DotTune: New AF tune technique, no photos required

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bemyzeke
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p.2 #1 · DotTune: New AF tune technique, no photos required

binary visions wrote:

That is, allow the camera to autofocus, then switch the camera to manual, enter live view, and see what focus adjustment is needed to achieve critical focus. Change the values, allow the camera to autofocus, check live view... etc.

+1. I have done this with good results. It is also made easy with the on-body AF/M switch on Nikon.

Nothing against the technique that OP suggested, but looks like it will need too many tries to get it right.

Feb 14, 2013 at 02:49 AM

Steve Perry
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p.2 #2 · DotTune: New AF tune technique, no photos required

Next time I'm fine tuning, I'm going to give it a go. Thanks!

Feb 14, 2013 at 03:28 AM

afairley
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p.2 #3 · DotTune: New AF tune technique, no photos required

While the green dot has too much "play" to make it useful for critical focusing in my experience, you should be able to use the transition point from arrow to dot (provided you always focus in the same direction) to get tighter results, and you should be able to AF Tune for that.

I have used the OP's method, BTW, and it agreed with what I got using LenAlign and FocusTune.

Feb 14, 2013 at 09:23 PM

snapsy
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p.2 #4 · DotTune: New AF tune technique, no photos required

I've published a DotTune tutorial on YouTube. Video Link

Feb 18, 2013 at 08:00 PM

liamtoh1
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p.2 #5 · DotTune: New AF tune technique, no photos required

Thanks for the video. Very helpful in understanding your DotTune technique.

Feb 19, 2013 at 12:17 AM

Jan Brittenson
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p.2 #6 · DotTune: New AF tune technique, no photos required

Nice!

I wonder if the dot is available over USB... if so, this could be automated...

Feb 20, 2013 at 01:38 AM

snapsy
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p.2 #7 · DotTune: New AF tune technique, no photos required

Jan Brittenson wrote:
Nice!

I wonder if the dot is available over USB... if so, this could be automated...

It's interesting you should ask because FoCal just released a new beta of their software that appears to add a shutterless technique that works in 30 seconds and requires the user to set the lens to MF. They call it TurboCal. It's only supported on Canon, maybe because the information isn't available over USB on Nikon bodies. I haven't used it myself but someone on the Canon forum has and said it produced results similar to DotTune.

Feb 20, 2013 at 02:10 AM

James R
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p.2 #8 · DotTune: New AF tune technique, no photos required

Snapsy,

Thanks for the post. I'll give it a try this week. Everybody should appreciate your effort whether they use this method or not, or it works or not.

Feb 20, 2013 at 02:28 AM

C Napa
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p.2 #9 · DotTune: New AF tune technique, no photos required

Tag for later

Feb 20, 2013 at 03:18 AM

TTLKurtis
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p.2 #10 · DotTune: New AF tune technique, no photos required

So out of curiosity how does this work with a zoom lens? For example I ran this test with a 24-70mm lens with the following results:

@24mm: -3 to +7 => +2
@50mm: -3 to +4 => -1.5
@70mm: -5 to +8 => +1.5

If you average the three together, you're looking at a +.67 adjustment. So round up to +1 and that's the proper adjustment, or should the adjustment ideally be the same at any focal length of the zoom lens and the lens should be calibrated by the manufacturer?

Feb 20, 2013 at 05:58 AM

pburke
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p.2 #11 · DotTune: New AF tune technique, no photos required

TTLKurtis wrote:
So out of curiosity how does this work with a zoom lens? For example I ran this test with a 24-70mm lens with the following results:

@24mm: -3 to +7 => +2
@50mm: -3 to +4 => -1.5
@70mm: -5 to +8 => +1.5

If you average the three together, you're looking at a +.67 adjustment. So round up to +1 and that's the proper adjustment, or should the adjustment ideally be the same at any focal length of the zoom lens and the lens should be calibrated by the manufacturer?

use 1.0 unless you mostly shoot at 24mm, then use 2 - not that big of a difference. Would be much more difficult to decide if you had +2 at 24mm and e.g. -8 at 70mm

Feb 20, 2013 at 02:10 PM

TTLKurtis
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p.2 #12 · DotTune: New AF tune technique, no photos required

Then the mid range is off by more then see what I mean?

Feb 20, 2013 at 02:35 PM

pburke
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p.2 #13 · DotTune: New AF tune technique, no photos required

I'd say that's when you do test shots and decide what you want to do. These values are so close, that with hyperfocal distance you're only going to see some impact when shooting wide open, and at close range.

Feb 20, 2013 at 02:44 PM

BenV
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p.2 #14 · DotTune: New AF tune technique, no photos required

going to give this a try when I get home, it seems logical enough.

Feb 20, 2013 at 03:07 PM

TTLKurtis
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p.2 #15 · DotTune: New AF tune technique, no photos required

So if I tend to shoot wide open (2.8) - what I'm wondering is if these adjustments should really be the same throughout the range and if its something that Nikon would be able to calibrate or if this is the nature of a zoom

Feb 20, 2013 at 05:33 PM

Jay968
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p.2 #16 · DotTune: New AF tune technique, no photos required

I am very confused trying to do this. What am I doing wrong?
I go into live view and focus. Then I switch the camera to viewfinder view and turn off the auto focus. I don't see any difference in the green focus confirmation dot no matter WHERE I set the micro adjust to. I can go from -20 all the way up to +20 but the green dot is always green no matter where that is set.
What am I not understanding?

Feb 23, 2013 at 02:58 PM

snapsy
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p.2 #17 · DotTune: New AF tune technique, no photos required

Feb 23, 2013 at 05:00 PM

Jay968
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p.2 #18 · DotTune: New AF tune technique, no photos required

No way was the DOF too big. This was just a quick try at this just to see how and if it worked. I was using the 24-70 set at f2.8, about 9 feet or so from the subject with the lens set at 70mm.
One thing I thought about afterward was that I did have the camera set to AF-C rather than AF-S (using only the center focus point) but not sure if this should make a difference since the body had the AF turned off anyway.

Feb 23, 2013 at 06:51 PM

michaelwatkins
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p.2 #19 · DotTune: New AF tune technique, no photos required

Jay968 wrote:
I am very confused trying to do this. What am I doing wrong?
I go into live view and focus. Then I switch the camera to viewfinder view and turn off the auto focus. I don't see any difference in the green focus confirmation dot no matter WHERE I set the micro adjust to.

I've seen this with my D800 when I was DotTuning my Sigma 35/1.4.

What I did instead of switching the lens into manual focus mode or the body or both was to set AF to AF ON only rather than AF on the half-press of the shutter.

Focus in live view via AF-ON (or manual focus); turn live view off, depress shutter to the half-view, adjust AF Tune, repeat as necessary.

Does DotTune work? I've checked out two lenses that I extensively profiled using software and to my satisfaction can state that the DotTune method gives me excellent results that are consistent with a software analysed tune. What's more... you can do it anywhere, in the field, if necessary, no laptop necessary, no software, no pre-printed target even if in a pinch.

I'd purchased a discounted copy of Reikan FoCal Pro a few weeks ago when I got my Siggy 35/1.4 and through much testing with it, determined that there is definitely something of a bell-shaped curve for optimum tune results. FoCal has an AF tune consistency function which plots quality of focus per exposure and in addition allows for multiple exposures at each AF Tune value. What becomes obvious when you see the results plotted on a chart that the highest quality of focus does not necessarily coincide with the most consistent focus. A tightly grouped cluster of plot values with no anomalies sitting way out there is the ideal, and often this ideal would be at an AF Tune value that didn't necessarily deliver the absolute maximum focus quality.

When I ran FoCal Pro against my Sigma, the peak of the bell curve / most consistent result suggested AF Tune of -7 or -6. DotTune came back with -7 or -6 the first time I did the exercise in less than ideal lighting, -7 or -8 when I used a chair with a patterned fabric as the target, and -7 or -8 in ideal lighting with a high contrast AF test target.

So I've used -7, made a number of close in to infinity exposures, and am very happy with the consistency and quality of focus.

Costs nothing but some time to try; if you are considering buying AF tuning software I'd suggest going through the DotTune process first.

Your mileage may vary. Past results are no guarantee of future performance. Warning, continued use may result in the growth of a leathery tail.

Feb 24, 2013 at 12:24 AM

Jay968
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p.2 #20 · DotTune: New AF tune technique, no photos required

When you talk about AF-ON you are referring to the Autofocus menu option number A4 and A1 to priority release correct? You are choosing AF-ON only rather than Shutter AF-ON?

Feb 24, 2013 at 02:50 AM

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