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24-85 minimum focus and infinity focus microadjust procedure

 
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szk71



Joined: 13 Oct 2009
Posts: 1

PostPosted: Sun Jul 04, 2010 1:55 am    Post subject: 24-85 minimum focus and infinity focus microadjust procedure Reply with quote

Here’s the method of adjusting the 24-85 I used for my lens. It’s a method of adjusting the overall focus, then minimum focus and lastly, infinity focus. I think this method will work for any of the lenses, presuming that you find the corresponding -3 value for your lens at step 6 for minimum focus, and the corresponding -5 value at step 6 for infinity focus. So basically, “Starting with firmware version 3.00, you may store a simple "curve" in the lens so that different adjustments can be applied based on focusing distance.”

1. For the overall adjustment, use the micro-adjust feature for the 24-85 shown on the micro-adjust thread. Focus test all focal lengths at about 1 meter and adjust if needed.

2. Now check minimum focus for accuracy. If it needs adjustment, run through the steps 1 through to 5 as you normally would, then at step 6 replace the given values with the following values: F/16 on camera body, F/8 on lens. Now go to step 7 and run through to step 11 as you normally would.

3. Now check infinity focus accuracy. If it needs adjustment, again run through the steps 1 through to 5 as you normally would, then at step 6 replace the given values with the following values: F/16 on camera body, F/4 on lens. Now go to step 7 and run through to step 11 as you normally would, however keep in mind that for infinity setting, a “negative value causes the point of focus to move away from you, curing a front-focus issue. A positive value causes the point of focus to move towards you, curing a back-focus issue. You will also use a value which is approximately twice as big for the infinity adjustment. For instance, what would have been +4 is now -8 for the infinity setting”.

Sorry about the lack of clarity.
Good luck.
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Sun Jul 04, 2010 2:07 am    Post subject: Reply with quote

You may do it separately at 24, 35, 50 and 70mm, and the settings will affect the immediate vicinity. For instance, your 28mm and 24mm share the same setting, but that is an independent setting from 35mm.
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EHRphoto



Joined: 30 Dec 2008
Posts: 8

PostPosted: Sun Jul 04, 2010 5:27 am    Post subject: Reply with quote

Thank you very much for the details. Glad to find this thread finally. Smile
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Eddy Rahardja
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