AFMA Auto Focus Micro Adjustment

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Paganman2

Senior Member
I am interested to hear how much adjustment folks have had to do with there camera with the AF-S 70-300ED VR attached, i settled om +3 after doing some testing at long distance comparing to live view at about 3 miles away, a comparison with two chimney ventilation pipes that where at 45deg to each other and about 100feet away, and the battery test with five in a line again at 45deg to the camera and about 20feet away, all this was done at 300mm and f5.6, i think i have got it ok.

How are you doing it and what are your settings ?

P.
 
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mikew_RIP

Senior Member
Not any help with the 70-300 but on the 150-600 with it having such a vast range and possibly very shallow DOF, i set mine to what i expected to be the closest focusing distance i would be able to use @ 600mm wide open,i ended up using +9 and work with the hope that any other combination of settings would give me more DOF due to focal length Fstop and a subject further away.
 
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Geoffc

Senior Member
As distance increases so does depth of field and therefore the focus accuracy becomes less critical. I do my long lenses at about 25' as that's where I experience the problem. Also, on a zoom you adjust at the focal length you are likely to use as it only fully affects one setting.

On my lenses I've had it as much as -20.


Sent from my iPad using Tapatalk HD
 
J

J-see

Senior Member
I tune mine at the length I shoot most but I prefer not to tune them at a too long distance. I don't even pay attention to the 50x crap they prescribe. I tuned the 200mm and the Tam at 400mm at maybe 5 meters.

I dot-tune them which is ridiculously simple and fast.

After tuning, all I need to check is the shortest focus distance and infinity and some shots to see if it's as I want.
 
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Paganman2

Senior Member
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Paganman2

Senior Member
J-see said:
I tune mine at the length I shoot most but I prefer not to tune them at a too long distance. I don't even pay attention to the 50x crap they prescribe. I tuned the 200mm and the Tam at 400mm at maybe 5 meters.

I dot-tune them which is ridiculously simple and fast.

After tuning, all I need to check is the shortest focus distance and infinity and some shots to see if it's as I want.
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There are these two chimneys with metal funnels about 100 feet away from me, they are about 3 feet apart and at a 45 deg angle between me and them, i have focused on the front one at f5.6 and 250 - 300mm and find i can see a subtle difference in focus between the front one(In focus) and the back one(slightly off) so i assume the adjustment is ok?

I have done the same with a row of five batteries about 20 feet away and again at 45deg, when i focus on the center batt again at f5.6 with 250 - 300mm after adjusting mine to +3 i am seeing the center batt sharp, and gradual out of focus behind with a more pronounced out of focus in front, so again i guess this is ok?

P.
 
J

J-see

Senior Member
Paganman2 said:
There are these two chimneys with metal funnels about 100 feet away from me, they are about 3 feet apart and at a 45 deg angle between me and them, i have focused on the front one at f5.6 and 250 - 300mm and find i can see a subtle difference in focus between the front one(In focus) and the back one(slightly off) so i assume the adjustment is ok?

I have done the same with a row of five batteries about 20 feet away and again at 45deg, when i focus on the center batt again at f5.6 with 250 - 300mm after adjusting mine to +3 i am seeing the center batt sharp, and gradual out of focus behind with a more pronounced out of focus in front, so again i guess this is ok?

P.
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The problem in fine-tuning focus at sight is that the least reliable factor is we ourselves. It's very hard for us to correctly eyeball anything since a lot of external factors influence how we perceive sharpness.

That's why I use the cam's "dot" to fine-tune. The cam doesn't care about any external factor and it is either in focus or out of focus. A program will do as fine.

You don't even need anything at 45° since all you need to find out is the range the cam considers "in focus". The moment I know my range, I pick the middle and that's it. At no point do I even take a shot and check the DoF. That's what I do when finished and only to check if I didn't mess up during my tuning.
 
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J

J-see

Senior Member
Paganman2 said:
How do you dot tune yours J see?

P.
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First: this is how I do it which doesn't imply it's the only or even best manner. It works for me. I encountered the method somewhere but I can't recall where exactly.

I put my cam on a tripod and level it out so it is perfectly horizontal. I don't want any angle while focusing. Then I set up a focus target at a distance, something which has plenty of contrast and makes focus as easy as possible for the cam. It requires enough light too.

Then I go to live-view and manually focus the lens (fully zoomed in) until it is as sharp as possible. Then I switch the lens to manual, same with the cam and make sure the focus method is AF-S, single shot. I also close live-view since I'll be using the viewfinder now.

I press my back-button to activate focus and since the lens is on manual, all the cam does is show one of those: <O> or some of them in the viewfinder.

All I need to do now is go to the AF-fine tune and find both ends of my range. I do not touch the focus ring on my lens else I have to redo everything. I start somewhere and check if it gives the in focus dot. If it doesn't, or the dot is blinking combined or not with a front or back arrow, I adjust the value until I directly have a dot each time I press the focus button. I work my way through the range until the dot starts blinking again. Once I know that range between a solid dot at the one end and a solid at the other, I just need to set the middle.

While tuning my Tam, I got the first solid dot at +5 and the last at +12. +4 and +13 did blink and occasionally show an arrow so they were no good.

From +5 to +12 = 7 divided by two is 3.5. So I can set it on either +8 or +9 and that's it.

After that I shoot subjects at different ranges to check if they're always in focus and also check the minimal and infinity to see if that still works.
 
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Paganman2

Senior Member
J-see said:
First: this is how I do it which doesn't imply it's the only or even best manner. It works for me. I encountered the method somewhere but I can't recall where exactly.

I put my cam on a tripod and level it out so it is perfectly horizontal. I don't want any angle while focusing. Then I set up a focus target at a distance, something which has plenty of contrast and makes focus as easy as possible for the cam. It requires enough light too.

Then I go to live-view and manually focus the lens (fully zoomed in) until it is as sharp as possible. Then I switch the lens to manual, same with the cam and make sure the focus method is AF-S, single shot. I also close live-view since I'll be using the viewfinder now.

I press my back-button to activate focus and since the lens is on manual, all the cam does is show one of those: <O> or some of them in the viewfinder.

All I need to do now is go to the AF-fine tune and find both ends of my range. I do not touch the focus ring on my lens else I have to redo everything. I start somewhere and check if it gives the in focus dot. If it doesn't, or the dot is blinking combined or not with a front or back arrow, I adjust the value until I directly have a dot each time I press the focus button. I work my way through the range until the dot starts blinking again. Once I know that range between a solid dot at the one end and a solid at the other, I just need to set the middle.

While tuning my Tam, I got the first solid dot at +5 and the last at +12. +4 and +13 did blink and occasionally show an arrow so they were no good.

From +5 to +12 = 7 divided by two is 3.5. So I can set it on either +8 or +9 and that's it.

After that I shoot subjects at different ranges to check if they're always in focus and also check the minimal and infinity to see if that still works.
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Thank you so much for doing all that, can i just ask a few questions please -
In LV when you say manually focus the lens (fully zoomed in) do you mean with the 70-300Vr you would zoom in to 70mm?
And when you focused on your subject in LV and got a a solid focus dot, then if you get the same with both AF-S and AF-C solid focus dot, would you consider that spot on.

P.
 
J

J-see

Senior Member
Paganman2 said:
Thank you so much for doing all that, can i just ask a few questions please -
In LV when you say manually focus the lens (fully zoomed in) do you mean with the 70-300Vr you would zoom in to 70mm?
And when you focused on your subject in LV and got a a solid focus dot, then if you get the same with both AF-S and AF-C solid focus dot, would you consider that spot on.

P.
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Since we can only set one value for every individual lens, if I tune a zoom, I set it to the most used length. If you're using the 300mm most of the time, pick that one. If not, pick any other you shoot mostly.

With fully zooming in live-view I meant the zoom option live-view has to zoom in at your shot. Not the lens. That's best to see how accurate your manual focus is. It doesn't matter if the cam thinks this is correct focus or not since I set it manually to perfect focus and after fine-tuning, it'll agree with me this is correct focus.

AF-S or AF-C single dot probably won't make much difference besides the fact that AF-C adjusts focus and in that is not as reliable. AF-S should get focus and that's it. It no longer corrects once focus is obtained. Therefor AF-S is preferable.

To add: should you have a lens where the range exceeds your fine-tuning limits; if +20 or -20 still give a solid dot, don't bother trying to get it tuned and send it in.

It's really a very fast and simple method and once you've done it a couple of times, you can check and tune any lens within a couple of minutes.
 
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Paganman2

Senior Member
Thank you for that J see, i think where i was testing indoors on batts was wrong, as firstly i dont have a tripod so i just had to rest the camera on a chair, also although i compared focus to LV zoomed in, i did not do this in manual focus mode, all the time i was in AF mode mainly AF-S i just assumed that as long as the in focus point was the same between LV and normal and centered on the subject i wanted to be in focus, this would indicate good focus?

P.
 
J

J-see

Senior Member
Paganman2 said:
Thank you for that J see, i think where i was testing indoors on batts was wrong, as firstly i dont have a tripod so i just had to rest the camera on a chair, also although i compared focus to LV zoomed in, i did not do this in manual focus mode, all the time i was in AF mode mainly AF-S i just assumed that as long as the in focus point was the same between LV and normal and centered on the subject i wanted to be in focus, this would indicate good focus?

P.
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The problem with not using a tripod is that the constantly pressing buttons will move your cam. You need to be able to fix its position else you can no longer rely on the focus dots. If you move it ever so slightly forward or backwards, you might get a larger range than it actually had and will set the middle wrong.

You have to set focus in live-view, switch the lens to manual when done and then exit it and use the viewfinder. I'm not even sure if live-view and normal shooting use the exact same focus methods so I'm using live purely to see what I'm doing when setting correct focus manually. After that, only the dots in the viewfinder are important.

If you skip any step or use another method for anything I would no longer know if the result will be correct.

Also: use something easy to set focus on. I have a book cover here that has some black and white shapes which make it almost impossible to not see what is sharpest and they make it very easy for the cam too.

Another also: when changing values in AF fine-tune, you have to set a value and press ok. Only then you can press focus and check it. Going through them without affirming them each time is no guarantee that value is applied. Only when pressing ok you're sure.
 
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J

J-see

Senior Member
Paganman2 said:
I will have a go at dot tuning - but without a tripod any ideas of the best way to do this.

P.
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Any flat surface will do, like a table, but you'll need something holding the cam in position or anything you can press the cam against so the distance will remain identical and the cam can't move left or right.

You have to improvise and the better you can secure the cam, the more reliable the results.
 
D

Don Kuykendall_RIP

RIP :(
You can also remove the shade from a lamp and mount your camera on it. The screw on most lamps is the same as a tripod mount. Just be sure your lamp is heavy duty enough to hold the camera stable.
 
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Paganman2

Senior Member
J-see said:
Any flat surface will do, like a table, but you'll need something holding the cam in position or anything you can press the cam against so the distance will remain identical and the cam can't move left or right.

You have to improvise and the better you can secure the cam, the more reliable the results.
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Ok i will try that, does this method take into account front or back focusing errors, is it doing the same as if you had a scale at the side of a target?

p.
 
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