Canon Lens Date Code Help

Deputydawg

My used Canon 100-400 arrived in the mail today. I purchased it used off of Amazon for 1150.00. It looks like its in new condition, had all the original paperwork, box, case, Hoya UV filter, tripod ring, and hood. As far as I can tell its in working order. I hear people always talking about Date Codes on here when buying or selling a lens. The one on this lens is UA 1021. Is this one of the good lens dates? I think its a 2012 lens if I looked it up right. And my final question is did I get a good deal?

ziggy53

Deputydawg wrote: »

... As far as I can tell its in working order. ...

This is where I recommend that you put your emphasis. If the lens does not work to your satisfaction, it really doesn't matter when it was assembled. Likewise for the "good deal".

The first thing that I do is to check a new (or new to me) lens for autofocus accuracy and speed. While the speed thing is more subjective, as in "Is the speed sufficient for my intended use?", focus accuracy can decide whether you keep the lens or return the lens (or sell the lens if you don't have return privileges).

When I test a new lens I often choose a few different subjects for comparison:

1) A brick wall, shot straight on and squared with, using a tripod. This is a pretty good test for front-focus, back-focus, field curvature and vignetting issues. If a camera/lens combination does not focus accurately in this test, something needs to be serviced. Make sure to test at least twice MFD from the wall.

2) A fence line or similar, shot at an angle to the subject. Put a singular strong-contrast target on the top of the middle post and use a single focus point in the camera to focus against the target. This shows focus accuracy and/or how easily distracting for/aft objects influence AF accuracy (compared to the above wall shot). It also shows bokeh tendencies at different aperture settings.

3) A focus target/chart like in the following:

http://regex.info/blog/photo-tech/focus-chart

I do recommend testing these charts at twice minimum focus distance or greater. Most lenses, especially most zoom lenses, do not do their best at MFD. True macro lenses are the major exception.

4) A US stop sign, or similar very high contrast signage, both centered and off center and to the side and/or corner. This can show chromatic errors and off-axis errors.

5) A spectral highlight at night. (Point source ideally, but a street light at some distance will do.) Try to avoid "blooming" of the source but allow some white clipping. This shows internal reflections and dispersion problems. Again, test both in the center and with the subject at the sides or corners.

6) Now just shoot "typical" subjects for your use of the lens(es). It's important that the lens perform correctly for your intended uses.

Feel free to use JPGs and just give image links or directory links, but any significant issues and comparisons you may want to add inline to a post describing particular issues. These may be crops and display 100 percent if you wish. 100 percent crops aren't really fair unless you intend to print "very" large, but it can be easier to display comparisons for examination and to demonstrate problems.

paddler4

Ziggy,

Thanks for posting these suggestions again. I chanced on this post today, a few days after receiving a refurbished lens that I had planned to test. I photographed a brick wall at lunch time, and tonight I found that something is misaligned--one specific corner is very soft. Back it goes.

Dan