Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-25-2018, 08:43 PM   #1
Site Supporter
Site Supporter
BruceBanner's Avatar

Join Date: Dec 2015
Location: Blue Mountains, NSW, Australia
Posts: 2,771
Infinity Adjustment

What's the deal with infinity adjustments... like... how can you tell if you suspect the lens you own may benefit from it?

I own a SMC Pentax-A 24mm 2.8, I enjoy a lot of the shots it produces but sometimes I feel that when I push it to focus infinity there is still a softness there that shouldn't be, like it needs to go a tad farther. It could be me of course (user error), but I did note that a 'For Sale' post recently for a partially broken A 24mm 2.8 (missing piece to make it work in 'A' mode) also had an infinity adjustment made during it's attempted repair. It got me thinking... maybe mines needs it to?

a) how to test?

b) how to adjust?

Cheers!

Bruce

03-25-2018, 08:53 PM   #2
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 47,789
QuoteOriginally posted by BruceBanner Quote
What's the deal with infinity adjustments... like... how can you tell if you suspect the lens you own may benefit from it?

I own a SMC Pentax-A 24mm 2.8, I enjoy a lot of the shots it produces but sometimes I feel that when I push it to focus infinity there is still a softness there that shouldn't be, like it needs to go a tad farther. It could be me of course (user error), but I did note that a 'For Sale' post recently for a partially broken A 24mm 2.8 (missing piece to make it work in 'A' mode) also had an infinity adjustment made during it's attempted repair. It got me thinking... maybe mines needs it to?

a) how to test?

b) how to adjust?

Cheers!

Bruce
If you suspect a lens isn't able to focus to infinity, test it out in live view, and stop it down to rule out softness wide open. It should be able to render distant objects. Adjustment could be done at a repair shop, I think. Also keep in mind that the amount that the focusing ring can go past infinity may vary with ambient temperature.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

03-25-2018, 09:57 PM   #3
Site Supporter
Site Supporter




Join Date: Jul 2017
Location: Arizona
Posts: 887
That was my lens listed for sale.
I cant really describe just "how" I determined it wasn't quite hitting infinity , other than it just wasn't quite there . I always felt that it was hitting the hard stop just shy as my images weren't quite as sharp as I knew the lens could be.
After Eric adjusted it , the difference was easy to see. I asked him to intentionally set it a hair past the oo stop, as there is nothing worse than to come up short.
I shoot a lot in Live View with focus peaking , and would rather have it a hair past oo to come back to focus , rather than not quite getting there in the first place.
This is a somewhat common occurrence on older MF lenses I'm finding out.
03-25-2018, 10:06 PM   #4
Site Supporter
Site Supporter
BruceBanner's Avatar

Join Date: Dec 2015
Location: Blue Mountains, NSW, Australia
Posts: 2,771
Original Poster
QuoteOriginally posted by Ronald Oakes Quote
That was my lens listed for sale.
I cant really describe just "how" I determined it wasn't quite hitting infinity , other than it just wasn't quite there . I always felt that it was hitting the hard stop just shy as my images weren't quite as sharp as I knew the lens could be.
After Eric adjusted it , the difference was easy to see. I asked him to intentionally set it a hair past the oo stop, as there is nothing worse than to come up short.
This is a somewhat common occurrence on older MF lenses I'm finding out.
That's kinda what I'm feeling at the moment, but I don't like to trust my instincts too much. I took a picture of my daughter on the weekend (it just hit Explore now), and it's a very close up shot with that lens, the sharpness is incredible (on the K-1), her eyes just perfectly in focus, so I feel that sharpness is somehow missing from infinity landscape stuff I tend to do more with that lens.

03-25-2018, 10:09 PM   #5
Pentaxian




Join Date: Oct 2009
Location: North
Photos: Gallery
Posts: 4,244
QuoteOriginally posted by BruceBanner Quote
I feel that when I push it to focus infinity there is still a softness there that shouldn't be
Thats about the best that I can go with unfortunately if you have only one camera.
I usually base it on what I recall from my usage on another camera and also with my A7 which has the adapters which all allow the focus to go past infinity.
03-25-2018, 10:19 PM   #6
Site Supporter
Site Supporter
BruceBanner's Avatar

Join Date: Dec 2015
Location: Blue Mountains, NSW, Australia
Posts: 2,771
Original Poster
QuoteOriginally posted by pinholecam Quote
Thats about the best that I can go with unfortunately if you have only one camera.
I usually base it on what I recall from my usage on another camera and also with my A7 which has the adapters which all allow the focus to go past infinity.
Oh I have a Pentax KP as well as K-1, can we ascertain more data from having two camera bodies?
03-25-2018, 10:21 PM   #7
Site Supporter
Site Supporter




Join Date: Jul 2017
Location: Arizona
Posts: 887
While in LV with Focus Peaking....I noticed it would get right at the point for FP to "pop" into view......but never quite made it.
I have lots of manual lenses so knew what was going on.
When a inexpensive little Rikenon P 28mm 2.8 was sharper than the SMC-A 24mm at infinity , I started investigating. My suspicions were easily confirmed.
Eric also verified it was coming up short.

---------- Post added 03-25-18 at 22:23 ----------

QuoteOriginally posted by BruceBanner Quote
Oh I have a Pentax KP as well as K-1, can we ascertain more data from having two camera bodies?
Unless your camera is somehow defective in the registration distance or mount department , this isn't a camera issue , its a Lens issue.
03-25-2018, 10:28 PM   #8
Site Supporter
Site Supporter
BruceBanner's Avatar

Join Date: Dec 2015
Location: Blue Mountains, NSW, Australia
Posts: 2,771
Original Poster
QuoteOriginally posted by Ronald Oakes Quote
While in LV with Focus Peaking....I noticed it would get right at the point for FP to "pop" into view......but never quite made it.
I have lots of manual lenses so knew what was going on.
When a inexpensive little Rikenon P 28mm 2.8 was sharper than the SMC-A 24mm at infinity , I started investigating. My suspicions were easily confirmed.
Eric also verified it was coming up short.

---------- Post added 03-25-18 at 22:23 ----------

Unless your camera is somehow defective in the registration distance or mount department , this isn't a camera issue , its a Lens issue.
Maybe it's worth posting off to Pentax Australia for an inspection (I forget the people that handle that stuff for Australia, they're really good IIRC). I really like the lens.

03-25-2018, 10:48 PM   #9
Site Supporter
Site Supporter




Join Date: Jul 2017
Location: Arizona
Posts: 887
QuoteOriginally posted by BruceBanner Quote
Maybe it's worth posting off to Pentax Australia for an inspection (I forget the people that handle that stuff for Australia, they're really good IIRC). I really like the lens.
Try this first. Put your camera in LV with focus peaking......then focus out to about 40-50 feet.....slowly focus to infinity and watch your screen. If you don't see the focus peaking "Pop'' or brighten up right as you are hitting the infinity stop then there is a problem.
Were talking splitting hairs here with the focus ring , and watching closely the pattern in LV with FP.
When I test a lens , I love it when the hard stop engages right after the FP "Pop" effect......that means I'm not going to come up short and will have the utmost sharpness out of whatever lens I'm testing.

I should have also added to open your lens up to 2.8 first ! Also try it at different Apertures to see where you get the maximum effect in LV with FP.

Sorry.....I'm not doing a very good job of trying to explain this

Last edited by Ronald Oakes; 03-25-2018 at 11:24 PM.
03-26-2018, 03:10 AM - 1 Like   #10
pjv
Moderator
Loyal Site Supporter
Loyal Site Supporter
pjv's Avatar

Join Date: Mar 2015
Location: Melbourne, Australia
Photos: Gallery
Posts: 5,716
QuoteOriginally posted by BruceBanner Quote
Maybe it's worth posting off to Pentax Australia for an inspection (I forget the people that handle that stuff for Australia, they're really good IIRC). I really like the lens.
C.R.Kennedy
03-26-2018, 05:49 AM   #11
Resident fiddler
Loyal Site Supporter
LensBeginner's Avatar

Join Date: Sep 2014
Photos: Albums
Posts: 4,488
That also happens with my M 200/4.
I tried to open it but don't have JIS screwdrivers of the required size.
Noticed it with the K-01, hadn't noticed it with the K100Ds, so it really was something minor.
03-26-2018, 06:32 AM   #12
Pentaxian




Join Date: Oct 2009
Location: North
Photos: Gallery
Posts: 4,244
QuoteOriginally posted by BruceBanner Quote
Oh I have a Pentax KP as well as K-1, can we ascertain more data from having two camera bodies?
My M85/2 which I had for years and ok for infinity focus from K7, K5, K30 was somehow way out on the K1.
My K24/2.8 needed a bit of adjustment and after that, I feel that it works rather fine as a landscape 24mm for FF.
I have infinity focus issues on 2 other lenses as well on the K1.
So I sent all of them for adjustment.

So yes, to me using another camera can serve as a guide if the lens is out.

The local service center told me that the camera was in spec.
Personally, I have encountered matching issues between cameras (fine on another K5, issues on my K5, etc)
I am not surprised since the camera and lens have tolerances and the stack up tolerances may be fine between new lens > new camera, but not with old ones.
03-26-2018, 07:01 AM   #13
Veteran Member
Kombivan's Avatar

Join Date: Nov 2017
Photos: Gallery
Posts: 494
I have a 28-200mm sigma bought it new works perfectly on a film camera but on digital it seems short in infinity and its out of focus all through the range on any dslr I have any thoughts?
03-26-2018, 07:55 AM - 1 Like   #14
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 5,243
QuoteOriginally posted by LensBeginner Quote
That also happens with my M 200/4.
I tried to open it but don't have JIS screwdrivers of the required size.
Noticed it with the K-01, hadn't noticed it with the K100Ds, so it really was something minor.
This is either pedantic or useful information, but you don't need screwdrivers to open that lens. The barrel in front of the focus ring unscrews, similar to the K135/2.5. But then you need screwdrivers for the actual adjustment, so it's kind of pedantic, sorry.

The moon or stars are good for testing infinity focus if you have dark enough skies. A comparison to another lens of the same focal length should work. If you have to look closely to pick a winner at 100 feet but one is obviously fuzzy at infinity, that's a problem.
03-26-2018, 08:58 AM   #15
Resident fiddler
Loyal Site Supporter
LensBeginner's Avatar

Join Date: Sep 2014
Photos: Albums
Posts: 4,488
QuoteOriginally posted by Just1MoreDave Quote
This is either pedantic or useful information, but you don't need screwdrivers to open that lens. The barrel in front of the focus ring unscrews, similar to the K135/2.5. But then you need screwdrivers for the actual adjustment, so it's kind of pedantic, sorry.

The moon or stars are good for testing infinity focus if you have dark enough skies. A comparison to another lens of the same focal length should work. If you have to look closely to pick a winner at 100 feet but one is obviously fuzzy at infinity, that's a problem.
Thanks! was following the pics on wiratama, but it was some months ago
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!
24mm, adjustment, af, camera, center, da15mm, focus, infinity, issue, k-mount, kp, lens, lenses, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
FA 43mm infinity focus adjustment Rapfl Pentax SLR Lens Discussion 7 06-01-2017 02:39 PM
Infinity Adjustment for K24mm f2.8 sibyrnes Repairs and Warranty Service 3 04-04-2017 11:34 AM
All lens needs AF fine adjustment, does the camera need a global adjustment? Thanks bennyxyz Troubleshooting and Beginner Help 9 04-21-2016 12:36 PM
Why don't all lenses have infinity exactly on the infinity stop? peterh337 Pentax SLR Lens Discussion 19 01-15-2011 08:53 PM
infinity focus adjustment on M42 lenses Lowell Goudge Pentax SLR Lens Discussion 11 08-20-2009 01:49 PM



All times are GMT -7. The time now is 11:20 AM. | 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