## Lens Defects

On this page are the results of the survey on photographic lenses for SLR and DSLR cameras. The results are based on input from photographers who own lenses manufactured by Canon, Nikon, Pentax, Minolta/Sony, Tamron, Tokina and Sigma. There have been 4449 survey responses so far

There have been responses about Canon lenses from 3320 users

There have been responses about Sigma lenses from 1695 users

There have been responses about Tamron lenses from 1082 users

There have been responses about Tokina lenses from 419 users

There have been responses about Nikon lenses from 614 users

There have been responses about Pentax lenses from 409 users

There have been responses about Minolta/Konica/Sony lenses from 194 users

There have been responses about Other lenses from 422 users

The data presented here is based on the Lens Defect Survey. No survey is 100% reliable and as someone once may have said 'There are lies, damned lies, and statistics' (Mark Twain quoting Benjamin Disraeli). So be aware that:

**First**the survey doesn't sample random users. It samples users who were directed here from one of two or three other websites.**Second**it doesn't sample all users, only those motivated to fill in the survey.**Third**, some people like to mess with surveys and give bogus data. While efforts have been made to detect and eliminate obviously bogus data, it can't all be eliminated.**Fourth**, it's possible that people with complaints are more likely to be motivated to leave their data than those who are happy with their lenses.**Fifth**, there is no differentiation here between cheap Photographic lenses and expensive lenses. You might expect cheap SLR lenses to have lower quality control and perhaps a higher numbers of defects, but on the other hand you might expect buyers of expensive SLR lenses to be more critical and so find more defects!

My requirement before publishing any numbers is that there should be data on at least 100 lenses by any single photographic lens manufacturer and that data must come from at least 25 different users. With less data than that the data would be even more unreliable. The idea is that the more reports received, the better the statistics will be and no single user has a huge influence on the averaged data. I'd really like to see data from at least 100 different users on at least 300 different lenses before I feel reasonably comfortable with the numbers.

The probabilities assume that the distribution of defective SLR lenses is completly random, i.e. doesn't depend on which lens you chose or where it is shipped from. This may not be true, in fact it probably isn't. Some models may be more likely to show defects that others. There could also be bad batches of lenses and if the store you buy from has a bad batch, your chances of getting a defective lens in exchange for a defective lens would be higher than if the distribution was totally random.

The bottom line is therefore that these numbers should be treated with some skepicism. When there are enough entries I may be able to do some more statistical analysis, but the results are only as good as the input data, and I have no direct control over that. As they say in the TV ads for 'psychic advisors', this data is for amusement purposes only. It's interesting, but don't read things into it that may not be there.

## Survey Results

Note: Values are greyed out if there are less than 300 lenses sampled

**Canon lenses** - 14700 with 1134 defects

The probability of getting a good lens is 92 %

The probability of getting 5 Canon lenses in a row is 67 %

**Sigma lenses** - 3339 with 760 defects

The probability of getting a good lens is 77 %

The probability of getting 5 good Sigma lenses in a row is 27 %

**Tamron lenses** - 1685 with 253 defects

The probability of getting a good lens is 85 %

The probability of getting 5 good Tamron lenses in a row is 44 %

**Tokina lenses** - 570 with 99 defects

The probability of getting a good lens is 83 %

The probability of getting 5 good Tokina lenses in a row is 39 %

**Nikon lenses** - 2681 with 229 defects

The probability of getting a good lens is 91 %

The probability of getting 5 good Nikon lenses in a row is 64 %

**Pentax lenses** - 1825 with 117 defects

The probability of getting a good lens is 94 %

The probability of getting 5 good Pentax lenses in a row is 72 %

**Minolta/Konica/Sony lenses** - 690 with 64 defects

The probability of getting a good lens is 91 %

The probability of getting 5 good Minolta/Sony lenses in a row is 61 %

**Other lenses** - 1174 with 130 defects

The probability of getting a good lens is 89 %

The probability of getting 5 good Other lenses in a row is 56 %

If you found this survey interesting and informative, please tell others about it...

Note for a random distribution of defective SLR lenses the cumulative probability of getting 5 good lenses is a row is lower than that of getting one good lens, but that does not mean that if you have 4 good lenses the chances of the next lens being good are lower. It's like tossing a coin. There is always a 50% chance of it showing tails. If you toss it 9 times and it comes up tails each time, the chance of it coming up tails on the 10th toss is still 50%. However the cumulative chance of getting 10 tails in a row is only 1%, because the chance of getting the first 9 tails in a row was only 2%.