When do I have to calibrate my 5D2?

I have noticed a slow process in which pictures in my 5D2 become soft. The degradation is so slow, that I am getting used to the softness and ignore the problem. When the picture is too soft, they are rejected by curators. I understand that DSLR calibration is a normal event that occurs several times during the lifetime of the camera. I send the camera to the shop and I never pay less than $120 for calibration.

My question: how can I evaluate at home when the right time to calibrate the camera is? How much soft is too soft?

I've never heard of calibrating a camera.
Seems if the photo is soft it would most likely be the lens and not the camera.
I've had my mkii since they came out and it's just as sharp now as the day I bought it.

What are they telling you they are calibrating?

They check with computer the exact point where the focus locks. The computer tells the error to the camera and sets the new focal point. They tell me it's normal for a camera like this, that works hard, to go to maintenance every now and then. It's called micro-adjustment for back focus or front focus. It is not related to autofocus - I set the focus manually with live view x10 and nothing in the picture is in focus. It affects all lenses. I set the fisheye lens to infinity and pointing at infinity and nothing is in focus. I guess it's like a "dioptre" for human eye. My camera is near sighted? Someone else in the forum had this problem and it was fixed after calibration.

Interesting. I'll have to read more about this.
If it's something I should be doing, maybe I need to check that out.
But isn't backfocus calibration done with a lens?
Do you send in a lens with the camera?

Well, like I said my camera seems to be just as sharp now as when I bought it. Actually, it depends on what lens I use.
For video I hate using my Canon 24-105L because it's "too" sharp. I don't like the look.
Last year I bought a set of Ziess lenses I use for video, they are really sharp too and all manual focus.
Love using them.

I send body + lenses.

Yet, my questions was: how can I evaluate at home when the right time to calibrate the camera is? How much soft is too soft?

Ok, that makes sense camera and lense.
But what if you use more than one lens?
Usually I'll change lenses 2 or 3 times to different focal lengths.

I guess someone else that may have experience with calibrating a lens to camera will have to answer the question.
But my guess is, any softness is too much. If it isn't an error in focusing by the user.

I understand the body can store calibration info for 20 lenses.
Do you really get sharp image in 100% magnification?
Some people told me image does not have to be sharp at 100%.
I believe my camera and lenses have really hard time with me comparing to your system. That is because I shoot mainly in the outdoors and lot's of timelapses, while your system works in your studio. Jake, are you starting travel photography?

With the 24-105L lens at 100% I can count the hairs on a persons eyelashes if I'm taking a portrait. It's pretty sharp.
Even the Ziess lens aren't that sharp.

I guess it really depends on if you're shooting for video which isn't as sharp as if you're taking photos for stock. They always want it to be sharp at 100%

We have budgeted to do at least 2 studio shoots with actors each month this year. We'll see if we actually get that ambitious.
We've always talked about doing more travel shoots and that is also something that is going to happen a couple of times this year.
The expense of traveling is something we have to weigh in the equation.

Here's something of interest on this subject:

http://www.the-digital-picture.com/Reviews/Datacolor-SpyderLensCal-Review.aspx

The spyder is intended to correct autofocus problems. I am not sure it's my problem.