Back Button Focus -- any insights

mommytotwo · 07-04-2007, 02:07 PM

I have been trying this out on the K100 does anyone here use this and if so how well does it work for you. I am currently doing the focus recompose method, but wondered if I would have better luck with the change focus point method.

Just found this forum but have been using Pentax for years, since I started with the K1000. I am saving up to get the 10D and a new lens, when and if they finally come out with them.

PDL · 07-04-2007, 11:50 PM

I have de-coupled the AF from the shutter button to the AF button on my K10D. This gives me the freedom of determing what is picked to be in focus. I choose the "thing" to focus on, point the camera at it, press the AF button, compose and shoot.

This method (when using DA lenses) also allows me to move effectively to manual focus as necessary.

I have also set my *ist Ds to use the OK button instead of the the shutter button - so it is not only the K10D that has this feature. Using this method similar to the method currently in use on your K1000.

PDL

mommytotwo · 07-05-2007, 12:36 PM

Do you use AFS or AFC ? I am trying out different methods of focusing and trying to find one that works consistantly well for me, still not sure what way to go.

I haven't reivewed the photos using AFC, but don't think I will like it.

PDL · 07-05-2007, 11:34 PM

I normally use AF-S. This last weekend I was experimenting with my new lens in manual mode and set the camera by accident when switching out of manual mode to AF-C. It was disconserting to say the least, but that was because I do not use it much. AF-C would be usefull if the subject is moving - although I have read in some threads that when using AF-C the camera will not shoot until focus is locked. Very strange behavior - your mileage will vary.

It comes down to preference - I use AF-S because that is the closest to the manual focus methods I grew up with using my manual SLR's in the 70's. My first Autofocus SLR was a Pentax SF-1 - and I used AF-S on it too. Just do not like the constant movement of AF-C.

Personal choice on my part.

PDL

Last edited by PDL; 07-05-2007 at 11:44 PM.

Mechan1k · 07-07-2007, 06:20 PM

Originally posted by PDL

I have de-coupled the AF from the shutter button to the AF button on my K10D. This gives me the freedom of determing what is picked to be in focus. I choose the "thing" to focus on, point the camera at it, press the AF button, compose and shoot.

This method (when using DA lenses) also allows me to move effectively to manual focus as necessary.

PDL

I was thinking about doing this myself recently as I was trying to take shots where AF wanted to focus on things that I did not want to. And I found the AF button is within reach of my thumb as it is.

I might give it a try and see how I feel using it ... I guess it's a case of getting used to doing it that way ... but I'd say in the end you get more flexibility on getting your focus point the way you want it.

Monza76 · 07-17-2007, 05:11 AM

I use the OK button on my DS for the AF. Since the focus points are set to select from the four way switch, it gives me total AF control frommy right thumb. I use AF-S almost exclusively. This method is especially useful with DA lenses since you can touch up the focus manually after pressing the OK button and not have to hold the "half pressed" position on the shutter release.

Peter Zack · 07-17-2007, 05:18 AM

I also use the AF button on the K10D but that can also depend on the things I'm shooting. Sometimes just for speed or other reasons I'll switch it back to the shutter button. I wish it was possible to make that switch back and forth in the menu a little faster. The camera is almost always in AF.S. The AF button makes it possible to make sure the item I want is the focus point and make manual adjustments, focus and framing etc. The focus is always in the center point mode as well.

Deni · 07-17-2007, 06:02 AM

If you're using the focus then recompose method, then you have to use af-s. If you use af-c then the camera will refocus when you recompose.

Focusing and then recomposing does not always mean a properly focused photo. If you're shooting at very wide apertures, lets say f/2, at close distance, recomposing doesn't really work right, so I have found.

If you have an af lens then why not use the 11 af points the k10/100d provides? They'll give you a much better focused image than the focus+recompose way (might be a tad slower though).

If you have manual focus lenses, or don't/can't use the af then achieving proper focus when the subject is not in the center, especially in close distances at wide apertures, can be quite a challenge. I've seen some split image focusing screens that have some focusing circles on the corners, like the one on the center.

Myself, I've set the ok button to reset focusing to center, so I can change af points faster/easier this way, especially if I have to move from one side of the screen to the other.

axl · 07-17-2007, 12:34 PM

Originally posted by Deni

Myself, I've set the ok button to reset focusing to center, so I can change af points faster/easier this way, especially if I have to move from one side of the screen to the other.

I'm using it the same way, plus I set AE to lock with AF. I'm mostly about landscapes, and I find that way to be the easiest. I compose, choose AF point, focus (or set hyperfocal distance in MF) and shoot...
always in AF-S, works well for me

07-04-2007, 02:07 PM	#1
mommytotwo Inactive Account Join Date: Jul 2007 Location: Minnesota Posts: 7	Back Button Focus -- any insights I have been trying this out on the K100 does anyone here use this and if so how well does it work for you. I am currently doing the focus recompose method, but wondered if I would have better luck with the change focus point method. Just found this forum but have been using Pentax for years, since I started with the K1000. I am saving up to get the 10D and a new lens, when and if they finally come out with them.

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07-04-2007, 11:50 PM	#2
PDL Pentaxian Join Date: Oct 2006 Location: PNW USA Photos: Gallery Posts: 2,128	I have de-coupled the AF from the shutter button to the AF button on my K10D. This gives me the freedom of determing what is picked to be in focus. I choose the "thing" to focus on, point the camera at it, press the AF button, compose and shoot. This method (when using DA lenses) also allows me to move effectively to manual focus as necessary. I have also set my *ist Ds to use the OK button instead of the the shutter button - so it is not only the K10D that has this feature. Using this method similar to the method currently in use on your K1000. PDL

07-05-2007, 12:36 PM	#3
mommytotwo Inactive Account Join Date: Jul 2007 Location: Minnesota Posts: 7 Original Poster	Do you use AFS or AFC ? I am trying out different methods of focusing and trying to find one that works consistantly well for me, still not sure what way to go. I haven't reivewed the photos using AFC, but don't think I will like it.

07-05-2007, 11:34 PM	#4
PDL Pentaxian Join Date: Oct 2006 Location: PNW USA Photos: Gallery Posts: 2,128	I normally use AF-S. This last weekend I was experimenting with my new lens in manual mode and set the camera by accident when switching out of manual mode to AF-C. It was disconserting to say the least, but that was because I do not use it much. AF-C would be usefull if the subject is moving - although I have read in some threads that when using AF-C the camera will not shoot until focus is locked. Very strange behavior - your mileage will vary. It comes down to preference - I use AF-S because that is the closest to the manual focus methods I grew up with using my manual SLR's in the 70's. My first Autofocus SLR was a Pentax SF-1 - and I used AF-S on it too. Just do not like the constant movement of AF-C. Personal choice on my part. PDL Last edited by PDL; 07-05-2007 at 11:44 PM.

07-07-2007, 06:20 PM	#5
Mechan1k Veteran Member Join Date: Jun 2007 Location: Sydney, Australia Posts: 2,891	Originally posted by PDL I have de-coupled the AF from the shutter button to the AF button on my K10D. This gives me the freedom of determing what is picked to be in focus. I choose the "thing" to focus on, point the camera at it, press the AF button, compose and shoot. This method (when using DA lenses) also allows me to move effectively to manual focus as necessary. PDL I was thinking about doing this myself recently as I was trying to take shots where AF wanted to focus on things that I did not want to. And I found the AF button is within reach of my thumb as it is. I might give it a try and see how I feel using it ... I guess it's a case of getting used to doing it that way ... but I'd say in the end you get more flexibility on getting your focus point the way you want it.

07-17-2007, 05:11 AM	#6
Monza76 Guest	I use the OK button on my DS for the AF. Since the focus points are set to select from the four way switch, it gives me total AF control frommy right thumb. I use AF-S almost exclusively. This method is especially useful with DA lenses since you can touch up the focus manually after pressing the OK button and not have to hold the "half pressed" position on the shutter release.

07-17-2007, 05:18 AM	#7
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	I also use the AF button on the K10D but that can also depend on the things I'm shooting. Sometimes just for speed or other reasons I'll switch it back to the shutter button. I wish it was possible to make that switch back and forth in the menu a little faster. The camera is almost always in AF.S. The AF button makes it possible to make sure the item I want is the focus point and make manual adjustments, focus and framing etc. The focus is always in the center point mode as well.

07-17-2007, 06:02 AM	#8
Deni Veteran Member Join Date: May 2007 Location: Tirana, Albania, South Europe, Planet Earth Photos: Gallery \| Albums Posts: 621	If you're using the focus then recompose method, then you have to use af-s. If you use af-c then the camera will refocus when you recompose. Focusing and then recomposing does not always mean a properly focused photo. If you're shooting at very wide apertures, lets say f/2, at close distance, recomposing doesn't really work right, so I have found. If you have an af lens then why not use the 11 af points the k10/100d provides? They'll give you a much better focused image than the focus+recompose way (might be a tad slower though). If you have manual focus lenses, or don't/can't use the af then achieving proper focus when the subject is not in the center, especially in close distances at wide apertures, can be quite a challenge. I've seen some split image focusing screens that have some focusing circles on the corners, like the one on the center. Myself, I've set the ok button to reset focusing to center, so I can change af points faster/easier this way, especially if I have to move from one side of the screen to the other.

07-17-2007, 12:34 PM	#9
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	Originally posted by Deni Myself, I've set the ok button to reset focusing to center, so I can change af points faster/easier this way, especially if I have to move from one side of the screen to the other. I'm using it the same way, plus I set AE to lock with AF. I'm mostly about landscapes, and I find that way to be the easiest. I compose, choose AF point, focus (or set hyperfocal distance in MF) and shoot... always in AF-S, works well for me