70-200mm F2.8L II AFMA

This is more of a rant than any thing. Sure you can adjust your lens with the microadjustment. But is it not possible to make a $4500 camera and a $2300 just play together on there own without tuning it?


I bought the 70-200mm F2.8L II a week and half ago. I thought when I took it out to the Zoo it felt like it was Back Focusing a little.


So today I decided to test it out. I started with the lensalign at 200mm. With the 1D Mark IV it was back focusing quit a bit. I ended up at minus 7. Then tested my main 5D Mark II with it and it was almost dead on, maybe a very very slight back focus and it was left at zero.


Then things get interesting. I set it up at 70mm. Now at minus 7 everything is front focused. I take it all the way back to zero, and I end up with a very slight front focus at 70mm. I test the 5D Mark II and it has a very slight front focus at zero, so I call it good at zero and put it up.


So now I test the 1D Mark IV at 135mm, at zero it has a slight Front Focus. So at this point I am wondering what the heck is going on at 200mm.


So I reset up the 1D Mark IV at 200mm with the setting zero. Again everything back focuses at 200mm.


So to size it up, at setting zero at 70mm it front focuses a bit, at 135mm it front focuses a bit and at 200mm it back focuses quit a bit.


I was puzzled by this, but from what I can tell the 5D Mark II does the same thing only to a less amount. Maybe the 1.3 crop factor magnifies the results on the 1D Mark IV.


Thing is there is no setting that would be an acceptable average with the 1D Mark IV. You either realize it does this at 200mm and go with it, or correct the 200mm end and end up with the rest of the range front focusing. Of course at a fair distance with your aperture stoped down you will not notice it. Only real close tight wide open shots will it start to matter.


I would be curios if any one that has this lens with say a 7D has noticed this, if the crop factor does make it more pronounced it would be even worse on the 7D.

Sucks, doesn't it. I heard Nikon ran an add saying they don't have micro adjustment because they "get it right" at the factory! Actually I made that up. I did have one lens that was different in adjustment depending what distance I was shooting at. That's where I turned my function on and off, although playing with menus in the heat of battle sucks. I left the AFMA set to +7 or whatever for a certain distance and if I were to go to a shorter distance, turn the function off...or increase the DOF and deal with anything later. Better to have to much in focus and make an adjustment in PS later than to try and clone in a tiger'seye later:) I am curious what part of physics and multiple moving lenses play in your problem. I remember you and Neuro talking about the give/take factor related to theaperture. Seems like they would work with tighter tolerances than that. I worked at a Japanese factory before and their answer to dealing with tolerances was to turn off that test. Easier to beg forgiveness I guess. Kinda surprised me. Maybe the head Canon folks don't know that there is a problem, or that it is being downplayed by the people whose problem this is. It reminds me of this 10-15 foot laser level that had a plus/minus 1/2"( Might as well say it's an inch off). The biggest different between this and several thousands dollar worth of camera gear is,well, several thousand dollars. Sorry I rambled.It just seemsthat everyone is having problems with AFMA. Is it because we now have cameras with enough pixels in them to see that they are soft, or is profit taking a front seat, or does AFMA need two or three points of reference/distance for a proper "adjusted" curve that will fix all problems?

This is why I kinda gave up on AFMA-ing my zooms. I do appreciate the difference I get with the primes, though.

andnowimbroke, I almost believed that, then I thought back to all the Nikon rifle scopes I have owned and how they always had problems, one of which was recoil float and accuracy. So I knew what you said about Nikon just couldn't be true.


pilooo I can relate to that. The primes work very will with adjustments.


I re did all the test today, and I tested my 7D with it as well. The 7D performed similar, however the results aren't as consistent with the 7D as they are with the 1D Mark IV. (what I mean is comparing them side by side on the same lens you can see how much more accurate the 1D IV is).


I think there is some ratio or curve in play here (that andnowimbroke mentioned), that Canon maybe does take in to account. Even though the 1D Front Focuses at 70mm and Back Focuses at 200mm, the pictures taken at that those lengths almost all had an acceptable focus for the exact point of focus. (meaning it feel within the dof) What really varied was whether the DOF fell in front of or behind that point.


If I didn't get anything else accomplished in the two days of messing with this, at least I know what to expect of the 70-200mm F2.8L II.

In all seriousness, when I first read the name of the post I thought to myself, "AFMA? Does he mean auto-focus my a^%?" [6]


Then I read the post and decided that interpretation works too. So sorry to hear about your catch-22.

I have a question that is somewhat related to this post,....


I will be performing these AFMAs when I receive the lensalign mk II.


Does anyone know if having a UV filter on the lens while performing this test makes any difference?


Todd

Quote:

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Originally Posted by Todd Ovick

I have a question that is somewhat related to this post,....


I will be performing these AFMAs when I receive the lensalign mk II.


Does anyone know if having a UV filter on the lens while performing this test makes any difference?

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Todd


I never take the filter off and have never noticed a problem that I could associate with it. For example the problem I was talking about above, all of my results were consistent with each other. Meaning that that if I repeated the same test over and over the result was exactly the same. In fact I did over 800 shots in this set of tests. The AF system of the camera was focusing the same place each time.


I have heard people say you should remove it, and its always because of other problems they are having.


But my thinking is this. If you are getting some really wild results and think your lens is bad. Then take the filter off to test. But if you are going to have this filter on in real life shooting, and your lens with the filter on is consistent with itself (meaning for instance you have a prime lens and it is showing a group of shots that average a back focus). Then you should leave the filter on and simulate your real life shooting set up so that when you go out to take pictures it will be the same as you calibrated for.


Think about it this way, what good would it be if the filter did make the lens back focus or forward focus. Then you took it off and made your settings, then you put the filter back on and make it inaccurate and go out and take pictures. You end up with a lot of out of focus pics.


Rick

Quote:

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Originally Posted by HDNitehawk

leave the filter on and simulate your real life shooting set up so that when you go out to take pictures it will be the same as you calibrated for.

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Yeah, thats kinda what i was thinking,...


This whole AFMA is new to me so I want to try and get it right...


Thanx for your input Rick.


Todd

Hmm.....I have seem to have several focus issues with my 7D and 70-200mm 2.8L IS II. I get the gut feeling mine is just not right.....It sounds like I am not alone. I am going to order the Lens Align and give it a shot.

Quote:

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Originally Posted by Chris

Hmm.....I have seem to have several focus issues with my 7D and 70-200mm 2.8L IS II. I get the gut feeling mine is just not right.....It sounds like I am not alone. I am going to order the Lens Align and give it a shot.

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Chris


I am not sure there is really anything wrong with the one I have, I think it is just the way the AF tracks and works with the Zoom.


The 1D Mark IV was the most noticeable. Maybe because its AF was the most accurate and it had the most accurate results. But out of all the shots, even though it would favor BF at 200mm and a FF at most of the other ranges, the focus point (zero number always fell within the DOF). It may be the way the designers intended, so that the AF system would produce the most accurate results possible at each length. In real life practice you might not notice this unless you were shooting wide open and fairly close. This may very well may be the way this lens is supposed to perform.


If nothing else, I know exactly how the lens performs at each length and I can adjust my shooting style accordingly. I took it with me today and took about 140 pictures. It performed flawlessly on the 5D Mark II.


I arrived at my opinions after 1044 test shots in two days with the 1D IV (not counting the 5D and 7D shots). I would be curios to hear someones perspective that has tested it very thoroughly.


Rick