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DPChallenge Forums >> Photography Discussion >> Missed focus or crappy lens?
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 08/28/2011 11:32:47 AM · #1
A lot of times I am not happy with the sharpness of my images. I am using 25-105mm on 5D II. The images are not sharp in my opinion more often than they are. Once in a while I will get a nice super sharp image. I have not done any comparisons at all but I am wondering if it's the lens or it's me not focusing it properly. Like I said I did not compare settings of the sharp image vs the settings of non sharp image using this lens and I have not compared my focusing with this lens to my focusing using another lens. A lot of times I will see an image the hubby took with his lens and his seems to be super sharp comparing to mine. He is shooting with a different camera/different lens and he is a lot bigger than me so he just might be holding the camera more steady. Having said that, is there any way one can draw any conclusion that perhaps the lens is not that great or it's definitely me not focusing properly?
 08/28/2011 11:50:54 AM · #2
need some examples with exif data..
 08/28/2011 11:57:00 AM · #3
Problem solved

Focus after you take the picture
 08/28/2011 12:01:17 PM · #4
On a tripod and do loads of test shots at different distances.
Then study the evidence, would be my advice.
 08/28/2011 12:06:41 PM · #5
Originally posted by mike_311:
need some examples with exif data..

OK, here you go: Image
 08/28/2011 12:19:50 PM · #6
Well, it actually looks to me like there is some camera shake going on there... which is odd, because you are using an IS lens. The shutter speed on your test image was 1/100s, which should be fast enough even without IS, unless you have relatively unsteady hands. I'm wondering if the IS system is doing something it shouldn't?
I see you shot that at f/16. You may be seeing some mild effects of diffraction at that aperture. Try opening up the aperture a little more, f/11 or perhaps even f/8, and see if that helps. Also, try turning off the IS, and see if that helps. If turning off the IS makes a big, positive difference then the IS system is malfunctioning.
 08/28/2011 12:24:45 PM · #7
Not to rip off the thread but what is this "diffraction" you speak of? I take macros once in awhile and try to get it to f18+ for DOF reasons. Should I not do that b/c of diffraction?

Originally posted by kirbic:
Well, it actually looks to me like there is some camera shake going on there... which is odd, because you are using an IS lens. The shutter speed on your test image was 1/100s, which should be fast enough even without IS, unless you have relatively unsteady hands. I'm wondering if the IS system is doing something it shouldn't?
I see you shot that at f/16. You may be seeing some mild effects of diffraction at that aperture. Try opening up the aperture a little more, f/11 or perhaps even f/8, and see if that helps. Also, try turning off the IS, and see if that helps. If turning off the IS makes a big, positive difference then the IS system is malfunctioning.

08/28/2011 12:37:50 PM · #8
Originally posted by kenskid:
Not to rip off the thread but what is this "diffraction" you speak of? I take macros once in awhile and try to get it to f18+ for DOF reasons. Should I not do that b/c of diffraction?


Tiny apertures cause diffraction as light rays pass through them. This is the actual, physical diameter of the aperture causing the problem. F/stop is defined as focal length divided by diameter of aperture. A 100mm lens at f/8 has a 12.5mm aperture. The same aperture on a 50mm lens is f/4, and on a 25mm lens it's f/2 — so the lponger the lens, the smaller an f/stop you vcan use without worrying much about diffraction. Your 60mm lens at f/18 probably IS showing the effects. I rarely used my 60mm macro at smaller than f/11, and usually shot at f/8 when I could.

R.
 08/28/2011 01:02:50 PM · #9
Originally posted by kirbic:
Well, it actually looks to me like there is some camera shake going on there... which is odd, because you are using an IS lens. The shutter speed on your test image was 1/100s, which should be fast enough even without IS, unless you have relatively unsteady hands. I'm wondering if the IS system is doing something it shouldn't?
I see you shot that at f/16. You may be seeing some mild effects of diffraction at that aperture. Try opening up the aperture a little more, f/11 or perhaps even f/8, and see if that helps. Also, try turning off the IS, and see if that helps. If turning off the IS makes a big, positive difference then the IS system is malfunctioning.


Thanks kirbic, this is very helpful. I do think it's me being unable to hold the camera steady (tiny person with a huge camera). I will also try turning IS off to see if that helps
08/28/2011 01:50:01 PM · #10
well to me its looks good, but i agree with the camera shake, try opening the aperture or bump your iso so that you can get a faster shutter and see if you can get sharper images.

the rule of thumb is to have the shutter no less than a reciprocal of the focal length so your shutter speed at that length should be equal to or greater than 1/100, unless you are using a tripod.
 08/28/2011 01:59:35 PM · #11
OK, here is another one (same lens, same settings), which I think is much much better so perhaps it's not the lens but ME! What do you think?
Image 2
 08/28/2011 02:00:11 PM · #12
Originally posted by maggieddd:
Thanks kirbic, this is very helpful. I do think it's me being unable to hold the camera steady (tiny person with a huge camera). I will also try turning IS off to see if that helps

If you are testing the quality of the lens and/or the functioning of the IS system you should be making test shots using a tripod, the timer or a remote, mirror lock-up, etc., to try and isolate the issue. Shoot a series of images of the same test target (a grid like graph paper is good) changing only one variable* at a time -- remember to keep track of the settings for each shot! -- and evaluate those.

*aperture, IS on/off, etc.
 08/28/2011 02:45:39 PM · #13
While I don't have any experience with the 24-105 I'd be amazed if it really is that soft. Have you tried looking at results from manual focusing? Perhaps this article is relevant - //www.canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths/

Message edited by author 2011-08-28 14:59:32.
 08/28/2011 02:50:20 PM · #14
Originally posted by HawkinsT:
While I don't have any experience with the 24-105 I'd be amazed if it really is that soft. Have you tried looking at results from manual focusing? Perhaps this article is relevant - //www.canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths/

Thanks, check my image 2 above, would you say that this one is adequately focused?

Message edited by author 2011-08-28 14:50:49.
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