Pentax K3 ii and back Button Focusing


davidrobinson

Link Posted 28/02/2021 - 22:12
I am struggling to get sharp images of birds in flight with my recently purchased K3 ii. I know it can focus sharply but my BIF photos dont seem as sharp as what my K5 iis produced with the same Sigma 150-500 lens attached. I thought I would try using the rear focus button but the camera struggles to stay locked on the subject. I had a Little Egret in flight pressed and held the back button, the camera focused on it fine but as soon as I started shooting the focus swapped to the wooded area behind. I held the back button all the time the camera and was shooting and it was set to continuos AFC, Continuos shooting M, AF Select Expanded (M). I've tried other settings with very little luck. I thought if the AF button was held then the shutter release had no effect on focus but am I wrong. I have also tried AF2 in button customizing but I still cant get the camera to maintain focus on a BIF. I seem to get better results with the half press shutter and then shoot AFC, but even then I dont think my images are as sharp as the K5 iis produced. What am I doing wrong? Any suggestions gratefully recieved.
Last Edited by davidrobinson on 28/02/2021 - 22:14

doingthebobs

Link Posted 28/02/2021 - 22:46
Are you using the camera shake reduction or the lens image stabilisation?

Best to use one or the other. If you use both they start to fight each other!

All the best, bob.
Bob

davidrobinson

Link Posted 28/02/2021 - 22:53
doingthebobs wrote:
Are you using the camera shake reduction or the lens image stabilisation?

Best to use one or the other. If you use both they start to fight each other!

All the best, bob.

Hi Bob, I've tried both but not at same time, if back button is used the lens shake reduction doesnt work anyway because it needs the shutter half press to trigger it. I've been shooting at 1/1250 second so altough shake reduction may help I dont think it would be critical. The Sigma lens can be set to pan mode but it doenst seem to help either.
Last Edited by davidrobinson on 28/02/2021 - 22:53

womble

Link Posted 28/02/2021 - 23:06
How is the focus on static things? You may need to do some focus adjustment. Won't help with tracking, but might improve the results when it does.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

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davidrobinson

Link Posted 01/03/2021 - 09:44
womble wrote:
How is the focus on static things? You may need to do some focus adjustment. Won't help with tracking, but might improve the results when it does.

Static focusing is pretty good provided I use the half press shutter method. Probably no sharper than the K5 ii but as the detail from the sensor is better it probably makes the final image better. I'm pretty sure the focusing of the lens is pretty well spot on, if I let the camera auto focus on a subject I cant improve it by tweaking the focus ring.
My real gripe is a cant get the back button to work as I think it should with birds in flight.
Last Edited by davidrobinson on 01/03/2021 - 09:47

womble

Link Posted 01/03/2021 - 10:13
Mike might be able to help. I rarely photograph things that have moved in the last century or so...
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

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davidrobinson

Link Posted 01/03/2021 - 10:15




Hand held Sigma 150-500 at 500mm, 1/500 sec, ISO 100, spot focus.
These are images of Little Egret, before and after cropping. I dont think there is much wrong with the focusing although I did use some sharpening in RAW edit and I applied PSE editor's shake reduction to tweak it a little more, it wasnt bad before.
Last Edited by davidrobinson on 01/03/2021 - 10:19

Chrism8

Link Posted 01/03/2021 - 10:23
The sample images look pretty good to me even as small as they are. When I use BBF, and its generally on larger metal birds in flight than the feathered variety, I have spot focusing enabled.
Chris

www.chrismillsphotography.co.uk

" A Hangover is something that occupies the Head you neglected to use the night before".

-------------------------------------------------------------
K1 - Sigma 85mm F1.4, Pentax 150 -450 F4.5 / 5.6, Pentax FA 24 - 70 F2.8

Sigma 100-300 F4, Samyang 14mm F2.8, Pentax 70-200 F2.8

K3iii + K3ii + K5iis converted to IR, Sigma 17 - 70 F2.8, Pentax 55 - 300 F4.5 / F5.6 PLM

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davidrobinson

Link Posted 01/03/2021 - 10:29
Chrism8 wrote:
The sample images look pretty good to me even as small as they are. When I use BBF, and its generally on larger metal birds in flight than the feathered variety, I have spot focusing enabled.

Dont think I've tried spot focusing with BBF because I struggle to keep birds in the centre. When you use BBF and spot focus do you have to keep the plane in the centre of frame for BBF to stay locked on it?

Chrism8

Link Posted 01/03/2021 - 10:48
[/quote]Dont think I've tried spot focusing with BBF because I struggle to keep birds in the centre. When you use BBF and spot focus do you have to keep the plane in the centre of frame for BBF to stay locked on it?[/quote]

Not generally, but it helps to keep the largest part within the spot focusing area. BIF images with pentax is more difficult imho than perhaps other manufacturers, its a skill that takes honing and the success rate perhaps isn't as many as canikon, but when you do get it right, its worth it !!




The Hawk is a tad noise, shot at 1600 ISO ( K3ii )



Chris

www.chrismillsphotography.co.uk

" A Hangover is something that occupies the Head you neglected to use the night before".

-------------------------------------------------------------
K1 - Sigma 85mm F1.4, Pentax 150 -450 F4.5 / 5.6, Pentax FA 24 - 70 F2.8

Sigma 100-300 F4, Samyang 14mm F2.8, Pentax 70-200 F2.8

K3iii + K3ii + K5iis converted to IR, Sigma 17 - 70 F2.8, Pentax 55 - 300 F4.5 / F5.6 PLM
Last Edited by Chrism8 on 01/03/2021 - 10:48

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davidrobinson

Link Posted 01/03/2021 - 10:54
Chrism8 wrote:

Dont think I've tried spot focusing with BBF because I struggle to keep birds in the centre. When you use BBF and spot focus do you have to keep the plane in the centre of frame for BBF to stay locked on it?[/quote]

Not generally, but it helps to keep the largest part within the spot focusing area. BIF images with pentax is more difficult imho than perhaps other manufacturers, its a skill that takes honing and the success rate perhaps isn't as many as canikon, but when you do get it right, its worth it !!




The Hawk is a tad noise, shot at 1600 ISO ( K3ii )


[/quote]
Right I'm going to persist with it, we get plenty of aircraft here so will try them first, they are more predicatble. What do you use, "select spot" or "spot"

Chrism8

Link Posted 01/03/2021 - 11:46
Go just for " Spot " David
Chris

www.chrismillsphotography.co.uk

" A Hangover is something that occupies the Head you neglected to use the night before".

-------------------------------------------------------------
K1 - Sigma 85mm F1.4, Pentax 150 -450 F4.5 / 5.6, Pentax FA 24 - 70 F2.8

Sigma 100-300 F4, Samyang 14mm F2.8, Pentax 70-200 F2.8

K3iii + K3ii + K5iis converted to IR, Sigma 17 - 70 F2.8, Pentax 55 - 300 F4.5 / F5.6 PLM

Helpful

davidrobinson

Link Posted 01/03/2021 - 12:40
Chrism8 wrote:
Go just for " Spot " David

Thanks Chris,
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