Anybody tried DotTune AF finetuning?

Raffwal · 02-24-2013, 12:50 PM

A photographer has published a video presenting a method for finetuning individual lens AF using the MF focus confirmation. Has anybody tried the method and how well does it work with Pentax MF focus confirmation?

DotTune: Autofocus fine tuning in under 5 minutes - YouTube

JinDesu · 02-24-2013, 12:57 PM

Hm - I'll try this later with my Sigma 50 F1.4. It's a very logical concept.

Pontax · 02-24-2013, 03:13 PM

Very complicated i think but would like to try it out. I use CIF, first set focus manually then adjust AF microadjustment until the shutter fires, voila. This applies only to MF lenses.

AndrewShirley · 02-24-2013, 03:53 PM

Looks good to me. I just tried it on my Sigma 70-200 and realized I had dialed-in too much compensation previously. Sure enough, using the new setting works marvelously.

borno · 02-24-2013, 04:02 PM

It's not as complicated as it sounds and seems pretty good.

JinDesu · 02-24-2013, 05:25 PM

Just tried it on tripod with my Sigma 50 1.4. Took a few tries to get it correct. It says my lens needed +85 micrometers, when my previous testing method said I needed +60 micrometers. That's reasonably close to each other, in my opinion. As such, I have it set currently to +80 micrometers.

milesy · 02-24-2013, 06:00 PM

this looks like a great method

**JimJohnson** · 02-25-2013, 10:18 AM

Using this technique with the lens wide open (f/3.5 - 4.5) I had a usable focus range of +7 to -10 ... that is a lot of wiggle room! The results were about the same at either 35mm or 70mm. I set the AF Fine Adjustment to -1.

I had used this method previously to calibrate the kit 18-55 and came up with -4 at mid-range. I understand I am referring to two different lenses, but to me it does confirm a small front focus deviation with my camera.

The most important thing to me out of this test is that using the focus indicator with manual lenses may not be all that dependable unless I am using a fast lens wide open. The same would likely be true for Catch In Focus shooting.

crossmr · 02-25-2013, 11:15 PM

Quite a range on my K-30 with the Tamron 28-75 F2.8..
-4 to +8 which gives me a midpoint of about +2

TOUGEFC · 02-25-2013, 11:28 PM

Ive used it with my D700 and have had pretty good results with it

crossmr · 02-25-2013, 11:44 PM

Want to calibrate my 70-300 tamron as well, but I don't really have 3.5 meters in my small apartment to lay it out

managed to get a space with light..
-10 to +5 for this lens..
who knows if it would go below -10 or not.
Not sure what to think when it hits the lower limit.

RBellavance · 02-27-2013, 08:45 AM

Brilliant ! It works very well, and is by far the easiest AF fine-tuning method I've tried so far.

lushdimple11 · 10-29-2017, 06:14 AM

Originally posted by crossmr

Want to calibrate my 70-300 tamron as well, but I don't really have 3.5 meters in my small apartment to lay it out

managed to get a space with light..
-10 to +5 for this lens..
who knows if it would go below -10 or not.
Not sure what to think when it hits the lower limit.

Hi, can you please share the steps to finetune zoom lenses? The video is about finetuning the AF on prime lenses only. Thank you

ShawnH · 03-01-2018, 09:30 PM

I have used this method, it is quick and works just fine. Now if you want to make things interesting use it on the side focus points. On my 35mm f2.4 & 50mm f1.8 plastic lenses the side point yields substantially different values. When calibrated a side point yields sharp focus on the target but the rest of the image is degraded. I assume this is due to decentered elements. This issued renders the Select Point auto focus setting useless. Note: Unlike what some would say, I found the side point very accurate when calibrated. My 40mm f2.8 limited & 35mm f2.0 suffered much less from this issue.

abruzzi · 03-03-2018, 10:19 PM

Originally posted by lushdimple11

Hi, can you please share the steps to finetune zoom lenses? The video is about finetuning the AF on prime lenses only. Thank you

The video alludes to it briefly, but basically if a lens needs a different adjustment at different focal lengths, you have to decide do you a) pick your most used focal length in the range and tune to that exactly or b) check different parts of the range and find a value somewhere in the middle of the range. The second option is a comprimise because the focal behavior of a zoom changes, but the camera only has a single value to configure.

So for instance, it you have a 16-85, and at 16 your range is -5 to -10 and at 85 your range is +5 to +10, you could say you have two values -7.5 and +7.5 so the midpoint is 0. But that assume the change is linear. So if you try a few more values, you could average them.

02-24-2013, 12:50 PM	#1
Raffwal Veteran Member Join Date: Oct 2010 Location: The North Posts: 879	Anybody tried DotTune AF finetuning? A photographer has published a video presenting a method for finetuning individual lens AF using the MF focus confirmation. Has anybody tried the method and how well does it work with Pentax MF focus confirmation? DotTune: Autofocus fine tuning in under 5 minutes - YouTube

02-25-2013, 10:18 AM	#8
JimJohnson Loyal Site Supporter Join Date: Jan 2012 Location: Summer:Lake Superior - Michigan Winter:Texas Hill Country Photos: Gallery Posts: 2,774	K-r with Pentax F 35-70 Using this technique with the lens wide open (f/3.5 - 4.5) I had a usable focus range of +7 to -10 ... that is a lot of wiggle room! The results were about the same at either 35mm or 70mm. I set the AF Fine Adjustment to -1. I had used this method previously to calibrate the kit 18-55 and came up with -4 at mid-range. I understand I am referring to two different lenses, but to me it does confirm a small front focus deviation with my camera. The most important thing to me out of this test is that using the focus indicator with manual lenses may not be all that dependable unless I am using a fast lens wide open. The same would likely be true for Catch In Focus shooting.

02-25-2013, 11:15 PM	#9
crossmr Veteran Member Join Date: Jul 2009 Location: Liverpool, UK Posts: 318	Quite a range on my K-30 with the Tamron 28-75 F2.8.. -4 to +8 which gives me a midpoint of about +2 Last edited by crossmr; 02-25-2013 at 11:43 PM.

02-25-2013, 11:44 PM	#11
crossmr Veteran Member Join Date: Jul 2009 Location: Liverpool, UK Posts: 318	Want to calibrate my 70-300 tamron as well, but I don't really have 3.5 meters in my small apartment to lay it out managed to get a space with light.. -10 to +5 for this lens.. who knows if it would go below -10 or not. Not sure what to think when it hits the lower limit. Last edited by crossmr; 02-26-2013 at 12:11 AM.

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02-24-2013, 12:57 PM	#2
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Hm - I'll try this later with my Sigma 50 F1.4. It's a very logical concept.

02-24-2013, 03:13 PM	#3
Pontax Senior Member Join Date: Oct 2011 Location: Bornholm Photos: Gallery \| Albums Posts: 160	Very complicated i think but would like to try it out. I use CIF, first set focus manually then adjust AF microadjustment until the shutter fires, voila. This applies only to MF lenses.

02-24-2013, 03:53 PM	#4
AndrewShirley Inactive Account Join Date: Mar 2007 Location: Barrie, Ontario, Canada Posts: 421	Looks good to me. I just tried it on my Sigma 70-200 and realized I had dialed-in too much compensation previously. Sure enough, using the new setting works marvelously.

02-24-2013, 04:02 PM	#5
borno Veteran Member Join Date: Nov 2006 Location: md-usa Photos: Gallery \| Albums Posts: 2,580	It's not as complicated as it sounds and seems pretty good.

02-24-2013, 05:25 PM	#6
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Just tried it on tripod with my Sigma 50 1.4. Took a few tries to get it correct. It says my lens needed +85 micrometers, when my previous testing method said I needed +60 micrometers. That's reasonably close to each other, in my opinion. As such, I have it set currently to +80 micrometers.

02-24-2013, 06:00 PM	#7
milesy Veteran Member Join Date: Jan 2009 Location: Melbourne Photos: Gallery Posts: 379	this looks like a great method

02-25-2013, 11:28 PM	#10
TOUGEFC Veteran Member Join Date: Nov 2009 Location: Brisbane Photos: Gallery Posts: 3,561	Ive used it with my D700 and have had pretty good results with it

02-27-2013, 08:45 AM	#12
RBellavance Veteran Member Join Date: Nov 2006 Location: Near Montréal, Canada Photos: Gallery Posts: 1,716	Brilliant ! It works very well, and is by far the easiest AF fine-tuning method I've tried so far.

10-29-2017, 06:14 AM	#13
lushdimple11 Junior Member Join Date: Oct 2016 Posts: 28	Originally posted by crossmr Want to calibrate my 70-300 tamron as well, but I don't really have 3.5 meters in my small apartment to lay it out managed to get a space with light.. -10 to +5 for this lens.. who knows if it would go below -10 or not. Not sure what to think when it hits the lower limit. Hi, can you please share the steps to finetune zoom lenses? The video is about finetuning the AF on prime lenses only. Thank you

03-01-2018, 09:30 PM	#14
ShawnH Forum Member Join Date: May 2017 Posts: 65	I have used this method, it is quick and works just fine. Now if you want to make things interesting use it on the side focus points. On my 35mm f2.4 & 50mm f1.8 plastic lenses the side point yields substantially different values. When calibrated a side point yields sharp focus on the target but the rest of the image is degraded. I assume this is due to decentered elements. This issued renders the Select Point auto focus setting useless. Note: Unlike what some would say, I found the side point very accurate when calibrated. My 40mm f2.8 limited & 35mm f2.0 suffered much less from this issue.

03-03-2018, 10:19 PM	#15
abruzzi Veteran Member Join Date: Apr 2017 Location: New Mexico Posts: 788	Originally posted by lushdimple11 Hi, can you please share the steps to finetune zoom lenses? The video is about finetuning the AF on prime lenses only. Thank you The video alludes to it briefly, but basically if a lens needs a different adjustment at different focal lengths, you have to decide do you a) pick your most used focal length in the range and tune to that exactly or b) check different parts of the range and find a value somewhere in the middle of the range. The second option is a comprimise because the focal behavior of a zoom changes, but the camera only has a single value to configure. So for instance, it you have a 16-85, and at 16 your range is -5 to -10 and at 85 your range is +5 to +10, you could say you have two values -7.5 and +7.5 so the midpoint is 0. But that assume the change is linear. So if you try a few more values, you could average them.