free k7 focus adjustment tool

someone linked to this free fine-focus adjustment tool in another thread ages ago, but i came across it and found it much much more useful than those print out sheets that so many people seem to advocate. i thought i'd share it here since i thought it would be useful to many.

http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html

download the little gif file. open it up. and check your af by spotting interference patterns in live view. full instructions are on the page i've linked to.

it has benefits over those print out tests in that it is easy to focus on a flat computer screen (i could never be sure i have placed the af point accurately on a piece of paper at an angle), and it's clearly visible if you have critical focus from the interference pattern in live-view, so no transferring images backwards and forwards between your computer.

all of my lenses needed some type of fine adjustment, apart from the 15mm da limited. none of them were particularly far off. but i look forward to seeing whether this picks up my accuracy in real-world scenarios.

Thank you so much for this. I was always unsure if my focus adjustments using paper charts was accurate or not. I can't wait to try it tonight. I'll post my results tomorrow.

gillbod said:

someone linked to this free fine-focus adjustment tool in another thread ages ago, but i came across it and found it much much more useful than those print out sheets that so many people seem to advocate. i thought i'd share it here since i thought it would be useful to many.

http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html

download the little gif file. open it up. and check your af by spotting interference patterns in live view. full instructions are on the page i've linked to.

it has benefits over those print out tests in that it is easy to focus on a flat computer screen (i could never be sure i have placed the af point accurately on a piece of paper at an angle), and it's clearly visible if you have critical focus from the interference pattern in live-view, so no transferring images backwards and forwards between your computer.

all of my lenses needed some type of fine adjustment, apart from the 15mm da limited. none of them were particularly far off. but i look forward to seeing whether this picks up my accuracy in real-world scenarios.

Click to expand...

Thanks! I have to say this is the best way I have tried myself so far, to fine tune AF. The Nikon AF chart is good, and the author great. Probably all designers of AF test charts learned from his method something of value. However, its time has come and I IMHO can't recommend it when methods such as this are available. This way is tops because it allows you to focus on the center of your lens (don't get too close) and avoid field curvature problems and other issues when you get close as you must with the Nikon chart.

I have been using another chart (not the Nikon) which is good; and I just used this method and both are in agreement. However this is the most simple, quick, and accurate method for most any lens for AF fine tuning that I have seen.

--
jamesm007,

http://www.flickr.com/photos/jamesm007/

Thanks for sharing this. Looks interesting... just tagging for now.

--
Dave
http://thegreekcat.blogspot.com

Thanks for post it. Looks interesting..

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All I want is a digital back for my trusty K1000 . . .

Thanks for posting!

In the short time that I have had my K-7, I've not fealt that I have got really crisp focus in my shots - there's a certain amount of softness to the shots, whereas I tend to like the base image to be quite sharp.

Of course, that could just be down to the default sharpening or noise reduction settings, and I probably just need to find the right combination of settings for the camera to suit may tastes, but it does make a little doubt creep in sometimes (especially as focus issues do seem to be a hot topic for conversation in this forum). Still experimenting in that respect.

It's good to have a test like this, both to put your mind at rest, and to make fine adjustments if necessary, as well as to possibly identify real rather than imagined faults.

I actually tried this quickly last night - I'll repeat again when i have more time over a longer distance and over a range of focal lengths, but just as a quick proof of concept, it seemed to work, and confirmed that the focus with my Sigma 18-250 OS appeared fine, so that's a relief.

Neither my kit lens or the Sigma has a shallow enough depth of field to use some of the focus diagrams that rely on seeing which parts of the diagram are in focus in relation to the aiming point - a fair amount of the diagram is in focus both in front and behind the point of focus, which rather defeats the object. So, having a focus check that doesn't rely on depth of field was a definite advantage for me.

The most difficult part - with the Sigma lens - was to remember to keep switching both the body and the lens from manual to auto focus when switching in and out of live view! Having the additional focus control switch on the lens adds a little additional hassle to the process, but other than that, very very simple.

thanks for the post!
will try this
--
'when 900 years you reach, look as good you will not'
-- master yoda

http://jordanpaw.zenfolio.com

Thanks for the post. Used the chart to test my lenses. One appeared to be adjusted incorrectly according to chart. I am now in process of verifying new adjustment by taking a lot of pictures.

Thanks

this technique works much better with a calibrated monitor, so do calibrate...

Well, it took me a few days and I did try it with my brand new DA15, however I could not get consistent results with the focusing.

It's not the fault of this chart, I could see the patterns and when focus was sharp easily enough. The problem is that every time I would turn the lens to infinity and snap it back into focus, it would focus a little bit differently (kind of like in a small narrow range, but never exactly in the same spot). Since the lens was a wide angle, the problem would be worse when I set it to the closest focusing end and snap it back into focus the other way.

In the end, I was still not sure if the lens was focusing optimally. Like I said, however, this isn't a problem with the chart, it is just how the focusing system works on my K20. Perhaps I should have tried it with a more standard or telephoto lens, but I didn't have that much space between my setup and the monitor. I'll try again later with a different lens.

Regardless, I think this technique is superior to paper test charts.

As I mentioned above, using this chart corrected one my lenses (DA70), but a few days ago I tried shooting a stack of books with stacked pages facing me to test the AF at F2.4. I was surprised to see that books below which were protruding about 4 inches were more in focus than the top book that I was focusing on. I thought that it might be that AF is selecting the books below instead of what's in the center of the lens. I then stacked all books evenly and started shooting again, changing AF calibration each time and re-focusing using AF and examining sharpness in the LCD. I ended up with the same setting that I had originally before the monitor test. Not sure why, but the monitor AF test didn't work for me as well.
The AF focusing was always set at center-point.

Sergio SF said:

The AF focusing was always set at center-point.

Click to expand...

You mean the AF indicator dot was at the centre point in the viewfinder ? ;-)

Have you checked that the actual focus point coincides with the indicator in the viewfinder? The actual AF point may be offset, due to QC issues, leading to out of focus shots with obliquely shot subjects. Very easy to confuse with BF/FF issues.

Check that your AF points are not offset, by using a high contrast target (e.g. drawn with a felt pen) and noting where focus capture is you focus away from the target in each direction.
--
Mike
http://flickr.com/rc-soar

Mike, thanks, but I did check that sometime ago. It's on target - i.e. on the red square in the middle of the lens.

Sergio SF said:

Mike, thanks, but I did check that sometime ago. It's on target - i.e. on the red square in the middle of the lens.

Click to expand...

The AF sensors are actually much larger than the red squares, even the center one. They are actually roughly the same size as the "circle" etched in the center of the viewfinder.

I didn't know that. So what should one do when focusing on the eye (of a person) and the sensor covers the eye and "skull bones" around it? Where does it focus, in the deeper part (the eye) or protruding facial features?
I mean when using AF.