K7 Sharpness

I've had my K7 for a few months now. I had a K100D Super before that, and recently bought a bargain of an *ist DS to share with my girlfriend.

I shoot with a few lenses particularly:

Sigma 24-70mm f2.8
Pentax A 50mm f1.7
Sigma 100-300mm (maybe f4-6.7) recently replaced by Pentax DA 55-300mm

I am really struggling to get sharp images with the K7. At first I thought it was just me not being used to the new camera, but now I am not so sure... I am convinced that I took sharper photos with the K100D and currently with the *ist DS.

Could there be something wrong with my camera? Or is there something I am doing wrong?

I am really not happy with my camera right now, and to be honest, having used a Nikon over the weekend which produced much better results I am considering switching...

It may be the difference in sensor - the Ds and K100D have a CCD sensor, the K-7 a CMOS. It produces noticeably different results, even with the same lens.

Maybe you could post a couple of examples so others can come up with more (and probably better!) suggestions?

Hi,

I also owned a K100D which I sold to by the Pentax KX, which has and still gets great reviews. However I still feel the K100D produced sharper and better quality images. I thought initially it may have been a poor kit lens but not so sure now. I am a bit disappointed to be honest but will keep trying to get to the bottom of this issue.

Kind Regards Willie

This is one of the reasons I sold my K-7.
I think it was the shutter induced blur studied here

Pete

Are you comparing print against print or pixel against pixel?

I'll try to post two photos taken under the same conditions with same settings etc... But I'll have to take them at the weekend I expect, unless I can find two similar pictures.

But surely the different sensor shouldn't produce worse results? Different yes, but worse?

I do hope it's not the shutter induced blur. That doesn't seem overcome-able.

And I'm comparing images on screen - both on camera screen and on laptop. Not looking at a pixel level. Even at 1:4 you can see the photos just are not sharp.

Shutter blur is around 1/160 so out of my head.

What might be the problem is that the focus is not spot on with the K7 but you can adjust that in the camera.

But that isn't fair because you're comparing pixel for pixel.
You should zoom the photos so that the subjects on the photo are the same size.
The k7 has roughly twice as much pixels so zoom the K7 to 25% (1:4) and the K100D super to 50% (1:2), or print them both.

Also because the K7 has twice the pixels it's twice as demanding on the lens.
Best to judge the sensor would be to use the 50mm at f/5.6, that's probably the sharpest you can get.
Also when you use the K7 make one photo with live view, with that photo you can compare if the focus is spot on or not.

I am comparing them like this. I'm just saying that viewing a photo from the K7 at 1:4 - not even filling my 13" macbook screen, you can tell that the photos are just not sharp, nevermind in comparison to any other photos.

It could be the AF, but I am not convinced. I'll get a focus chart and give a go at calibrating.

Raw. I'm using DNG.

I am perfectly willing to accept that I might be the problem! I don't really care, I just want better photos!

This was with the Tamron 17-50mm at 28mm f3.2 from the in camera jpeg, hand held (but at 1/1600s probably not a factor). And 100% crop. If you want to benchmark. You can probably squeeze more from RAW and by sharpening.
I'd guess you should get similar from your Sigma 24-70mm.

Admittedly it was a bright day and in dull weather like we've had all summer it can be a bit flat.

[IMG]http://i740.photobucket.com/albums/xx49/df8/26e58ff3.jpg[/IMG]
[IMG]http://i740.photobucket.com/albums/xx49/df8/0ce93e6e.jpg[/IMG]

I can see that the images look over exposed to me, my K7 produces sharp images but only when all the settings are right. My old CCD cam was less fussy.Try the 55-300 at F8-F11 at 1/80 with a 160 ISO. I find these settings to give vibrant sharp nice images. I always shoot Raw.

Regards
Chris

Okay, sorry, i thought you were comparing.

No need for that to just simply check.
The Contrast AF of the liveview use that actual image so it's spot on and bypass the phase AF.
So if there is a differnce then the phase AF is most likely not spot on.

Which?

Yours looks spot on though.

You don't need a focus chart. Just shoot at max aperture ( use your 50/1.4 to start with ) at something with detail in reasonable light and at a 45 degree or so angle. Take a few shots and see if what you are aiming at is in focus or not compared to the focus indicator saying it's in focus.

I've had a K10D, a K20D and three K-5s ( one went back ) and most of my lenses needed AF calibration on all cams.

I feel they look as though some detail has been lost because of the exposure setting. That is how I see it.Of course there are so many variables,I have worked out the settings that work for me and my K7.
Regards
Chris