Micro adjusting your DSLR

I've got my 'new' Sony a77ii and a whole bunch of lenses. Now comes the fun part - taking them all out and testing them in the field.

I enjoy testing cameras and lenses - always have. But I'm not really the 'brick wall and colour chart' kind of tester. I'm more of a 'how does it actually perform out in the real world' type of guy.

With one exception - the micro adjustment of lenses. For this sort of testing you kinda have to resort to some charts to be a little more 'exact' in your results. You are, after all, effecting the autofocusing results of said lenses.

Having said that, you don't have to spend hundreds of dollars on the fancy lens calibration charts that you need a degree in origami to be able to fold in exactly the right angle. A simple downloaded focusing chart off of the interwebs will do. Just do a google search and you'll come up with plenty of them.

But before we get underway with all of this AF micro-adjustment palaver, the question needs to be asked - "do I need to micro adjust my lenses?" And that's a very good question. The answer to which may very well be a resounding 'no'!

Are you happy with the results from your lenses? Do they look sharp to you? Do you have any fast (f1.4 - f2.8) lenses where autofocus will be critical? Or are all your lenses zooms, with an f4 - f5.6 range? If you don't have any fast glass, then chances are the aperture ranges you are using won't show up any 'slight' autofocus alignment issues.

But if you aren't happy with the sharpness you are getting out of your lenses, or if some seem sharp while others not so much, then maybe you need to consider in-camera micro-adjustments for certain lenses? That is, of course, if your camera actually supports such a thing. Many don't.

In-camera micro adjustment is a feature in more hi-end enthusiast or professional level DSLR's. You won't find this option on any of your Canon Rebels. And mirrorless cameras don't need to be micro-adjusted, since autofocusing happens directly at the sensor level, whereas DSLR's use separate AF modules. Sometimes these can be ever so slightly out of alignment, necessitating micro-adjustment. In the 'good-old-days', you would have to send you camera and lens(es) in to Canon/Nikon etc to have them calibrated if you thought the autofocus was 'out'. Photographers' talked of their camera either front or back focusing - especially portrait photographers who would lock the AF onto the eye of a model, only to find that the camera had focused ever so slightly in front of, or behind, the point of focus.

I haven't started using my a77ii yet, so I can't say that I'm having any focusing issues whatsoever. But I do have some very nice, fast, prime lenses for it. So I thought it was worth going through the motions, just for giggles. First up, the Minolta 85mm f1.4.

As mentioned earlier, their are lots of different suggestions online as to how to go about micro-adjusting your lenses. I decided to try a couple of different options, to see if they gave me the same results. Firstly, I found a chart where you set the camera up at a 45 degree angle and then focus on the chart laying flat, at a horizontal line with measurements down either side. Access your micro adjustment menu (check your manual since it will be different for each make of camera), and then shoot at a series of steps (I did 0,5,10,15,20,-5,-10-15-20) with your camera locked down on a tripod, 2 sec timer, aperture wide open, all stabilization turned off (since you are on a tripod). Take the images into Photoshop, enlarge to 100%, and check the areas of sharpness. It will soon become very evident as you go through the images whether this particular camera/lens combination is front or back focusing (or not).

It may be tricky to tell from the above re-sized image for the web, but the a77ii with 85mm f1.4 was ever-so-slightly front-focusing. On initial inspection a +10 adjustment looked the sharpest, but then I refined the process by shooting from +5 to +10 and reviewing the results. After inspecting this set closely, I determined that +7 was the sharpest of the lot.

Not totally convinced, I tried a second method. The 'flat-image-on-a-wall' test. This time you shoot some text on a wall with the camera parallel to the words. Same procedure with the camera (tripod, wide-open, self-timer etc). And wudda ya know - same result! It must be true 😀

Again, it might be hard to tell in these low-res images, but trust me - '0' was nowhere near sharp enough, and +7 sharpens things up nicely. Job done.

My a77ii can retain up to 30 lens adjustments - automatically. Meaning once you have adjusted the lens, the camera will remember it again once that particular lens is mounted on the camera. Brilliant. And I don't know about you, but I think even I might struggle to have 30 lenses to worry about?

So yes, it would seem that at least some of my lenses will benefit from micro-adjusting. And it also seems that either process will give you the exact same results.

But don't take my word for it. Download the charts, grab a fast prime, and try it yourself (as long as your camera supports micro adjustments). You may just breath some new life into that 50mm f1.8 that never quite felt sharp enough?