180mm Macro lens for telephoto use

Does anybody use their 180mm macro lens for both macro work and telephoto work? If so, do you need two different autofocus micro adjustments? If so, what are those AFMA values you use at both ends? Is the calibration spread huge?

The question about AFMA does not make sense.

If one needs to use AFMA, then it means he/she has a defective camera.
If you also have a defective camera, then the AFMA adjustment required by your camera will likely be different.

Focus on the 180 is very slow and the lens is heavy. The lens is not a multi-purpose lens. It's designed for macro photography and makes a cumbersome telephoto lens. My 2 cents.

CheshireCat wrote in post #18319790
The question about AFMA does not make sense.

If one needs to use AFMA, then it means he/she has a defective camera.
If you also have a defective camera, then the AFMA adjustment required by your camera will likely be different.

It could be the camera or it could be the lens or it could be a combination of both. So not sure what you are saying. I have lenses needing Afma on my 7D but not my XT and vice versa well the XT doesn't have afma but it's soft. Personally if I need different afma values depending on subject distance then I send the lens back if it's within the exchange policy or I send it to canon for calibration

I think my Canon 180mm macro is defective. See below. Are the diverging track marks normal? Shouldn't the OOF areas be smooth instead of crooked?

That is perfectly normal. Your lens is ok.

AFMA is used to correct for manufacturing tolerances. Your camera is not defective if you need to use it. That's why it's there in the first place. Every lens will benefit from AFMA assuming you can both measure it accurately and have a fine enough adjustment. The reality is there isn't a lot of difference between a +1 or a +2 and zero so most people won't notice if it's off a little. Most of the people who say a lens/camera combo doesn't need it could actually realize a small benefit from a small AFMA adjustment. It is difficult to measure with that much accuracy however without dedicated software like FoCal (which I highly recommend btw).

CheshireCat wrote in post #18319790
The question about AFMA does not make sense.

If one needs to use AFMA, then it means he/she has a defective camera.
If you also have a defective camera, then the AFMA adjustment required by your camera will likely be different.

What I'm getting at is this. My 180mm lens requires a minimum of -8 AFMA because it severely back focuses when doing macro work. But that AFMA requirement drops as I shoot farther away. For example, when I shoot at 25 time the focal length (15ft), the lens requires a -6 AFMA (also, the sharpest aperature slides from f5.6 to f8, which I found strange). I haven't tested the lens at telephoto distances, say 50x or more, but wouldn't be surprised if the AFMA changes dramatically the farther away you stand from the subject.

I think I'll just use it for macro work only. That's what it was designed for anyway. Then I don't have to worry about AFMA shifts. But would like to know what is typical for this lens so I don't worry about owning a bad copy (needing a -8 AFMA already make me uneasy). This lens hasn't been updated in over 20 years, so maybe I should expect flaws.

FEChariot wrote in post #18320036
It could be the camera or it could be the lens or it could be a combination of both. So not sure what you are saying. I have lenses needing Afma on my 7D but not my XT and vice versa well the XT doesn't have afma but it's soft.

Well, then some piece of your equipment is defective.

AFMA's purpose is to "fix" a mismatch between the light paths of the image sensor vs the AF sensor. And is to be used in case you dropped the camera and cannot have it calibrated in time for a shooting event.
The way AFMA works, is that it adds a fixed error (yes, an error) to what the AF sensor actually sees in focus. Anyone should be horrified about this.

Most users incorrectly think AFMA can magically fix a defective lens (or a lens with focus-shift by design), also because manufacturers are pushing this feature to lower production quality control.

In other words, if you need AFMA, it might be one or more of the following:
- Your camera is defective, and needs to be calibrated.
- Your lens is defective, and needs to be repaired.
- Your lens is ok but has focus-shift by design (e.g. 50/1.2), however AFMA can only compensate for it in a restricted use case scenario and will do more harm than good in most cases. Just use Live-View focusing if you need to use the lens stopped-down.

vengence wrote in post #18320160
AFMA is used to correct for manufacturing tolerances. Your camera is not defective if you need to use it. That's why it's there in the first place. Every lens will benefit from AFMA assuming you can both measure it accurately and have a fine enough adjustment. The reality is there isn't a lot of difference between a +1 or a +2 and zero so most people won't notice if it's off a little. Most of the people who say a lens/camera combo doesn't need it could actually realize a small benefit from a small AFMA adjustment. It is difficult to measure with that much accuracy however without dedicated software like FoCal (which I highly recommend btw).

Do you work at Canon ?

Manufacturing tolerances should be strict enough to avoid visible focus errors (and I am not even talking about using a software to count line pairs).

In any case, if I buy a 50 MP camera that does not resolve 50MP because of manufacturing tolerances, then the camera is defective. My money is perfectly working, why shouldn't my camera be ?

ksbal wrote in post #18320192
The photo you show is normal.

One thing I learned the hard way was you need to watch what light you do your adjustment under. I tried to mfa my 50mm 1.4 under white florescent, not realizing that light made a difference... it was way off when using the lens in daylight or flash. So experiment with that, just in case you are doing macro photography under one light condition, and then taking portraits under another. JMHO YMMV.

And you live like this? You speak as though this is normal. I can't imagine how a normal lens would require a different AFMA for daylight than any other light source. Perhaps imperceptible differences, but "way off" differences? Now I'm worried.
Here is a video showing the problem with the Nikon D600. I'm hoping this phenomena indicates a camera that can be repaired rather than a chronic problem one must live with.

https://www.youtube.co​m/watch?v=IWKpT4SHWWQ

texshooter wrote in post #18320168
What I'm getting at is this. My 180mm lens requires a minimum of -8 AFMA because it severely back focuses when doing macro work

Like I said, the typical AFMA for any lens is 0 (ZERO).
If you have to use AFMA, then it means that you need to add an error to what your AF sensor sees in focus. That error will be widely different for each user who has a defective product.

I would rule out a focus-shift by lens design, because on a macro lens it would be a ridiculous engineering issue. However, I have never used the EF 180mm, so you never know

Before blaming the lens, check it on another body. Sensor misalignment is much more noticeable when shooting macro, so people may think the camera is ok even if it is not.

Also, I suggest using Live View focusing until you find the problem and have it fixed.

texshooter wrote in post #18320168
What I'm getting at is this. My 180mm lens requires a minimum of -8 AFMA because it severely back focuses when doing macro work. But that AFMA requirement drops as I shoot farther away. For example, when I shoot at 25 time the focal length (15ft), the lens requires a -6 AFMA (also, the sharpest aperature slides from f5.6 to f8, which I found strange). I haven't tested the lens at telephoto distances, say 50x or more, but wouldn't be surprised if the AFMA changes dramatically the farther away you stand from the subject.

I think I'll just use it for macro work only. That's what it was designed for anyway. Then I don't have to worry about AFMA shifts. But would like to know what is typical for this lens so I don't worry about owning a bad copy (needing a -8 AFMA already make me uneasy). This lens hasn't been updated in over 20 years, so maybe I should expect flaws.

There is practically no difference between -8 and -6. Even -8 is only around the DOF for the lens when the aperture is fully open, compared to no adjustment at all. So your lens is not "severely back focusing" based on what you say. But it might be slightly backfocusing.

Still, it is a bit surprising that you would need as much as -8. That is more than I would expect.

Are you sure you are doing the adjustment correctly? Every time I do my lenses I end up with a different number. (Not greatly different, but different.)

Archibald wrote in post #18320229
Are you sure you are doing the adjustment correctly? Every time I do my lenses I end up with a different number. (Not greatly different, but different.)

I'm using the Lens Align with Focus Tune. The proof is in the graph....

ksbal wrote in post #18320205
This seems to be a rather extreme take on mfa. I think there is always a compromise in mass production and qc of equipment before sale. I think mfa was put in responding to a need of photographers rather than because manufacturers are trying to lower quality control.. they are just letting an educated consumer have a tool that can help bring the tolerence between the camera and the lens into alignment.

Lens Rentals has an excellent article on QC and lens production.

Thanks for the link, very interesting, but it has more to do with lens optical performance rather than focusing errors.
Almost all the times one has to use MFA, it is because of sensors misalignment. And this is a quick and inexpensive fix for Canon.