Grrrr - e520 Front Focus

Started Oct 15, 2009 | Discussions thread
The Big One
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Re: Grrrr - e520 Front Focus
In reply to The Big One, Oct 16, 2009

Well, I would like to put a huge 'Thank You!' out to HappyFamilyMan. Sure enough, this approach works, and I now have perfect focus on my 14-54 @ 54mm. I have detailed some of what I did, in case someone else wants to try this.

(First, a disclaimer - I took a risk doing this. You may not be as lucky. Don't blame me, or anyone else, if you destroy your camera, burn your cat, or anything in between.)

Absolute first thing I did was to take a 'before' shot as a benchmark. You can see a 100% crop below:

As you can see, it is front focusing by about 12mm give or take. I then took another shot on my E-300, to verify that it was the camera, and not the lens. This shot was 100% perfect focus.

Next I got familiar with the camera's innards. First, I put the camera in cleaning mode, to see how things worked inside. As you can see, there are two knobs exactly as described in the D70 AF article. The lower one is the AF one:

Now I don't know how Oly handles these things, but they are not allen keys, or anything else with something which can be turned via tools. They are completely smooth, both inside and out. My guess is that they have a friction-fit rubber or plastic device which they use for the adjustments. However, like HappyFamilyMan did, I ended up using needle nose pliers, and it worked fine. (I did make a couple of scratches on the knob itself, but that actually helped me to see how far it was being turned; the satin black finish on it previously was impossible for me to see how far it had turned, if indeed it had turned at all).

One thing to note: at first I used cleaning mode, as I didn't want to touch the mirror assembly at all. However, after a couple of iterations, I found that it was better IMHO to use some masking tape (not very sticky) to tape the mirror into the 'up' position. The reason for this is that, in cleaning mode the actual sensor is exposed; when you just tape the mirror up, the shutter stays closed and protects the sensor.

It took a number of iterations to get it working as I wanted. First, I had to actually see if twisting the knob did anything. Sure enough, it did. Then I needed to see how much (and which way) to move. On my copy, twisting the knob counter-clockwise resulted in moving the focus point back (away from the camera). Clockwise resulted in moving forward. (I don't know if this will be consistent for all cameras, though, as the knobs are basically a cam which wider and narrower parts). However, in my case, making the knob thicker resulted in moving focus back.

If you do this, you should also be aware that this thing is sensitive . Moving it maybe 10 degrees resulted in about 1cm of focus point travel. The first few iterations resulted in me overshooting back and forth, before I got the hang of it.

Finally, I arrived at what I considered correct. You can see a 100% crop below:

As you can see, this is just about perfect.

Some things to note about this method vs. Olympus's adjustments and (more elegantly) the E-30 focus adjustments:

-This method treats all lenses the same. You cannot make adjustments on just one lens. (I know you can do this on the E-30; presumably you can do this if you send the camera in to Olympus for adjustment, although I have no idea how they do that. Perhaps they only use software for adjustments, and the knob I am changing is just for rough adjustments?)

-This seems to be at least partially focal-length dependent. My 40-150 MKII lens is now perfectly focusing at 150mm, but is front focusing quite a bit at 40mm. This is not a huge deal for me, since the main place I require critical focus is in portraiture, and that is pretty much just done with the 14-54@35-54mm, so I adjusted for that particular lens / focal length.

Hopefully this helps someone who is otherwise unable to get their camera fixed! If nothing else, I found out for myself how SLR AF works, and more about the mirrors and shutter than I knew before.

Cheers
--
--Wyatt
http://photos.digitalcave.ca

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