Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-12-2012, 06:05 PM   #1
Junior Member




Join Date: Jun 2012
Location: Silver Spring, MD
Posts: 40
40mm Limited 2.8, soft?

Hello all!

I just moved up to a K5, I really couldn't resist. But the 40mm that I also got recently seems a bit soft.

How does one know if it has quality control issues? Here are some samples, taken at 2.8 and with relatively fast shutter speeds:
http://i.imgur.com/R54nQ.jpg
imgur: the simple image sharer (focusing on the text on the speaker)
imgur: the simple image sharer (focusing on the Logitec logo)
http://i.imgur.com/CQhcj.jpg
http://i.imgur.com/sFw5m.jpg
http://i.imgur.com/vUPnl.jpg (focusing on the O in Only)

I got it used of Amazon, so someone could have just been trying to pawn off a lens with quality control issues. Maybe I'm just being crazy though, but I hate to think I'm just learning on a bad lens. What do you all think?

08-12-2012, 06:07 PM - 2 Likes   #2
Pentaxian
Pål Jensen's Avatar

Join Date: Dec 2007
Location: Norway
Photos: Albums
Posts: 3,064
It isn't soft. It is just shallow depth of field. Stop the lens down to a smaller aperture!
Nice dog!
08-12-2012, 06:11 PM   #3
Junior Member




Join Date: Jun 2012
Location: Silver Spring, MD
Posts: 40
Original Poster
Okay, I am just being crazy. Though I have noticed that it has problems finding the AF point in the live view. As in it says it's focused but it's way off.

I wonder what could be the cause of that?

And thank you, he's cute.
08-12-2012, 06:31 PM - 1 Like   #4
Loyal Site Supporter




Join Date: Jun 2009
Location: Tumbleweed, Arizona
Photos: Gallery | Albums
Posts: 5,002
The K5 has a fine focus adjustment that can be applied individually to each of up to an inventory of 20 lenses. Based on the last image, it looks like it may be front focusing a bit, in that the word "Others" is more in focus before you get to "only". Take a look at page 136 in the K5 manual (and you can also find it on line). You can apply a bias of -10 to +10 to each individual lens or just a blanket bias to all the lenses.

Pentax in this way lets you fine tune the AF for each individual lens you have within your kit.

It is caused by a calibration mis-match within the manufacturing process. Each item is calibrated to specific accuracy +/- tolerances. Both the body and lens may be within their specific accuracy, one with a + tolerance and the other the - tolerance. This way you are able to individually tune each individual lens to your body. The higher end camera bodies offer this capability. Same thing happens to C, N, S, and O, along with the third party lens vendors. Sigma will take a body and lens and match them to each other, however you are out your equipment for at least a couple of weeks, plus round trip shipping and their tuning charge.

This way its a DIY operation....




Last edited by interested_observer; 08-12-2012 at 06:40 PM.
08-12-2012, 06:37 PM   #5
Junior Member




Join Date: Jun 2012
Location: Silver Spring, MD
Posts: 40
Original Poster
Under C4 of custom functions correct?

So if something is front focusing then I would apply a negative value? On the one with the laptop mouse the text in front of the mouse is also in focus so I think I agree with you.

Thanks for the help.
08-12-2012, 08:52 PM   #6
Loyal Site Supporter




Join Date: Jun 2009
Location: Tumbleweed, Arizona
Photos: Gallery | Albums
Posts: 5,002
Here is a process to determine the adjustment and then to apply it.

08-12-2012, 11:01 PM   #7
Pentaxian
reeftool's Avatar

Join Date: Dec 2007
Location: Upstate New York
Photos: Gallery | Albums
Posts: 8,012
On the shot of your dog, the lens is razor sharp in the nose area. Look at the hairs. This is exactly what to expect from a fast lens. I don't know what your focus point was but the sharpest area looks pretty centered. Pal Jensen's advice is right on.
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!
40mm, control, image, issues, k-mount, lens, pentax lens, quality, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Very soft DA15 Limited Lens shaolin panda Pentax SLR Lens Discussion 6 07-03-2012 06:41 PM
For Sale - Sold: White K-x and 18-55mm, DA 40mm Limited, DA 70mm Limited Jend Sold Items 6 03-10-2012 06:23 PM
DA* 50-135 or 70mm limited and 40mm limited freewheelin25 Pentax SLR Lens Discussion 22 11-08-2011 03:53 AM
For Sale - Sold: DA 21mm limited, DA 40mm limited, DA* 16-50mm, DA* 50-135mm kphelan Sold Items 13 05-24-2011 02:47 PM



All times are GMT -7. The time now is 04:15 PM. | See also: NikonForums.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