[DDoram]

While I haven't used the K3 for portraits yet, I am finding that having more focus points to select from allows for more precise AF compared to all previous bodies including K5IIs.

Dale

[lister6520]

Metering and AF are completely decoupled.

............

The metering sensor is actually used in conjunction with AF but only for continuous focus with subject tracking (expanded area AF). Since the AE sensor has so many points that it can actually 'see' and image it can recognise movement and follow it, much as it does with tracking AF in live view except that it then uses the AF sensor to do the actual focusing while the AE sensor is helping the camera to decide which PDAF focus point to use.

For focusing in AF.S or AF.C without tracking the AE sensor does not participate at all.

As regards the effect of different lighting affecting the focus, that was a problem which AFAIK the K5 is the last Pentax to have. That issue was resolved in the K-30 and then the K-5II with the something they called a diffraction lens in the PDAF module. Not really sure what they mean by it but it was introduced in the K-30 to solve the problem of misfocus in tungsten and other difficult light and has been included in all subsequent models.

If you use tungsten modelling lights then I guess the K-3 will actually be a big improvement in AF accuracy over the K-5 but then so will a K-5ii or even a K-500.

[pentax user]

Have you tried the technique of using AF-C and using the AF button? I found going to this method, rather than the half press has increased my keeper rate about 5x easily (if not more). You can use the selected focus point and hold the AF button and it will compensate for those micro movements from either yourself or you subject.

Here is an example of a difficult focus situation. My daughter doing spins. While not every shot is spot on focus wise, most are good enough. Was shot at f2.0, 1/1500, ISO 200. Admittedly it is with a K-3 which has a faster focusing system than the original K-5, but the OP's studio situations wouldn't be as extreme as this. Click image to go to high res version....



edit: was made using JPG's from the camera. No PP applied (other than in camera JPG processing)

don't have a k3 but how's that work to increase keeper? the shutter button and the af button are held down the whole time. why decouple them?

[krebsy75]

I've had success with K-5II cams and the 77mm at f/2. Check out the portraits on my Flickr.

[dcBear78]

don't have a k3 but how's that work to increase keeper? the shutter button and the af button are held down the whole time. why decouple them?

Normally you lock focus with half press of the shutter button then there is a brief wait for you to get your shot. In that time either you or your subject may move slightly and your focus is now just out.

By changing this you get the benefit of AF-C with it constantly holding focus (while pressing AF button) and a shot is taken everytime you press the shutter button, still in focus. Plus the focus, recompose ability of AF-S.
There was a good thread here a while back explaining it. There are a couple menu items you change to achieve this.

I first tried it on my K-30 and was blown away by keeper rate instantly more than doubling. I now have the luxury of choosing which pictures I like, not which ones are in focus. I was a centre point focus and recompose shooter and had to learn to use the focus points (where K-3 is better) to use this technique. Now there is no way I would go back to my old method.

[Winder]

I have read a lot of good reviews of the K-3, but I have yet to find an answer to maybe the most important question for me... AF precision in Single AF mode.

I shoot with the K-5 mk1 today and mostly portraits. My favorite lens is the FA77 but the results are similar with other portrait lenses. I shoot at around f/2.5 mostly and after a photosession of a couple of hundred images the results are usually something like 70-80% keeper rate (focus within acceptable limits) and 40-50% is perfectly focused. These figures might vary a bit depending on color temperature, backlit scenes etc. I use single point AF and choose the point suitable for my composition (wish they where wider sometimes). Single AF-mode. I'm not interested in continuous AF, tracking capabilities or improved AF speed. Just want higher keeper rate. Will the K-3 / SAFOX 11 be an improvement compared to the K-5?

I was using the K-5 mk1 and moved to the K-3. AF is much more accurate using the center AF point. I shoot a lot of wide aperture. F/2 is very, very common and the AF accuracy at wide aperture is remarkably better.

[pentax user]

Normally you lock focus with half press of the shutter button then there is a brief wait for you to get your shot. In that time either you or your subject may move slightly and your focus is now just out.

By changing this you get the benefit of AF-C with it constantly holding focus (while pressing AF button) and a shot is taken everytime you press the shutter button, still in focus. Plus the focus, recompose ability of AF-S.

In afc mode, the shutter being held down it's not suppose to focus continuous?
I couldn't fine the link of the thread, can you post it?

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Last edited by pentax user; 12-07-2013 at 06:44 PM.

[Winder]

I have read a lot of good reviews of the K-3, but I have yet to find an answer to maybe the most important question for me... AF precision in Single AF mode.

I shoot with the K-5 mk1 today and mostly portraits. My favorite lens is the FA77 but the results are similar with other portrait lenses. I shoot at around f/2.5 mostly and after a photosession of a couple of hundred images the results are usually something like 70-80% keeper rate (focus within acceptable limits) and 40-50% is perfectly focused. These figures might vary a bit depending on color temperature, backlit scenes etc. I use single point AF and choose the point suitable for my composition (wish they where wider sometimes). Single AF-mode. I'm not interested in continuous AF, tracking capabilities or improved AF speed. Just want higher keeper rate. Will the K-3 / SAFOX 11 be an improvement compared to the K-5?

To add one point.

The K-3 is not going to give you the image quality improvements over the K-5 that the K-5 had over the K-7. The K-3 has a lot of small improvements and some big improvements over the K-5. When you add all the different improvements together they make the K-3 a much better camera. Speed, AF, resolution, image processing, no AA filter, better SR..... The K-3 is really a much better camera to work with.

[klkitchens]

Normally you lock focus with half press of the shutter button then there is a brief wait for you to get your shot. In that time either you or your subject may move slightly and your focus is now just out.

By changing this you get the benefit of AF-C with it constantly holding focus (while pressing AF button) and a shot is taken everytime you press the shutter button, still in focus. Plus the focus, recompose ability of AF-S.
There was a good thread here a while back explaining it. There are a couple menu items you change to achieve this.

I first tried it on my K-30 and was blown away by keeper rate instantly more than doubling. I now have the luxury of choosing which pictures I like, not which ones are in focus. I was a centre point focus and recompose shooter and had to learn to use the focus points (where K-3 is better) to use this technique. Now there is no way I would go back to my old method.

Just mucking around with this on my hard to catch dogs. Loving it. Nice tip. Cannot wait for real usage.

[dcBear78]

In afc mode, the shutter being held down it's not suppose to focus continuous?
I couldn't fine the link of the thread, can you post it?

I don't necessarily mean continuous shooting. This method improves focusing ability for single shots.

I'll see if I can find the thread...

[dcBear78]

Here we go...

https://www.pentaxforums.com/forums/38-photographic-technique/236970-perfect-focus-everytime.html

[pentax user]

read the thread, still don't get it.
This method improves focusing ability for single shots not for burst mode?
i normally use burst mode and afc for sport.

[dcBear78]

Basically it works by having the camera focus right up to the instant you press the shutter button.

So it even helps for burst mode as it reduces those micro adjustments between when you focus and actually less the shutter button. It's hard to explain and I felt the same way until I tried it for myself.

Add to that you get the benefits of single and constant focus modes without having to change settings.

[DonThomaso]

Thank you for the link to perfect focus everytime! I will definitely try out that technique on my next shoot. Seems like it could solve my problems since I have very carefully calibrated the lenses and the focus is of randomly (both front and back).

[klkitchens]

Ok... tested this out last night as I said on my dogs and got the feel of it.

Used it today at my church's Christmas program. Not portrait per se, but live, low light shooting.

Shot 223 or so images. I think I counted missed focus on 2-3 of them. Some were bad lighting and too much noise. But this is 100% my new method. The K-3 has the right idea for moving the focus area too and once you get the hang of where that is, you're golden. I could do everything with my eye to the viewfinder, it was amazing.

Will post some high ISO shots later, but thank you!