How Do You Test a New Lens?

[HDNitehawk]

I think I would check it for the infamous clicking noise when you zoom in and out first. If it does it and it bothers you I wouldn't go any farther and send it back.

Second common problem that I hear about is the AFMA not being consistent from one end of the lens to the other. For example, and I do not have the exact numbers, I had one that was +1 at 24mm, about the same at 35mm and 50mm then took a dive at 70mm.
Some of the copies are soft at 70mm. At 24 and 35 it should be one of the sharpest lenses you own. If you own a 70-200mm II and it is close to or better than it at 70mm I would call it good.

Once you get a good copy you are comfortable with, it is a great lens.

For me the final lens requirement I was looking for was as good or better than my primes at 24 and 35. At least equal to my 70-200mm. Consistent through the range for AFMA. Of course I checked out the usual things like centering and such also.

Good Luck

[Joel Eade]

I do own a 35 f/1.4 and version II 70-200 f/2.8.....if it is as sharp as those it will be great. Hopefully they are beyond the clicking problem now. Thanks!

[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

[Joel Eade]

Thanks for all the help....the lens arrived today. On inspection it is physically flawless and no click with zooming or focusing. I took several shots of detailed subjects with varying f-stops and the 4 corners appear equally sharp so I do not suspect de-centering. I will have to see about investing in Reikan FoCal so I can do a definitive AFMA test but so far I see no issues. I will shoot a bunch of images this weekend and look at them in more detail. Unless I run into AFMA issues I will probably keep it.

[Joel Eade]

Test shot with the 24-70mm f/2.8L II @ 50mm

I filled the frame with this little bulletin board and of course this is not a flat surface. Focus point was in the center. I converted the image with ACR and no adjustments then saved it as a jpeg with no post processing

Hand held with no flash
ISO 3200
f/4.5
1/80

[Dave Throgmartin]

Joel,

I haven't used it, but some have reported excellent results using the "dot tune" AFMA method. I should probably get around to AFMA, but my lenses to date seem to work fine without it.

Dave

[Joel Eade]

Joel,

I haven't used it, but some have reported excellent results using the "dot tune" AFMA method. I should probably get around to AFMA, but my lenses to date seem to work fine without it.

Dave

Thanks Dave, I have tried that method and it does work pretty well. I have experimented with AFMA settings by simply making small changes, taking a
picture and zooming in to evaluate. I find it very difficult to visually find much difference in images unless you change the AFMA value by 10 or more. I tend to like the practical approach (like dot tune) rather than the extreme analytical approach (like FoCal). I have used this philosophy on my super-tele lenses and the images seem fine to me. Basically I am in agreement with you on this one

[Kayaker72]

For those interested, after testing NINE copies, my odyssey with the 24-70 II appears to be over.

A quick recap (first three digits of the serial number):

October - December 2013 (ordered from Adorama and Amazon)

• Copy 1 (032): Clicking while operating the zoom ring
• Copy 2 (032): Clicking while operating the zoom ring
• Copy 3 (062): Had AFMA vs aperture issues at 70 mm
• Copy 4 (062): Small bubble in front element (otherwise excellent)
• Copy 5 (042): Clicking while operating the zoom ring
• Copy 6 (042): Clicking while operating the zoom ring
• Copy 7 (950): Extremely soft at 70 mm, similar AFMA issues as Copy 3
• Copy 8 (950): Perhaps an acceptable copy, but ~20% resolution drop (based on Reiken #) from f/4 to f/2.8 at 70 mm and my 24-105 was sharper (according to Reiken) at every aperture at 70 mm.

I returned all these copies. #8 may have been acceptable, but frustration was high at that point, it didn't "wow" me at 24 mm, and had the noted extreme drop at 70 mm plus my 24-105 was sharper at 70 mm and close at 24 mm and 50 mm.

June 2014 - I caught one of the 15% off a refurbished lens from the Canon Store. I decide to try it again.

• Copy 9 (961): Excellent lens.

Across the board sharper than my 24-105 mm, especially at 24 mm. Little resolution drop at 70 mm from f/4 to f/2.8.

I used the firework show in Portsmouth NH as my landscape test:
5DIII, 24-70II @ 50 mm, 8 sec, f/9, ISO 100

Small-8781 by kayaker72, on Flickr

And my neice was up a day earlier. In reviewing those photos, this lens is a keeper.

[neuroanatomist]

I don't know, Brant. That flag looks awfully blurry… Are you sure it's not a decentered element?

Congrats on finally getting a good copy, it's an excellent lens and I'm sure you'll enjoy it!

[HDNitehawk]

I don't know, Brant. That flag looks awfully blurry… Are you sure it's not a decentered element?

I think it is a Image Stabilization problem. I would keep the lens and if it bothers him he can send it to Canon and tell them the IS isn't working.

9 copies Brant, congrats on finally finding a good one.