[TMoneytron]

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?

[Pål Jensen]

It isn't soft. It is just shallow depth of field. Stop the lens down to a smaller aperture!
Nice dog!

[TMoneytron]

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.

[interested_observer]

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....

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Last edited by interested_observer; 08-12-2012 at 06:40 PM.

[TMoneytron]

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.

[interested_observer]

Here is a process to determine the adjustment and then to apply it.

• Fixing Front and Back Focus - Introduction - PentaxForums.com
• PENTAX DSLRs: Front or Back Focusing Problems? Free test (Lens Alignment) charts for Pentax, Nikon, Canon, Sony, Olympus.

[reeftool]

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.