OK, finally I bought new lens. It's sigma 50mm 1:2.8 DG macro. Could you give me a piece of advice how to test that lens? I want to check if everything works fine, and I want to learn how to use it as well. If you have some suggestions or well-tried methods, please post them in that thread.
If you have a scanner try a comparative approach. Scan a drawing or print at a specific resolution. Then use your macro lens to copy the same print or drawing. Compare both digital images. You will need to level the camera above the print so that the same sized image is produced equalling the scanned image.Originally Posted by Banner1976
Hi,
The easiest method is to see on slrgear.com where You will find that this lens was tested.
All the best
Radu Dinu
As I recall, Amberglass gave a good link to a video on how to do this yourself properly.
EDIT: Found it at last, read this post
Last edited by Dave Humphries; 21st January 2010 at 12:42 PM. Reason: add link
Do not worry about the fact that you have a Canon. Just apply the equivalent feature settings that applies to your camera, and skip the ones that's not available on your camera.
If you click on the "more info" on the video description, you can download a PDF file detailing the steps within the video.
http://www.youtube.com/watch?v=HS0hlQ9lSps
The best way to test if the lens suits your needs is to use it as you are willing to do.
If the results are what you expect, be happy.
If not, try to find out what went wrong and what is the cause of the problem.
I read and hear a lot of people who are testing their new lens. I think testing a lens in a proper way is not easy at all. If you think there is something wrong withy it you might post some problematic pictures and discuss what the cause of it can be. Quite often the problem is not the lens but something else.
If you watch the video Hans, it's true that 90% of so called "bad copies" are actually the result of human error on the photographer. But of all my years of shooting, I've only actually had to return one commercial grade bad copy. The lens constantly "soft focused" on me.
But not everyone can afford commercial grade lenses or brand name lenses. Quality control is more of an issue with third party lenses than name brand commercial grades. Though Tamron, Sigma, and Tokina have improved over the years, they still have issues with quality control. It's still good to know how to test your lens than wondering if it's constantly you or your camera that results in "soft focusing".
As you mention it Amberglass, the problem is lot of times not the lens.
What I just want to say is as long as the lens gives good results why then "test" it?
I cannot imagine what the fun is in shooting brick walls, newspapers or rulers.
I receive my new 70-200 lens next monday. Im not going to test it by shooting these things.
The first thing I will do is shooting items that I normally shoot. In my case people and buildings. If the results are good, then I don't see the added value of another test like a brick wall.
Just remember Hans that you MUST apply capture sharpening to a RAW shot if you're evaluating sharpness.
Thanks or mentioning Colin.
This also is something people forget in PP.
No worries Hans. The reason I mentioned it is that in many lens tests and comparisons capture sharpening typically has about 5 times more influence on the result than the difference between two lenses or between one lens and a "perfect" result - and yet - most photographers don't apply capture sharpening (which is a normal and necessary part of post-processing).
Don't mean to butt in here, but could you please define "capture sharpening". I've never heard that term before.
FWIW, I just purchased 2 Sigma's at Christmas - a 30mm f/1.4 and the 50-150mm f/2.8. I had already ordered my lenses when I came across several "reviews" complaining of front focusing problems with the 50-150. When mine arrived I ran the tests recommended here. Much to my dismay the 50-150 displayed problems at the closest focus distance. Fortunately, my 50D has a Custom Function Microfocus Adjustment that was able to compensate for the problem. Further tests (admittedly, subjective) in the field revealed that the front focus problem didn't occur at normal shooting distances. A comparison of the 50-150mm to my Canon USM 70-300mm yielded results showing the Sigma (without the Microfocus Adjustment applied) to be on par with the Canon USM.
Happily, the 30mm had no front focus problems and it's informal field testing yielded results similar to the 50-150 - on par with Canon's USM and EF-S lenses.
My 2¢ worth.
Hi Terry,
I wrote a bit about it here. Perhaps have a read through that thread, and then I can answer any questions you might still have after that?
Colin, thanks. I read the posts at the link you provided and will probably have to go back and reread them again several times before it all sinks in.
I do have a few questions. I don't want to hijack this thread so I hope it's OK that I post them on the "When/How to Best Sharpen a Digital Photograph" thread. If you have a few minutes and could reply there, I'd appreciate it.
Thanks again for your time.
Regards,
Terry
I would only test a lens if I find an obvious focusing or exposure error in a "normal" photo. For instance, if I'm taking a portrait at shallow DOF (say f/4) and focus on the eyes of my victim, err, subject, but when I examine the photo on my computer I notice that it is the ears and not the eyes that are sharper in focus, and I notice this consistently, and try enough samples to convince myself it is not my error, then I go on and do a thorough front/back focus test. Most of my photography (landscapes, etc.) is at f/11, so if I do a couple of shots at wider apertures and it comes out "close enough," I'm good to go. I find that precise, surgical focusing is not needed unless I'm shooting macros, and for those, I don't bother with AF and switch to MF instead.
Posting Permissions 
Reply With Quote