How Do You Test a New Lens?

[Kayaker72]

Congrats on the new glass Joel! I am still very tempted by the lens, despite the issues I had last fall. In addition to the IQ at wide apertures, I was very impressed with the AF speed, especially in lower light.

My testing procedures are roughly as follows:

1. Quick evaluation of box and wrapping of lens to see if I think is has been handled/used previously. I've yet to receive a lens were I thought it was, but I've heard this is possible.
2. Physical inspection of the lens. Looking for dents, deformaties, missing screws etc.
3. Run both the zoom and focus rings slowly across their entire range multiple times listening and feeling to see if they should function as they should. This is where I first heard the clicking with the zoom ring.
4. Holding up the lens to light and looking for flaws both at the front and rear elements and throughout the zoom range. This is where I first caught something wrong with the EF 17-35 that I bought on ebay.
5. Inspect with a flash light. Move it off axis/at an angle to the lens and look through both the front and rear elements. This step I found the air bubble in a EF 24-70 II and verified the fungus in the EF 17-35 I bought used (since returned).
6. Mount on camera and fire off a few shots to make sure AF/AE/etc are working.
7. AFMA. I use Focal Pro.
8. After entering in the AFMA, I run an aperture sharpness test and AF consistency test using Focal.
9. Finally, and I only started doing this, but I've been taking shots of the ISO 12233 chart you can download. I've done this to try to compare different lenses, such as the 70-200 ii, 24-105, and the various 24-70 ii's @ 70 mm and similar settings. This also allows you to look at corners as well as the center (which is what FoCal focuses on).

Edit: BTW, you can also do a vignetting test to look for decentering. But I've gone to looking at the corners in step 9 to evaluate for decentering. Similar to what Roger discusses. If you do a vignetting test, I found you really need to have a lot of consistent/uniform light on your subject.

It seems like a long list, but most of the steps happen pretty quickly. And, if things go well, it all is done fairly quickly. As I ran into some issues, it did take me a bit more time. BTW, a lot of this is based on recommendations I received here at TDP and Roger's write ups.

A couple of comments on Focal:

1. Take the time to set the system up well. Adequote lighting is key (>10 EV), but so is making sure everything is perfectly square and that the sensor plane and plane of the focal test chart are parallel.
2. In the Aperture Sharpness test, there is a button that lets you "find peak focus." I get slightly better results when this is selected, but in my quick investigation, I haven't identified the difference of when this is activated or not. With the 5DIII, it may be AFMA related as Focal can't control AFMA of the 5DIII. If in doubt, I tried to run the test both ways.
3. The AF Consistency test lets you select phase or contrast detect, just make sure you are testing the one you want (Phase)

Again, congrats on the new glass.

I hope this helps.

Thanks,
Brant