Microadjust Confuses Me Again....WTF?

I swore I was done with the 85L, but I came up with a new need for this lens and so now I have a 'UZ' version of the 85L II.

I put it on my 1D4 and took a few shots. All were awful, clearly backfocused by a huge degree.

So I set up a test and dialed in the 1D4....negative 17 on the MA got the lens right. I took a bunch of handheld shots afterwards and the lens is hitting just fine. So MA to the rescue, right?

But I also have a 5Dc. Is this lens going to be usable at all on my old body that lacks MA? I mounted the lens and checked.....it nails focus every time. In fact, the 85L II is more consistent on my 5Dc than it is on the microadjusted 1D4.

This isn't the first time I've run into this either. My 50L needed a lot of MA to work on the 1D4, but it is perfect on the 5Dc.

And the problem isn't that the 1D4 is always wrong in one direction. Sometimes it needs negative MA, sometimes positive.

How can this make sense? Why do all my lenses work just fine on the body that does not allow for MA, but they really need MA on the other?

focus is dependent on both the body and lens combined, not one or the other alone. A lens may hypothetically be 100% accurate but may vary on separate bodies. This is what you're experiencing.

My guess is that, in your case, your 1D4 has focus issues and if it bothers you enough you could send it into canon or just use the MFA feature

It almost sounds like the 1D4 has a problem.

S.Horton wrote in post #14064243
It almost sounds like the 1D4 has a problem.

I get that, but for two things:

1) When I dial in the MA, the 1D4 hits well in general, especially when tracking fast action. My comments on how the 5D seem a bit more consistent are for just static setups.
2) I had the same issue with the 1D3. The 1D3 also demanded MA before it would focus perfectly, but once dialed in it was great. In fact, I think the 1D3 has the best AF system of any EOS camera I have ever had so far. I loved the 1D3 AF.

I just think it is strange that the one camera I have that does not allow MA seems to work just great without it. But every EOS I have had that allows MA also demands MA. It's strange. You would think the 5Dc would be off with some of these lenses, but it isn't.

JeffreyG wrote in post #14064127
I swore I was done with the 85L, but I came up with a new need for this lens and so now I have a 'UZ' version of the 85L II.

I put it on my 1D4 and took a few shots. All were awful, clearly backfocused by a huge degree.

So I set up a test and dialed in the 1D4....negative 17 on the MA got the lens right. I took a bunch of handheld shots afterwards and the lens is hitting just fine. So MA to the rescue, right?

But I also have a 5Dc. Is this lens going to be usable at all on my old body that lacks MA? I mounted the lens and checked.....it nails focus every time. In fact, the 85L II is more consistent on my 5Dc than it is on the microadjusted 1D4.

This isn't the first time I've run into this either. My 50L needed a lot of MA to work on the 1D4, but it is perfect on the 5Dc.

And the problem isn't that the 1D4 is always wrong in one direction. Sometimes it needs negative MA, sometimes positive.

How can this make sense? Why do all my lenses work just fine on the body that does not allow for MA, but they really need MA on the other?

My mk iv does he same thing. My 85 wasn't bad only 2 or 3 clicks negative, but my 50L was all over the place. My old 5d mkii seemed to always be spot on, but I have had to send in my lens for calibration more with the mkiv. Oh well who knows. I love this camera so much I am having a hard time even thinking about getting rid of it.

JeffreyG wrote in post #14064261
I get that, but for two things:

1) When I dial in the MA, the 1D4 hits well in general, especially when tracking fast action. My comments on how the 5D seem a bit more consistent are for just static setups.
2) I had the same issue with the 1D3. The 1D3 also demanded MA before it would focus perfectly, but once dialed in it was great. In fact, I think the 1D3 has the best AF system of any EOS camera I have ever had so far. I loved the 1D3 AF.

I just think it is strange that the one camera I have that does not allow MA seems to work just great without it. But every EOS I have had that allows MA also demands MA. It's strange. You would think the 5Dc would be off with some of these lenses, but it isn't.

I agree, too. The MKIII is the only body I needed MA on at all. The other two, a 30D and MKIIN, don't have issues. Maybe the MA system itself means there can be MA issues. (If that made sense)

S.Horton wrote in post #14064269
Maybe the MA system itself means there can be MA issues. (If that made sense)

It's like a conspiracy theory. Canon bagged on getting these bodies right because they have MA. Let the user figure it out.

That's probably not right.....but man I have to wonder some times.

I'm not kidding on how perplexed I was today. I set up this complex focus test setup (I use three flat surfaces with lots of detail) and worked to get the 1D4 / 85L II working. I was thinking.....-17, this thing will never work on the 5D.

So I get the 5D out and shoot the same test set from the tripod.....and I get five shots perfectly focused. How the hell is that possible? If I adjust a couple more lenses I'll' start believeing that the 1969 moon landings were a hoax, or that wearing a tinfoil hat will stop the aliens from reading my thinking.

I think you may be right. Install an MA system, relax your manufacturing tolerances, thus save money making the things (fewer rejects/re-works) and add a 'feature.'

That really is the only explanation. I only own Ls and primes. Only on the MKIII have I had to do something about MA. The two other bodies, never a problem.