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Archive 2013 · DotTune: New AF tune technique, no photos required
  
 
Sern
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p.6 #1 · DotTune: New AF tune technique, no photos required


I had read in other fine tuning instructions that you took into account the 1.5 factor of a Dx when determining the distance to subject. I guess it's not making sense to me then.

Thanks guys for the replies.



Jun 05, 2013 at 05:58 PM
binary visions
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p.6 #2 · DotTune: New AF tune technique, no photos required


I believe the "rule" is only meant to determine a somewhat normal focus distance when using a given lens. It's not hard and fast - everyone's use of a lens will differ somewhat. When determining a normal focus distance, the DX crop factor would be taken into account.

Don't stress about it. Figure out a normal focus distance for you, and go with it.



Jun 05, 2013 at 06:06 PM
jasoncallen
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p.6 #3 · DotTune: New AF tune technique, no photos required


Very very cool method, snapsy! I just successfully applied this to my office's D700 (results agree with LensAlign), and will be doing the same to my own D700 tonight


Jun 05, 2013 at 08:40 PM
jasoncallen
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p.6 #4 · DotTune: New AF tune technique, no photos required


Update: Just used DotTune on my own set of lenses and D700 at home, and the results speak for themselves... My beater of an old 70-300 f/4-5.6 AFD that was never sharp on my film bodies, and has sat on a shelf since 1999, is now actually focusing sharply on my D700!

The original post and accompanying video should be stickied on the top of the Nikon forum. Great contribution, Snapsy! Thanks!



Jun 09, 2013 at 03:47 PM
jeffparks
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p.6 #5 · DotTune: New AF tune technique, no photos required


Should the pattern be viewed on computer screen, or printed?



Oct 05, 2013 at 09:05 PM
snapsy
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p.6 #6 · DotTune: New AF tune technique, no photos required


jeffparks wrote:
Should the pattern be viewed on computer screen, or printed?

I use a printed pattern but an on-screen one might work just as well. Might even be better since you can utilize moiré during the LV stage to establish more precise focus.



Oct 06, 2013 at 12:12 AM
DSL67
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p.6 #7 · DotTune: New AF tune technique, no photos required


I will have to try this. Thanks!


Oct 08, 2013 at 02:06 AM
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p.6 #8 · DotTune: New AF tune technique, no photos required


i tried this method and i have a few observations .
when setting the adjusted value and half pressing - u need a to observe the dot a lot , how it comes up ( instantly quick or a bit delayed or delayed ) if u dont pay too much attention u will get a very wide range . u have to do a lot of tinkering putting values high and low to check how quick the dot appears / if its a tad deleayed , or really delayed , U can pick out only when it instantly comes up and the range will be smaller



Nov 04, 2013 at 01:10 AM
cmarqz
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p.6 #9 · DotTune: New AF tune technique, no photos required


Thanks for this, snapsy. Got my Sigma 35 dialed in with this technique.

I see there are those that fine-tuned their zooms. Is there a certain way of fine tuning a 70-200 2.8? Tried to search (probably didn't try hard enough), but couldn't find what I was looking for.

I did the DotTune for different focal lengths and got the following results:

70mm, range of -11 to -13: -12
105mm, range of -12 to -17: (-14.5) -15
135mm, range of -8 to -10: -9
200mm, range of -7 to -13: -10

Do I use the average of the results?

jasoncallen wrote:
Update: Just used DotTune on my own set of lenses and D700 at home, and the results speak for themselves... My beater of an old 70-300 f/4-5.6 AFD that was never sharp on my film bodies, and has sat on a shelf since 1999, is now actually focusing sharply on my D700!

The original post and accompanying video should be stickied on the top of the Nikon forum. Great contribution, Snapsy! Thanks!

Jason, did you do the DotTune at certain focal lengths or just at 300m?



Dec 07, 2013 at 08:59 PM
snapsy
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p.6 #10 · DotTune: New AF tune technique, no photos required


cmarqz wrote:
Thanks for this, snapsy. Got my Sigma 35 dialed in with this technique.

I see there are those that fine-tuned their zooms. Is there a certain way of fine tuning a 70-200 2.8? Tried to search (probably didn't try hard enough), but couldn't find what I was looking for.

I did the DotTune for different focal lengths and got the following results:

70mm, range of -11 to -13: -12
105mm, range of -12 to -17: (-14.5) -15
135mm, range of -8 to -10: -9
200mm, range of -7 to -13: -10

Do I use the average of the results?


Yeah, on Nikon bodies you have to average the results...or use the tune value for one of the focal lengths if you use a particular length most often. Newer Canon bodies support 2 tune values for zooms, one at the widest focal length and another at the tele end, and their firmware automatically interpolates between the two for the middle focal lengths.



Dec 08, 2013 at 04:41 AM
 

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cmarqz
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p.6 #11 · DotTune: New AF tune technique, no photos required


Good to know. Thanks!


Dec 08, 2013 at 07:08 AM
coresare
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p.6 #12 · DotTune: New AF tune technique, no photos required


Using the Dot Tune method on my Nikon 85mm f/1.4G I get the following.

f/1.4 -1
f/2.0 -3
f/5.0 -8
f/8.0 -11

Is this result pretty common? That's a pretty wide range of fine tuning based on aperture. I really hope Nikon implements multiple AF Tune values in their next generation cameras as it seems simple enough to implement. Maybe they could even implement it with current generation with firmware.



Dec 18, 2013 at 09:14 PM
Gaylon Holmes
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p.6 #13 · DotTune: New AF tune technique, no photos required


coresare wrote:
Using the Dot Tune method on my Nikon 85mm f/1.4G I get the following.

f/1.4 -1
f/2.0 -3
f/5.0 -8
f/8.0 -11

Is this result pretty common? That's a pretty wide range of fine tuning based on aperture. I really hope Nikon implements multiple AF Tune values in their next generation cameras as it seems simple enough to implement. Maybe they could even implement it with current generation with firmware.


That doesn't seem proper to me. I believe I'd want to use a LensAlign and see if you get similar results.

Quite honestly, I've only tuned my lenses using the maximum aperture, never checked 'em at smaller apertures. Not sure I truly want to do so now :-)



Dec 18, 2013 at 09:20 PM
RLDubbya
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p.6 #14 · DotTune: New AF tune technique, no photos required


Finally had some time to play with this, using the Nikkor 14-24/2.8 . Used a FoCal target, tripod mounted the camera, and made sure that center AF point was in-line vertically with the center of the target, and that the camera was level.

The 800e seems to be spot-on, so I didn't try many variations.

The 7100 is a different story, apparently. I set the lens to 24mm, did a LV focus, and then switched to viewfinder, and didn't get a green dot. I ran the AF tune to -20, and got the green dot. I was in AF-S mode in the viewfinder, and AF-S Spot in LV.

I then turned AF tuning off, and repeated the test at 14mm. Again, no green dot. Set AF on, -20, and no green dot.

Went back to 24mm, and no green dot. Hmmm.

I then checked the instructions, and found that I should have dialed in a + value, as the arrow was pointing to the right. Did so, to +20, and got the green dot at 24mm.

I guess I'll chalk up the first -20 correction working to cosmic rays.

Still didn't get the dot at 14mm.

I then changed VF focus to AF-C, D51. Got the green dot at 14mm. I found that as long as I used more than one focus point, I could get the green dot, repeatedly and consistently.

I also found that if I switched to 1.3 crop mode, AF-S, the green dot would at least flicker.

I then took a couple images, one with LV, one with VF & AF dialed in and focus achieved, and one with AF not dialed in, and VF focus not achieved. Looking at them on my monitors, I can't see a heck of a lot of difference, honestly.

In the WTF category, there's a clear difference in exposure between LV and VF modes. Using Auto White Balance on the camera, LR reports different values for Color Temp and Tint, and LR's histogram reports different RGB values. Not a huge difference, but clearly visible to my eye; more visible than the difference in focus.











Dec 19, 2013 at 08:40 PM
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p.6 #15 · DotTune: New AF tune technique, no photos required


I want to test my 70-200 f2.8 VRII today. The problem is, I don't know how far back to be from the test chart to test it at a 200mm focal distance. Should it be 20 ft? Thanks for the help.

B



Dec 28, 2013 at 03:46 PM
lifthard2001
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p.6 #16 · DotTune: New AF tune technique, no photos required


blutch wrote:
I want to test my 70-200 f2.8 VRII today. The problem is, I don't know how far back to be from the test chart to test it at a 200mm focal distance. Should it be 20 ft? Thanks for the help.

B


I think the formula is focal distance in mm times 50 so 200 x 50 =10000mm and that equals 400 inches which equals 33.3 feet . I hope this helps



Dec 28, 2013 at 03:55 PM
snapsy
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p.6 #17 · DotTune: New AF tune technique, no photos required


FYI: After considerable testing I've created new AF target based on a cross-hatch of variable width lines. This new target produces much consistent results compared to the focus chart I used in the video. You can download the new target here.


Feb 16, 2014 at 02:38 AM
blutch
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p.6 #18 · DotTune: New AF tune technique, no photos required


Snapsy, I'm going to dot tune my 300mm f4 with and without 1.7 TC with my new D800 today. Can you remind me how to figure out the distance away I should be?
Thanks

B



Feb 16, 2014 at 05:46 PM
snapsy
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p.6 #19 · DotTune: New AF tune technique, no photos required


Typical is 50x focal length but many times I like to use even longer distances, sometimes even infinity.


Feb 16, 2014 at 06:08 PM
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p.6 #20 · DotTune: New AF tune technique, no photos required


blutch wrote:
Snapsy, I'm going to dot tune my 300mm f4 with and without 1.7 TC with my new D800 today. Can you remind me how to figure out the distance away I should be?
Thanks

B


You should fine tune at the most common distance you would use that lens at, no formulas needed really



Feb 16, 2014 at 06:11 PM
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