I tweaked my 35L for 8' and now it's way out at 20." So I am not certain that, at big aperture of F1.2-F1.8 that many lenses will not AF properly over the entire distance range.
Don't forget that some lenses actually exhibit what is known as "focus shift" as the aperture is stopped down. Modern lens designers try to avoid or minimize it, but it does exist.
I needed a +15 micro adjustment for my 35L. ALthough I use the lens mostly at about 2-3 meters, it doesn't seem to have any problems focusing at infinity. The same for my 85L II and 135L (both needed +5).
Some lenses perform better at closer distances while other perform better at long distances and some perform good at both closer and longer distances. Maybe the MA exaggerates these design related characteristics in some way?
Here's an interesting finding. The 200 1.8 is dead on at 10 ft. -no adjustment. At 60 ft. it requires -13. Between 10 and 60 feet the microadjustment required follows a linear progression from 0 to -13. But at or near infinity it will miss the focus unless I dial the adjustment back to -10 or less. Now for the catch. When I attach the 1.4x extender it is dead on focus at all distances with no adjustment at all!
I'd love to have a Canon engineer explain this.
Since Canon has taken the ingenious descision to orphan the 200 1.8 I want to know what inside this lens is adjusted for autofocus corrections. I'll get the tools and take it apart myself if I have to - no problem.
The 35L also requires +7 at up to 8 ft. and +12 at 15 ft. keeping in mind I want to shoot at f1.4 to f2 with this lens and still have a subjects eyes in focus and not her ear
I think these "modern" zoom lenses are not parfocal like the older manual focus lenses and the engineering dept have overlooked that maybe due to time constraints. As far as primes, I think the design of the lens in correlation to distance scale has also been overlooked as well... As photographic equipment gets more complex, one would expect the lens designs to be the same, but it's not always what it should be, even though it looks good on paper. Ah... engineering at its worst.
Any recent(within 2-6 months) on this? I have tried and tried the AF MA and it is NEVER the same at any distance!!!!
My 300mm f/2.8 IS is "dead on" anywhere but every other lens is off.
Any speculation or newer good tests??
dan
mdbassman wrote:
Any recent(within 2-6 months) on this? I have tried and tried the AF MA and it is NEVER the same at any distance!!!!
My 300mm f/2.8 IS is "dead on" anywhere but every other lens is off.
Any speculation or newer good tests??
dan
My results are 100% repeatable. But this is with a 5DMK2. With the lenses adjusted they are all spot on at 20X focal length. I am using a one ope Tape's adjustment targets.
eonflux wrote:
By the way...Is the Canon 1Ds Mk III the first and only camera to have this feature? Do any of the other Canon models allow you to perform this mod...what about Nikon?
Auto-focus is a crutch that you shouldn't really need anyway. Not much more than a fancy marketing ploy to sell more lenses and cameras. It's a fad that will die off in a few years.
Eschew AF. Train yourself in the way of MF and your world will be a happier place.
eonflux wrote:
I finally received my RRS L-Bracket in the mail yesterday. With that said, I thought it was time to see what this camera can do (1Ds MkIII). Of course, I had to make sure my lenses were tack sharp. In order to do that, I had to find out what the "AF Microadjustments" was all about.
One word...WOW!!! I thought my lenses were sharp and sweet before. Shoot, based on my results, I should have thrown the lenses away. Of course, I would never throw them away. That's like asking a crack head to give up his supplier. In short, these lenses are far sharper now than ever before (except for the 85mm).
In the end, I made the following adjustments...Tell me what, if any, were your adjustments? I'm curious to see what others are experiencing.
Canon 14mm f/2.8 MkII (at f/8)
+20
Canon 50mm f/1.4 (at f/8)
-10
Canon 85mm f/1.8 (at f/8)
0 (no adjustment needed)
Canon 135mm f/2 (at f/8)
-20
Canon 135mm f/2 (w/ 1.4x MkII) (at f/8)
-10
Canon 24-70mm f/2.8 (at f/8)
+5
Canon 70-200mm f/2.8 (at f/8)
-20
Canon 70-200mm f/2.8 (w/ 1.4x MkII) (at f/8)
-20
Tamron 28-75mm f/2.8 (at f/8)
-20
By the way...Is the Canon 1Ds Mk III the first and only camera to have this feature? Do any of the other Canon models allow you to perform this mod...what about Nikon?
All of the +20 and -20 adjustments seem to indicate a problem with your micro adjustment approach or equipment. Other posters have brought up other problems (MA only works at some distances, what distance to use when MA'ing, etc.) ... these can also be caused by a bad approach to MA.
Paratima wrote:
Auto-focus is a crutch that you shouldn't really need anyway. Not much more than a fancy marketing ploy to sell more lenses and cameras. It's a fad that will die off in a few years.
Eschew AF. Train yourself in the way of MF and your world will be a happier place.
Yeah,right. Unless you are shooting an 85 at f1.2 on a full frame 20mp+ camera. Back when my eyes were 20/15 (exceeding 20/20) I might have been able to accomplish the exact focus in that setup using my eyes. Now? my eyes are down to 20/30 or so. I'm getting old and then I'll die... In the meantime I need autofocus as a crutch to stand, not something to lean on
When they start using the pixels sites on the sensor as the autofocus mechanism things will improve.
