AF.C with auto-select works, the results are quite spot on for me. It is almost insane to shoot completely in AF.C and auto-select as I don't find the combination to work satisfactory due to the frequent foul up on AF that refuses to lock on any target. It is very unsettled feeling to use K20D to picture the terns in flight. The terns are crazy for one as they don't fly in a straight pattern. The AF is not responsive enough to focus on the bird upon first half-press.

Changing to MF make the job less insane due to the less noise from the AF motor and no foul up from the AF. Unfortunately, I get lots of focus errors especially when the bird are farther away in a distance and I have to guess on MF from the default focusing screen

I think you have hit the glass ceiling of what Pentax can offer at this stage of the AF game. I went through that already. I am still shooting AF (esp. under 200mm) except macro and those for the fastest action shots

Here are the suggested MF practice steps and setting

Good light ........manual exposure... 1/1500s or faster .... burst.... SR off..... F 5.6 - F8 depends..... MF to around 120 ft on distance dial

Concentrate on your practice subject (say a licence plate of a parked car ) around 90 ft away

Raise up your camera , fire right away ( off focus of course) .

The fun (critical) part now : Turn your focus dial anticlockwise until you hit the focus spot on (really not taking long for a minor turn of around 30 degree).

Time the frames you wasted (OOF) and you will know how long it takes you to focus.

I bet that will take you one second to lock focus of a fixed subject (30 degree turn).

Once you get used to the pace then you will be ready for flying bird. Make sure you target birds around 120 - 90 ft away. That is my practice and you may improvise or improve over mine as you are pretty in it already. Birds too far out will not help you as you need that to fill a bigger part of your frame. Also bird too far out will require you to make bigger turn of the focus ring


Daniel, are you using a katz-eye focusing screen or something similar for your MF work? I am hitting an area that both my skills and the AF responsiveness in Pentax have much rooms for improvements.

I have a split screen on my DL and not on my K100D & 20D. Really not much help for fast shots . Quite helpful for macro and slow shots though.

from Hin Man
I find AF working harder than the usual single center focal point that I mostly used. It happens few times that AF motor is grinding to a halt in repeated shots after the bird's movement. When that happens, half-press don't seem to trigger AF. I have to point the lens to ground and re-focus with half-press to reset.

The beauty of MF for this way of shooting :

1. Your camera cannot BF or FF. The fault or credit entirely goes to you.

2. Focus hunting will be minimal as your focus ring is turned only one way (not back and forth)

3. Your other AF method involves you pressing the shutter for one shot which has generated vibration to your camera body. In my set up, I actually waste/give up the 1st couple of shots

I really hope these are temporary measure before we have the ideal Pentax . And all we need to do is to point our camera in the general direction of a flying bird and the camera will finish the rest. Well one day we hope


Last edited by danielchtong; 05-19-2009 at 03:16 PM.
05-19-2009, 03:05 PM   #2
danielchtong's Avatar

Join Date: Jul 2007
Location: Toronto
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Original Poster
Here is the beauty of consecutive focused shots. And if , and only if, Pentax has 6 fps , I am sure I will have more keepers in between these shots

The first three were taken within the same second (see the exif all taken on 08-Oct-2007 10:30:46) with manual exposure & focus. There is zero way that Pentax AF can manage this (3fps) no matter what lens you use.

Of course I cannot show you the 2 shots prior to this batch - they were off focus before I could lock on.

05-19-2009, 03:27 PM   #3
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
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Thank you so much for sharing the detailed information on the practice drill. That is something that I really need to keep working on. The Forstern's terns is a challenge and beauty to shoot as they don't often fly in a straight line, but there are moments that they do and there are other moments that they do slow down a bit in hovering over a spot looking for food. The trick is getting ready for those moments.

I did try the burst shots but I was mostly out of focus after the 1st shot. It is my user error.

I will need to keep practicing the drill as you have suggested. Thanks again!

Last edited by hinman; 05-19-2009 at 05:10 PM.

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