How can you tell if a lens is "softer" than it should be?

[Caecus Veritas]

I am just getting into photography. purchased an XSi couple of weeks ago and recently bought 24-70mm f/2.8L and 50mm f/1.8 II lenses. been having lots of fun shooting and experimenting with all these crazy number of settings.

While browing through different websites, I've read complaints about defective (or needing calibration) new lenses that are "softer" than they should be. I've also read about other XSi owners complaining about AF not properly working, yielding in pics that are not as sharp as they should be.

Being a novice, what would be the best test to check if my equipments are as they should be?

 

[alfa147x]

Originally posted by: Caecus Veritas

I am just getting into photography. purchased an XSi couple of weeks ago and recently bought 24-70mm f/2.8L and 50mm f/1.8 II lenses. been having lots of fun shooting and experimenting with all these crazy number of settings.

While browing through different websites, I've read complaints about defective (or needing calibration) new lenses that are "softer" than they should be. I've also read about other XSi owners complaining about AF not properly working, yielding in pics that are not as sharp as they should be.

Being a novice, what would be the best test to check if my equipments are as they should be?

This is what i do, print out grid paper with different line thickness then manual focus them and take pictures, then with your computer blow the pictures up and look how sharp the lines look

Im no professional, but i like this way

 

[Deadtrees]

Originally posted by: alfa147x

Originally posted by: Caecus Veritas

I am just getting into photography. purchased an XSi couple of weeks ago and recently bought 24-70mm f/2.8L and 50mm f/1.8 II lenses. been having lots of fun shooting and experimenting with all these crazy number of settings.

While browing through different websites, I've read complaints about defective (or needing calibration) new lenses that are "softer" than they should be. I've also read about other XSi owners complaining about AF not properly working, yielding in pics that are not as sharp as they should be.

Being a novice, what would be the best test to check if my equipments are as they should be?

This is what i do, print out grid paper with different line thickness then manual focus them and take pictures, then with your computer blow the pictures up and look how sharp the lines look

Im no professional, but i like this way

No. You shouldn't use MF unless you're testing the lens to see if it's got element alignment problem. What you need to do is just take pictures in AF mode using the possble shallow aperture and examine them at 100%. What works good is taking portrait shots focusing on the eye. If you want to be really picky, use various AF test charts.

 

[GrJohnso]

First, before you read my bloated reply, just remember how the internet usually works for reviews in general. If something works, no one says a word, and all is well. If something is bad, it will be posted, copied, broadcast, until you'd think everything ever created was bad. >99.9% of DSLR's and lenses are fine. Assume yours is fine until proven otherwise. Don't waste your time proving something is wrong, with the odds are it's just fine. Life's too short for test photos that'll only lead to stress if you do them incorrectly, when you could just be out taking photos and enjoying the world....

Now, onto testing and trying to prove that your lens or camera is good or bad...

The problem is, what are you comparing your results to? I mean, what is the standard of measure you are using to label something as soft/sharp, etc? You can compare the lenses to each other, but they are pretty different. You have a zoom and a prime, with different aperture ranges. The 50mm should be a lot sharper than your zoom at f2.8, but that doesn't make the zoom a bad lens with that one test. It's gong to get sharper until somewhere between f4 to f8. The 50mm will be at it's sharpest somewhere in that range too. One lens may start to drop off again earlier than the other, so you'll have to figure that out by testing as well.

The only real measure of good vs bad is if you have more than one of each lens to compare, and more than one body to shoot with. You can take a look at some of the online sites that do lens reviews and check their sample images, then try to duplicate the test on your own and compare, but that's still kinda iffy..

Too many people get hung up "is this good, is this bad, is this sharp enough", etc... Each lens has it's own personality. They have sharp settings, and not sooo sharp settings.. Take a bunch of test shots of the exact same subject, in the exact same light, and compare the results. This will tell you what you lens can do best, it's usable range, and what results you should be able to expect. Work in that range, and you'll be happy.

Most importantly, have fun and take pictures, photos, what'ev... Use the gear as it's intended....

 

[Caecus Veritas]

Thanks for all the replies! i suppose it is a good idea not to fret over getting the most "perfect" copy and just worry about my skills first.. heh

 

[Deadtrees]

Originally posted by: Caecus Veritas
Thanks for all the replies! i suppose it is a good idea not to fret over getting the most "perfect" copy and just worry about my skills first.. heh

Canon cameras/lenses are known for having more AF issues compared to other brands.

1. Hit and miss AF. Even when both of the lens and camera doesn't have AF calibration problems, AF is off once in a while. Some says this is due to Canon's using CMOS AF sensor. There's nothing you can do about this one so you'll have to take it as is or move to 1D lines of Canon.

2. AF calibration problem either on the camera or lens. Some Canon cameras do have AF problems. In this case, no matter what kind of lens you mount, AF will be always off (Well, Not always because there're possibilites where you could have a camera that has -1 AF and the lens has +1 AF creating perfect AF combination). Also, each AF points can have different AF calibration settings meaning that the center AF might be perfect when other AF points are not, or the other way around.

More often than cameras that have AF problems, lenses are the ones that cause AF problems. The first 50mm f/1.4 lens I had front focusing problems on my AF-correct camera. When shooting portraits, All the AF was on the subject's boobs instead of eyes where I aimed for. I ended up getting sharp boob shots and blurry face shots.

The moral of this story is: you shouldn't worry much about getting the perfect copy but to make sure you got the decent copy.

BTW, there's no 24-70mm f/2.8 that focuses perfectly on every focal length. You either have to give up 24mm in favor of 70mm or the other way around. Most people prefer to have correct AF set at 70mm as 24mm wouldn't show much of AF problem due to it being wide angle. Unluckly, my 24-70's correct AF is set at 24mm and I plan to hav it changed somday.