K-1 AF viewfinder problem

gerardbaron · 08-07-2016, 06:35 PM

I am having problem with the AF on the viewfinder with the 28-105mm
when the lens is extended after about 80mm.
I am using point focus.
I reset all the setup with no success.
AF works fine in liveview
I think the problem came when I update the firmware to 1.20.
Any suggestions?
Thank for your help

SteveD · 08-07-2016, 06:52 PM

May not mean a thing but did you read the thread https://www.pentaxforums.com/forums/190-pentax-k-1/327333-strange-af-issue-da-300-a.html?

gerardbaron · 08-07-2016, 07:05 PM

Yes I read this thread, I did what it is recommended with no success.

stevebrot · 08-07-2016, 08:07 PM

I don't own either the K-1 or the D FA 28-105, but I will ask the standard hard questions:

What do you mean by problem? Does the camera not attempt AF? Is it unable to attain focus? Is focus inaccurate? Something else?
Do you have problems with PDAF (viewfinder AF) with any other lens?
Have you been able to test your 28-105 on another Pentax body?

...and lastly...Both camera and lens are still under warranty. Have you been in conversation with Ricoh/Pentax? If either lens or camera is less than a month old, have you been in conversation with your dealer to arrange for possible exchange?

Steve

Last edited by stevebrot; 08-07-2016 at 08:15 PM.

Grognard · 08-07-2016, 10:16 PM

I think K-1 users may refer to this issue as "PDAF Freezing", because the lens doesn't move at all, but the AF signal is flickering.
From all my observations and personal experiences I speculate that this issue attributes to Pentax's SDM design deficiency which cannot be handled well by K-1.

The reason: My DFA 24-70 (a Tamron rebadge SDM, you guys all kown) is clearly free of such issue. But DA* 300 and DFA 28-105 (mentioned by the original poster) both use Pentax's own SDM, which does not own a good reputation among Pentaxians.
Now that the "PDAF Freezing" issue can be solved by switching to CDAF, I hope this issue can be setteled by a future firmware release. I will add this point to the pinned thread.

biz-engineer · 08-07-2016, 10:55 PM

Originally posted by Grognard

But DA* 300 and DFA 28-105 (mentioned by the original poster) both use Pentax's own SDM

It is very short cut to a conclusion. What I know for sure is that the DFA150-450 and DFA70-200 supposedly Ricoh design (like DFA28-105) have totally different SDM designs, there is no comparison with "old" DA300 SDM, I don't know about the DFA28-105.

Kunzite · 08-08-2016, 01:06 AM

The D FA 28-105 doesn't use a SDM motor at all - it's using a DC motor. But I'm not sure if the difference is relevant in this case.

Paul the Sunman · 08-08-2016, 04:58 AM

Originally posted by gerardbaron

I am having problem with the AF on the viewfinder with the 28-105mm
when the lens is extended after about 80mm.
I am using point focus.
I reset all the setup with no success.
AF works fine in liveview
I think the problem came when I update the firmware to 1.20.
Any suggestions?
Thank for your help

I've had no problem with this combination, and am on 1.20.

gerardbaron · 08-08-2016, 12:10 PM

Originally posted by gerardbaron

I am having problem with the AF on the viewfinder with the 28-105mm
when the lens is extended after about 80mm.
I am using point focus.
I reset all the setup with no success.
AF works fine in liveview
I think the problem came when I update the firmware to 1.20.
Any suggestions?
Thank for your help

I try the FA 28-105mm on a K-5: same problem
I mount another lens on the K-1. AF works like a charm
So I decide to return the lens and exchange it for a new one 20-105mm same lens.
The new lens works perfectly.
Problem solved.

08-07-2016, 06:35 PM	#1
gerardbaron Senior Member Join Date: Apr 2011 Location: Mississauga (Canada) Photos: Albums Posts: 139	K-1 AF viewfinder problem I am having problem with the AF on the viewfinder with the 28-105mm when the lens is extended after about 80mm. I am using point focus. I reset all the setup with no success. AF works fine in liveview I think the problem came when I update the firmware to 1.20. Any suggestions? Thank for your help

08-07-2016, 07:05 PM	#3
gerardbaron Senior Member Join Date: Apr 2011 Location: Mississauga (Canada) Photos: Albums Posts: 139 Original Poster	AF problem Yes I read this thread, I did what it is recommended with no success.

08-07-2016, 08:07 PM	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	I don't own either the K-1 or the D FA 28-105, but I will ask the standard hard questions: What do you mean by problem? Does the camera not attempt AF? Is it unable to attain focus? Is focus inaccurate? Something else? Do you have problems with PDAF (viewfinder AF) with any other lens? Have you been able to test your 28-105 on another Pentax body? ...and lastly...Both camera and lens are still under warranty. Have you been in conversation with Ricoh/Pentax? If either lens or camera is less than a month old, have you been in conversation with your dealer to arrange for possible exchange? Steve Last edited by stevebrot; 08-07-2016 at 08:15 PM.

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08-07-2016, 06:52 PM	#2
SteveD Senior Member Join Date: Jun 2016 Posts: 112	May not mean a thing but did you read the thread https://www.pentaxforums.com/forums/190-pentax-k-1/327333-strange-af-issue-da-300-a.html?

08-07-2016, 10:16 PM	#5
Grognard New Member Join Date: Jun 2016 Posts: 23	I think K-1 users may refer to this issue as "PDAF Freezing", because the lens doesn't move at all, but the AF signal is flickering. From all my observations and personal experiences I speculate that this issue attributes to Pentax's SDM design deficiency which cannot be handled well by K-1. The reason: My DFA 24-70 (a Tamron rebadge SDM, you guys all kown) is clearly free of such issue. But DA* 300 and DFA 28-105 (mentioned by the original poster) both use Pentax's own SDM, which does not own a good reputation among Pentaxians. Now that the "PDAF Freezing" issue can be solved by switching to CDAF, I hope this issue can be setteled by a future firmware release. I will add this point to the pinned thread.

08-07-2016, 10:55 PM	#6
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232	Originally posted by Grognard But DA* 300 and DFA 28-105 (mentioned by the original poster) both use Pentax's own SDM It is very short cut to a conclusion. What I know for sure is that the DFA150-450 and DFA70-200 supposedly Ricoh design (like DFA28-105) have totally different SDM designs, there is no comparison with "old" DA300 SDM, I don't know about the DFA28-105.

08-08-2016, 01:06 AM	#7
Kunzite Pentaxian Join Date: Apr 2007 Location: Romania Posts: 15,132	The D FA 28-105 doesn't use a SDM motor at all - it's using a DC motor. But I'm not sure if the difference is relevant in this case.

08-08-2016, 04:58 AM	#8
Paul the Sunman Pentaxian Join Date: Aug 2011 Location: Melbourne Photos: Gallery Posts: 4,843	Originally posted by gerardbaron I am having problem with the AF on the viewfinder with the 28-105mm when the lens is extended after about 80mm. I am using point focus. I reset all the setup with no success. AF works fine in liveview I think the problem came when I update the firmware to 1.20. Any suggestions? Thank for your help I've had no problem with this combination, and am on 1.20.

08-08-2016, 12:10 PM	#9
gerardbaron Senior Member Join Date: Apr 2011 Location: Mississauga (Canada) Photos: Albums Posts: 139 Original Poster	Originally posted by gerardbaron I am having problem with the AF on the viewfinder with the 28-105mm when the lens is extended after about 80mm. I am using point focus. I reset all the setup with no success. AF works fine in liveview I think the problem came when I update the firmware to 1.20. Any suggestions? Thank for your help I try the FA 28-105mm on a K-5: same problem I mount another lens on the K-1. AF works like a charm So I decide to return the lens and exchange it for a new one 20-105mm same lens. The new lens works perfectly. Problem solved.