# AFMA frustrations



## TheJock (May 4, 2016)

Hi folks, 
I’m seeking some guidance regarding the DoTune method for setting up my 1.4xIII +100-400L (mark1) on my 5DIII.

I watched the video, downloaded an A3 size focus chart with lots of horizontal and vertical black lines, I set up my distance to the maximum I have available (about 21 meters on the roof of my housing block) then obtained critical focus in live view and followed the videos guidance from there.

The problem is that when going into AFMA in the menu you have to go all the way in each time, so I set it in increments of +5 to see if the “dot” would display the flickering as explained in the video, this is where the problem starts as the green dot remained fully illuminated all the way up to +20.

Am I missing something with this method? I know I should be focusing at 50X (so 28 meters for this lens combo) at maximum aperture (which is f8) but surely I should be seeing some sort of results with the”dot”?
Any assistance would be gratefully received as I’m sure that there must be some sort of AFMA required (i.e. you can’t expect it to be 100% perfect first time you attach the lens combo, right?). :-[


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## neuroanatomist (May 4, 2016)

Stewart K said:


> I’m seeking some guidance regarding the DoTune method



My guidance would be to use another method. IMO, DotTune is a case where you get what you pay for... I've found that it works well for some lenses but gives spurious results with others. I far prefer Reikan FoCal for calibration.


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## TheJock (May 4, 2016)

neuroanatomist said:


> Stewart K said:
> 
> 
> > I’m seeking some guidance regarding the DoTune method
> ...


LOL, I had actually thought about that, but after watching all the videos and reading all the comments I thought how can this ultra simple method NOT be the method of choice...neuro to the rescue!!!
I will cease with my efforts for the day as the equipment seems to work well as is, cheers mate


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## rfdesigner (May 4, 2016)

Stewart K said:


> Hi folks,
> I’m seeking some guidance regarding the DoTune method for setting up my 1.4xIII +100-400L (mark1) on my 5DIII.
> 
> I watched the video, downloaded an A3 size focus chart with lots of horizontal and vertical black lines, I set up my distance to the maximum I have available (about 21 meters on the roof of my housing block) then obtained critical focus in live view and followed the videos guidance from there.
> ...



I've had success with DotTune.. and I've also done Foucault testing of telescopes. I would worry about getting consistant results outdoors, I found I could only do focault testing indoors otherwise air currents would disturb results.

In your case I would make DotTune work on a shorter lens indoors first.. if you can do that successfully then you can have another play at longer focal lengths, but if you have to do it outdoors, I would be wary of sunny conditions.

Also cost is no guarentee of quality.


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## Krob78 (May 4, 2016)

rfdesigner said:


> Stewart K said:
> 
> 
> > Hi folks,
> ...



Indeed, I have and use Reikan FoCal for calibration as well and I like it very much, quite satisfied with it. That said, I still have my large 45 degree "speed square" and yard stick for some fun and free afma calibrating every now and again! Perhaps not as precise as my Focal setup but definitely cheap and actually pretty decent results overall...


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## neuroanatomist (May 4, 2016)

rfdesigner said:


> Also cost is no guarentee of quality.





Krob78 said:


> That said, I still have my large 45 degree "speed square" and yard stick for some fun and free afma calibrating every now and again! Perhaps not as precise as my Focal setup but definitely cheap and actually pretty decent results overall...



Agreed, a basically free DIY setup can certainly work fine. My recommendation for one such AFMA setup is below (bascially a homemade LensAlign setup). My point wasn't that free is bad, but that I've found DotTune to be unreliable. If it works for you, great...seems to be not working for the OP.


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## Valvebounce (May 4, 2016)

Hi Stewart. 
I have tried the DotTune method as I had varying results I now have Reikan FoCal. 
Is it possible that the problem is the DOF, at 100mm @f8 you have 9m DOF and at 400mm @f8 you have over 500mm DOF according to a calculator I just chucked the numbers in. Just a thought, trying to work through the procedure in my head without a camera and I'm approaching so confused I will have smoke coming out my ears! ;D

Cheers, Graham.


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## Old Sarge (May 4, 2016)

neuroanatomist said:


> rfdesigner said:
> 
> 
> > Also cost is no guarentee of quality.
> ...


That looks like an excellent set up for a quick and accurate check of autofocus. In fact, I may just use that as I prepare for our vacation the end of the month. Thanks for the diagram.


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## Krob78 (May 12, 2016)

Old Sarge said:


> neuroanatomist said:
> 
> 
> > rfdesigner said:
> ...


Agreed, Dot tune to me is a waste of money. FoCal is far superior all the way around. I like it a lot.


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## Bboogie (May 13, 2016)

First time here, I ran Reikan Focal twice and it gave me different results, first i got -3 then the second it went to -4, i ran Turbo Cal it gave me a -2, this is for a 50L it's rather strange because i did the 24-70 both ends and it gave me -2 on wide and +1 on tele, twice, all test is done with the settings and distance provided by Reikan. Thanks.


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## kaihp (May 13, 2016)

Bboogie said:


> First time here, I ran Reikan Focal twice and it gave me different results, first i got -3 then the second it went to -4, i ran Turbo Cal it gave me a -2, this is for a 50L it's rather strange because i did the 24-70 both ends and it gave me -2 on wide and +1 on tele, twice, all test is done with the settings and distance provided by Reikan. Thanks.



First off, you're not likely to see a difference of just one AFMA unit. Others have explained that there 8 units corresponds to the DoF at the maximum opening.

Secondly, the 50L is an f/1.2, vs the 24-70 is an f/2.8 (or f/4, you didn't say which version). It will be harder to get critically sharp focus at f/1.2 than f/2.8.

Third, the 50L is a relatively 'old' design, and some of the newer lenses (including the 24-70/2.8L II) has extra sensors internally to improve the accuracy of the focus distance measurement.


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## rado98 (May 13, 2016)

Try installing Magic Lantern. It can do DotTune automatically and it can even set/test afma past the -20/+20 restriction.


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## Bboogie (May 13, 2016)

@kaihp Thanks


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## Bboogie (May 13, 2016)

Does it defeat the purpose if i go closer than the required distance for the 50L, I'll try doing that tonight. Thanks again.


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## Mt Spokane Photography (May 13, 2016)

Bboogie said:


> Does it defeat the purpose if i go closer than the required distance for the 50L, I'll try doing that tonight. Thanks again.



Generally, a five point tolerance is considered to be within spec by Canon. Seeing a small variation is normal, there are many factors that affect AFMA.


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## Refurb7 (May 13, 2016)

Bboogie said:


> First time here, I ran Reikan Focal twice and it gave me different results, first i got -3 then the second it went to -4, i ran Turbo Cal it gave me a -2, this is for a 50L it's rather strange because i did the 24-70 both ends and it gave me -2 on wide and +1 on tele, twice, all test is done with the settings and distance provided by Reikan. Thanks.


Having a slightly different result each time is completely normal.


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## Refurb7 (May 13, 2016)

Bboogie said:


> Does it defeat the purpose if i go closer than the required distance for the 50L, I'll try doing that tonight. Thanks again.


The required distance is the minimum. I would not go closer. If you go closer, you're likely to throw off the AF for longer distances.


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## Bboogie (May 13, 2016)

Thank you,.


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## dcm (May 13, 2016)

Bboogie said:


> Does it defeat the purpose if i go closer than the required distance for the 50L, I'll try doing that tonight. Thanks again.



Reikan has a nice write up on the distance limits for testing. I'd stick with their recommended distance if possible. 
http://www.reikan.co.uk/focalweb/index.php/online-tools/test-distance-target-size-calculator_original/target-distance-size-information/

Reikan also discusses how microadjustment varies with distance (it's not constant), particularly when you get closer. Moving too close can throw the adjustment off for longer distances. Unless, of course, that is the only distance you ever shoot at with that lens. Check out this document.
http://s449182328.websitehome.co.uk/focal/dl//Docs/FoCal%20Test%20Distance_1.1.pdf


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## the.unkle.george (May 14, 2016)

Light color temperature also effects focus calibration, and at least the 50mm f1.4 tends to focus shift when you stop down. ie, the focus moves closer to the camera when you stop down from f1.4 to f5.6. 
If you want dead on accuracy at 1.2, use magnified live view.


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## rpt (May 14, 2016)

I use Reikan Focal. I swear by it. I used the inclined ruler method earlier but was not too satisfied. I have not tried dot tune although I have ML on my 5D3.

One thing to ensure is that you have sufficient light on target and a stable tripod. If not your readings are going to be wildly off. Even when I do it in the day, I have a light source pointed at the target as clouds cause disruptions.


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## Don Haines (May 14, 2016)

I tried the dot tune method with my camera. Results were very inconsistent..... I ended up getting Reikan Focal and have been very pleased with the results.


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## rfdesigner (May 14, 2016)

Don Haines said:


> I tried the dot tune method with my camera. Results were very inconsistent..... I ended up getting Reikan Focal and have been very pleased with the results.



I can't quite understand this. I know you Don ought be be doing it right but I'd be interested in exactly how you were doing it, my experience is the exact opposite.


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## Don Haines (May 14, 2016)

rfdesigner said:


> Don Haines said:
> 
> 
> > I tried the dot tune method with my camera. Results were very inconsistent..... I ended up getting Reikan Focal and have been very pleased with the results.
> ...


I found the dot tune method to work with the longer lenses and came close to the Reikan values, but with the wide lenses I had no success....


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## rfdesigner (May 15, 2016)

Don Haines said:


> rfdesigner said:
> 
> 
> > Don Haines said:
> ...



What happens?.. I can understand it on some wides where the focal length can vary a bit across the field of view, I'm just trying to see what's going on with a view to modifying my technique.

My 28f1.8 has a fair bit of focus difference across the field of view (not a simple curved focal plane), however I use either centre point or my two most outer points 99% of the time, and these seem to be at about the same focal length.


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## lw (May 18, 2016)

I share the frustrations of AMFA.
You want to try it on a Sigma 150-600mm which via the dock gives you the option to set the MFA for 4x focal lengths each at 4x distance settings. That is 16x dot tune sessions. After a while you know the best approach is just to buy a mirrorless camera 

I too have found dottune to be less reliable - and equally the automated dottune in ML - though I was critised on the ML forums for daring to suggest it didn't work very well. 

The issue seems to be at longer focal lengths where I would get lots of variability in the results.
I would let it do the adjustment using dottune ML, then repeat it to double check, and get a different result.
Then I would try a different target and get a different result again.

I have found Reikan Focal to be more successful and consistent. However, the issue with the longest focal lengths is placing a suitable target somewhere at distance.
Whilst Reikan suggest that the distance need not be so great, the Sigma dock allows me to adjust it at both 14m and infinity. So putting the Reikan target at something like 30m is itself a challenge!


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## Woody (May 18, 2016)

lw said:


> I share the frustrations of AMFA.
> You want to try it on a Sigma 150-600mm which via the dock gives you the option to set the MFA for 4x focal lengths each at 4x distance settings. That is 16x dot tune sessions. After a while you know the best approach is just to buy a mirrorless camera
> 
> I too have found dottune to be less reliable - and equally the automated dottune in ML - though I was critised on the ML forums for daring to suggest it didn't work very well.



Here is my experience.

With Canon lenses mounted on Canon cameras, Dot-tune implementation in ML works very well for me (16-35 f/4 IS, 24-105 f/4 IS, 70-200 f/4 IS, 50 f/1.4, 100 f/2.8 IS). My target is a block of flats 120 m away.

But with Sigma 30 f/1.4 Art lens, the results using the Dot-tune method are totally off. I can tell the target is not in focus, but the camera insists it's OK. Sigh...

So, I fell back on LensAlign. Target is ~ 1.5 m away. Results tested so far are reliable.

My guess is 3rd party lenses don't communicate correctly with Canon bodies, thus resulting in inaccuracies registered by the Dot-tune technique. More traditional methods like LensAlign and FoCal work fine with 3rd party lenses.

Ultimately, I agree the best solution is MILC or a DSLR equipped with DPAF. ;D


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## lw (May 18, 2016)

Woody said:


> Here is my experience.
> 
> But with Sigma 30 f/1.4 Art lens, the results using the Dot-tune method are totally off. I can tell the target is not in focus, but the camera insists it's OK. Sigh...



Interesting that it was your Sigma as well that gave you issues. 
I did all my other Canon lenses using Focal. But because of the distance issues tried dottune ML instead with the Sigma, and like you failed.


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## scottkinfw (May 18, 2016)

Bboogie said:


> Does it defeat the purpose if i go closer than the required distance for the 50L, I'll try doing that tonight. Thanks again.



Moving the camera may affect final result.

sek


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## ritholtz (May 18, 2016)

Woody said:


> lw said:
> 
> 
> > I share the frustrations of AMFA.
> ...


I have same 30mm sigma. I did simple test with ruler. It just focus wherever it wants on chart. There is no method to it. Did same test with Canon 85mm 1.8. It is always focussed at same location.


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