Focus adjustment question

<p>The thread on the enlargements on the LCD got me wondering about something. What is the best way to optimise the focus adjustments? On an oblique image/ruler or aimed square on on a focus chart/brick wall/something else with lots of fine detail? The oblique view will obviously do the best job of measuring and detecting back/front focus, but does it allow the best adjustment of the lens to compensate for it. A specific worry of mine would be a slight misalignment of the focus sensor used.</p>

 

<p>I tried the oblique image/ruler business and despite all the write-ups of this I found it very difficult to determine optimum focus with this technique. I just wasn't convinced that the camera was focusing on exactly the same spot each time. I had better results setting up my camera on a tripod, setting the autofocus point to center (so that I know it's trying to focus in the center of the image, where I was going to evaluate the photos), and shooting the side of a wood cabin at various focus adjustment settings. I evaluated the photos in-camera (I love how you can do that on the K-7) and picked the best one.</p>

<p>Henk,<br>

Over the past two years I've found <a href="http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html">this</a> approach with the on-screen focus chart to be the easiest and most effect AF tweaking tool. What I especially like is that you can do this indoors anytime.</p>

<p>Keith Cooper's article is from a Canon perspective somewhat, but applies well to Pentax.</p>

<p>ME</p>

<p>Michael,<br>

Thanks for the link. I've tried it and found that the lens which I suspected of backfocusing seems to be pretty much spot on. FWIW, I haven't found the need to adjust focus on any of my lenses.<br>

I'll still try some more conventional testing with something from the real world like a focus chart or a brick wall.</p>