Percentage of bad ones

what would be the proportion of bad lenses to good ones. let say in the case of sigma 30 1.4 or sigma 10-22.

Browsing the forum it presents a very bleak picture if somebody has to buy a lens where there is no return policy.

I would say that in most cases, the percentage of bad lenses to good ones is really low. The problem here...most people don't post threads raving about their great lenses....just the bum ones.

Well said. And this goes for any online forum (especially DPR).

The reason i asked this question is that i am in india and one of my friend who is comin here from us can bring the lens (looking for 10-20 sigma or canon 10-22). I dont think i have the luxury of returning it if its a bad copy. thinking of going with canon since i believe qc of canon is better.

sanil wrote:
what would be the proportion of bad lenses to good ones. let say in the case of sigma 30 1.4 or sigma 10-22.

Browsing the forum it presents a very bleak picture if somebody has to buy a lens where there is no return policy.

don't buy any lens with no return policy - seriously

Have your friend do a focus test before he brings it to you.

I think a good portion of the complaints result from user error as much as too slow shutter speed for focal length etc. With super wide lenses some people just don't understand that the perspective change is not an optical flaw. These folks that fail to research why the results fall short of their expectations are usually also the most vocal.

Gerhard

Almost all the "bad ones" are my fault with most lenses unfortunately....

There are some bad copies or lens with problems over some body (like everything manufactured; think about cars, tv, etc). The fact is that we don´t know how many copies are manufactured & how many "real" copies need recalibration. I am pretty sure the porcentage is very low.

The only thing you need is test it when you buy.

LoL. Look who is complaining. In Romania's photography stores we pay the equivalent of 550$ for a new 50 f/1.4 900$ for a 70-200 f/4 L and a mind boggling 1900$ for a bloody 70-200 f/2.8 L (non IS) and there is basically no return policy. Fortunately the black market does wonders for those outrageous prices and you also get to test the lenses. Never buy a lens without testing it first.

Unfortunately, there is no Sigma dealer/distributer in India, The nearest Sigma dealer you have is in Karachi - Pakistan. So send an email to them, or contact them through their website. www.smiphoto.com
And ask them if they can do something for you incase you get a bad copy.

I got all my Sigma lenses from them and All of them are good copies.

Thank you all.
thanks Farrukh, I shall try this option.

Sanil

The percentage of "bad copies" is really very low. Sometimes--but rarely-- there is a general problem in design or manufacture that results in perhaps an entire substandard batch; those cases get publicized in the forums pretty quickly because they're easy to verify.

There are several reasons people complain about "bad copies." It actually takes some experience, effort, and technique to determine what's good and bad.

Experience: Back in the "film days," using 35mm, we were glad to get sharp 11x14 (A4) prints, and positively overjoyed to get 16x20 (A3) prints that looked sharp at arms' length. Even then, it took the best of technique to do that well. Canon's design standard is only that a 6x9 print should look sharp viewed from one foot away.

Today, people commonly enlarge digital images to 100 percent (the equivalent of a 1x2 meter print!) and put their noses to the monitor...then complain that the image isn't "tack sharp!" Of course it isn't...the system was never designed to be "tack sharp" at that great an enlargement.

Also, at that much magnification you will see variations between lenses that are well within the manufacturer's tolerances. Just because a variation is visible at 100 percent magnification doesn't mean that one lens is "bad" and the other is "good." Both are good and within acceptable tolerances, even though one is slightly better than the other.

Canon recommends printing the picture at your normal enlargement sizes...if it looks sharp then, then it's sharp.

Technique: Autofocusing is not totally automatic. It requires the user to intelligently give it the proper focusing target. Autofocus systems have the same strengths and weaknesses as split image rangefinders. People who have experience with split image rangefinders should use the same techniques for autofocusing that they used with the split image rangefinder.

There are a number of quirks to know about Canon autofocusing, such as which marks are blind to horizontal lines and which marks are blind to vertical lines, and if a person doesn't know those quirks, he may call a lens "bad" that's actually operating just as designed.

Canon 10-22:
32,642 in circulation, 1148 bad.

Sigma 30mm 1.4 :
14,688 in circulation, 702 bad.

Source?