Gear Talk > EOS Bodies - For Stills
How does Mk. III handle 2 micro AF adjustments?
neuroanatomist:
--- Quote from: bkorcel on May 01, 2012, 02:20:58 PM ---According to the documentation the camera will extrapolate AFMA between the two ranges for a zoom.
--- End quote ---
What it states is: "When shooting with the intermediate range (focal length) of a zoom lens, the AF's point of focus is corrected relative to the adjustments made for the wide-angle telephoto ends."
'Corrected relative to the adjustments' is a bit ambiguous. For example, if you enter -5 at the wide end and +7 at the long end, will it run a gradient of adjustments across the zoom range (progressing from -5 to +7 in small steps as you zoom)? Or will it abruptly switch from -5 to +7 adjustment at the midpoint of the zoom range (or some other arbitrary point)?
That's the question on the table. To answer it doesn't even require that the adjustments be the right ones to give correct focus - just picking random (different) adjustments for each end and seeing what the middle looks like would do the trick.
neuroanatomist:
--- Quote from: Mt Spokane Photography on May 01, 2012, 02:37:04 PM ---Looking at my AFMA test shots, the AFMA value is interpolated between the two extremes.
Thus, for my 28-300mmL, at
28mm, AFMA = -13
135mm, AFMA = -8
300mm, AFMA = 0
--- End quote ---
Thanks! How finely? For example, what do 85mm and 200mm look like on the 28-300mm?
neuroanatomist:
Also worth noting, below are the FoCal results for my 28-300mm on my 5DII. So, if I adjusted only at the two ends, the interpolation would be useless...
Mt Spokane Photography:
--- Quote from: neuroanatomist on May 01, 2012, 02:42:43 PM ---
--- Quote from: Mt Spokane Photography on May 01, 2012, 02:37:04 PM ---Looking at my AFMA test shots, the AFMA value is interpolated between the two extremes.
Thus, for my 28-300mmL, at
28mm, AFMA = -13
135mm, AFMA = -8
300mm, AFMA = 0
--- End quote ---
Thanks! How finely? For example, what do 85mm and 200mm look like on the 28-300mm?
--- End quote ---
I sold the lens last week, so I only have the images taken at those three points after calibrating it and my 5D MK III with Focal. They indeed do not look like a linear interpolation from two points is going to be very good on a 10:1 zoom.
I bought the lens locally from Craigslist, but decided it wasn't my style of lens. I use two zooms for outdoor walkaround, 24-105mm f/4 L, 70-200mm f/4L IS, and 100-400mm L. Indoors its all primes. My 70-200mm f/4 gets seldom used, so it may be sold too.
neuroanatomist:
--- Quote from: Mt Spokane Photography on May 01, 2012, 03:14:51 PM ---I bought the lens locally from Craigslist, but decided it wasn't my style of lens. I use two zooms for outdoor walkaround, 24-105mm f/4 L, 70-200mm f/4L IS, and 100-400mm L.
--- End quote ---
As did I, and for me the jury is still out. It worked well as a travel lens, combined with the 35L for indoors/night. Not sure how much use it'll get outside of that - am hoping it will be useful for local outings with my daughters, where previously I'd take the 24-105mm and 70-200mm f/2.8L IS II. But I'm thinking I may ultimately prefer the combo of the 24-105 and the 70-300L.
As with all my CL purchases, I bought cheaply enough that I can re-sell and most likely make a profit.
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