Home › Forums › Photography Q&A › Lens Sharpness Test
- This topic has 9 replies, 4 voices, and was last updated 8 years, 8 months ago by James Staddon.
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June 21, 2015 at 7:42 pm #11720Mr. QuebecParticipant
To make a long story short, I bought a new lens : a Canon EF 28-105mm f/3.5-4.5 USM.
I would like to know how this lens’ optics can compare with my kit lens 18-55. I’m planning to keep one with my 7d and sell the other with my T3.
I’ve done some quick tests and it seems at first glance that my 18-55 is sharper than the 28-105. But I would like to know how to compare correctly these two lenses’ optics.- This topic was modified 54 years, 4 months ago by .
June 22, 2015 at 8:29 am #11742Ezra MorleyModeratorCongratulations on your new lens, @Mr-Quebec! I know how you feel, as I also just got a new lens, and wanted to see how “sharp” it is. My purchase was a Pentax 55-300mm Weather Sealed lens, and unfortunately, my sharpness tests didn’t make me very happy… 🙁
I hope your’s turns out better than that! My advice would be to print out a test chart, there are lot’s of different charts, but I found this one just the other day, and I think it should work: http://www.graphics.cornell.edu/~westin/misc/ISO_12233-reschart.pdfYou’ll want to print it at the largest size, and highest print quality possible. Then tape it up on a wall, or something similar, and make sure you have lot’s of light. (Be sure that your chart is perfectly perpendicular to your camera, you don’t want any bumps, or bulges in the paper to throw off your results.) You want to be shooting at base (your lowest) ISO. Try it at wide angles, mid-way, and full telephoto. Take pictures wide open, (f/3.5 on the wide end) and stopped down. Remember that diffraction will kill your resolution if you go much over f/13 or so… Don’t just do all your tests from one distance either, do some from 5 meters, from 10m, and from 20m. My 55-300 is very sharp up close ~5m, but at 40-50m, it’s pretty rotten.
Don’t rely on the autofocus to get it focused correctly. Use Live View with 10x magnification to manually focus. Your new lens could very well be back/front focusing on your new body, which would cause it to seem less sharp than your kit lens.
You’ll also have to remember that your 7D has a much higher resolution sensor than the T3, so the results won’t really be exactly comparable.
While you’re at it, compare the focal lengths. 18mm is a decent wide angle lens, but 28mm really isn’t very wide. You want to be sure that it’s wide enough for your intended purpose.
I hope that gives you something to work with for now! Let us know how it turns out!
June 22, 2015 at 7:31 pm #11755Mr. QuebecParticipantThanks!
I couldn’t print the test page correctly today, so I don’t have nothing serious yet. However, on 10x magnification on live-view, at least on the center, the picture looked really sharp. I was surprised! Maybe I have a little front or back focusing issue, I don’t know.Don’t just do all your tests from one distance either, do some from 5 meters, from 10m, and from 20m.
I don’t understand what you’re meaning. My lens is a 28-105, and at 20m, it will be hard to judge of the sharpness if only what I can see is a tiny paper sheet…
While you’re at it, compare the focal lengths. 18mm is a decent wide angle lens, but 28mm really isn’t very wide. You want to be sure that it’s wide enough for your intended purpose.
Personally, I found the 105mm on that lens very attractive. For me, I found 55mm too limiting. I don’t play in the wide-angle very often, so I hope that this will not be an issue.
You’ll also have to remember that your 7D has a much higher resolution sensor than the T3, so the results won’t really be exactly comparable
I wonder if it can be a good idea if I set my 7D on a tripod and test my two lens on similar focal lengths on the same body?
June 22, 2015 at 8:54 pm #11756Ezra MorleyModeratorI don’t understand what you’re meaning. My lens is a 28-105, and at 20m, it will be hard to judge of the sharpness if only what I can see is a tiny paper sheet…
Yeah, I guess you’re right about that. I was using a 300mm, so that wasn’t really a big concern with me! 🙂 You could print something like this…
That would give you something large enough to see at a further distance.
I wonder if it can be a good idea if I set my 7D on a tripod and test my two lens on similar focal lengths on the same body?
That would be an excellent idea! That way you’d be able to see first hand the differences in focal length, and sharpness.
June 24, 2015 at 7:41 pm #11893Mr. QuebecParticipantI’ve compared both of my lens to find out that my 28-105 is sharp, but my 18-55 is a little sharper at about 28mm and 55mm. One thing that may have influenced my test is that the 18-55 was at a narrower aperture than my 28-105mm (f/5.6 vs f/4 and f/4 vs f/3.5). However, I took also a picture at f/8 on the 28-105, and it was still softer. For sure, it’s better to have a softer 105mm than a 55mm who needs heavy cropping…
I’m really not sure about which one I should keep. The only things that make me hesitate about the 18-55 is its sharpness and its IS feature. On all the other points, my 28-105 is a clear winner. It’s faster (in terms of aperture) than my 18-55. It’s way more solid (it’s the first metal mount lens I ever had) and the autofocus is faster and a lot more quieter. Full-time manual focus is also enabled on this lens. It makes me very hesitant…
I must say that my test was done at only a few feet from the test page. Next thing to check will be sharpness at a greater distance.- This reply was modified 54 years, 4 months ago by .
July 2, 2015 at 10:01 am #12059David FrazerParticipantHi @Mr-Quebec,
I thought you might enjoy looking at this comparison of your two lenses on dxomark.com. It looks like their test came up with pretty much the same results as yours.
July 7, 2015 at 8:15 pm #12065Mr. QuebecParticipantThanks for the link, @dfrazer!
Next thing to check will be sharpness at a greater distance.
I tested both lenses at about 15m. Sharpness seems to be equal with my two lenses! That’s odd, with my 28-105mm, the closer the subject is, the softer it looks, and the farther it is, the sharper it seems.
- This reply was modified 54 years, 4 months ago by .
July 10, 2015 at 12:01 pm #12112James StaddonKeymasterThis sounds like a fun project, @mr-quebec. Though it may not be as helpful as doing your own tests, The-Digital-Picture offers a Lens Image Quality Comparison Tool which might aid in your research.
I obviously don’t know all the factors involved, but if you find yourself limited with 55mm as max and you don’t find yourself using the 18mm much, then you’ll probably enjoy experimenting with the 28-105mm for a while. I assume the 18-55mm is the cheaper of the two and should be easily picked up in the future again if you start to miss the wide angle perspective. Or maybe experiment with a wider lens. There are a lot of options out there.
- This reply was modified 54 years, 4 months ago by .
July 16, 2015 at 8:24 pm #12211Mr. QuebecParticipantThanks for the link, @jamesstaddon! That 28-105 seems to have slightly better results than mine. Probably that’s because my manual focusing abilities are very limited ( I didn’t played with that very much…)
Anyway, I decided to keep the 28-105mm with my 7D. I tested it in real life situations, and I am really happy with it.P.S., @buddingphotographer, that test page you linked, is it okay to download and print it? It’s copyrighted.
August 4, 2015 at 11:53 am #12564James StaddonKeymaster@mr-quebec, you should be fine using the graphic for personal use. Wherever it goes, make sure the copyright line stays with it. 🙂
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