p.30 #1 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
snapsy wrote:
If that's the case then it sounds like the 1D Mark III behaves different than all other Canon/Nikon bodies in that it doesn't keep the dot continuously illuminated in MF mode when focus has been established. So to DotTune the body use the same procedure described in the video but change the criteria for what represents a "solid confirmation" - instead of relying on a continuous confirmation, use the single flashing dot (or single beep) instead. It'll produce less precise feedback than relying on the continuous method but it should get you to the right midpoint. Good luck and please report back your results!...Show more →
Hello snapsy:
I wished another Canon 1D3 owner / user would comment on the results they got, IF they used the "Dot-Tune" AF MA procedure?
I would like to know if they achieved MF - SOLID green AF Confirmation.
Perhaps someone will be following this newest posting to the thread... and comment..?
I am now beginning to think that there might be an issue with the entire AF system within the camera.
I am addressing the issues, the serial # - is within the range, unfortunately. However the person I got the camera from had Canon check it out and said it was fine, did not need servicing.
p.30 #3 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
ELSELS wrote:
Hello Shutterbug2006:
I am addressing the issues, the serial # - is within the range, unfortunately. However the person I got the camera from had Canon check it out and said it was fine, did not need servicing.
Thanks,
Ed
~ ~ ~
If it falls in the serial number range, and experiences the problems associated with the AF issue, they will repair it at no charge, to whoever owns the camera - not just the original purchaser, regardless of if they looked at it before for that problem.
Unless it's been reported stolen. In that event, you might not get it back.
p.30 #4 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I tried a quick test, shooting a subject, outside my upstairs apartment window...
Was the heat on in your apartment and cold outside ? Heat pouring out the window will cause noticeable convection and most definitely cause blurry photos. Try the same test outside away from any heat source.
p.30 #5 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
snapsy wrote:
1. With the camera mounted on a tripod, enter Live View and establish critical focus on a high-contrast subject over the center point. Exit Live View.
2. Set the lens to MF (Manual Focusing). Be careful not to jostle the focus ring when you move the switch - you don't want to alter the focus you established in step #1.
3. Set AF tune to 0.
4. Look through the viewfinder to see if the camera thinks the subject is in focus by checking if the green focus confirmation dot is lit. You'll need to half-press the shutter (or AF-ON) while doing this to keep the metering/rangefinder from going to sleep. Assuming you get confirmation, increase the AF tune value and recheck the viewfinder, leaving the lens set to the original focus you established in step #1 - do not refocus the lens. You want to keep increasing the AF tune value until you no longer get a green confirmation dot. As you reach the edge of the range the green dot will either fail to light up or it may flicker...you may need to cycle the half-press of the shutter several times to confirm that the confirmation you get is consistent. You're done when you find the highest positive AF tune value that gives you a consistent green-dot confirmation - that value represents the positive end of the AF tune range....Show more →
The D750 does not give a green dot but a white dot.
After completing steps 1and 2 and confirming that I have set AF tune to 0 in step 3. I continue to get a solid White dot through a range of -13 to +20. I've assigned AF/ON to the AE-L/AF-L button for back button focusing if this makes any difference. Focus was originally set using LV and center focus point. Lens then set to Manual focus.
p.30 #6 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
MRomine wrote:
The D750 does not give a green dot but a white dot.
After completing steps 1and 2 and confirming that I have set AF tune to 0 in step 3. I continue to get a solid White dot through a range of -13 to +20. I've assigned AF/ON to the AE-L/AF-L button for back button focusing if this makes any difference. Focus was originally set using LV and center focus point. Lens then set to Manual focus.
p.30 #8 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I have a 5D3 & 24-70 f2.8L II.
I used the Dottune method and the wide end needs +1 and the tele end needs -1.5 so I used -1.
At some of the extreme values during the half press focus would take a long time to light up focus confirmation or light up randomly. I considered those values as not good focus confirmation.
So does it seem like the tolerances on the body and lens are pretty good? Even before MA I was getting some pretty sharp pictures wide open.
p.30 #9 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
garycoleman wrote:
I have a 5D3 & 24-70 f2.8L II.
I used the Dottune method and the wide end needs +1 and the tele end needs -1.5 so I used -1.
At some of the extreme values during the half press focus would take a long time to light up focus confirmation or light up randomly. I considered those values as not good focus confirmation.
So does it seem like the tolerances on the body and lens are pretty good? Even before MA I was getting some pretty sharp pictures wide open.
Pretty sure the 5D3 can do separate adjustments for wide and tele. I know the 6D can.
p.30 #12 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Hi
I ran a dot tune test today following the instructions to the letter
Im not sure what to do in the situation i came up against
Zero was my starting point and i got a perfect focus dot at zero and the problem is that all the way to positive 20 the focus dot stayed constant
BUT if I went from Zero in a negative direction then the focus dot stayed constant until minus 15
So bearing in mind it was constant focus upto +20 and constant down to minus 15 im not really sure what value to enter as this is 35 steps in total
Can anyone offer advice please
p.30 #13 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
currymonster wrote:
Hi
I ran a dot tune test today following the instructions to the letter
Im not sure what to do in the situation i came up against
Zero was my starting point and i got a perfect focus dot at zero and the problem is that all the way to positive 20 the focus dot stayed constant
BUT if I went from Zero in a negative direction then the focus dot stayed constant until minus 15
So bearing in mind it was constant focus upto +20 and constant down to minus 15 im not really sure what value to enter as this is 35 steps in total
Can anyone offer advice please...Show more →
There is a procedure that allows you to tune for lenses whose confirmed range extends beyond either +/- 20. Here are the instructions:
p.30 #14 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Thanks
I will check it out
One other thing i noticed today was I could calibrate a 18-140 zoom at say 50mm but when i tried the test at 100mm i had to calibrate with different set of values so does this mean my previous calibration at 50mm is now out
p.30 #15 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I had difficulty getting a solid five seconds of confirmation light on my Canon 7D. I taped a small flashlight to the wall to light up the target and it solved the problem. I mentioned this on DPReview and the flames came out. But I think that if dim (i.e., "not bright") lighting affects focus confirmation behavior, it can affect it most at the margins. And with Dot Tune, the margins matter, so I think that ensuring a well-lit focus target is important.
p.30 #17 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
snapsy wrote:
I recommended 50x in the video because that was the prevailing convention but in my testing since then I've found that tuning @ infinity produces the best results for most lenses, particularly those which exhibit distance-specific tuning variability. For such lenses I found that the AF tune value at MFD-to-50x doesn't work well @ intermediate and infinity distances but the tune value infinity works well at all distances. For infinity I use a natural target outside, like a roof or a tree.
I'm not sure if saying this here is smart but I guess I'll risk it. There possibly may be an answer as to why you get better results at 50x than MFD to 50x. This is based on this article. Page 1, paragraph 4. Each MFA adjustment = ⅛ of the Depth of Field. I have see that before and used to wonder what does that actually means and decided to explore it.
This is just a theory and not written in stone. I could be wrong which is perfectly fine. I'm only basing this on what Canon is telling me.
First of if Canon provides a value of ⅛ then DO Field must have a value. No matter how many ways I looked at it I concluded that is has to be the total DO Field based on f stop, focal length and distance to target. I just picked a 50mm lens, f 2.8 and 8.2 ft to target which is 50X and the calculator gave me a total DOF of 0.87 ft. Divided that by 8 = each MFA shift = 0.10875
Here are two examples of my 300L F4 IS. One is at 50ft to target is 5ft which is close to MFD. All other input is the same.
As you can see the total DO Field is quite a bit different. If you do the math then it shows the MFA shifts are not constant but variable based on f stop, focal length and distance to target. At 50ft the shifts are 1.89 and 0.015 at 5ft. MFA may be more prone to error the closer you are to you target. If the theory is correct you have to me more careful as you get closer.
DO Field is something that is projected through the lens and is what you see on the final image. What about at the sensor level? I wondered why Canon would say ⅛ of the DO Field and not DO Focus. While you could do the math there would be a decimal point followed by a lot of zeros. DO Field is what most people can relate to so that is probably why Canon used that instead of DO Focus.
As you can see here that we don't really need to know the value of the shifts at the sensor level. If you change the DO Field then the DO Focus at the sensor changes proportionally.
I think even knowing what the DO Field MFA shifts are is not that critical either. Knowing that the MFA shifts are variable based on f stop, focal length and distance to target and as you get closer the shifts become smaller is more important.
So I don't know if this holds water but I could not come up with any other explanation for what Canon means by ⅛ of DO Field.
p.30 #19 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
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.
p.30 #20 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
dgdg wrote:
Appreciate all your research.
The beautiful thing about dot tune, however, is I don't have to fiddle with all this.
David
I didn't either and I won't. Although a good tool I'm not a huge MFA fan. I have wondered over the years why there are so many suggested distances. That was one of the reasons. Even Canon has two. 50X and the distance you normally shoot at which I believe is the their latest recommendation. I'm working with thousands of dollars of precision equipment and was always curious of how these different distances impacted MFA.
I can't do much about any of it except pay attention to the distances I work at. It was really out of curiosity more than anything. I sort of concluded that and was looking for the Dot Tune video to familiarize my self with it again, the search led me here and I came across snapsy's posts. This was after I did that research and then found the posts about distances. I want to check my 100-400 with the 1.4.
