Pentax k-x AF Problems


Lowela

Link Posted 18/02/2011 - 16:23
Hello guys! I have been using my Pentax K-x for almost 9 months now and I just realized I usually get soft pictures with the AF on and it's difficult to get sharp photos with MF as well... Is this a usual problem with k-x? or are there settings which I can do to avoid this problem? Reviews usually say that k-x have good picture quality...

robbie_d

Link Posted 18/02/2011 - 16:55
Hi.

It might be best if you can post a couple of examples in order to illustrate the problem you're having.

Off the top of my head it could be:

Camera selecting a different focus point to the one you're intending. More possible with the K-x (and K-m) due to the lack of AF illumination points. You're best off setting the camera to use the centre point and using the "focus and recompose" technique.

When using MF, are you ensuring the focus indicator (little green hexagon in the viewfinder) is lit up before taking your picture?

Is Shake Reduction turned off?

Is ISO set to auto? If ISO isn't set to auto but to a value like 100 and you're shooting aperture priority, the camera may not be able to use a shutter speed that's fast enough to ensure a sharp photo.

Are you using shutter priority (or manual) mode and selecting a shutter speed that's too long for a sharp handheld shot. The rule of thumb is 1/(focal length x 1.5), although with sensor based SR you can get away with shutter speeds a couple of stops longer.

Are you doing a lot of shooting in low light? AF has a harder time in lower light.

There could be a number of other reasons but the list above will give you a few areas to start looking at.
If you can't say something nice about Pentax, you won't say anything at all.

Apparently.

Smeggypants

Link Posted 18/02/2011 - 22:12
Have you calibrated the AF to your lenses.

I bought a second hand K10D with Sigma 17-70 attached as a second body last year, Pictures were way OOF until I calibrated the camera's AF. I suspect that's why the previous owner sold the kit and perhaps wasn't aware about the necessaity makign sure the AF is calibrated.

The K10D can onykl be calibrated via a hidden paramter in debug mode. Im' not sure about the K-x ? isn't it a newer model?
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

Blythman

Link Posted 18/02/2011 - 22:23
I believe it can be calibrated too via debug mode. Not for individual lenses though
Alan


PPG
Flickr

Smeggypants

Link Posted 19/02/2011 - 02:13
Blythman wrote:
I believe it can be calibrated too via debug mode. Not for individual lenses though

Same for the K10D

I found that my Sigma lenses required around 210um and the 10-17 fish eye needed about 130um. I left my K10D in d3ebug mode and simply changed setting when I changed lenses. Not a big deal really
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

Lowela

Link Posted 20/02/2011 - 10:47
robbie_d wrote:
Hi.

It might be best if you can post a couple of examples in order to illustrate the problem you're having.


Hi! Thank you for your post. Where can I post my photos in this forum? forgive me, most of the times I just check the gallery and recent forums.... Usually, I try to do some PP tweaking with the contrast and saturation to make my photos better... But I envy those who take sharp pictures without the added effort...

robbie_d wrote:

When using MF, are you ensuring the focus indicator (little green hexagon in the viewfinder) is lit up before taking your picture?

Is Shake Reduction turned off?

Yes I always wait until I see a green light before clicking and I always have the SR on. Sometimes as well, photos look so sharp in the camera but when I check them in a big monitor they're not as good...

Lowela

Link Posted 20/02/2011 - 10:51
Blythman wrote:
I believe it can be calibrated too via debug mode. Not for individual lenses though

How can I do that? I only have the 18-55 mm lens that came with it and the 70-300 mm Tamron Telephoto/Macro lens in my collection... I still want to practice though before I'll try the expensive ones...

i-Berg

Link Posted 20/02/2011 - 11:08
Lowela,

Post images in the 'Your Photos' section of the PU Site. Start a new thread just as you have here. Read the instructions in the first 2 posts in the 'Your Photos' forum.

There is a difference in how you post an image to the forum, as opposed to how you do that into the Gallery. You will need to upload that image to somewhere like for eg Photobucket or Flickr first, then link your image to the post on the Your Photos forum from there.

Have a go at that, and if you need assistance, ask here.
http://www.pbase.com/iberg
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