I have fixed my front focus problem - how to

Started Sep 10, 2006 | Discussions thread
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Wagga Contributing Member • Posts: 622
I have fixed my front focus problem - how to

I have been disappointed with some of the results I got with my Pentax FA 50mm 1.4 when used at maximum aperture ("I focussed on the eyes but I got the nose instead" sort of complaint..).

I did the focussing test last night and it confirmed that I have a front focussing problem.

There were a few threads on this subject lately and decided to have a go at adjusting the focus on the camera.

The test chart can be downloaded at http://focustestchart.com/chart.html

Here are the results before I made the adjustments:

and after I made the adjustments:

Now, for those of you who are adventurous, this is how to do it:

1. Remove the 8 screws on the underside of the camera. (Don't mix them up, as there are 2 different threads: 4 identical threads around the battery compartment - they are attached to plastic and 4 identical threads on the other side - they are attached to metal).

2. Remove the sole and you will see 3 adjustable Allen screws (Allen = hexagonal head):

http://forums.dpreview.com/forums/read.asp?forum=1036&message=15793746

http://www.penta-club.ru/forum/index.php?act=Attach&type=post&id=4849

Take an Allen key (I think it's 1.5mm) key and turn the screws COUNTERCLOCKWISE to correct FRONT FOCUS, CLOCKWISE to correct BACK FOCUS. Turn each screw by the same amount.

As I had a front focus problem, I turned the three screws counterclockwise. The 12 o'clock position became 10 o'clock after the first round of adjustments.

3. Put everything back together and make a focussing test.

4. I had a second round of adjustments as the correction I applied was insufficient and the 3 screws are now at 8 o'clock.

That's all. It was simple, far less stressing than my first attempt at cleaning the sensor and focussing is spot on. The whole operation didn't take one hour.

I hope I haven't created a problem for later, but I can always return the screws to their original position.

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Wagga [Jean]

[UTC/GMT + 2 hours]

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