Pentax AF Fact and Myths

whoelse · 29th January 2008

I read an article sometime ago comparing a one pass AF used by N/C and two pass AF by Pentax. While 2 pass is slower, it's more accurate. Something similar like the manual focus era, you will focus back and fore to get the sharpest focus in the viewfinder... I can't find the full article but saw this post and I cut/paste here.

"The second interesting suggestion comes out of a post where it was explained that shooting can get tripped up by the autofocus because unlike Nikon or Canon, the Pentax system seems to do a double-check of the focus after a first guess. The camera won't fire until this is finished. Nikon and Canon just do the one pass, and this leads to quicker, yet sometimes innacurate focusing.

The poster went on to say that this can be circumvented by putting the camera in AF C, and taking the picture between the first focus, and the double check as you can trip the shutter at any time in AF C. He found that the Pentax system was correct the first time as much or more than the Canon/Nikon cameras he compared it to.

A setting in the Custom menu for the AF C or AF S to do only one pass, and calling it "AF Hi-Speed" would open that choice. People would realize it could be less accurate, but a welcome choice to some complaining about AF speed."

ilario · 29th January 2008

Where do u find that AF Hi Speed setting? Dont seem to see it in the custom menu..

night86mare · 29th January 2008

Originally Posted by ilario

Where do u find that AF Hi Speed setting? Dont seem to see it in the custom menu..

i think it's a suggestion la! doesn't exist

flipfreak · 29th January 2008

are u able to provide the link to the article and was the writer able to provide facts or proof on what he had written?

whoelse · 29th January 2008

Originally Posted by flipfreak

are u able to provide the link to the article and was the writer able to provide facts or proof on what he had written?

searching too. maybe u guys can help. was quite a informative one but forgot where i saw it.

lizzy · 30th January 2008

http://forums.dpreview.com/forums/re...ssage=26547922
this guy mention that K20D have a custom function for single pass AF

fengwei · 30th January 2008

Originally Posted by lizzy

http://forums.dpreview.com/forums/re...ssage=26547922
this guy mention that K20D have a custom function for single pass AF

Yes, it is true. Actually in K10D it's already there. Just set the AF/MF switch to AF/C

But it doesn't work that well on K10D though. Hope it's got improved on the new camera.

snapnut · 30th January 2008

The K100D AF Mode can be set in the menu to AF-C... I wonder if it has the same effect

fengwei · 30th January 2008

Originally Posted by snapnut

The K100D AF Mode can be set in the menu to AF-C... I wonder if it has the same effect

Should be the same

Zenten · 31st January 2008

There is no issue with AF speed, imho, it's with the accuracy of the AF-C .............

lizzy · 3rd February 2008

looks like pentax has improved AF speed in K20D... hope it is true

http://forums.dpreview.com/forums/re...ssage=26612962

29th January 2008	#1
whoelse Member Join Date: Oct 2003 Posts: 1,227	Pentax AF Fact and Myths I read an article sometime ago comparing a one pass AF used by N/C and two pass AF by Pentax. While 2 pass is slower, it's more accurate. Something similar like the manual focus era, you will focus back and fore to get the sharpest focus in the viewfinder... I can't find the full article but saw this post and I cut/paste here. "The second interesting suggestion comes out of a post where it was explained that shooting can get tripped up by the autofocus because unlike Nikon or Canon, the Pentax system seems to do a double-check of the focus after a first guess. The camera won't fire until this is finished. Nikon and Canon just do the one pass, and this leads to quicker, yet sometimes innacurate focusing. The poster went on to say that this can be circumvented by putting the camera in AF C, and taking the picture between the first focus, and the double check as you can trip the shutter at any time in AF C. He found that the Pentax system was correct the first time as much or more than the Canon/Nikon cameras he compared it to. A setting in the Custom menu for the AF C or AF S to do only one pass, and calling it "AF Hi-Speed" would open that choice. People would realize it could be less accurate, but a welcome choice to some complaining about AF speed."

29th January 2008	#2
ilario Member Join Date: Dec 2007 Posts: 163	Re: Pentax AF Fact and Myths Where do u find that AF Hi Speed setting? Dont seem to see it in the custom menu.. __________________ Functional disorder

29th January 2008	#4
flipfreak Member Join Date: Nov 2007 Posts: 5,370	Re: Pentax AF Fact and Myths are u able to provide the link to the article and was the writer able to provide facts or proof on what he had written? __________________ My Portfolio \| My Blog

30th January 2008	#6
lizzy Member Join Date: Dec 2004 Posts: 247	Re: Pentax AF Fact and Myths http://forums.dpreview.com/forums/re...ssage=26547922 this guy mention that K20D have a custom function for single pass AF

30th January 2008	#8
snapnut Member Join Date: Oct 2004 Posts: 218	Re: Pentax AF Fact and Myths The K100D AF Mode can be set in the menu to AF-C... I wonder if it has the same effect

31st January 2008	#10
Zenten Senior Member Join Date: Jun 2004 Posts: 6,204	Re: Pentax AF Fact and Myths There is no issue with AF speed, imho, it's with the accuracy of the AF-C ............. __________________ Nikomi Canpen Zenten :eek: Not exactly 100% Natural but definitely the closest you can get to it

3rd February 2008	#11
lizzy Member Join Date: Dec 2004 Posts: 247	Re: Pentax AF Fact and Myths looks like pentax has improved AF speed in K20D... hope it is true http://forums.dpreview.com/forums/re...ssage=26612962