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Forum: Pentax DSLR Discussion
07-05-2015, 09:29 PM
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I do not view that as a positive thing.
ROFL...firmware updates for feature roll-out is lame. It is an indication of time-to-market taking precedence over true development cycle. I will repeat that word...lame...
Steve
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Forum: Pentax DSLR Discussion
07-27-2015, 01:04 AM
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I am glad that this post has shifted slightly to AF concerns with Pentax, as it is the major problematic issue that we have with these bodies. Thanks for your input everyone with regard to it. Being a landscape photographer I do find that it is a huge issue. For obvious reasons, mainly landscape photographers shoot in low light situations (dawn or dusk) for better lighting results and due to poor lighting conditions the Pentax AF system struggles. As pointed out when using manual focus in landscape your can acquire better retults but I find that on the APSC system with such a small viewfinder and LCD it is so hard to get so accurate. The naked eye can't really fine tune that well within small detail. For me at the moment I rely on selecting my AF subject in liveview and shoot. I cannot see a better way to get better results at this stage.
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Forum: Pentax DSLR Discussion
07-26-2015, 05:40 PM
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I am not sure that I am reading your comment above accurately. This is my interpretation:- You use mostly manual focus using a mix of both the viewfinder and focus confirm
- You use focus confirm more often when the light is dim
- You are getting poor results (soft images?) at the aperture settings where the lenses should be at their sharpest
- You were unaware that there is a difference in the AF point sensitivity since it is not mentioned in the published K-3 specs or user manual
- Your results vary according to program line
- The camera will frequently acquire focus when nothing in the frame is in focus
- You did not have these problems when shooting with the K-5, K-30, or K-50.
It is the last three points that are most troubling.
Here are a few bullet points with my comments:- I also own and use mostly manual focus lenses
- I never use AF or focus confirm for critical focus with any of my lenses
- The stock focus screen is not particularly good for manual focus. The focus sensitivity is only about f/4. Likewise the apparent DOF is more than what is really present.
- Due to limitations of the stock screen (see above), I have an aftermarket screen with split-image focus aid
- I almost always get acceptable manual focus
- Focus confirm will often light when the split image is clearly not matched. In those cases, there would be missed focus if I took the camera's advice.
- Focus confirm uses exactly the same sensor as the AF system.
The difference is that it uses the center focus point only. I suggest using the center point with focus confirm since it is cross-point and has f/2.8 sensitivity.
- For general shooting where focus is not critical, I often use my AF lenses and am usually satisfied with the results, even in low light
- I almost always use AF-S, center point only for AF
- Program line should not affect the AF or focus confirm performance directly, though use of wider apertures may make mild missed focus more obvious. Similarly, a longer exposure time might cause blurring due to camera/subject motion.
- Only a gross failure would result in missed focus across the full frame
- Even at narrow apertures (for greater DOF), there is still only one plane of focus. With high magnification (pixel peeping at full resolution) this is more obvious
- With a high resolution sensor and pixel peeping, missed focus is more evident than with a lower resolution sensor. The same is true for softness due to poor quality optics and camera/subject motion.
You are correct that the focus point sensitivity specs are not in the user manual, though they have been published by Ricoh/Pentax in their promotional materials and widely quoted by many reviewers. The diagram below was taken from the review on this site
It is hard to tell what is causing your poor results. The AF performance (focus confirm included) on your K-3 should be better than that of the other three cameras you listed. You might want to try some controlled shots on tripod using focus peaking in magnified live view (SR off). That will at least allow you to eliminate focus and camera motion as the cause.
Steve
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