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Forum: Pentax SLR Lens Discussion 01-23-2017, 10:42 AM  
Fa35/2 ca?
Posted By stevebrot
Replies: 21
Views: 1,524
The DOF for acceptable focus depends on both aperture and focus distance. If the point-of-focus at that aperture had been the front of the train, most of the rest of the train would have been in focus as would much of the foreground. Instead the point-of-focus was at least 5 meters in front of the train with the front being outside the range of acceptable focus. This is clear from the photo.

F/5.0 would have been adequate if the point-of-focus was proper, but sadly, it was not. You might want to consider center-point focus* or manual focus using pre-focus technique.


Steve

* Tell the camera where to focus and it will do a better job of doing so. Some find setting the body up for back-button-only focus along with using a set AF point helps for cases like your photo. Pre-focus at the portion of the frame where you want the front of the train and shoot when the train actually gets there.
Forum: Pentax SLR Lens Discussion 01-23-2017, 10:18 AM  
Fa35/2 ca?
Posted By stevebrot
Replies: 21
Views: 1,524
The photo was taken with the sun low and the light was not full spectrum. The red cast is because there was little blue. Part of the red on the wires is simply reflection...at least that is my interpretation.


Steve
Forum: Pentax SLR Lens Discussion 01-23-2017, 10:15 AM  
Fa35/2 ca?
Posted By stevebrot
Replies: 21
Views: 1,524
The camera locked on the best focus available...i.e. something stationary. In this case, it was something several meters in front of the train. That is how AF-A, Auto 11 works. :(


Steve
Forum: Pentax SLR Lens Discussion 01-23-2017, 05:22 AM  
Fa35/2 ca?
Posted By stevebrot
Replies: 21
Views: 1,524
#1 has sharpest focus on the wires at top and nearest track at bottom and is degraded as the wire runs towards the train. Not knowing your technique or AF point used, it is hard to say why. FWIW, I use my copy of the FA 35/2 with no AF fine adjustments on my K-3 (SAFOX XI).


Steve
Forum: Pentax SLR Lens Discussion 01-23-2017, 04:54 AM  
Fa35/2 ca?
Posted By stevebrot
Replies: 21
Views: 1,524
Agreed. My experience has been that the Lightroom correction for LaCA is very effective. Adobe got that feature right.

As for the example images...

I spent some time looking at #1 and while there is slight LaCA, it is exacerbated by overall softness. Whether that is caused by missed focus, air quality, or something in post-processing (noise reduction?) is not clear.

For #2 and #3, the LaCA is obvious, but I would be hard put to place the blame on the primary lens. I would like to see the same scene without the auxiliary optic. Again, Lightroom would probably clean up both with a general increase in contrast/sharpness overall.


Steve
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