In Camera Microfocus Adjustments

MFA 300mm

Some higher end cameras have the ability to store microfocus adjustment profiles for particular lenses.  I have never really found the need until recently, but when needed it really makes a difference.  If you've ever felt a lens you own, or have rented, is a bit soft, have a lookNot every camera has this, so consult your owner's manual before you read this, decide you want to use it and then discover your camera does not have this capability and then get angry with me for bringing it up. I recently completed a deep dive test on full frame 28-300 lenses for my Canon bodies.  Canon's 28-300 was the winner, but not by a huge margin and as I mentioned about their 16-300 crop sensor lens, the one to really look at is Tamron's NEW 28-300/3.5-6.3 DI II VR lens.  You cannot beat it for Image Quality / Investment ratio.  It's also about ¼ the weight of Canon's cannon.

In the focus target tests, the Canon was marginally sharper and had better contrast, at most focal lengths, but got soft at 300mm.  Now when I say soft, I don't mean blurry, I mean not razor sharp.  So I embarked on a time consuming series of tests using my focus target and using the focus adjustment function in the 1Dx.

The net of the long story is that focus adjustment made enough difference to make the lens completely viable for critical work at 300mm, whereas I would have normally said, it's good, not great, but as it is the kind of lens you would only use when you were only willing to carry a single lens, probably good enough.

After applying the focus adjustments and saving them in the camera body, that lens performed even better in subsequent testing,  Could I see the difference in fall foliage?  No.  Could I see the difference in a hawk's eye?  Yes.  It was just that much sharper.  Now I probably could have corrected this using software in post production, in fact I know I could because I did using Piccure+.  But it's really nice to know I don't have to go that route every time now, because I have the lens dialled in for that body.

Micro focus adjustments are rarely needed on primes or even high quality traditional range zooms, but these all in ones, particularly older all in ones like the Canon 28-300 may benefit from this subtle tuning.  If you have a lens you believe to be soft, and your camera offers micro adjustment give it a try.