p.2 #2 · Why is the 5D3's AF system so sensitive to the lens you use?
Pixel Perfect wrote:
Well ignoring a few groups that have either junk lenses that no one on earth would use with their 5D III or a single lens, the main difference between the groups is that of f/2.8 lenses and f/4 or slower lenses. Of course you only get the maximum potential with the fast glass, but even f/5.6 lenses work dam well on the 5D III and you still get 21 x-type points.
But that's the whole point. You can't ignore them. It does not matter if you and I think they are junk or whether we'll actually use them on 5D3 or not. If you use them, they'll work fine with maximum AF capacity. And that leaves the original question - Why?
p.2 #3 · Why is the 5D3's AF system so sensitive to the lens you use?
Access wrote:
But isn't the 100 macro one of the lenses that is (rumored) to be replaced soon? Again maybe wanting to give people a reason to pay for the upgrade.
It was usurped by the 100L IS macro - which does get the benefit of the outer AF points.
p.2 #5 · Why is the 5D3's AF system so sensitive to the lens you use?
It might also have to do with the “field curvature” of the lens. Some lenses are more “flat field” than others. So if a given lens is more “curve field” you can’t depend so much on its outer focus points. Just a guess though.
p.2 #6 · Why is the 5D3's AF system so sensitive to the lens you use?
WesN wrote:
It might also have to do with the “field curvature” of the lens. Some lenses are more “flat field” than others. So if a given lens is more “curve field” you can’t depend so much on its outer focus points. Just a guess though.
Wes N.
Yeah but 100L is a flat field f/2.8 lens and disappointingly not in group A, yet 35L that has field curvature is group A. 100L can't even take advantage of the center super high precision focus points at all, for some reason.
ETA: Yakim - any guesses as to what group MF ZE lenses fall into? I am curious to try my 50MP and see if the center point gives any more apparent accuracy than some of the surrounding points. I am kind of missing the simplicity of 5D2 and the matte focusing screen, MF FTW.
p.2 #7 · Why is the 5D3's AF system so sensitive to the lens you use?
mco_970 wrote:
Yeah but 100L is a flat field f/2.8 lens and disappointingly not in group A, yet 35L that has field curvature is group A. 100L can't even take advantage of the center super high precision focus points at all, for some reason.
p.2 #8 · Why is the 5D3's AF system so sensitive to the lens you use?
mco_970 wrote:
So is the 40 STM in group D??
Yes.
Probably it is just designed to sell more lenses or get people to upgrade (the manual even admits that some lenses may not work at all in certain countries or regions). Similar to game consoles or DVD players with 'region lockout' perhaps the future will be a lens lockout scheme designed to prevent grey-market lenses from being sold into markets where the local price is higher.
If not my guess is that it would be due to the different attributes of the lenses drive (focus) motors, feedback circuity or lack thereof, and required aperture and maybe just lens quality at the corners. Ie. the f/2.8 dual cross points might require a high precision motor and full feedback, working down in terms of requirements from there.
p.2 #9 · Why is the 5D3's AF system so sensitive to the lens you use?
mco_970 wrote:
ETA: Yakim - any guesses as to what group MF ZE lenses fall into? I am curious to try my 50MP and see if the center point gives any more apparent accuracy than some of the surrounding points. I am kind of missing the simplicity of 5D2 and the matte focusing screen, MF FTW.
Guesses? Sure. Alongside other top-notch MF lenses like the 24/3.5 II.
p.2 #10 · Why is the 5D3's AF system so sensitive to the lens you use?
Access wrote:
Probably it is just designed to sell more lenses or get people to upgrade (the manual even admits that some lenses may not work at all in certain countries or regions). Similar to game consoles or DVD players with 'region lockout' perhaps the future will be a lens lockout scheme designed to prevent grey-market lenses from being sold into markets where the local price is higher.
I think this is probably about on target, and if so, it ticks me off.
Access wrote:
If not my guess is that it would be due to the different attributes of the lenses drive (focus) motors, feedback circuity or lack thereof, and required aperture and maybe just lens quality at the corners. Ie. the f/2.8 dual cross points might require a high precision motor and full feedback, working down in terms of requirements from there.
I would agree with this, but I checked the online PDF and it shows the new 24/2.8 IS and 28/2.8 IS both being group B, which means they don't work with the f/2.8 column of diagonal center points. They use only one diagonal point - the center. So obviously these two lenses can work with diagonal points, and they are brand spanking new lens so the drive and circuitry is in place, AND they have great corner sharpness... Somewhere along the line Canon decided to 'differentiate' them into a lower tier.
I should have known Canon would foil my plans to build a small super high quality kit with their new primes, because my plan involved being able to use the super high precision and cross type side columns, and I'm finding that those just aren't supported with the glass selection I want.
I've done a bunch of FoCal multipoint testing of 5D3 and 7D and 5D2 and am just not seeing that for still subjects, 5D3 is much of an upgrade for me in terms of focus consistency and accuracy (and this mirrors my field experience thus far with 5D3). For moving subjects, hells ya... But I'm still not sure that 5D2 and 7D isn't a better pair for me than having a single 5D3.
For field macros I am thinking 5D2 w/ the matte screen is going to be a better option - about the same precision for the center point as per my own testing is showing, but I have the option of high quality MF assistance from the screen. I guess I need to do a bit more shooting and using side points of 5D3 versus MF on 5D2.
p.2 #11 · Why is the 5D3's AF system so sensitive to the lens you use?
I see the 35 f2 is a Cat A lens. I wonder where the 35 f2 IS will be situated. Its unfortunate to see that the 100 macros lose the high precision from the 5D2.
mco_970 wrote:
I've done a bunch of FoCal multipoint testing of 5D3 and 7D and 5D2 and am just not seeing that for still subjects, 5D3 is much of an upgrade for me in terms of focus consistency and accuracy (and this mirrors my field experience thus far with 5D3). For moving subjects, hells ya... But I'm still not sure that 5D2 and 7D isn't a better pair for me than having a single 5D3.
For field macros I am thinking 5D2 w/ the matte screen is going to be a better option - about the same precision for the center point as per my own testing is showing, but I have the option of high quality MF assistance from the screen. I guess I need to do a bit more shooting and using side points of 5D3 versus MF on 5D2....Show more →
This whole subject is of interest to me because the upcoming f8 capability of the 5D3 is causing me to consider replacing my 7D with a 5D3 + TC for reach-limited 100-400 use. (The 5D2 + 100-400 IQ is so much better than the 7D when its not reach limited and I'm usually in one-shot in these cases.) I wonder if the f8 firmware upgrade will add any changes to the focus categories?
p.2 #12 · Why is the 5D3's AF system so sensitive to the lens you use?
Jeff Nolten wrote:
I see the 35 f2 is a Cat A lens. I wonder where the 35 f2 IS will be situated. Its unfortunate to see that the 100 macros lose the high precision from the 5D2.
I don't know that it loses precision - it still uses the cross type sensors just not any of the diagonals? And there are more cross types available on 5D3... If you are an AF only shooter, there are still advantages. But a higher hit rate than 5D2 center point may not be one of them.
And the poor old 180 macro is in group G! Can't even try using the side points with it.
I am also really interested to see where the new 35/2 IS falls. That is what got me started reading and being annoyed.
Jeff Nolten wrote:
This whole subject is of interest to me because the upcoming f8 capability of the 5D3 is causing me to consider replacing my 7D with a 5D3 + TC for reach-limited 100-400 use. (The 5D2 + 100-400 IQ is so much better than the 7D when its not reach limited and I'm usually in one-shot in these cases.) I wonder if the f8 firmware upgrade will add any changes to the focus categories?
It is an interesting question... They could definitely limit the use of it drastically.
I wonder if ML guys could implement some hacks to undo some of the software limitations (and if any good would come from it).
p.2 #13 · Why is the 5D3's AF system so sensitive to the lens you use?
I've been reading the user manual and for the 5D3 they are saying high precision at f4 while the 5D2 only said that for f2.8 (for applicable points) so I'm putting faith in the general comments here that whatever category your lens is in, the focus is improved. For my 100-400 it looks like I'll be limited to the center cloud compared to the 7D's full set.
From the 1DX f8 announcement, f8 will be for the center point only but the four expansion points can be enabled. I'll be able to live with that
p.2 #15 · Why is the 5D3's AF system so sensitive to the lens you use?
5D III will autofocus quite well with 400mm F5.6 / Tamron 1.4X TC combination
the image quality is good wide open at F5.6
I have been using it with success for birds, and birds in flight
p.2 #16 · Why is the 5D3's AF system so sensitive to the lens you use?
mco_970 wrote:
I think this is probably about on target, and if so, it ticks me off.
I would agree with this, but I checked the online PDF and it shows the new 24/2.8 IS and 28/2.8 IS both being group B, which means they don't work with the f/2.8 column of diagonal center points. They use only one diagonal point - the center. So obviously these two lenses can work with diagonal
The thing is, if this is a ploy, it won't work on us because of the hacks available. They might be able to get the people who don't know ML exists but that's it.
I think what is evident is that if there was some kind of semi-systematic way or reasoning behind placing the lenses into groups, it was done so haphazardly or chaotic that a lot of lenses just kinda fell through the cracks.
I just imagine a scene from the TV show "the office" or such where the boss walks in and says "hey wait... I own that lens... and that one... and that one, make them group A. And this one... Dwight owns, I don't like Dwight, so let's make it a group D! Yeah, that will show 'im."
p.2 #17 · Why is the 5D3's AF system so sensitive to the lens you use?
The post-f8 update 1DX user manual does not change any lens categories that I can find. It adds the 40 mm STM to group D. Lenses that become f8 with an extender become group H which states that "Subject tracking is superior and high precision focusing is achieved." with the center point. I assume this will apply to the 5D3 update.
This and comments like Abqnmusa's are very encouraging indeed! Nice image.
