Sharpness testing

[RichardC27]

As some of you may know, I've just got a 120-400mm Sigma lens. I've done one shoot with it, and been pretty pleased with the results, but I've heard of various QC problems with Sigma lenses, leading to some people saying they've ended up with a soft copy.

So, to put my paranoia at rest, how do I do an effective sharpness test on my new lens? As I say, it seems fine, but I don't really have anything to compare it to.

 

[Richard Peters]

If you think it's fine don't test it...you could end up upsetting yourself for no good reason

 

[Yv]

there are tests, googling should find them, but if it aint broke.....

 

[SuperCNJ]

Hi,

try this: http://www.focustestchart.com/chart.html

You will need to print it and follow the instructions.

Good luck

 

[StewartR]

try this: http://www.focustestchart.com/chart.html

That chart is for testing front/back focus, not sharpness.

Here is a good (but thorough) tutorial.

Here is another tutorial.

The test chart I use for testing sharpness is the ISO 12233 one here. I've had a few lenses which were "bad copies" and it's pretty obvious when you look at the test shots. The most common issue is misalignment of an element, and the symptom is that one side or corner of the chart looks much less sharp than the others.

 

[RichardC27]

Thanks everyone, I've given it a go under less than ideal conditions and everything seems ok with the lens.