Elmerviking

I recall reading an article in an old magazine about testing lenses. The article claimed that once in a while you could get a poor Leica lens, even if they were assembled by hand, matching lens element to each other. The photomagazine draw the conclusion that you had to test at least three ex to get a more accurate verdict. I understand that specification nowadays are much tighter and that most manufacturing is made by robots. Mistake still can happen, and do. Quality control is not 100% and sometimes it takes some time before you detect a flaw ( missing lubrication for example).
Most, if not all, lenstesters test only one ex. That might explain why their conclusion sometimes wary from good to “average” to excellent.
Bottom line : do your own validation and don’t trust lens testers too much!
Thoughts?

PixelStan77 Loc: Vermont/Chicago

Elmer, When I buy a lens, the first thing I do is test it Lens Test Target so if I find any concern I can return it with no penalty to B&H photo

Elmerviking

I agree with you! Whatever I buy the first thing I do is reading the negative reviews. Many times you understand that the reviewers don’t get it. When I bought my Nikon D7100 I checked as many reviews I could find. One common “flaw” was the limited buffer size. That didn’t bother me at all...I have never shot more than 4 consecutive shots in all my life!
I am therefore very happy with my choice!

imagemeister Loc: mid east Florida

Rigorous testing should always be the FIRST thing you do !

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jerryc41 Loc: Catskill Mts of NY

I've read similar articles - buy multiple lenses and compare them. Great idea, but not very practical. I always test a new lens when I receive it, but I'm not fanatical about it. I've never had to return a lens.

Pablo8 Loc: Nottingham UK.

I've only ever returned one lens, Sigma 15 ~30 zoom. Used it on my Nikon Film cameras. Found out it would not focus beyond 10ft.. Sigma replaced, as they could not repair, so got an 18~35mm F.1.8 Art lens. Very pleased with this lens, great results, and can use it on my Nikon FF and crop digital bodies. Instant facility to check results.

camerapapi Loc: Miami, Fl.

It is a good thing to know that the perfect lens does not exist. Today there are stricter manufacturing of lenses than what we had before. Companies like Ernst Leitz have an excellent quality control so it is very hard for me to understand that among two similar Leica lenses there is a big difference. A big difference among other manufacturers perhaps but not Leica. Leica is the standard for quality but we have to pay the price. I am convinced that a similar lens by another manufacturer can do a remarkable job at a fraction of the Leica price.
It does not seem very practical to me to buy several lenses of the same focal length to test for the best one.

Elmerviking

In the early 1970 I purchased a new Leica M4 with a Summicron 50 mm lens. The body was made in Germany, but the lens was made in their new plant in Canada. When I came home and examined everything carefully I found that the lens had an air bubble in a glass and the shade was rattling..not fitted to the lens. Poor quality control!
The camera store replaced it with no problems and told me that they have hade many problems with stuff made in the Canada plant, which at that time was new. Of course they had same quality control as Germany and were trained the same way.
When people are involved, like QC, mistakes can always happen!
By the way, my post suggested that Reviewers should test more than one lens!

speters Loc: Grangeville/Idaho

They usually do not test just one example, but several at several times over quite a long period to test consistency in a line-up as well!

John_F Loc: Minneapolis, MN

Just exactly how does one test a lens, what steps and measures. Short of an optical bench and precision measuring instruments, how do you test.

Strodav Loc: Houston, Tx

Good subject. The first thing I do is test a new (used) lens on the body(s) I plan to use it on. I don't understand why a serious photographer wold not check her/his gear. How many times have you seen a review saying a lens is a little soft wide open (smallest DOF). Is it soft or just a little front or back focused that disappears at a higher f stop (wider DOF), but could be taken care of with AF fine tune wide open? I really like that both Sigma and Tamron allow you to tune a lens at various distances (even primes) and various focal lengths (zooms) so you can get the absolute maximum performance the lens can give. My experience is that some lenses from the camera manufacturer (in my case Nikon) are slightly off, but not as far off as, say, a Tamron lens, but I can tune the Tamron lens. I think another thing many photographers don't understand is that AF is a random process. If you take 5 or 10 shots of the exact same subject moving the focus off a bit between each shot, tripod mounted, remote release AF will not be at the exact same point for every shot. You can see this if you use Focus Tune to check your lenses. So, (especially wide open) a lens might be tack sharp sometimes, but not always. If you tune it, you can get a much better keep rate.

Elmerviking

Good point Stroday!
I asked Dp review if they AF fine tune the lens before they test it. They never emailed me back.

Strodav Loc: Houston, Tx

Here's a good tutorial, but your eyes can blur reading it: https://www.bhphotovideo.com/explora/photography/tips-and-solutions/how-to-test-your-lens , but here's how I do it. Find a focus target online, print it out 8 1/2 x 11 best quality, hang it on a wall in a well lit area. Mount your camera with lens on a tripod using a remote release and set it for either jpg or raw (it doesn't matter for the test), low fixed ISO like ISO 100, M mode with aperture wide open. VR off, AF on. Move the tripod so your target covers about 1/4 to 1/3 of the viewfinder as you want to use the center / sharpest part of the lens. Take some test shots and adjust the shutter speed to get the exposure about right as most focus targets are black and white and do not average 18% gray. Take 2 or 3 shots in LV mode moving off of focus a bit before each shot as you want to force the lens to focus. In my experience, LV will give you the best sharpness the camera / lens is capable of. Now move to AF and take 3 to 5 shots again moving off of focus before every shot. Upload your images into your post processing software and examine. If your LV shots are not sharp, you've got an issue. If the LV shots are sharp, but the AF shots are not its time to look at the AF fine tuning feature of your camera. If both the LV and AF shots are tack sharp you are good to go.

Strodav Loc: Houston, Tx

Thanks and I'd really like an answer to that question as well. BTW, not complaining, but its strodav from my name DAVe STROng.

Elmerviking

Sorry Dave...my eyes are getting worse..I am 73