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Dot-Tune: Autofocus Fine Tuning in under 5 minutes
  
 
EL_PIC
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p.10 #1 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


My thoughts exactly.
Statistical Quality has been replaced with Robotic Commodity.



Mar 04, 2013 at 10:04 PM
Zenon Char
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p.10 #2 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


EL_PIC wrote:
Do any camera or lens manufacturer use this method at final QC ??
or any other method ??


We were discussing Nikon vs Canon service on another site. Scroll down to the last image. I'll be you won't find this in the QC room.

http://www.ppmag.com/web-exclusives/2011/12/care-and-repair.html



Mar 04, 2013 at 11:20 PM
gandini
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p.10 #3 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Dot-Tune with 1DX

I just starting using Dot-Tune with my 1DX, and I noticed the "ends" of the in-focus range were very hard. The tutorial, which I know uses a Nikon camera, shows the green focus dot flickering. It's as if the edges of the in-focus range are fuzzy. When tuning (the 85f1.2LII) I got focus confirmation with +9, no confirmation with +10. This was true for all focus range edges for multiple lenses.
I wonder if this is also the experience for those of you using the 1DX, or other Canon cameras? It sure makes finding the focus range, and then the center for MA very straight-forward!



Mar 07, 2013 at 11:33 PM
snapsy
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p.10 #4 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


gandini wrote:
Dot-Tune with 1DX

I just starting using Dot-Tune with my 1DX, and I noticed the "ends" of the in-focus range were very hard. The tutorial, which I know uses a Nikon camera, shows the green focus dot flickering. It's as if the edges of the in-focus range are fuzzy. When tuning (the 85f1.2LII) I got focus confirmation with +9, no confirmation with +10. This was true for all focus range edges for multiple lenses.
I wonder if this is also the experience for those of you using the 1DX, or other Canon cameras? It sure makes finding the focus range, and then
...Show more

The VF feedback for the transition area between a confirmed and non-confirmed AF tune value can vary body to body and lens to lens. Nikon bodies have a rangefinder so they'll usually have a soft transition, alternating between a dot and flickering dot/arrow. On my 5DM3 I've seen both soft transitions, where the dot flickers just once in 5 seconds or has the slightest of lags, and hard transitions, where it goes from a solid dot to no-dot.



Mar 08, 2013 at 12:15 AM
drphilgandini
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p.10 #5 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Thanks snapsy. I was hoping that my post might elicit responses from Canon owners who have tried Dot Tune, to see what their experience was. I notice that people post about using Dot Tune, sometimes mention the lens, but never mention the camera body. For me, Dot Tune seems to work exceptionally well on the 1DX, which could be (and I only hypothesize here) due to the fact that the 1DX contains the most sophisticated AF system Canon has on offer.


Mar 08, 2013 at 03:27 AM
tuxbailey
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p.10 #6 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Thanks for the great technique. I was able to MA my 6 lenses in less than an hour (3 prime, 3 zoom.) It breathes new life in my 85 f1.8. I have been procrastinating on lens calibration after getting the 5D3 because it was such a tedious process. It turned out that I needed a -7 adjustment for it. And my 50 f1.8 needed a -10. Luckily, all my threshold were within the -20 to +20 range.

One thing that is interesting is that for the extreme, sometimes it will fail to acquire focus for couple seconds after the shutter is pressed, then it acquires. However, subsequent shutter press will acquire immediately. Nevertheless, I chalk that up as unreliable because I could repeat it after moving to other adjustment values.



Mar 11, 2013 at 04:33 AM
snapsy
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p.10 #7 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


tuxbailey wrote:
One thing that is interesting is that for the extreme, sometimes it will fail to acquire focus for couple seconds after the shutter is pressed, then it acquires. However, subsequent shutter press will acquire immediately. Nevertheless, I chalk that up as unreliable because I could repeat it after moving to other adjustment values.


I've seen this as well. And you're right, any lag should disqualify the AF tune value, even if a subsequent half-press is successful. This is also why I suggest performing several confirmations on the peripheries of the tune range, to gain extra precision.



Mar 11, 2013 at 05:07 AM
Shield
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p.10 #8 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


First of all, thank you snapsy for this great AFMA workflow.

Last night I started Dottuning lenses, and my 135/2 is all over the map. I ended with about 13 different tests and basically averaged out the results. Does the focus limiter on the side of the lens affect the liveview/contrast detect focusing? I assume it wouldn't as I'm 50x focal length (i.e. 265.748 inches) away.
My 85 1.8 was pretty much dead-on, but with the 135 was anywhere from -7 to +2 on the (-) side and +8 to +18 on the + side.



Mar 12, 2013 at 01:33 PM
gandini
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p.10 #9 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


I found the light in which you DotTune is important. I was in daylight shadow, but the sky was cloudy and so the ambient light varied from sunny to cloudy. The method seemed to work best (quicker focus and harder end points) with brighter light, (which makes sense, I presume.)
Is it possible that your 135mm results are due to varying, or low, light conditions?



Mar 12, 2013 at 07:20 PM
snapsy
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p.10 #10 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Shield wrote:
First of all, thank you snapsy for this great AFMA workflow.

Last night I started Dottuning lenses, and my 135/2 is all over the map. I ended with about 13 different tests and basically averaged out the results. Does the focus limiter on the side of the lens affect the liveview/contrast detect focusing? I assume it wouldn't as I'm 50x focal length (i.e. 265.748 inches) away.
My 85 1.8 was pretty much dead-on, but with the 135 was anywhere from -7 to +2 on the (-) side and +8 to +18 on the + side.


The limiter wont affect the AF tune provided you have it set so that focus can be properly established in LV for the distance of your target. For your 135mm where you see test-to-test range variability (up to 10 AF tune unit differential on either end between tests), is that with the exact same target distance and lighting?



Mar 12, 2013 at 08:05 PM
 

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Papathanassiou
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p.10 #11 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


No one as far as I can see has tried this method on the old manual focus lenses, Leica, Contax, Minolta, etc! All have adaptors, some with comfirmation focus points, a lot or some of these lenses are not that accurate I have found! If you do your critical focus using Live View, obviously Manually using Snapsy method you can really get them to be very accurate! I have done the latest Zeiss 35mm F2.

Papa.



Mar 13, 2013 at 07:21 AM
Ian.Dobinson
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p.10 #12 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Papathanassiou wrote:
No one as far as I can see has tried this method on the old manual focus lenses, Leica, Contax, Minolta, etc! All have adaptors, some with comfirmation focus points, a lot or some of these lenses are not that accurate I have found! If you do your critical focus using Live View, obviously Manually using Snapsy method you can really get them to be very accurate! I have done the latest Zeiss 35mm F2.

Papa.



Correct me if I'm wrong but won't you get the same spread with an MF lens whatever the MA setting is ? So I'd assume that you still wouldn't be able to rely on the confirmation .

Eg. You get best focus in live veiew and find the dot tune range is 0 - +8 . Now I'd think that if you set the MA to 4 then your focus confirm range is still going to be a spread of 8 either side of the new mid point (4)
But I would also think you could purposely set it to a minus point (and get very OOF) but the range would still be a spread of 8 around that midpoint .


Maybe I'm wrong though



Mar 13, 2013 at 07:53 AM
thw2
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p.10 #13 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


I just recently gave the dot-tune method a try (I have the LensAlign kit). Reliable and fast. I love it!


Mar 13, 2013 at 12:39 PM
gandini
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p.10 #14 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


I recently DotTuned 8 lenses on my 1DX. What I found so interesting about the method, and the results, is that MA=0 was within the focus range for all lenses. That is, if you use MA=0 as the default setting when you get a new body, or a new lens, it's very likely your lens will "focus" and you will get focus confirmation in the view finder. However, once you employ DotTune to find the middle of the focus range, you realize that it might not be (is often) not 0, but that the range covered 0. All but one lens (135L) has a DotTune setting other than 0, although few are greater than +-5.
Not only does this method provide a fast and accurate MA, it gives you an insight into how your camera's AF system works. Pretty neat!



Mar 13, 2013 at 03:09 PM
snapsy
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p.10 #15 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Ian.Dobinson wrote:
Correct me if I'm wrong but won't you get the same spread with an MF lens whatever the MA setting is ? So I'd assume that you still wouldn't be able to rely on the confirmation .

Eg. You get best focus in live veiew and find the dot tune range is 0 - +8 . Now I'd think that if you set the MA to 4 then your focus confirm range is still going to be a spread of 8 either side of the new mid point (4)
But I would also think you could purposely set it to a
...Show more

You're correct. DotTunning a MF lens means you'll be centering the range of VF confirmation properly, which is always suggested. But even with the midpoint of the AF tune properly configured, you'll still have a (small) range of focus ring positions that yield solid VF confirmation when you are manually focusing. So time permitting, the best way to MF via the VF confirmation is to turn the focus ring to establish the range of positions that produce confirmation (basically a DotTune procedure but using the focus ring instead of AF tune adjustment), then move the focus ring to the middle of that range for the best focus of that subject. Naturally this requires a bit of finesse on the part of the shooter.



Mar 13, 2013 at 07:25 PM
Papathanassiou
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p.10 #16 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


snapsy wrote:
You're correct. DotTunning a MF lens means you'll be centering the range of VF confirmation properly, which is always suggested. But even with the midpoint of the AF tune properly configured, you'll still have a (small) range of focus ring positions that yield solid VF confirmation when you are manually focusing. So time permitting, the best way to MF via the VF confirmation is to turn the focus ring to establish the range of positions that produce confirmation (basically a DotTune procedure but using the focus ring instead of AF tune adjustment), then move the focus ring to the
...Show more

I Apologise Ian because I couldn't get my head around what you meant!

What I should have stated with these Third Party Manual Focus lenses is that most are wide angle, say up to 50mm,
and doing the Dot Tune adjustment if required, and then going by the VF confirmation in the view finder you will be after the adjustment, getting a more accurate focus. Hope you get what I 'm trying to explain, sorry that is the best I can do!

Papa.



Mar 13, 2013 at 08:26 PM
gse53
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p.10 #17 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


I am going to try this method and compare to the results of FoCal, which I just bought.

As far as the recommended distance, here is Reikan's recommendations

Recommended distance for testing



Mar 13, 2013 at 08:56 PM
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p.10 #18 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Wow, I just watched this video... amazing! Can't wait to try it!


Mar 14, 2013 at 04:43 AM
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p.10 #19 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Just did this with 5 lenses and two cameras. Took about an hour but I think it was well worth it. Adjustments ranged from 0 to +10. I took some test shots after adjusting and everything looks great. I was close to getting FoCal but now I don't see the need. I do think I will redo the test of the 50 though - the variation between bodies is too large . . .

Here are my stats in case anyone is setting up a database for this:

1DX (3/14/13)
70-200 2.8 II @70 = (+5) @200 = (+5)
24-70 2.8 II @24 = (+4) @70 = (+4)
50 1.2 = (+10)
100 2.8 L = (+9)
300 2.8 (ver 1) = (+7)


5DIII (3/14/13)
70-200 2.8 II @70 = (+5) @200 = (+5)
24-70 2.8 II @24 = (0) @70 = (+1)
50 1.2 = (0)
100 2.8 L = (+7)
300 2.8 (ver 1) = (+4)


Approximate Testing Distances:
24mm 4.0'
50mm 8.2'
70mm 11.5'
100mm 16.4'
200mm 32.8'
300mm 49.2'



Mar 14, 2013 at 09:10 PM
Jeff1010
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p.10 #20 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Here is my result on 5D3 & 70-200 f/2.8 II.

@200mm, white LED light (~5000K)
-9 to +7, avg = -1

@200mm, halogen light (~3000K)
-7 to +9, avg = +1

@70mm, white LED light
-11 to +5, avg = -3

@70mm, halogen light
-5 to +11, avg = +3

I used the same target, brightness, tripod, etc. I just turned on one light, and switched off the other light. These numbers were very consistent and reproducible.

I have known this but phase detection focus shifts with light temperature. A couple of years ago, I returned 3 camera bodies and after months of frustration testing 6 camera bodies and lenses, I finally realized that focus shifts depending on light temperature. Under warm incandescent light, cameras front-focuses (or move in that direction). Under whiter light such as LEDs and florescent lights, cameras back-focus. Even outdoors, there is a shift going from sunlight to shade, mid-day to dawn/dusk. I don't know why this can't be compensated in camera electronics since auto-balance sensor can measure color temperature.

I have to say the 5D3 focus accuracy in various conditions is much, much better than the 7D for example but if you examine closely, you can get frustrated with any camera. I am happy with my camera/lens combination in this case. The MFA average is exactly zero.

The Dot-tune method seems to work well but I don't believe in the MFA since the value changes with light temperature, distance, and with focal length (in case of zoom lens). If you set the MFA to any value other than 0, it will make things worse in some other conditions. If my camera/lens need MFA, I would send them back and get them calibrated. I do understand that it can be beneficial if your camera/lens is offset to one direction but in my experience, focus consistency gets worse when MFA is enabled and set to a non-zero value.



Mar 19, 2013 at 07:34 AM
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