Pentax K5 and 35mm SMC-DA F/2.4 AL - focusing problems

Exhale · 02-02-2017, 07:08 AM

First of all, i want to say hello to everybody, i just entered the Pentax world and i can't see forward to learn everything about this system.. i'm italian and i hope you'll excuse me if i don't write correctly.

I got myself a used K5 last week, i used only mirrorless before (Fuji XT1 and Samsung NX1), and i wanted to have a new "serious toy" to play with..

In this days i'm shooting with the "plastic fantastic", but i have some troubles focusing properly.

First of all, I made some tests and the lens doesn't seem to have front or back focus problems: Imgur: The most awesome images on the Internet and Imgur: The most awesome images on the Internet

Now, if i shoot in a 1 to 2 meters range from the subject the lens won't miss any focus, but if i try to shoot subjects 3-6 meters far from me, here comes the issues.

IE, look at this two photos (iso 1600, f2.8, 4 meters from the subjects)

Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet

On the first photo the focus spot was on the face of the boy with the red sweater, on the second the spot was on the girl with the dark blue sweater.
Both times the camera seemed to lock properly the focus on the faces, but as you can see the focus went on the thins behind them.
Those are two examples, but it happens every time i shoot on a subject that has some objects or coloured wall just behind.

So, am i doing something wrong or is that a bad copy of the lens?

bm75 · 02-02-2017, 08:00 AM

Welcome to the Forum! Matteo

---------- Post added 02-02-17 at 04:22 PM ----------

AF troubles are really common in many threads. Try center point selection and the old AF-lock and recompose tecnique. It will do the job. I always use the single center point with my k5 and find it adequate. My k5 (or my tecnique...) exactly lacks in portrait, especially missing focus on the eyes in ambiented portraits (when the figure of the person occupies minus of 1/3 of the entire frame) . In that case my k5 backfocuses. I know it so I try to compensate with MF for that. I also got a oME53 eyecup that magnifies the viewfinder thus helping me with MF.
Read the manual for best camera settings.

Best regards.

Matteo

aaacb · 02-02-2017, 09:42 AM

Aside from af inaccuracies, it could be that your subject moved a bit or that the total af area included some of the background, in the second example in particular, the background is pretty high contrast (af points are actually not exactly points...). Also I've heard the k5 isn't too accurate in certain artificial light.

About af fine tune: On some/most (all?) lenses af is not equally accurate for all distances. So if you fine tune af (or leave defaults), you may experience what you describe... you fine tune for one distance but compromise a bit of sharpness for other distances.
I have that lens and had the same experience. My lens is not very consistent, I'd say one in three is slightly off but only when viewed 100%. When fine tuning af, defocus and refocus multiple times to check your pdaf settings vs contrast detect on the chart, so the camera actually refocuses for each test shot, it will give you an idea of what's the distribution.

Exhale · 02-02-2017, 09:53 AM

I tried to fine tune, and in artificial light seems to work correcting +9 if shooting from a certain distance.. said that, i find pretty much frustrating not knowing if a picture will turn out focused or not.. i bought the lens from amazon and i'm thinking to return it and try with the 50 f 1.8

vector · 02-02-2017, 10:16 AM

I had a similar problem with a DA35 on a K5 - actually 2 of them. Bought the lens and no amount of fine tuning ever got it to focus reliably on either of the K5's we owned. It wasn't just front or back focusing - it was all over the place. Unfortunately I didn't test and return it in time so it ended up unused, in a drawer. Later I got a K3 and decided to try it out - worked perfectly on the K3 with minimal fine tuning.

As my wife still shoots her K5 I decided to try our luck on another DA35 and it works just fine on both our K5's. So there is definitely something to be said for finding testing your lens and making sure you get one that works well on your camera. I would suggest that you exchange the DA35 if you still can and try another copy.

Exhale · 02-02-2017, 10:26 AM

Thanx vector, i think i'll return the lens and try another copy. I just tried to focus and shoot the things that the 35 just couldn't reach with the standard 18-55. It worked perfectly.

Too bad the kit lens is terrible until you stop down to f6.0 at least

**TER-OR** · 02-02-2017, 10:56 AM

I have this a little bit with the FA100 f2.8. Close subjects are tack-sharp. Distant, not quite so much. I'm not doing anything right now. I see this with the 55-300, but am not sure whether it's the lens or the camera or the fact that farther subjects can have some atmospheric effects. Nothing seems OOF, just not crisply detailed.

You may want to do the standard tripod and distance tests, just to define the issue.

02-02-2017, 07:08 AM	#1
Exhale New Member Join Date: Feb 2017 Posts: 18	Pentax K5 and 35mm SMC-DA F/2.4 AL - focusing problems First of all, i want to say hello to everybody, i just entered the Pentax world and i can't see forward to learn everything about this system.. i'm italian and i hope you'll excuse me if i don't write correctly. I got myself a used K5 last week, i used only mirrorless before (Fuji XT1 and Samsung NX1), and i wanted to have a new "serious toy" to play with.. In this days i'm shooting with the "plastic fantastic", but i have some troubles focusing properly. First of all, I made some tests and the lens doesn't seem to have front or back focus problems: Imgur: The most awesome images on the Internet and Imgur: The most awesome images on the Internet Now, if i shoot in a 1 to 2 meters range from the subject the lens won't miss any focus, but if i try to shoot subjects 3-6 meters far from me, here comes the issues. IE, look at this two photos (iso 1600, f2.8, 4 meters from the subjects) Imgur: The most awesome images on the Internet Imgur: The most awesome images on the Internet On the first photo the focus spot was on the face of the boy with the red sweater, on the second the spot was on the girl with the dark blue sweater. Both times the camera seemed to lock properly the focus on the faces, but as you can see the focus went on the thins behind them. Those are two examples, but it happens every time i shoot on a subject that has some objects or coloured wall just behind. So, am i doing something wrong or is that a bad copy of the lens?

02-02-2017, 08:00 AM	#2
bm75 Veteran Member Join Date: Aug 2014 Location: Italia Photos: Albums Posts: 354	Welcome to the Forum! Matteo ---------- Post added 02-02-17 at 04:22 PM ---------- AF troubles are really common in many threads. Try center point selection and the old AF-lock and recompose tecnique. It will do the job. I always use the single center point with my k5 and find it adequate. My k5 (or my tecnique...) exactly lacks in portrait, especially missing focus on the eyes in ambiented portraits (when the figure of the person occupies minus of 1/3 of the entire frame) . In that case my k5 backfocuses. I know it so I try to compensate with MF for that. I also got a oME53 eyecup that magnifies the viewfinder thus helping me with MF. Read the manual for best camera settings. Best regards. Matteo Last edited by bm75; 02-02-2017 at 08:08 AM.

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02-02-2017, 09:42 AM	#3
aaacb Pentaxian Join Date: May 2016 Photos: Gallery Posts: 3,724	Aside from af inaccuracies, it could be that your subject moved a bit or that the total af area included some of the background, in the second example in particular, the background is pretty high contrast (af points are actually not exactly points...). Also I've heard the k5 isn't too accurate in certain artificial light. About af fine tune: On some/most (all?) lenses af is not equally accurate for all distances. So if you fine tune af (or leave defaults), you may experience what you describe... you fine tune for one distance but compromise a bit of sharpness for other distances. I have that lens and had the same experience. My lens is not very consistent, I'd say one in three is slightly off but only when viewed 100%. When fine tuning af, defocus and refocus multiple times to check your pdaf settings vs contrast detect on the chart, so the camera actually refocuses for each test shot, it will give you an idea of what's the distribution.

02-02-2017, 09:53 AM	#4
Exhale New Member Join Date: Feb 2017 Posts: 18 Original Poster	I tried to fine tune, and in artificial light seems to work correcting +9 if shooting from a certain distance.. said that, i find pretty much frustrating not knowing if a picture will turn out focused or not.. i bought the lens from amazon and i'm thinking to return it and try with the 50 f 1.8

02-02-2017, 10:16 AM	#5
vector Pentaxian Join Date: May 2015 Location: Alberta Posts: 713	I had a similar problem with a DA35 on a K5 - actually 2 of them. Bought the lens and no amount of fine tuning ever got it to focus reliably on either of the K5's we owned. It wasn't just front or back focusing - it was all over the place. Unfortunately I didn't test and return it in time so it ended up unused, in a drawer. Later I got a K3 and decided to try it out - worked perfectly on the K3 with minimal fine tuning. As my wife still shoots her K5 I decided to try our luck on another DA35 and it works just fine on both our K5's. So there is definitely something to be said for finding testing your lens and making sure you get one that works well on your camera. I would suggest that you exchange the DA35 if you still can and try another copy.

02-02-2017, 10:26 AM	#6
Exhale New Member Join Date: Feb 2017 Posts: 18 Original Poster	Thanx vector, i think i'll return the lens and try another copy. I just tried to focus and shoot the things that the 35 just couldn't reach with the standard 18-55. It worked perfectly. Too bad the kit lens is terrible until you stop down to f6.0 at least

02-02-2017, 10:56 AM	#7
TER-OR Site Supporter Join Date: Apr 2009 Location: Dundee, IL Photos: Gallery \| Albums Posts: 6,699	I have this a little bit with the FA100 f2.8. Close subjects are tack-sharp. Distant, not quite so much. I'm not doing anything right now. I see this with the 55-300, but am not sure whether it's the lens or the camera or the fact that farther subjects can have some atmospheric effects. Nothing seems OOF, just not crisply detailed. You may want to do the standard tripod and distance tests, just to define the issue.