Posted by Joe Rogers on January 15, 2010 at 7:55 PM
From time to time on this forum and others individuals make statements concerning this or that lens being tack sharp and this other lens being soft at the edges, center, or wherever the hell and I would like to know of a simple method of objectively determining this that does not require a degree in calculus. There may not be a simple way....I dont know..I have a couple of lenses on which I would like to have some objective method of testing without just taking the word of some reviewer.
Thanks so much,
Joe Rogers
Posted by Bret Edge on January 15, 2010 at 10:47 PM
Joe: All of my tests are done in the field and I probably can't claim they are objective. But, when I review them at full resolution in Photoshop edge softness is, or isn't, very noticeable. For example, on the 5D2 my copy of the 17-40mm lens was completely unacceptably soft at the edges. The 16-35mm, version 2, nice and sharp.
So, I guess I'm just saying that I don't lay out a newspaper and photograph it at various apertures to determine if the edges are sharp. I just shoot in the field, look at the full resolution images and make a decision based on that. Real world testing, I guess you'd call it.
Posted by Scott Bacon on January 16, 2010 at 9:12 AM
Like Bret, I test my lenses in the field conditions in which I normally shoot and compare images at 100% in Lightroom - center, edges and corners. I'll usually take images at a range of apertures that I normally use, f/8 - f/22. The results are sometimes subtle, sometimes obvious. My goal is to make nice large prints of nature and landscape. So while I try to ensure that I use the best equipment within my budget, I also keep in mind a measure of practicality. Because I've never sold an image of a lens chart...
Posted by bill meikle on January 16, 2010 at 9:25 AM
I sometimes shoot the rear license plate of the car from the driveway (sad I know) since that is pretty controlled and has enough detail on the labels that I can compare, but it isn't scientific!
Posted by Paul DeCesare on January 16, 2010 at 12:23 PM
OK Joe, here's a test you can try, totally unscientific:
1) Take a shot of something you like, bird, tree, whatever, and make sure it's sharp (via tripod, high shutter speed, etc).
2) Open the image in your editor and set the view at 50% (at 100% you'll see too much garbage that will disappoint).
3) Apply a 10% boost in Saturation and Unsharp Mask set at 120%, 1.0 Radius, 0 Threshold.
Sit back and have a look. Forgetting composition, etc, just look at image quality. If you go WOW!, then you've got a keeper. If the image makes you feel a bit unsatisfied, get it on eBay ASAP.
BTW, the reason for the saturation and sharpness adjustment is to get back what gets a bit lost in digital transfer.
I'm sure there's 97 ways to test lenses, but this one seems to be a good reference test for me. Just like Bret, when I got my 5D2, my 17-40mm looked like a kit lens. The wow came back when I got the 16-35mm/2.8.
One last thought: I went through a lot of lenses, and now (finally) and completely satisfied with my set, but unfortunately it meant a lot of $$$, because I have all 2.8 versions (16-35, 24-70, 100mm macro, 70-200). This is not a "look at my lenses" list, it's just to show that it took going to pro lenses to get the wow I've always wanted. I guess that for the most part, price does reflect image quality. I think I'll probably get death threats with that statement, I expect some juicy rebuttals! lol!
Posted by Joe Rogers on January 16, 2010 at 8:08 PM
Thanks all for the good information.....basiclly I've been field testing myself although today I went back and did a more extensive comparison of the two lens on which I wanted some answers using some of the criteria here. Of the two that I compared, a Nikon 20-35 and a Tamron 17-35 I found that the Nikon is much sharper, yeilding better color at around f/8 (20mm) than the Tamron but the overall sharpness on the Tamron catches up to a great degree around f/16. I will explore this more and Paul, I will certainly try your technique as well.....thanks all for the help.
Joe Rogers
Posted by Joe Rogers on January 16, 2010 at 8:52 PM
Thanks all for the good information.....basiclly I've been field testing myself although today I went back and did a more extensive comparison of the two lens on which I wanted some answers using some of the criteria here. Of the two that I compared, a Nikon 20-35 and a Tamron 17-35 I found that the Nikon is much sharper, yeilding better color at around f/8 (20mm) than the Tamron but the overall sharpness on the Tamron catches up to a great degree around f/16. I will explore this more and Paul, I will certainly try your technique as well.....thanks all for the help.
Joe Rogers
Discussion
6 repliesThanks so much,
Joe Rogers
So, I guess I'm just saying that I don't lay out a newspaper and photograph it at various apertures to determine if the edges are sharp. I just shoot in the field, look at the full resolution images and make a decision based on that. Real world testing, I guess you'd call it.
1) Take a shot of something you like, bird, tree, whatever, and make sure it's sharp (via tripod, high shutter speed, etc).
2) Open the image in your editor and set the view at 50% (at 100% you'll see too much garbage that will disappoint).
3) Apply a 10% boost in Saturation and Unsharp Mask set at 120%, 1.0 Radius, 0 Threshold.
Sit back and have a look. Forgetting composition, etc, just look at image quality. If you go WOW!, then you've got a keeper. If the image makes you feel a bit unsatisfied, get it on eBay ASAP.
BTW, the reason for the saturation and sharpness adjustment is to get back what gets a bit lost in digital transfer.
I'm sure there's 97 ways to test lenses, but this one seems to be a good reference test for me. Just like Bret, when I got my 5D2, my 17-40mm looked like a kit lens. The wow came back when I got the 16-35mm/2.8.
One last thought: I went through a lot of lenses, and now (finally) and completely satisfied with my set, but unfortunately it meant a lot of $$$, because I have all 2.8 versions (16-35, 24-70, 100mm macro, 70-200). This is not a "look at my lenses" list, it's just to show that it took going to pro lenses to get the wow I've always wanted. I guess that for the most part, price does reflect image quality. I think I'll probably get death threats with that statement, I expect some juicy rebuttals! lol!
Joe Rogers
Joe Rogers