p.4 #1 · DotTune: New AF tune technique, no photos required
Jay968 wrote:
Snapsy...question...
How does setting the final AF fine tune point to the middle of the accepted range account for the 1/3 2/3 rule?
When tuning to a 2-D target the distribution of front/rear DOF will follow the 70/30 rule or whatever the natural optical/CoC distribution is for a given shooting scenario. When tuning to a 3-D target like LensAlign the balance can be changed to suit one's preference, like the 50/50 balance many prefer. I made a short mention of this in the 'Additional Notes' section near the end of the DotTune video.
p.4 #2 · DotTune: New AF tune technique, no photos required
Jay968 wrote:
I have been using about 7 feet at the 50mm setting on my 24-70. All my post tuning tests have been done at a pretty large sampling of distances as I want to be able to see what happens at any distance if I tune anything. Even at the same 7 foot distance my results are off unless I do it manually. For instance, my manual tuning results in a +6 for that lens. Dot Tune results in -4 which does not produce sharp results at that 7 foot distance at 50mm. BTW if I do casually observe the results, they are ok. If I blow up the image especially by printing it and observing the actual depth-of-field, it is just way off.Dot Tune seems to produce a result which at best achieves focus at the EDGE of the depth-of-field. Often enough it is just beyond that. If I had shot a flat target on the wall, I am not sure I would have noticed anything wrong. That's why I asked about the 1/3 2/3 rule in my last post. Is it possible that for even more precise results the final AF tune number should be a little further into the depth-of-field than what a mid point may set it to? Well maybe not..since the goal of Dot Tune I guess is to be able to get the camera to focus at the same point that the live view focus is at....Show more →
Hmm...have you retried DotTune today with the lens and body set to AF and configured for back-button focusing, as described by Michael?
p.4 #3 · DotTune: New AF tune technique, no photos required
Yes, actually I spent a good part of today trying it, retrying it and re-checking my manual settings.
Sorry to be a pain about this. For whatever reason it just seems to not be working for me. I have only tried the one lens so far though. I need to try it with another.
p.4 #4 · DotTune: New AF tune technique, no photos required
Jay968 wrote:
When you 'tuned by eye' was this by looking through the viewfinder (or LCD), or did you view on a larger monitor, or better yet make some prints?
I tried two different approaches; I was using an inclined target similar to a ruler or the commercially available lens tuning aides. The problem with this approach - my fault probably - was I was shooting too close to the target, in addition to judging results by eye.
The second effort involved shooting a planar subject square to the camera. My guess is I was far too close, again, for this to work well, but still I was able to determine a range of acceptable values. Had I made notes of the upper and lower limits of that range, and then picked the middle point, maybe I'd have got the same results as FoCal or DotTuning. Instead, I sifted through 40 different tuning values times 5 or 10 images per tuning value, eliminated groups which had no or few in-focus images, eventually whittling them down to just a few from which I picked the group that returned the best focus quality and the most in-focus images.
I did not keep notes of that process but I thought it was sound. It is very likely that by coincidence a group near the outer range happened to look best to me at the time, probably by virtue of the test conditions. Again, had I marked the lower and upper bounds of what seemed to be generating acceptable (but not necessarily "the best") images, and then divided that range in half and used that value, maybe I'd have achieved the same results as FoCal or DotTuning. Instead I was too focussed on picking groups which appeared to achieve maximum focus quality. I think this may be a common trap by those new to autofocus tuning, like me.
p.4 #5 · DotTune: New AF tune technique, no photos required
Jay968 wrote:
Yes, actually I spent a good part of today trying it, retrying it and re-checking my manual settings.
Sorry to be a pain about this. For whatever reason it just seems to not be working for me. I have only tried the one lens so far though. I need to try it with another.
It's no pain at all. Can you try a different lens to see if you get better DotTune results? Preferably a large-aperture prime? Just to give us a baseline and eliminate the zoom from the equation for now.
p.4 #6 · DotTune: New AF tune technique, no photos required
snapsy wrote:
My pleasure.
I've mentioned it before but I think both Canon and Nikon have a wider range in VF confirmation than it otherwise should in order to make focusing with manual lenses easier and faster, basically adding some slop to make the in-focus point faster for photographers to find, and your discovery dovetails perfectly with this.
Not sure that my observation conflicts with this idea. When using some of the wonderful old MF Nikkors with a really long focus throw, I find that the VF "meatball" indicator stays lit for only a small fraction of the focus rotation. For newer MF lenses with considerably less focus throw one should observe even more "sensitivity" to the focus ring position.
A related question: is there any application of this tuning technique that can be applied to MF lenses?
p.4 #9 · DotTune: New AF tune technique, no photos required
James R wrote:
It seems it's not needed. MF is dependent on the photographer's visual acuity.
You can use DotTune on MF lenses, at least on Canon bodies. On Nikon bodies when the lens or body is set to MF (or implicitly via a MF lens), the firmware significantly expands the in-focus range of the VF confirmation, making it much less precise but also easier to focus, particularly for lenses with poor focus rings.
p.4 #10 · DotTune: New AF tune technique, no photos required
snapsy wrote:
You can use DotTune on MF lenses, at least on Canon bodies. On Nikon bodies when the lens or body is set to MF (or implicitly via a MF lens), the firmware significantly expands the in-focus range of the VF confirmation, making it much less precise but also easier to focus, particularly for lenses with poor focus rings.
I have read what you have posted about MF significantly expanding the in-focus range of the VF confirmation. However how do I reconcile this with my experience with some long focus throw MF Nikkor lenses (see post above). The VF "meatball" seems very sensitive to the focus ring position even with such lenses.
In any case, I assume the procedure would be to
-manual focus using eyeball + magnification in live view
-switch off live view and check VF indicator (using AF-ON button & half press of shutter)
-check at various positions of fine tune adjust and select middle of range.
p.4 #11 · DotTune: New AF tune technique, no photos required
snapsy wrote:
You can use DotTune on MF lenses, at least on Canon bodies. On Nikon bodies when the lens or body is set to MF (or implicitly via a MF lens), the firmware significantly expands the in-focus range of the VF confirmation, making it much less precise but also easier to focus, particularly for lenses with poor focus rings.
See you point. I don't use the green confirmation when MF, so, I never considered it.
p.4 #12 · DotTune: New AF tune technique, no photos required
blumesan wrote:
I have read what you have posted about MF significantly expanding the in-focus range of the VF confirmation. However how do I reconcile this with my experience with some long focus throw MF Nikkor lenses (see post above). The VF "meatball" seems very sensitive to the focus ring position even with such lenses.
In any case, I assume the procedure would be to
-manual focus using eyeball + magnification in live view
-switch off live view and check VF indicator (using AF-ON button & half press of shutter)
-check at various positions of fine tune adjust and select middle of range.
The expanded range of focus confirmation observed between MF/AF is in terms of AF tune units. The difference in confirmation in terms of focus-ring throw will depend on the particular lens and its focus ring characteristics. Yep, the procedure you list is correct.
p.4 #13 · DotTune: New AF tune technique, no photos required
I just wanted to thank you for the Dot Tune Method.
I shoot a D800 and have fine tuned my 300mm f/4 and 500mm f/4 with and without TC's with your method.
I also have the Lens Align kit. The Dot Tune method was so much easier and gave me results very close to Lens Align.
Now if I could only get my 500mm to find tune with 1.4 or the 1.7 TC, I would be very happy. I can not get a confirmed solid focus with either TC on the 500.
The 500mm f/4 VR versions and the 1.7 TC start to give me a solid dot with the adjustment at +20 and the default at +19.
The TC's work great on the 300mm , but not on the 500mm.
p.4 #15 · DotTune: New AF tune technique, no photos required
blumesan wrote:
I have read what you have posted about MF significantly expanding the in-focus range of the VF confirmation. However how do I reconcile this with my experience with some long focus throw MF Nikkor lenses (see post above). The VF "meatball" seems very sensitive to the focus ring position even with such lenses. .
I'm not sure how an AF focus tuning system can be used in conjunction with MF lenses, which by their very nature obviate the need for AF adjustment ! Maybe I'm missing something here.
Anyway I used quite a few older MF lenses on the Pentax K7 and then K5 and now use Zeiss lenses on the D800. To assist in accurate MF you do need to take the 'range' of the VF 'in-focus' indicator into consideration and find out .. for each of your MF lenses .. when turning the focus ring, from which direction focusing is most accurate. For every one of my lenses there is one direction that gives consistent sharp focus (when the VF 'in-focus' indicator lights up) and one direction that doesn't. You need to know which direction this is for each lens as it does vary.
p.4 #16 · DotTune: New AF tune technique, no photos required
I've been trying this technique this morning with my lenses. Maybe I'm doing somethng wrong, but no body/lens combo is giving me a green arrow and all te pictures look sharp. Is there something I am doing wrong or am I simply lucky? Bodies are d7000, d800 with 24-120, 70-200 and 500.
p.4 #17 · DotTune: New AF tune technique, no photos required
bipock wrote:
I've been trying this technique this morning with my lenses. Maybe I'm doing somethng wrong, but no body/lens combo is giving me a green arrow and all te pictures look sharp. Is there something I am doing wrong or am I simply lucky? Bodies are d7000, d800 with 24-120, 70-200 and 500.
Do you mean you're getting a confirmation at -/+ 20? Are you making sure to leave both the body and lens set to AF while you perform the DotTune?
p.4 #19 · DotTune: New AF tune technique, no photos required
snapsy wrote:
Do you mean you're getting a confirmation at -/+ 20? Are you making sure to leave both the body and lens set to AF while you perform the DotTune?
So do I tune the AF both ways untilI don't get a confirmation light in the viewfinder? That's not how I was reading the instructions so I may have missed that.
p.4 #20 · DotTune: New AF tune technique, no photos required
bipock wrote:
So do I tune the AF both ways untilI don't get a confirmation light in the viewfinder? That's not how I was reading the instructions so I may have missed that.
Right, you tune in both directions, finding the last AF tune value in on both sides that give a continuous confirmation, then take the midpoint of those two values.
