K-x image sharpness/softness issue

[suguti]

Hi there!

I aplogise in advance if there have been hundreds of topics on this and I realise that it's too early for me to make any conclusions on the camera without giving myself time and practice to really get to know it.

So, unwrapped my brand-new K-x today, jumped gleefully to take the first test pictures with it and the results were... midly terrifying. The issue being an uncanny softness and glow around the around the edges -- every picture looked as if I had turned the 'soft' filter on (which I hadn't). Also, in some of the pictures I wasn't really able to detect anything in-focus (I did not use a tripod but the shutter speeds were quick enough to rule out any shaking issues. The 11-point AF in its unpredictability might be to blame, I guess).

Some examples (all of these pictures were taken in broad daylight; in JPEG; SR on; no post-production other than resizing in PS):

1) kit lens @ 55mm, f5.6, 1/1000 sec:





2) kit lens @ 55mm, f5.6, 1/400 sec:





3) kit lens @ 55mm, f5.6, 1/1000 sec:






This one (kit lens @ 55mm, f5.6, 1/1000 sec) was taken in shade so the bright sunlight isn't to blame but the glow is still there (and nothing seems to be in focus):


(full resolution)


I have my own theories concerning this but I'd appreciate yours.

[racort]

Hi Suguti: Welcome to the forum

I don't know that I can be of help on your problem, but let me offer you a suggestion. I noticed that all those photos were shot at f~5.6. It appears you have plenty of sun and light where you are, Try shooting in av mode and try stopping down your aperture to at least f~8 and better yet f~16. Maybe that will help. Also make sure if your using the autofocus that it is set on af-s mode when you are shooting static images.
There is always the possability you have gotten a defective lens or camera also, but I haven't really heard of anything like that that on the various Pentax sites etc. as being an issue.
A few people on this this site have the KX, and from what I have seen, it is capable of shooting very sharp images.
If those suggestions don't solve your issues, then I would try a different lens.
Hope that helps.

[Mike Pearson]

suguti,

Welcome to the forum  sorry to see your dilema 

I really can't add much to what has been suggested and I am not very familiar with the Kx.

It does appear though from the examples that the autofocus is not working correctly.

Maybe, remove and remount the lens - reset all menu items to default - check that you have the latest firmware v 1.01 - ensure that the autofocus is set to af-s mode.

Hope you can resolve this easily.

Mike

[spyglass]

This is a situation where a series of test shots can hopefully outline and define any issues. As far as Pentax's Auto Focus system    I believe that any automated focusing system (from any manufacturer) tends to seek an average solution. I believe that in time and through use an operator will come to predict the likely "focus" conclusion. For any creative, close up, or portrait work, I find that when requiring a precise or critical focus point, you really have to do it manually. With the Focus system you have 4 choices : Average, Center Weight, Spot, and Selectable (which is just Spot, but you choose which of the AF point will be your Spot). It would be nice to know what Focus system option was used for each shot.

When I look at your examples I assume that you maintained the focal length & aperture for testing consistency. While I do applaud the kit lens and feel that it may possibly be the best kit lens of any manufacturer, I personally do not feel that it sings its sweetest tune at f5.6


#1 What focus option did you choose. I do not really see anything in focus.

#2 This photo reminds me of the Cokin creative filter that was basically a clear lens and a tube of vasoline. I get the impression that the flower is reasonably sharp, but there is an overall softness across the image (could be light wash - where light was reflected onto the front filter of element of your lens)

#3 & #4 because the purple flower makes up such a small portion of the overall image you would have select which AF point you required, or set your camera to lock focus with exposure, use spot focus, aim directly at the flower to determine focus and exposure, then while keeping the shutter button half depressed compose your shot and fire.

In regards to the "glow" you are referring to, are you talking about the bokeh (out of focus area shaping / blending). Bokeh will always play a strong hand in an image if the out of focus region contains highlights.

I would recommend setting up a test where you have similar objects in a long row (say 1m apart).  Use pop cans (something with writing on it). Make sure that the row of cans is not in a straight line heading away from you but angled off about 15 deg off center so you can see each can and they create the illusion that they are sitting side by side. Set you camera on a tripod (turn anti shake off as recommended with tripod use) and use the center spot and see if you can take a picture of each can.

Hopefully your camera is 100% and you will have better results after a short acquaintance period.

Spyglass

[calsan]

I think you are too close to the subject.
I use the kit lens every day and it definitely isn't a macro lens...

At 55mm and 25cm away, not much will be in focus.  This is just a fact of life: the focal plane will be too small.
Try taking them from about 40-50cm away - much more will be in focus.

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Also, set the focus point to Centre:  This way you learn to confirm focus on your subject, then frame the shot.  The only time I ever use multiple focus points is when using a telephoto lens and doing bird in flight shots.