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Dot-Tune: Autofocus Fine Tuning in under 5 minutes
  
 
thw2
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p.11 #1 · p.11 #1 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Jeff1010 wrote:
I used the same target, brightness, tripod, etc. I just turned on one light, and switched off the other light. These numbers were very consistent and reproducible.

I have known this but phase detection focus shifts with light temperature. A couple of years ago, I returned 3 camera bodies and after months of frustration testing 6 camera bodies and lenses, I finally realized that focus shifts depending on light temperature. Under warm incandescent light, cameras front-focuses (or move in that direction). Under whiter light such as LEDs and florescent lights, cameras back-focus. Even outdoors, there is a shift going from sunlight
...Show more

Your results are very informative.

Contrast AF is still the most dependable AF algorithm. On the OM-D, it's very fast too. But any AF advantage it has over phase-detect AF is negated by the slight EVF lag.



Mar 19, 2013 at 08:52 AM
Wahoowa
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p.11 #2 · p.11 #2 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


I've tried many many methods for AFMA. This is by far the fastest. I think I can now do this for any lens anywhere under a minute. Great method.


Mar 19, 2013 at 12:59 PM
snapsy
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p.11 #3 · p.11 #3 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Jeff1010 wrote:
I have known this but phase detection focus shifts with light temperature. A couple of years ago, I returned 3 camera bodies and after months of frustration testing 6 camera bodies and lenses, I finally realized that focus shifts depending on light temperature. Under warm incandescent light, cameras front-focuses (or move in that direction). Under whiter light such as LEDs and florescent lights, cameras back-focus. Even outdoors, there is a shift going from sunlight to shade, mid-day to dawn/dusk. I don't know why this can't be compensated in camera electronics since auto-balance sensor can measure color temperature.

Most cameras suffer from this, including the D800/E. AWB sensors probably aren't reliable enough to rely upon for integration into the PDAF logic.

Jeff1010 wrote:
I have to say the 5D3 focus accuracy in various conditions is much, much better than the 7D for example but if you examine closely, you can get frustrated with any camera. I am happy with my camera/lens combination in this case. The MFA average is exactly zero.

I agree, the 5DM3/1DX appear to be unique in their consistent ability to operate at a zero MFA. My theory is that they've tightened the manufacturing tolerances of these bodies.

Jeff1010 wrote:
The Dot-tune method seems to work well but I don't believe in the MFA since the value changes with light temperature, distance, and with focal length (in case of zoom lens). If you set the MFA to any value other than 0, it will make things worse in some other conditions. If my camera/lens need MFA, I would send them back and get them calibrated.

For bodies that need MFA I wouldn't suggest avoiding tuning just because PDAF operates differently in different lighting temperatures. I tune to my most used lighting temperature for a given lens and if I find myself in a lighting situation that differs significantly from what I tuned then I just tune again on location, which is fast and easy with DotTune but not so with other methods. I also have tungsten -> daylight deltas written down for my most used lenses (along with focus shift deltas) so mostly I just adjust the tune value by memory.

Jeff1010 wrote:
I do understand that it can be beneficial if your camera/lens is offset to one direction but in my experience, focus consistency gets worse when MFA is enabled and set to a non-zero value.

My experience is contrary, for reasons I explain here.



Mar 20, 2013 at 01:53 AM
Zenon Char
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p.11 #4 · p.11 #4 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Jeff1010 wrote:
Here is my result on 5D3 & 70-200 f/2.8 II.

@200mm, white LED light (~5000K)
-9 to +7, avg = -1

@200mm, halogen light (~3000K)
-7 to +9, avg = +1

@70mm, white LED light
-11 to +5, avg = -3

@70mm, halogen light
-5 to +11, avg = +3

I used the same target, brightness, tripod, etc. I just turned on one light, and switched off the other light. These numbers were very consistent and reproducible.

I have known this but phase detection focus shifts with light temperature. A couple of years ago, I returned 3 camera bodies and after months of frustration testing 6 camera bodies and
...Show more

I stopped using MFA a few years ago myself. First off I was always second guessing myself with older methods. I always got different results the next day. Also different results at different distances which is normal. I just decided to send my gear in as well and currently all of my gear is at zero. For the money I spend on gear I just feel more comfortable having a trained technician with all the equipment to calibrate to specifications even knowing there is variation. I have sent very little to Canon.

I had been contemplating getting FoCal until DotTune came out. I still may. I like DotTune for it's simplicity and it gives me a good picture of my gears performance and suspicions. People have posted that MFA is very useful for third party lenses.

One thing I do know we are definitely a minority. I would not be upset if the next generation of cameras came without it. After posting that on another site the majority of responses were people would not buy a body without it. The 60D does not have it and there was a real stir before release but it has proven to be quite good. No complaints from the masses. Mind you it is not a pro body.

Even the manual states not to MFA unless you really need it because it can effect AF. One Canon technician told was it was a temporary fix, another to use it. First one probably got fired because he costed Canon money . I can see a few ticks either way but anything over 5 I would send to Canon. This is not written in stone. Things do change.



Mar 20, 2013 at 03:19 PM
trueimage
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p.11 #5 · p.11 #5 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Sort of an aside question - can you print the Bob Atkins test chart on a normal office laser printer on say 11x17 paper? I don't have access to a photo printer right now...


Mar 20, 2013 at 09:49 PM
trueimage
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p.11 #6 · p.11 #6 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


snapsy wrote:
For bodies that need MFA I wouldn't suggest avoiding tuning just because PDAF operates differently in different lighting temperatures. I tune to my most used lighting temperature for a given lens and if I find myself in a lighting situation that differs significantly from what I tuned then I just tune again on location, which is fast and easy with DotTune but not so with other methods. I also have tungsten -> daylight deltas written down for my most used lenses (along with focus shift deltas) so mostly I just adjust the tune value by memory.


This sounds like something that could potentially be stored in a custom firmware like magic lantern, couldn't it? values based on the selected WB?



Mar 20, 2013 at 09:52 PM
snapsy
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p.11 #7 · p.11 #7 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


trueimage wrote:
Sort of an aside question - can you print the Bob Atkins test chart on a normal office laser printer on say 11x17 paper? I don't have access to a photo printer right now...


Yep, I print mine at 8.5" x 11" on a lowly laser printer.



Mar 20, 2013 at 09:56 PM
snapsy
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p.11 #8 · p.11 #8 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


trueimage wrote:
This sounds like something that could potentially be stored in a custom firmware like magic lantern, couldn't it? values based on the selected WB?


I believe the PDAF system is micro-controller driven and not available to ML. In theory ML could sample the WB periodically and swap in a configured temperature-specific tune value but I'm not sure how well it would work in practice.



Mar 20, 2013 at 09:58 PM
Jeff1010
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p.11 #9 · p.11 #9 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


snapsy wrote:
I agree, the 5DM3/1DX appear to be unique in their consistent ability to operate at a zero MFA. My theory is that they've tightened the manufacturing tolerances of these bodies.


Here is a blog with very good experimental results. It's very interesting to read, all 4 parts.
http://www.lensrentals.com/blog/2012/08/autofocus-reality-part-3b-canon-cameras



Mar 21, 2013 at 07:09 AM
jchin
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p.11 #10 · p.11 #10 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Thank you for this DotTune method. I'll be trying it out this weekend if time permits.


Mar 30, 2013 at 07:44 PM
 

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EyeBrock
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p.11 #11 · p.11 #11 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


This is great and easy. My results with five lenses/5D3 mirror what I gained with FoCal (give or take a point). As snapsy said, the range is must tighter compared to MA with the 5D2. Every lens had a 14-15 point range and was very close to factory zero (1 to 5).

So easy and so logical. I'm sold and its FREE!



Apr 01, 2013 at 02:10 PM
robinlee
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p.11 #12 · p.11 #12 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Hi snapsy, I MFA'd my EF500mm due to front focusing on my other thread I created last week and it needs +10 on it and now it is sharp. I have to thank you for your contribution and sharing in this forum. I will probably re-MFA once the ML with auto tune has been released.


Apr 01, 2013 at 02:57 PM
mikeinctown
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p.11 #13 · p.11 #13 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


I printed out the test chart for my wall to use on the shorter lenses, but when I try the 70-200, what would be the next best thing? (I am space limited and will have to go outdoors for that one) Also, how high contrast does my focus point need to be in order to have this work accurately?


Apr 02, 2013 at 12:40 PM
docnlaw24
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p.11 #14 · p.11 #14 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


tag


Apr 02, 2013 at 02:14 PM
snapsy
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p.11 #15 · p.11 #15 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


mikeinctown wrote:
I printed out the test chart for my wall to use on the shorter lenses, but when I try the 70-200, what would be the next best thing? (I am space limited and will have to go outdoors for that one) Also, how high contrast does my focus point need to be in order to have this work accurately?


The 50x focal length and test chart are just guidelines - you can actually use whatever focus distance and AF target you'd like, although I generally recommend against a distance below 50x. The lighting levels and target contrast should be good enough so that AF acquisition occurs instantly with no hunting or lag (ie, as fast as your camera body can focus with the particular lens you're using).



Apr 02, 2013 at 06:29 PM
sritri
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p.11 #16 · p.11 #16 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Snapsy - Being pretty anal about my equipment's shape rather than using it to enjoy photography, I sent in my 7D to Jamesburg for a paid AF check. It came back with a note that everything was in perfect order. However when I ran the FocalPro on it all my lenses showed a +/- 7. I resent it under repair warranty back to Jamesburg and now I can't seem to get a definite reading from FocalPro. I tried your excellently documented Dot-Tune method and the entire range of -20 to +20, the light is instantaneously green. Any tips to lead me to the correct method I should follow ?

I still feel it is ever so slightly front focussing as seen below (Focus confirmation is on the eye in both).






*







Apr 02, 2013 at 06:50 PM
robinlee
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p.11 #17 · p.11 #17 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


sritri wrote:
Snapsy - Being pretty anal about my equipment's shape rather than using it to enjoy photography, I sent in my 7D to Jamesburg for a paid AF check. It came back with a note that everything was in perfect order. However when I ran the FocalPro on it all my lenses showed a +/- 7. I resent it under repair warranty back to Jamesburg and now I can't seem to get a definite reading from FocalPro. I tried your excellently documented Dot-Tune method and the entire range of -20 to +20, the light is instantaneously green. Any tips to lead
...Show more

Hi Sitri, clearly the downy woodpecker is front focus. I have the same issue I posted on other thread and complete the MFA using this method and it needed +10. I think I calibrate at the MFD due to house size issue lol. Perhaps try with other lens with this method?



Apr 02, 2013 at 07:24 PM
mikeinctown
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p.11 #18 · p.11 #18 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


sritry, I really don't see anything in perfect focus with that second photo. perhaps you had some camera shake going on? At least in the first one you can clearly tell what is in focus and what is not.


Apr 02, 2013 at 07:35 PM
Stilltime
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p.11 #19 · p.11 #19 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Updated my D600 firmware and got around to trying this out today. On my 35/2D and 50/1.8G the range was 32, and I had to use the offset method as the OP had linked. On my 85/1.8G the range was 33, had to use the same offset info.

Dialed in values on D600 using the Dot-Tune method:
35/2D: -10
50/1.8G: -18
85/1.8G: -10

Almost seems as though my body itself is off... Now I have to just get out and shoot some more!

Thanks,

Chris C.



Apr 02, 2013 at 08:55 PM
snapsy
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p.11 #20 · p.11 #20 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes


Stilltime wrote:
Updated my D600 firmware and got around to trying this out today. On my 35/2D and 50/1.8G the range was 32, and I had to use the offset method as the OP had linked. On my 85/1.8G the range was 33, had to use the same offset info.

Dialed in values on D600 using the Dot-Tune method:
35/2D: -10
50/1.8G: -18
85/1.8G: -10

Almost seems as though my body itself is off... Now I have to just get out and shoot some more!

Thanks,

Chris C.


Did you make sure to leave your D600 body and lens in AF mode and use back-button focusing? Otherwise you'll get a tune range that includes +20 and/or -20. The reasons are discussed here (Nikon-specific).



Apr 02, 2013 at 09:39 PM
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