p.31 #2 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
jcolwell wrote:
I've read information that says, one step in the EOS Utility LiveView focus control interface ( < or > ) corresponds to a single step in the AF system. IOW, it's the smallest AF increment that you can use. The proportion of DOF that this corresponds to will vary with the parameters that affect DOF; namely, focal length, aperture, and distance. Further, this AF step size is the same as a single step in the AFMA value that you register in the camera.
I use this approach with a Lens Align II target, where the number of LiveView steps required to get the centre of focus at "zero" on the target is the same value that I enter into the AFMA registry. This consistently works for the six EOS DSLR, twenty+ EF lenses, and two extenders that I have performed AFMA tests with.
I'll look for the original reference about the relationship between EOS Utility LiveView focus steps and AFMA steps, and I'll post it here if I find it. OTOH, I'm not going to spend a lot of time looking for it, because I'm confident that it does work.
Also, some lenses (probably most lenses) are designed to put the centre of focus more or less in the middle of the DOF, while others are designed for different behaviour. For example, the SMC Pentax-A* 85/1.4 "portrait lens" has the centre of focus near the rear of the DOF, which provides increased separation between the subject and the background....Show more →
That would be helpful. Until a few days ago I always assumed that an MFA shift was one value across the board. Someone found a reference to Chuck Westfall who said the same thing but stated ⅛ of the DO Focus in another article which I don't have a link to. So now there is him and Rudy Winston's comment so I have to wonder what they mean. One is DO Field and the other Focus but they are proportional. One is just easier to visualize. Actually if he had of left it at "fine increments" even that is easier to understand. If he had of said DO Focus I'd be wondering what that meant even more than DO Field.
I'm not so concerned about the back and front as much as total DOF, distance and the effect on MFA.
Also when I was goofing around with this I was still wondering about the MFA shift being one constant value no matter what the input is. I thought perhaps Canon uses the standard 50mm 1.2 for that number but he did not say that.
So both used ⅛ of either DO field and Focus so that has to mean something. If I got it wrong it was an interesting journey.
p.31 #3 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
snapsy wrote:
I get best results by tuning at infinity rather than the recommended 50x focal length.
Kinda of embarrassed as to not getting what that means. What distance involved here? What do you set your lens aperture at? I found this on the net.
"True 'infinity' focus means that the lens will perfectly focus (disregarding lens aberrations) parallel rays of light to a point on the film or sensor plane, no matter what the aperture is."
p.31 #4 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Zenon Char wrote:
Kinda of embarrassed as to not getting what that means. What distance involved here? What do you set your lens aperture at? I found this on the net.
"True 'infinity' focus means that the lens will perfectly focus (disregarding lens aberrations) parallel rays of light to a point on the film or sensor plane, no matter what the aperture is."
p.31 #5 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Also Romy Ocon (liquidstone) once posted that he does MFA at MFD. At POTN someone said a company in Sweden I think MFA's all the long lenses at something like 21ft or so. All this made me curious.
So far I have concluded I won't do MFA less than 50X and try to do this at the distance I usually shoot at. At 560mm the best I can comfortably do indoors is about 15X. I know you stated roof tops, etc in another post snapsy. I read about others that use street signs, etc. I'm going to head out to a local park and give this a try at distance.
p.31 #6 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
snapsy wrote:
Any distant target will do, like a mountain, tree, rooftop of a house, etc...
I think my last post and yours came up a the same moment. I answered my own question about one part. Do you leave your lens wide open at those greater distances? I'm wondering if eventually you run out of room with regards to DOF. That article said " lens will perfectly focus no matter what the aperture is" so do you stop it down?
Are you the author of Dot Tune? It helped verify a brand new Canon lens was way out to lunch. That one went back to Canon. First time that has ever happened to me.
p.31 #7 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Zenon Char wrote:
I think my last post and yours came up a the same moment. I answered my own question about one part. Do you leave your lens wide open at those greater distances? I'm wondering if eventually you run out of room with regards to DOF. That article said " lens will perfectly focus no matter what the aperture is" so do you stop it down?
Are you the author of Dot Tune? It helped reverify a brand new Canon lens was way out to lunch.
AF phase detection/acquisition always occurs wide-open on DSLRs. DOF is not a concern when tuning at infinity. I am the author of DotTune (I go by "horshack" everywhere online except for FM).
p.31 #8 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Zenon Char wrote:
Someone found a reference to Chuck Westfall who said the same thing but stated ⅛ of the DO Focus in another article which I don't have a link to. So now there is him and Rudy Winston's comment so I have to wonder what they mean. One is DO Field and the other Focus but they are proportional. One is just easier to visualize. Actually if he had of left it at "fine increments" even that is easier to understand. If he had of said DO Focus I'd be wondering what that meant even more than DO Field.
Depth of Focus is the range at the sensor plane of focus, ... the range by which focus there can vary and still have the focus point appear to be in focus -- for some unspecified print size (8x10 is the usual standard) -- for some unspecified viewing distance (about 40 cm = 16 inches, like sitting at a table) -- with normal 20/20 visual acuity.
Depth of Focus and Depth of Field both get smaller as you increase print size while maintaining viewing distance. Viewing images at 100% on a large monitor is like viewing a 4 foot wide print from the same viewing distance.
The verb you seek is "have", as in "if he had have left it", though "if he had left it" and "if he had said" are even clearer and are more direct.
p.31 #9 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
snapsy wrote:
AF phase detection/acquisition always occurs wide-open on DSLRs. DOF is not a concern when tuning at infinity. I am the author of DotTune (I go by "horshack" everywhere online except for FM).
That sounds familiar. Thanks for your help. Looking forward to trying it out.
p.31 #10 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Monito wrote:
Depth of Focus is the range at the sensor plane of focus, ... the range by which focus there can vary and still have the focus point appear to be in focus -- for some unspecified print size (8x10 is the usual standard) -- for some unspecified viewing distance (about 40 cm = 16 inches, like sitting at a table) -- with normal 20/20 visual acuity.
Depth of Focus and Depth of Field both get smaller as you increase print size while maintaining viewing distance. Viewing images at 100% on a large monitor is like viewing a 4 foot wide print from the same viewing distance.
The verb you seek is "have", as in "if he had have left it", though "if he had left it" and "if he had said" are even clearer and are more direct. ...Show more →
I knew DO Focus is at the sensor. That was why I figured Rudy Winston used DO Field as most of the genera public would understand could relate to it better. I have know way of verifying this. Like I said if he had have just left it at "fine increments" I would not have been doing all of this.
I asked about limits of DOF because lens align sells a longer ruler but I guess that is for shorter distances to the target. I really did not want to run out of the +-20 limit. I am aware of the procedure for that.
p.31 #14 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
All my stuff is pretty good but I was not too sure about my 100-400 MK2 @ 400mm with my 1.4 MKII. I'm not sure about infinity but I figure my target was about at least 100 ft away.
It would still blink and beep quite happliy at +20 and the best response at the low end was +5. I was not too surpirsed as I have read some people had to MFA with a final result of about +12 at POTN with that combo. At +12 you figure you are hitting or close to 20. I took it off the TC and got about a +3 which I'm not going to worry about because my real world shots look great.
It appears that I could not even use Focal if I wanted to but there may be a work around. I have not looked at it for about 6 months. Dot Tune is simpler anyway and I don't have a laptop.
Can someone provide a little more detail about this. I know it works but defocusing to focus my $5000 worth of equipment makes me edgy Is direction important?
p.31 #15 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Zenon Char wrote:
All my stuff is pretty good but I was not too sure about my 100-400 MK2 @ 400mm with my 1.4 MKII. I'm not sure about infinity but I figure my target was about at least 100 ft away.
It would still blink and beep quite happliy at +20 and the best response at the low end was +5. I was not too surpirsed as I have read some people had to MFA with a final result of about +12 at POTN with that combo. At +12 you figure you are hitting or close to 20. I took it off the TC and got about a +3 which I'm not going to worry about because my real world shots look great.
It appears that I could not even use Focal if I wanted to but there may be a work around. I have not looked at it for about 6 months. Dot Tune is simpler anyway and I don't have a laptop.
Can someone provide a little more detail about this. I know it works but defocusing to focus my $5000 worth of equipment makes me edgy Is direction important?
p.31 #17 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I did not get a chance to try out the over 20 procedure yet and just left it on what I thought would be close at +14.
I'm going to try something out regarding distances hopefully in few days. Since I know this combo is out a lot I'm going to try Canon's method and align small pieces of tape on the lens barrel and focusing ring and try it at 100 ft and MFD and see how much the focusing ring moves for each distance. I will leave all camera settings alone, just change the distance to target. Currently based on what I am seeing and what Canon says I will always try to MFA at the distances I shoot at which is not very practical for most situations, I will always try to do this at least maintain 50X or basically infinity.
p.31 #18 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I hate to ask as it's probably a dumb question so please be kind.
I have been using the Dot-Tune method with great success but today I was attempting to MFA my 7d2 / 400 5.6L with a 1.4x iii and for some reason I cannot get a focus confirmation light in MF mode after focusing in AF mode. Works fine without the extender, no problem.
Will the 7d2 not give a focus confirmation light in MF mode with an extender?
p.31 #19 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I am pretty sure it still gives the AF beep confirmation with TC. I would first try to clean the contacts, and Also make sure to put the TC onto the lens before mounting onto the camera. I have seen on other threads the 7dii might have a sensitivity to the order of mounting.
p.31 #20 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
gschlact wrote:
I am pretty sure it still gives the AF beep confirmation with TC. I would first try to clean the contacts, and Also make sure to put the TC onto the lens before mounting onto the camera. I have seen on other threads the 7dii might have a sensitivity to the order of mounting.
Yes I have been following that as well. Canon recommends to put the TC on the lens first, then on the cam. Same for removing. Detach TC with lens from body first.
I wonder if powering down makes no difference in the order. There are no instructions for camera, lens or TC about powering down.
