Home · Register · Search · View Winners · Software · Hosting · Software · Join Upload & Sell

Moderated by: Fred Miranda
Username   Password

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Canon Forum | Join Upload & Sell

1       2       3              16      
17
       18              26       27       end
  

Dot-Tune: Autofocus Fine Tuning in under 5 minutes
  
 
drobertfranz
Offline
• • •
Upload & Sell: On
p.17 #1 · p.17 #1 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


tag


Jun 03, 2013 at 09:12 PM
Raoul_Jass
Offline

Upload & Sell: Off
p.17 #2 · p.17 #2 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Hi everybody !

First, thanks for all this !

This is really a LONG thread.
I've had no time so far to read everything...
Suggestion : Could anyone summarize a "FAQ" ?

I have a question indeed :
As DOF is NOT linear : (1/3 in front and 2/3 in back of the focus point), why are you taking the middle point between higher and lower MA value ?

(Sorry if this question has already been addressed)




Jun 17, 2013 at 02:59 PM
snapsy
Offline
• • • • •
Upload & Sell: On
p.17 #3 · p.17 #3 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Raoul_Jass wrote:
Hi everybody !

First, thanks for all this !

This is really a LONG thread.
I've had no time so far to read everything...
Suggestion : Could anyone summarize a "FAQ" ?

I have a question indeed :
As DOF is NOT linear : (1/3 in front and 2/3 in back of the focus point), why are you taking the middle point between higher and lower MA value ?

(Sorry if this question has already been addressed)


The youtube video in the OP has everything you should need. The midpoint of the tune range represents the midpoint of the AF, which accounts for the front/back DOF balance, provided focus was established at that DOF midpoint. You can adjust the DOF midpoint (using a 3-D target such as LensAlign) during the focusing step if you'd like to tailor the DOF balance to your needs (such as 50/50 vs 70/30).



Jun 17, 2013 at 03:12 PM
Raoul_Jass
Offline

Upload & Sell: Off
p.17 #4 · p.17 #4 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


snapsy wrote:
The youtube video in the OP has everything you should need. The midpoint of the tune range represents the midpoint of the AF, which accounts for the front/back DOF balance, provided focus was established at that DOF midpoint. You can adjust the DOF midpoint (using a 3-D target such as LensAlign) during the focusing step if you'd like to tailor the DOF balance to your needs (such as 50/50 vs 70/30).


Well, I don't get it.

You loose the focus confirm led because you're out of the DOF range (according to the "confirm" tolerance). So, if I'm not wrong, you have twice as much DOF to take into account when you decrease the MA value than when you increase it.
Thus, if I loose AF confirm at +7 and -5, I should set it to +3 and not +1 (middle point).
And this is indeed where I get the most accurate focus (this was the setting I found by trials and errors). (1DX + 85mm 1.2L II at 4m)





Jun 18, 2013 at 07:02 AM
snapsy
Offline
• • • • •
Upload & Sell: On
p.17 #5 · p.17 #5 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Raoul_Jass wrote:
Well, I don't get it.

You loose the focus confirm led because you're out of the DOF range (according to the "confirm" tolerance). So, if I'm not wrong, you have twice as much DOF to take into account when you decrease the MA value than when you increase it.
Thus, if I loose AF confirm at +7 and -5, I should set it to +3 and not +1 (middle point).
And this is indeed where I get the most accurate focus (this was the setting I found by trials and errors). (1DX + 85mm 1.2L II at 4m)

Think of it this way - if a body+lens combo focused perfectly out-of-the-box without any AF tuning required, the acquired AF should be at whatever the natural DOF balance is for the focus distance used, say 70/30...rather than the center of the DOF at 50/50. So if the focus point established by the photographer during DotTune is at the natural DOF balance then it's the midpoint of the tune range which should be used, without any compensation for front/rear DOF, since the AF tune range represented by the confirmation dot is presumably the same range used by the AF system itself whenever it acquires focus during an AF cycle.



Jun 18, 2013 at 01:21 PM
g-money
Offline
• • •
Upload & Sell: Off
p.17 #6 · p.17 #6 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Tag!


Jun 21, 2013 at 05:27 PM
tdodd
Offline

Upload & Sell: Off
p.17 #7 · p.17 #7 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Raoul_Jass wrote:
As DOF is NOT linear : (1/3 in front and 2/3 in back of the focus point), why are you taking the middle point between higher and lower MA value ?

(Sorry if this question has already been addressed)


DOF is also rarely 1/3 and 2/3 front and back. Assume we are going to check calibration at 50 X Focal Length for a 200mm lens. That gives a distance of 10m for the calibration. At 10m and f/2.8 the DOF will be....

on full frame : 20.4cm in front to 21.2cm behind (so very close to 50:50)
on 1.3 crop : 15.7cm in front to 16.2cm behind (so very close to 50:50)
on 1.6 crop : 13.0cm in front to 13.3cm behind (so very close to 50:50)

Calibrating at 25 X Focal Length, or 5m for a 200mm lens, the figure would be even closer to 50:50.

To get to a 1/3 - 2/3 DOF split with a 200mm lens at f/2.8 on a 7D you would need to focus at 250m away, yielding DOF of 63m in front and 126m behind.

All DOF figures courtesy of http://dofmaster.com/dofjs.html



Jun 21, 2013 at 07:54 PM
outlawyer
Offline
• • •
Upload & Sell: On
p.17 #8 · p.17 #8 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Any word on the Magc Lntrn implementation of automated method for 6D? Looked at the ML site but not sure what I'm seeing there...


Jul 22, 2013 at 02:25 PM
snapsy
Offline
• • • • •
Upload & Sell: On
p.17 #9 · p.17 #9 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


outlawyer wrote:
Any word on the Magc Lntrn implementation of automated method for 6D? Looked at the ML site but not sure what I'm seeing there...


I believe 6D support is already in the ML developer code base. Not sure when it will be included in an official release.



Jul 22, 2013 at 06:50 PM
badlydrawnboy
Offline
• • •
Upload & Sell: On
p.17 #10 · p.17 #10 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Question about the method: is it better to half-press the shutter button repeatedly to get multiple confirmations, or hold it down?


Jul 28, 2013 at 03:03 PM
 

Search in Used Dept. 



Lars Johnsson
Online
• • • • • • •
Upload & Sell: Off
p.17 #11 · p.17 #11 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


tdodd wrote:
DOF is also rarely 1/3 and 2/3 front and back. Assume we are going to check calibration at 50 X Focal Length for a 200mm lens. That gives a distance of 10m for the calibration. At 10m and f/2.8 the DOF will be....

on full frame : 20.4cm in front to 21.2cm behind (so very close to 50:50)
on 1.3 crop : 15.7cm in front to 16.2cm behind (so very close to 50:50)
on 1.6 crop : 13.0cm in front to 13.3cm behind (so very close to 50:50)

Calibrating at 25 X Focal Length, or 5m for a 200mm lens, the figure would be
...Show more

But do exactly the same thing with everything, and use a lens that is 14, 24, 35 or 50mm and then check with dofmaster again. With a wide angle lens you get more like 2-3% in front and 97-98% behind. With a normal 50mm you get 35-40% in front and 60-65% behind.
So on average with all lenses it's rather ok to say 1/3 in front and 2/3 behind.



Jul 28, 2013 at 03:37 PM
snapsy
Offline
• • • • •
Upload & Sell: On
p.17 #12 · p.17 #12 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


badlydrawnboy wrote:
Question about the method: is it better to half-press the shutter button repeatedly to get multiple confirmations, or hold it down?


I suggest doing both, especially as you approach the ends of the tuning range. Some lens/target combinations will manifest a failed confirmation more often during a long shutter press, and some with more frequent presses.



Jul 28, 2013 at 05:29 PM
tdodd
Offline

Upload & Sell: Off
p.17 #13 · p.17 #13 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


No. Not if you stick with a 50X focal length multiplier or closer and calibrate wide open. On full frame....

A 300/2.8 at 15m would give you 49:51%

A 200/2.8 at 10m would give you 49:51%

A 135/2 at 6.75m would give you 49:51%

A 100/2 at 5m would give you 49:51%

An 85/1.8 (or 1.4 or 1.2) at 3.75m would give you 49:51%

A 50/1.4 at 2.5m would give you 48:52%

A 35/1.4 at 1.75m would give you 47:53%.

A 24/1.4 at 1.2m would give you 46:54%.

A 14/2.8 at 0.7m would give you 35:65, but at a 25X multiplier - i.e. 0.35m it would be 43:57

If you switch to a crop sensor format the gap narrows further and if you shorten the subject distance from 50X FL to 25X FL then it narrows further still.


If you want to talk about slower lenses then that might change things somewhat, but for fast glass, which is where accurate focus is most critical, the 33:67 ratio is far from the norm when it comes to AF calibration at "normal" calibration distances.



Jul 28, 2013 at 05:44 PM
Lars Johnsson
Online
• • • • • • •
Upload & Sell: Off
p.17 #14 · p.17 #14 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


50x has nothing to do with DOF. It's only a recommendation for doing AF adjustment in a certain way or with a certain software. other software or lens makers recommend you to adjust your lenses at your normal shooting distance. How many people do you think use a 14mm lens at 0,7m as an average distance. Most people shooting landscape use wide angle at infinity or far away. The statement/question from the start was "DOF is NOT linear" and it isn't. Even if you try to prove it.
You also have more tele lenses than wide and normal lenses together in your comparison.

Raouls statement: "As DOF is NOT linear : (1/3 in front and 2/3 in back of the focus point) is a statement that have been used since many years back. Similar to the shutter speed statement that you need 1/50 sec to shoot with a 50mm lens. And 1/100 with a 100mm lens and so on. It's a rather good starting point and more accurate than saying "(1/2 in front and 1/2 in back of the focus point)



Jul 28, 2013 at 06:06 PM
jimlp
Offline
• •
Upload & Sell: Off
p.17 #15 · p.17 #15 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Tag



Aug 12, 2013 at 02:52 PM
boingyman
Offline
• • •
Upload & Sell: Off
p.17 #16 · p.17 #16 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Tag. Might have to do this soon.


Aug 12, 2013 at 05:28 PM
Todd Moon
Offline

Upload & Sell: Off
p.17 #17 · p.17 #17 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


outlawyer wrote:
Any word on the Magc Lntrn implementation of automated method for 6D? Looked at the ML site but not sure what I'm seeing there...


I'm using it right now on my 6D. It's great! However, I found one bug. If you don't register the lens manually first, the ML software won't notice this and it will think it's changing the MFA setting but it's failing to do so. Therefore, it will get a focus confirmation at every value it tests and it will just set the final AFMA to zero. To register the lens manually just go to the custom function and press the Q button to register it. (The screen will say "[Q] Register.") This opens the MFA setting screen and you just hit Set to back out. You don't need to actually change anything. You will know it worked if the previous screen now says "[Q] Change".

I didn't read the instructions on the ML web site, so maybe they mention this. Here are some quick instructions if the ones there aren't clear. I'm assuming you already know how far away your focus target should be, etc.

1. Make sure your lens is registered as per the above paragraph.

2. Setup your camera pointing at a focus target.

3. Make sure your center AF point is pointed directly at your focus target, and you only have the center point selected for AF.

4. Achieve critical focus in Live View focusing. I just put the lens in AF mode and use Live View's contrast detect mode to achieve focus. It's never let me down.

5. Put the lens in MF mode. (If you forget, Magic Lantern will abort the procedure when you start it.)

6. Enter the ML menu and highlight the Dot Tune menu option and press Set.

7. Scroll to the bottom option and choose whether you are setting the wide end of a zoom or the tele end of a zoom. The wide option is also the option for primes. You can also choose "All lenses", but who would do that?

8. Scroll to the top option to search the default -20/+20 range and press Set.

9. Wait and watch the screen. The software will open the standard Info screen you will see text appear explaining that you should already have achieved focus on your own, and to keep the camera still (obviously.) Then it scrolls through the MFA settings and starts plotting a graph on the top of the screen showing when it did and didn't achieve focus confirmation. It checks the whole range 4 times and then picks the center of the range where it achieved the best confirmations, and sets this value for you automatically.

10. If using the default -20/+20 range caused it to achieve solid focus confirmation at either of the two extremes (-20 or +20) then you should try again with the -40/+40 range. (Yes, it appears the software can set values higher or lower than the camera natively can.) The reason you want to broaden the range is in case it would have also found confirmation at -21, -25, or even lower. (Or past +20 on the positive side.) The technique will be unable to find the true middle unless you find both ends of where it stops achieving focus confirmation. For example, my 85mm f/1.8 needed a setting of +20. During testing, confirmation was still achieved all the way up at +32. This is an example of where the traditional Dot Tune technique would have failed since you can't natively set the value higher than +20. But Magic Lantern can go up to -100/+100! If you or ML select a value greater than or less than the default -20/+20 range then the Custom Function menu will display 0, but the MF setting will display the actual value.

It's brilliant!

Here's a photo of it in action:








Aug 13, 2013 at 12:35 AM
outlawyer
Offline
• • •
Upload & Sell: On
p.17 #18 · p.17 #18 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Still not seeing where you got this. Can anyone post a link? Thanks


Aug 14, 2013 at 08:18 PM
Todd Moon
Offline

Upload & Sell: Off
p.17 #19 · p.17 #19 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


I'm not really sure what you're asking. Magic Lantern is custom firmware for your camera that replaces and extends the built-in Canon firmware. The auto Dot Tune feature is just one of the many features in Magic Lantern. If you install the ML firmware it will be one of the menu options.

Are you asking where to get the Magic Lantern firmware itself? There is no official release of the ML firmware for the 6D yet, so I'm using a version I found in one of the threads on the ML forums.

I followed post #2 in this thread: http://www.magiclantern.fm/forum/index.php?topic=5530.0

It hasn't been updated since 6/19, so the link it contains will not contain the latest version. However, it is what I'm using.



Aug 14, 2013 at 08:31 PM
outlawyer
Offline
• • •
Upload & Sell: On
p.17 #20 · p.17 #20 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Oh....so there is only one available download, not different DL's for different bodies?

Downloaded the link in post 2, says "windows can't open this file"

Any other suggestions?

Edited on Aug 14, 2013 at 08:44 PM · View previous versions



Aug 14, 2013 at 08:35 PM
1       2       3              16      
17
       18              26       27       end




FM Forums | Canon Forum | Join Upload & Sell

1       2       3              16      
17
       18              26       27       end
    
 

You are not logged in. Login or Register

Username   Password    Reset password