p.11 #1 · DotTune: New AF tune technique, no photos required
Korben wrote:
Thanks a lot for the information! One more oddity: with the camera still firmly on the tripod since I left it this morning, I did a new tuning with AF-S/single/center point and now the values are +1 / -9 instead of +5 / -18. The range is wild, something doesn't make sense, either I'm doing something wrong or the lens/camera combo is out of whack. Any ideas?
Was the focus was locked between the two DotTune sessions?
p.11 #2 · DotTune: New AF tune technique, no photos required
CanadaMark wrote:
We will have to agree to disagree, and I still don't think you understand what I am saying based on your response. Nikon strongly cautions the method as well. Your experience is very different than mine, I don't think we will gain anything from arguing. If you are satisfied with this method then that's great and I'll leave it at that, but some of the things you are telling people are misleading.
My comments are based on about 6 months of intensive work and lots of feedback from users. What is your basis that the information I'm presenting is misleading? As for Nikon cautioning - if they didn't believe AFMA was useful they wouldn't include it on their cameras, nor would they have further extended the feature by automating it on their newest cameras. Same for Canon, Pentax, Sony, and others.
p.11 #3 · DotTune: New AF tune technique, no photos required
CanadaMark wrote:
We will have to agree to disagree, and I still don't think you understand what I am saying based on your response.
And to get more specific, you described why taking the midpoint of a large confirmed AFMA can't produce reliable results. I provided specific technical information about what your statement is incorrect. Rather than address this you reply that my response indicates that I don't understand what you're saying, then finish it that I'm being misleading. As always I've been very open to objective technical discussion about the technique but one thing I can't counteract are opinions based on feelings, unexplored observations, or platitudes rather than an objective technical basis.
p.11 #4 · DotTune: New AF tune technique, no photos required
I started each tuning session from scratch, that is setting AF tuning off, acquiring focus in LV (back button) switching off LV for the remainder of the steps with AF tuning on and using the shutter button to confirm between adjustments.
p.11 #5 · DotTune: New AF tune technique, no photos required
Korben wrote:
I started each tuning session from scratch, that is setting AF tuning off, acquiring focus in LV (back button) switching off LV for the remainder of the steps with AF tuning on and using the shutter button to confirm between adjustments.
This will bring in the focus-step variability I described earlier. If you re-establish focus between attempts and the focus is not verified within the precise point of the DOF then you may get variability between attempts. As a first step I would try two separate DotTune sessions using the same locked focus - this will establish that your technique for observing the confirmed range is correct and consistent (ie, using multiple half-shutter presses for each confirmed AFMA value and waiting 5 seconds for each, to eliminate any false-positives). Once this has been established you can then move on to seeing if the 2D focusing is sufficient for the AFMA precision you need and if not, adding 3D reference cues to get the AFMA tuned for a specific DOF (ie, defining how much of the DOF you want in front and behind of your focus subjects by way of the AFMA value chosen).
p.11 #7 · DotTune: New AF tune technique, no photos required
Hi guys,
I've got the D7200 and a new Tamron SP70-200 Di VC USD. The lense itself is really nice, but it seems to produce a front-focus.
I've read the guide about Dot Tune and I think I will give it a try.
But there are 2 questions left, and maybe you can help me out.
1) Why 50 x Focal Distance? Why not closer or further?
2) As I understood I should put the AF function on the AF/AL button to avoid any focus changes while half-pressing the trigger.
But wouldn't I have the same effect if I would switch the system to MF?
Notice: I know that the manual says, always switch body AND lense to MF, to avaid damages. But as far as i know this is just neccessary if a lense with "rod drive" (no idea how it's called in english) is in use.
So for my question I would suggest, that we say "the MF mode itself was activated correctly".
p.11 #8 · DotTune: New AF tune technique, no photos required
Some more thoughts about the 50x Focal dinstance stuff....
Where do I have to meassure this distance?
Let's say, we need 3.5m.
- Do I need to add the crop factor (APS-C / Nikon DX) and go to 5.25m distance or is the crop factor not important in this case?
- Which distance is meant?
Wall - 1st lense?
Wall - middle of the tripod?
Wall - sensor?
Wall - theoretical entrance pupil?
And if I am not sure, would it be a good idea to make the distance bigger?
p.11 #9 · DotTune: New AF tune technique, no photos required
Spawnie wrote:
Hi guys,
I've got the D7200 and a new Tamron SP70-200 Di VC USD. The lense itself is really nice, but it seems to produce a front-focus.
I've read the guide about Dot Tune and I think I will give it a try.
But there are 2 questions left, and maybe you can help me out.
1) Why 50 x Focal Distance? Why not closer or further?
2) As I understood I should put the AF function on the AF/AL button to avoid any focus changes while half-pressing the trigger.
But wouldn't I have the same effect if I would switch the system to MF?
Notice: I know that the manual says, always switch body AND lense to MF, to avaid damages. But as far as i know this is just neccessary if a lense with "rod drive" (no idea how it's called in english) is in use.
So for my question I would suggest, that we say "the MF mode itself was activated correctly"....Show more →
The 50x focal distance has been the historical rule of thumb for AF tuning. However after posting the video I have since switched to using a subject at infinity, which I've found produces better results esp for lenses that have distance-specific AF tune variability.
The reason you have to leave the body in AF mode on Nikon cameras is that when the body and/or the lens is in MF mode, the firmware widens the range of focus that produce a focus confirmation in the viewfinder. Presumably Nikon does this to make manual focusing faster/easier but at the expense of accuracy. I posted more details about this here.
