[rawr]

Overall, the image or lens doesn't seem to have big problems, aside from a small degree of motion blur evident throughout.

The edges are OK - I can even read the text on the [cable?] box on the wall.

FWIW, the image EXIF has [amongst literally thousands of other data points] some interesting details:

Distortion Correction : Off
Diffraction Correction : On

Focus Mode : AF-S (Focus-priority)
AF Point Selected : Auto; Single Point
Num AF Points : 33
AF Points In Focus : 3,8,9,25,32

Focal Length In 35mm Format : 15 mm
Subject Distance Range : Distant
Hyperfocal Distance : 0.94 m

Which suggests focus was on the middle of the scene, and a few points along the same plane. Since, according to the camera, the focus point was some distance away, you were lucky to get some of those near edges decently clear.

As an aside, DxO PhotoLab has a particularly good lens module for the Pentax 15-30 on the K-1 ...
When using ultra-wides, using a good RAW developer with good optical corrections and other smarts can make a big difference to the ultra-wide experience.

[scottyb70]

Ok I read the thread, tomorrow I will do test shots on tripod at different f stops.

[fotomarc]

I've never used the 15-30mm, but I would not be satisfied with those results. I don't know if the problem is with the lens itself, but pixel peeping at 100%, nothing really looks crisp to me. I checked some shots I've taken with ultrawides on a K-5 II and they seem significantly sharper. (The pixel pitch of the sensor is about the same as the K-1, so I think they should exhibit similar sharpness at the pixel level.)

Here are some thoughts on possible explanations:

1) Autofocus failed to get a lock and left the lens at the minimum focus distance.

I used exiftool to look at the DNG file, and the data shown included:

AF Predictor : -1021
AF Defocus : 7

I didn't find any documentation for the AF Predictor value, but the value seems kind of large to me (even though I don't know anything about it ), so I'm wondering if this was an autofocus issue. If autofocus isn't working correctly, it could indicate a problem with the lens, but I think you'd need to do some more testing to get a better sense of what the problem is. You could use a tripod and compare the results from phase-detect AF through the viewfinder and contrast-detect AF using Live View.

2) Shutter shock and/or mirror slap vibrations

I had noticed that the shutter speed was 1/125th, which is in the range where shutter shock has been reported to occur with the K-1 (and probably other cameras as well). You could try shooting with different shutter speeds to see if it makes a notable difference in your results. Try speeds of 1/250th and up to see if that helps. Results could be different with hand-holding vs. on a tripod. You can also try mirror lock-up and compare that with the electronic first-curtain shutter option for Live View (or shoot a Pixel Shift image, which uses the fully electronic shutter).

The shutter shock issue is lens-dependent. I don't know if people have reported issues when using the 15-30mm, but I suppose any lens could be significantly affected if there was something loose inside.

--

Later update: As I looked through more of my K-5 II photos with ultrawides, I found more that weren't as crisp as the first ones I looked at. I do think you should be able to achieve somewhat better results with the 15-30mm lens, though.

[rawr]

Another suggestion: when evaluating blur or softness issues, whether they are suspected to be lens or camera related, it's handy to shoot some test shots using direct flash.

Not only will the flash duration of 1/8000/sec (or even faster sometimes) likely freeze away any motion blur, but you''ll also be sure of putting some good, controlled light on the test scene.

Flash won't help much for vast landscape shots, of course, but for smaller test scenes or test targets it will.

[fotomarc]

That's a good suggestion about using flash for testing.

An update to my comments above -- I had been looking at the image using an unfamiliar viewer, which may not have applied any sharpening to the RAW image. I imported it into Lightroom and with its default sharpening, it looks a bit better, but still not crisp. Areas that seem noticeably soft to me include the garage roof and the tree trunk along the house on the right. Maybe the AF was okay and shutter shock or other camera movement blurred things. If you're shooting hand-held, also try turning on Shake Reduction.

[awscreo]

Doesn't look bad as a straight DNG. I think your lens is fine. As suggested by others, I'd add a tripod into the mix. Also, you should be using back button focusing, that makes a difference. And try using this the hyperfocal distance method. You'll be surprised and just how sharp your lens really is. I've found that most of the time, if my lens isn't producing images as sharp as I'd like, it's almost always an operator error issue. Adding a tripod, back button focus and using hyperfocal distance, reduces the amount of operator error significantly.

Excellent video showing how to use hyperfocal distance My SHARP FOCUS Technique - Back Button Focus & Hyperfocal || The Landscape Photography Journals E6 - YouTube

Nice video. Thanks for sharing! One thing I've noticed - when the guy zoomed in to 100% and pressed af screen did not go back to full view of the scene but stayed at 100%. Is that possible with k-1? I've noticed before, it's kind of annoying that k-1goes back to full scene and I need to zoom back to see if af nailed the focus..

[david94903]

Nice video. Thanks for sharing! One thing I've noticed - when the guy zoomed in to 100% and pressed af screen did not go back to full view of the scene but stayed at 100%. Is that possible with k-1? I've noticed before, it's kind of annoying that k-1goes back to full scene and I need to zoom back to see if af nailed the focus..

Yes. In LV, once I've zoomed in and full focused manually (autofocus will put LV back to full mode), I trigger the shutter with a remote release. I typically don't bother to zoom back out unless I'm planning on modifying the composition. This is the same with my K-3 too. However, with both cameras, if LV is left unattended for more than ten seconds or so, it will revert back to the original view. There may be a menu setting to adjust this time, or keep LV fully zoomed but I've never bothered to look for it.

[DimC]

Nice video. Thanks for sharing! One thing I've noticed - when the guy zoomed in to 100% and pressed af screen did not go back to full view of the scene but stayed at 100%. Is that possible with k-1? I've noticed before, it's kind of annoying that k-1goes back to full scene and I need to zoom back to see if af nailed the focus..

Was looking at that option too but couldn’t find it, therefore I’m doing manual focusing quiet often when in live view and 100% magnification.

[scottyb70]

Ok I went out and took some more pics from F 2.8 to F 16 @ 18mm auto focus set to spot, Live View, tripod on concrete, used remote control. The camera was level. When I tried all autofocus points the camera focused on the corner of the house , the big bush at the corner and the arborvitaes on the left.

Here are the pictures

Dropbox - IMGP0876.DNG f 2.8
Dropbox - IMGP0877.DNG f 4.0
Dropbox - IMGP0878.DNG f5.6
Dropbox - IMGP0879.DNG f 8.0
Dropbox - IMGP0880.DNG f 11
Dropbox - IMGP0881.DNG f 16

[scottyb70]

Here is a full shot of them side to side except for f4

[Sandy Hancock]

I only looked at f/2.8 and f/8.0, but they look pretty good to me.
Stop taking test shots and find some pretty landscapes

[fotomarc]

Yeah, these ones look nicely sharp. Clearly the optics are capable of sharp results in the way you used the lens here, so if your other results are consistently not satisfying to you, then you'd want to try to identify what factor(s) are responsible.

By the way, since you were using Live View, was the electronic shutter option enabled? (If it's enabled, the letters "ES" show up at the top of the Live View screen just right of center, with the standard information display.)

[david94903]

Great set of test shots. Good way to learn the lens. I think the image quality looks fine. I'd say your sweet spot is probably F11.

[bxf]

Our ability to view images at 100%, from a distance of about 30cm, has the unpleasant side effect of making many fine lenses appear inadequate...