Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-10-2019, 04:31 PM   #1
New Member




Join Date: Mar 2019
Posts: 3
Image shifts sideways during focus with DA 16-85mm, is this much normal?

Hi,

I acquired a used Pentax HD DA 16-85mm F3.5-5.6 ED DC WR Lens and put it on my K-70, first thing I noticed was the image in the viewfinder shifting during focus, both manual and auto.

In manual focus, the image shifts when you change the direction of focus ring. The same happens in auto focus but it's much quicker like a jitter.

Hopefully the sample videos will show you what I mean. Video 1 shows manual focus at max enlargement, Video 2 shows auto focus.

I've never had this before so I'm worried that possibly this lens is damaged and the focusing lens is decentering differently depending on which direction it is moving. But I'm also open minded enough to accept this is normal behavior for this lens if others also get it.

What yo you all reckon?

Thanks,
Stu

Attached Files
File Type: mpeg FocusShift1-converted.mpeg (959.7 KB, 57 views)
File Type: mpeg FocusShift2-converted.mpeg (984.3 KB, 34 views)
03-10-2019, 04:53 PM   #2
Moderator
Site Supporter
Loyal Site Supporter
MarkJerling's Avatar

Join Date: May 2012
Location: Wairarapa, New Zealand
Photos: Gallery | Albums
Posts: 10,141
QuoteOriginally posted by spayton Quote
Hi,

I acquired a used Pentax HD DA 16-85mm F3.5-5.6 ED DC WR Lens and put it on my K-70, first thing I noticed was the image in the viewfinder shifting during focus, both manual and auto.

In manual focus, the image shifts when you change the direction of focus ring. The same happens in auto focus but it's much quicker like a jitter.

Hopefully the sample videos will show you what I mean. Video 1 shows manual focus at max enlargement, Video 2 shows auto focus.

I've never had this before so I'm worried that possibly this lens is damaged and the focusing lens is decentering differently depending on which direction it is moving. But I'm also open minded enough to accept this is normal behavior for this lens if others also get it.

What yo you all reckon?

Thanks,
Stu
That's certainly peculiar. Is the front end of the lens loose?
03-10-2019, 05:02 PM   #3
Pentaxian




Join Date: May 2016
Photos: Gallery
Posts: 1,352
Mine does something similar when changing the direction of focus at 16mm. I've had the lens for over a year, it's sharp and never had an issue. It's only visible with magnification in live view.

Last edited by aaacb; 03-10-2019 at 05:14 PM.
03-10-2019, 05:06 PM   #4
Veteran Member
Aaron28's Avatar

Join Date: Jan 2015
Location: Huntsville, Al
Posts: 1,119
the battery display is depleted/dead.....maybe try with a fresh battery?

03-10-2019, 05:19 PM - 1 Like   #5
Pentaxian
c.a.m's Avatar

Join Date: Jan 2013
Location: Ottawa, Canada
Posts: 1,620
@spayton,


Stu, welcome to Pentax Forums! Sorry that your introduction deals with a possible fault with your lens.

I don't have that particular lens, so I can't offer much assistance. However, I believe a similar problem was mentioned by two members at this thread (in 2016 and 2018); see posts 16 and 19: experiences with 16-85mm - Page 2 - PentaxForums.com

One of the previous posters was @BigMackCam (also from the UK), who is very active in this forum.

- Craig

Last edited by c.a.m; 03-10-2019 at 06:18 PM.
03-10-2019, 06:21 PM   #6
New Member




Join Date: Mar 2019
Posts: 3
Original Poster
Thanks for the quick replies guys.

MarkJerling: Yes the front lens is a little loose, it has some movement, is that fixable?

aaacb: yes, despite this movement images mostly remain the same sharpness, there's a little change to softness in one corner

Aaron28: it does the same with fully charged batteries, well spotted though

c.a.m: yes an all too common 1st post asking for help. I've used this forum for much research prior to deciding upon a k-70, there's a huge amount of info here. The video link in post #19 shows pretty much the same thing, even the shifting direction is the same



it's looking like it's a problem seen before, doesn't always affect image sharpness but its quite annoying, especially when I want to do manual max magnification focusing on stars at night.

Fixing the loose front end may help, is this doable as a home repair?
03-10-2019, 06:44 PM   #7
Seeker of Knowledge
Loyal Site Supporter
aslyfox's Avatar

Join Date: Aug 2016
Location: Topeka, Kansas
Photos: Gallery | Albums
Posts: 12,831
you may want to review this thread first

Cross-head screws - a caution: - PentaxForums.com
03-10-2019, 10:04 PM   #8
Moderator
Site Supporter
Loyal Site Supporter
MarkJerling's Avatar

Join Date: May 2012
Location: Wairarapa, New Zealand
Photos: Gallery | Albums
Posts: 10,141
QuoteOriginally posted by spayton Quote
Thanks for the quick replies guys.

MarkJerling: Yes the front lens is a little loose, it has some movement, is that fixable?

aaacb: yes, despite this movement images mostly remain the same sharpness, there's a little change to softness in one corner

Aaron28: it does the same with fully charged batteries, well spotted though

c.a.m: yes an all too common 1st post asking for help. I've used this forum for much research prior to deciding upon a k-70, there's a huge amount of info here. The video link in post #19 shows pretty much the same thing, even the shifting direction is the same



it's looking like it's a problem seen before, doesn't always affect image sharpness but its quite annoying, especially when I want to do manual max magnification focusing on stars at night.

Fixing the loose front end may help, is this doable as a home repair?
I don't know if it's fixable or not. But yes, you're right - your video and that of the poster in the 2016 thread almost certainly shows the same thing.

03-11-2019, 05:02 AM   #9
Pentaxian
Jonathan Mac's Avatar

Join Date: Apr 2009
Location: Madrid, Spain
Posts: 5,527
My 16-85mm does the same but it doesn't seem to be a big problem. It also occasionally misses focus but I'm not sure if the two are related. Focus in live view is perfect. There's nothing loose on the lens (at least externally).
03-13-2019, 03:39 AM   #10
New Member




Join Date: Mar 2019
Posts: 3
Original Poster
With full zoom extension, of the 3 barrel sections, it is the most front facing section that has a little play in it. I'll do some tests to see if image quality changes depending on the movement of this section.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
auto, camera, da, direction, focus, focus with da, image, image shifts, lens, pentax help, photography, shifts, troubleshooting, video
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K1 Continuous Shooting Color Shifts Joe Dusel Pentax Full Frame 15 08-12-2018 04:51 PM
DA 16-85: How much decentering is too much? mgvh Pentax SLR Lens Discussion 10 06-06-2017 02:01 PM
Takumar Bayonet 28 f2.8 "shifts" during stop-down metering donutman_2000 Pentax SLR Lens Discussion 4 05-06-2011 04:45 PM
A question regarding Quick Shifts Focus augkyos Pentax SLR Lens Discussion 6 02-11-2011 02:30 AM
K7 image size shifts slightly solar1 Pentax DSLR Discussion 8 03-12-2010 05:15 PM



All times are GMT -7. The time now is 01:48 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top