Why Micro AF Adjustment is...

Started Apr 29, 2013 | Discussions thread
Zee Char Forum Pro • Posts: 14,798
Re: Why Micro AF Adjustment is...

The Aussie Viking wrote:

In an ideal world, we wouldn't have to micro focus. But as the Megapixels climb towards what the glass can resolve, what was once considered a great lens may now only be considered mediocre while other designs are still stellar.

Whilst everything is manufactured to tolerances, there will be variations, and that's why MFA works for some people and makes a difference. If every Camera and every lens came out at zero, we wouldn't need it. But if your Camera is say at +2, it may well be in spec (within acceptable tolerance) at that. And a Lens at +2 may well be so too. If it was Minus 2 for the lens, then it would be fine. But at +2, we would have a +4 result. Looking at the focussing "Bell curve" it's not that far out. But what is wrong in dialling a lens in to focus at the very peak of the Bell curve? Makes sense to me!

I went ahead and bought the AF software from Reikan, and for me, it has made a difference. I get no endorsement or reward from recommending it, but I have to say it's not just MFA I want to know about. It's pretty much a toolkit on a laptop.

Check the link below, and you'll see a bell graph to better understand what I mean.


I currently have a 50D, 2 x 7D's and a 6D awaiting delivery. On most of the lenses, it wasn't a huge difference, adjustments in the order of 3 or under, which the Bell curve would show you is not a lot. But one lens (18-200 Canon Lens) is out by +9, and it made a BIG difference for that one. My 100-400 was only a +2, but at minimum focussing distance at 400mm wide open, the DOF is 0.14 of an inch @ 6feet. (1.8 Metres and 0.34cm) Micro adjustment at this distance makes a big difference! I have some photo's from my 7D of a blue wren hopping around near my feet from Dubbo Zoo and I have unbelievable feather detail to the point it almost looks like an over-sharpened image at first glance.

The Pro version (which I purchased has other features such as AF consistency, aperture sharpness, dust analysis and multi point focus test.) It cost me just over $100AUD, which is peanuts compared to what I have spent on the "Back end" with colour Calibration and the like.

Apart from being able to see when the sensor actually NEEDS cleaning, I now know where the "sweet spot" is on each of my lens for aperture. Surprisingly enough, I have 2 x 17-55mm Lens, and one is better wide open than the other, and they have different MFA settings depending on which body. (+1 on 7D, +3 on 50D), hence my body observation earlier on tolerances.

I have the software on my laptop, and should I ever have the misfortune of dropping my gear when travelling, when I am back to the Caravan, I can re-calibrate it, and see if it has "shifted" and needs to go for repair. And make an adjustment to compensate and continue to use the lens until I get near a repair centre (few and far between in Australia). I can also see if dust has got in and made the AF inconsistent/sticky.

In a nutshell, people can knock MFA if they wish, but I'll keep my Laptop and targets with me and keep my gear shooting at it's very best it is capable of. And that's the name of the game isn't it?

-- hide signature --

I have been very close to purchasing Focal multiple times. I have read it is fully automated but apparently not with the 5D3. Not sure I want to spend that amount of money for that.

 Zee Char's gear list:Zee Char's gear list
Canon EOS 7D Mark II Canon EOS 5D Mark IV Canon EF 300mm f/4.0L IS USM Canon EF 70-200mm f/2.8L IS II USM Canon Extender EF 1.4x III +4 more
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