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Super Contributor
Posts: 252
Registered: ‎11-11-2012

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

I thought I made a previous reply to TTMartin and either I hit cancel or it  got pulled.  

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VIP
Posts: 10,135
Registered: ‎08-13-2015

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II


@kvbarkley wrote:

LensAlign by Michael Tapes is a good hardware solution that takes a lot of guesswork out of it.


DotTune is free, and it takes ALL of the guesswork out of it.  Try it some time, if your camera has AFMA.

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"Doctor told me to get out and walk, so I bought a Canon."
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Super Contributor
Posts: 252
Registered: ‎11-11-2012

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

So here it goes again. There is more to it. I don't care if it goes to 20, 11 is out of my comfort zone. I have had two Canon techs tell me that MFA is for emergencies only and if out badly should be sent in. Also there are warnings about using MFA in the manual everyone ignores.

 

Any Canon gear that I have owned (and I have had lots) that has been correclty calibrated from the factory or in separate servive departments (lens and body) usally only needs +- 3 to 4. I understand specifications and tolerances. I facilitated workshops on the Toyota manufacting system and statisical process control. I'm not going to send a lens in if it needs +- 4 because there is normal variation between the lens and body. I can see the benfit with 3rd party lenses.    

 

I usually shoot people with this lens and one day did a landscape at 70mm. When I turned the lens correction off the CA was very bad. Worse than what the specs say. It was my fault as I should have checked. It is off warranty now and I put off sending it in for a bit but I will.       

        

 

             

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Esteemed Contributor
Posts: 4,094
Registered: ‎02-17-2016

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

[ Edited ]

How do you tell with DotTune that your camera is perpendicular with the target?

 

ETA:

Actually, the lens align will work really well with the dot tune method. It provides a nice focus target and keeps the camera perpendicular to the target.

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Super Contributor
Posts: 252
Registered: ‎11-11-2012

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

[ Edited ]

You can to a certain degree if you want to but it is not perfect. Using the cameras eletronic level and using a level on the target which get is part way. I have chatted with the creator of Dot Tune at other sites. The latest is he found using his method works best for him at infinity. He uses street signs and roof tops.

 

I set up target at a pretty far distance and tried to keep everything as pepandicualr as I could. Dot Tune gave me the saem resutls as FoCal but I had trouble repeating it. Even a bit of wind will through it off. Atmospheric coditions like heat off a rooftop depending on what part of the day you do it. Don' t get me wrong. Dot Tune is very good and polpular. I chose FoCal and am very happy with it. Consistent and accurate. 

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Posts: 10,135
Registered: ‎08-13-2015

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

"How do you tell with DotTune that your camera is perpendicular with the target?

 

How?  By dead reckoning.  Smiley Happy  How do you tell that your target is perpendicular with the camera? 

 

Not unless you are focusing at macro distances, I don't see what critical difference it makes what the relative angles are.  The camera is only focusing on a single spot, or small area, anyway.  What significant difference does it make if that spot is perpendicular, or not?

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"Doctor told me to get out and walk, so I bought a Canon."
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Posts: 10,135
Registered: ‎08-13-2015

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

"I set up target at a pretty far distance and tried to keep everything as pepandicualr as I could. Dot Tune gave me the saem resutls as FoCal but I had trouble repeating it." 

 

Repeating which result?  Getting the same number for each approach?  Getting close to the same number from both approaches?

 

I do the focus calibration at least three times indoors, and on different days.  I use the average of all of the measurements as my correct setting.  I need just under two feet of distance for every 10mm of focal length.  I need about 20 feet for 100mm.

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"Doctor told me to get out and walk, so I bought a Canon."
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Super Contributor
Posts: 252
Registered: ‎11-11-2012

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

[ Edited ]

Getting the same number on different days with Dot Tune. I always get the same results using FoCal.   

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Super Contributor
Posts: 252
Registered: ‎11-11-2012

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

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VIP
Posts: 10,135
Registered: ‎08-13-2015

Re: micro adjustment results for canon 7D with 70-200 2.8 IS USM II

"I set up target at a pretty far distance and tried to keep everything as pepandicualr as I could. Dot Tune gave me the saem resutls as FoCal but I had trouble repeating it."

 

I conduct the tests indoor whenever possible, which takes temperature and humidity out of the equation, and get nearly the same result each time, +/- 1, which is also the margin of error for the method.  You cannot round off setting values at the and low end, and sometimes the final number winds up not being a whole number, so you're forced to round it off.

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"Doctor told me to get out and walk, so I bought a Canon."
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