I'm using a Pentax A50 1.7 and trying to figure out the best way to get pictures in sharp focus on my K-x.
I'm trying 3 different methods, but I just can't seem to get consistent results. The pic below is an example, but things would likely change if I retried it all again.
To try to standardize things, I'm using a tripod with the shutter delay, so shake should not be an issue. I set ISO to 400 on each so that isn't a factor. My focus is on an object about 5 feet away. Using F4, that should mean that I have about 5.9 inches of depth of field: about 1.7 inches in front and 4.2 behind. The picture is a 100% center group, but it's been resized down. I love using Catch-in-Focus (CIF), and I try to adjust focus very slowly, and there is plenty of focus adjustment available on the A50. In each instance I focused on the "Sharpie."
Left: Using CIF where I focus lens to nearest and then move out until shutter activated.
Center: Using CIF where I focus lens to infinity and them move in until shutter activated.
Right: Using LiveView and magnifying view to 10x to get best view of object.
As you hopefully can see in this set, the first one is the least sharp and, as would be expected considering the method I used, is front focused.
The second is actually the sharpest.
The one using LiveView is in the middle in terms of sharpness, and I seem to have the least success using this method.
When I've done other tests, sometimes the near>far CIF does the best job.
So, my questions:
- I would have thought that I have plenty DOF (there's only an inch between the Sharpie and the York County behind it), so I'm wondering why there is such a difference in sharpness.
- I would have thought that using LiveView and magnifying the view up to its maximum 10x would provide the best results. My eyes aren't that bad...
- Hmmm.... I just thought of something else. I had to microadjust the focus on the camera to get the best pics with my 18-135. (I had to crank it up to +150, but this really is the best setting for the 18-135 which is most often on the camera.) Would that microadjustment affect the CIF function when used with a manual lens?
- Also, why would the image be so much more overexposed using LiveView? I had to use -.7 EV to make it comparable to the pics using CIF. The lighting did not change.
I know that some people have installed a different (split-prism) viewfinder, but I'm not too keen about spending money on that.
Is there something else I should be trying to improve my skills at focusing?
Thanks!
Last edited by mgvh; 10-01-2012 at 11:07 AM.