My Brain Is Leaking

Got a minute? I'll waste it for you.

Saturday, August 13, 2011

New Camera was "back-focusing."

I recently upgraded my Sony Alpha-200 camera to an Alpha-580.  And when I say "upgraded" I really mean "replaced because my clumsy ass knocked my old camera onto the concrete."  Of course, everyone knows that when something breaks, it's always a good excuse to upgrade instead of sending the broken one in for service.

Upgrade time!!

After having owned the new one for a while and the feeling of "OMG THIS IS THE BEST THING SINCE THE INVENTION OF SCOTCH!" wore off, I started to notice that my images were a bit soft.  I originally chalked this up to the new camera being of much higher resolution (16MP vs 10MP) and that it may just be out-resolving the lenses I owned.
FALSE.
After downloading a test chart and printing it off (NOT using any company resources such as internet connection or the printer) I set up the camera and snapped a pic of it looking down at a 45 degree angle.


The idea is that you are supposed to focus on the dark line in the middle and the focus should degrade equally in front of and behind the line.  It might be hard to tell on this small picture, but the focus drops off around 10mm in front of the center line, and about 20mm behind the line.  Therefore, the perfect focus is around the 6mm line behind center.  Hence the term "backfocusing."

Of course, photographers don't take pictures of test charts all day (unless you have some sort of sick test-chart obsession),  so what this means in the real world is that whatever you're telling the camera to focus on will be slightly out of focus, and the object just a little further away from that point will be in focus.  For example, if you're trying to shoot some run-of-the-mill midget-porn and you focus on the midget-dong, you're actually going to get a great shot of some midget-balls.  And nobody wants to look at midget balls.

Except maybe this guy.

This phenomenon is caused when the autofocus sensor on a digital SLR camera is not the exact same distance from the back of the lens as the digital imaging sensor.  The camera thinks it's in focus according to the AF-sensor, but the image that gets captured is a little off.  To correct this, one needs to peel the sticker off the bottom of the camera next to the tripod mount, revealing three set-screws.
NOTE:  I can only vouch that this is true for Sony Alpha cameras.  (You Canon-fags and Nikon-bitches are on your own.)
Turning these screws adjusts the distance the AF-sensor is from the lens elements.  Clockwise rotation helps get rid of back-focus, and counter-clockwise will make it worse (or correct front-focus).  There are three screws so that the plane of the AF-sensor is triangulated, so you must turn the screws the same amount.  If not, one side of the frame will be more back-focused than the other.

For my camera, only 1/12th of a revolution of the set-strews was required.  I first turned them 1/6th of a turn (one point on the hex) and that went to far and into front-focus land.  After I backed the screws off 1/12th of a revolution, this was the result:


By looking at the 14mm and 20mm markings on both ends, I can conclude that my camera is now properly focusing.  No more migdet-balls for me.

Wednesday, August 03, 2011

I am now mobile.

*blows dust off of neglected blog*
So, I downloaded this handy Blogger app for my phone.  Now I can make short posts on the go. I just have to work one being more interesting.  I suppose short, boring posts about how I just had a half hour argument about sideburns are better than no posts at all.