Sharpness question (photography Q&A)

December 25, 2010 5 Comments

Question from a reader

I saw that you wrote an article on zoom lenses last month and wanted to see if might have an explanation for an issue I seem to be having with mine.  I have a Canon 40D and bought the 70-200mm L-series f/2.8 lens earlier this year to help me with weddings.  It does not have the image stabilization feature on it, but the reviews I read were really good for either lens.  The issue I seem to have is getting tack-sharp images, specifically in low light of slow moving subjects.

I auto spot focus on each shot making sure the focus sensor is on the face of the subject I’m shooting, but when in low light without a flash, it’s as though the camera doesn’t have enough information/light to make the image sharp.  I put ISO at 650 or 500 (higher than that makes it pretty grainy on my 40D) and even then it’s a little grainy.  I’ve also read some articles that say there is a zone in lenses that creates the most sharp images – a middle f-stop and middle/higher shutter speed (around 1/160 or 1/200 or so).  Since my exposure won’t come out with really high settings for these specific instances, I try to keep my f-stop around 3.2, maybe 3.5, but know that 2.8 affects my depth of field and that it doesn’t seem as crisp at that aperture.  I’d love to have it at f/8.0, but there’s no way the image would have enough light at that aperture.  I also try to keep my shutter speed around 1/80 of a second or 1/100.

I’ve even tried all of this on a tripod and still have the same result.  Some photographers I’ve talked to say they are able to take images from the back of a church with no flash and then zoom in/crop later and get great detail.  Am I missing something?  I am beginning to wonder if it’s my camera body…I can’t image the lens being faulty seeing how much it was and that it’s supposed to be the L-series.  I’d like to try the lens on another camera body, but haven’t had the opportunity to do that just yet.

So anyway, any insight you could provide on this issue would be amazing, as I’ve tried to do a lot of research and am just getting frustrated that I can’t get the images I want, even though I see the shot through my lens.  Thanks in advance for any help!

Jim’s answer about sharpness

Getting sharp images comes from a number of factors: (1) the shutter speed, (2) the lens, (3) the sharpening in post-processing, (4) image stabilization or a tripod, (5) pressing the shutter button softly, (6) holding the camera properly, and (7) proper focus.  If you get half of the factors right and mess up the other ones, then your photo still won’t look clear.  Once you get those fundamentals down, you may want to learn how to do back button focus on Canon or Nikon cameras.
When we start analyzing what is making the photos blurry, we are almost always tempted to blame the lens first.  You obviously recognized this and discounted it when you said it was a quality lens.  Honestly, I have never seen a Canon or Nikon pro lens be the main culprit of a blurry photo.  Sometimes they get off a tiny bit, but I’ve never seen them go crazy.
The most likely culprit is that your shutter speed is just too low.  You’re already shooting wide open with a high aperture and the lowest shutter speed you possibly can.  That leaves only two options: (1) Use flash, or (2) get a camera that can allow you to shoot at a higher ISO.  I recognize that #2 is not popular because it is expensive, but honestly that might be the most reasonable choice in this particular situation.
Usually I like to see the shutter speed to be equal to the focal length of the lens.  You said you shoot at 1/80 shutter speed to get more light, but that is too low when you’re handholding with a 200mm lens.
Two cheap tricks are (1) use a monopod to increase your stability without needing to lock down on a tripod, or (2) shoot RAW and dial in -.3 or even -.7 exposure compensation.  You can brighten the photos up later in Lightroom and the negative exposure compensation will increase your shutter speed to get the photo sharp.
Now, about the unpopular option of buying a new camera.  I know it’s not fun, but I see from your website that you’re shooting for profit, so it’s a business expense.  I shoot a Nikon D7000 ($1,400 camera) and I shot at ISO 5,000 for a model shoot last night and got pretty clean results.  If you could change from shooting at ISO 500 to shooting at ISO 5,000, your problems would disappear.  I hate recommending expensive gear, but since you shoot weddings in dim locations, I have to make an exception and recommend a step up whenever you can make it happen.

Further Reading:

Portrait Tips
Avatar of Jim Harmer

About Jim Harmer

Landscape photographer, author of six photography instructional books, writer of daily photography tips at Improve Photography, and all around geek. follow me on Google Plus and check out my About Me page.
View all posts by Jim Harmer →

5 Responses to “Sharpness question (photography Q&A)”

  1. Steve Solomon August 28, 2012 at 7:57 PM

    Excellent articles, Jim! Though I don’t think I have a “sharpness” or focus problem, I always enjoy reading about photography by photographers!

  2. Jane Davey October 26, 2012 at 7:01 AM

    Jim
    I am always looking for articles on how high to push my ISO on my D7000. I have been using it at 800 max., and hesitated to do that. I was surprised to read that you used it at 5000.
    How much post work did you have to do to clean it up?
    I would love to use it in a low light situation and not use a flash but I wasn’t sure if it would perform well.
    What would you say is the D7000 limit for acceptable noise levels.
    I enjoyed your article.
    Thanks, Jane.

  3. Satish Inuganti January 14, 2013 at 6:30 PM

    Jane,

    I own a Nikon D7000 and go up to ISO6400 in low light w/o any issues. All I do in PP, apply a bit of noise reduction in Aperture which takes 10 secs and I am good to go.

    Thanks
    Satish

  4. Satish Inuganti January 14, 2013 at 6:34 PM

    One thing I must mention though, I used to wonder the same way you are as to how other were able to use it beyond 800 until I fine tuned the AF on D7000 with all lens combos. Not sure if they are related but I am getting great results in low light with high ISO now

  5. dcgreen February 5, 2013 at 6:43 PM

    Hi, I’m interested to read that you shoot with a D7000 – so do I. Can I ask, please, have you ever had back focusing issues at wide apertures with it? Mine are so bad, the AF tuning is useless, and I’ve read this is a very common problem with D7000s.

    I’m actually all set to send mine back to Nikon to sort out but I’d love to know if you’ve had any back focusing at wide apertures problems or might know anything about it?

    Kind regards
    dcgreen
    Edinburgh, Scotland