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| This classic BAA image was created at a shutter speed of 1/30 sec. If you think that your equipment is the cause of your usharp images, please keep reading. Not sure who said this but I do agree: "Most lenses are sharper than most photographers." This print will be offered as a limited editon canvas print in several months. See the Bulletins or the BAA store here: https://store.birdsasart.com/shop/category.aspx?catid=31 for details on this print series. |
BASIC SHARPNESS TESTING
I receive several e-mails each week from folks who state that this or that camera does not focus properly or that this or that lens is not sharp. In 99% of these cases I am sure that operator error rather than equipment malfunction is the cause. That said, on rare occasion, folks using quality equipment from Canon or Nikon do experience real problems with focusing accuracy. If you are handholding, please do not complain about unsharp images. ( Handholding telephoto lenses can be done successfully only be a very few highly skilled folks.) I was walking around in Sabine Woods late yesterday afternoon. It was cloudy dark. I was working at ISO 800 with shutter speeds of about 1/60th second and even slower at times. There were two folks walking around handholding 500 f/4 lenses; they might as well have gone fishing as there was no way that they could create a sharp image without a tripod in those conditions. For most folks it is best to work on a tripod at all times when using your longest lens (unless you are handholding for flight or for action). Another factor to consider is that most of the folks who write complaining of unsharp image are using cameras with 1.6X or 1.5X multiplier effects. They need to realize that these cameras multiply vibrations and movement caused by operator error by the square of the equivalent focal length! So using a 500 lens with say an EOS-50D you are really working at an effective focal lenght of 800mm, not 500mm.
If you are using a tripod you need to check and note the shutter speeds of your unsharp images. I had one guy on an IPT complaining that none of his images were sharp. I checked his set-up and saw that he was working in near darkness at ISO 100 with shutter speeds in the 1/8 to 1/15 second range. Making sharp images with a long lens at such slow shutter speeds is simply not possible 99.99% of the time. When working at long effective focal lengths I am confident that I can make sharp images down to 1/60 second as long as I have time to lock the tripod head and provided that the bird does not move during the exposure. With the prime lenses alone, I can usually get down to 1/30 second. With the relatively new Canon 800mm lens and its new 4-stop IS system, I have made some sharp images at shutter speeds as slow as 1/6 sec. Here are two simple tests to determine if you have faulty equipment.
- Tape a sheet of newspaper to a sunlit outdoor wall on a relatively still day. Make sure that it is as taped down as flat as possible. (A magazine cover with fine print or a plastic or cardboard test chart are of course better options.) Mount your telephoto rig on a tripod. Lock down the tripod and the lens collar. Make sure that you are beyond the minimum focusing distance of your lens and that the distance range switch (if your lens has one) is set to full. Make a few images at the wide open aperture using both One-Shot and AI Servo AF with Canon gear or Single (S) or Continuous (C) AF with Nikon. Then do the same thing at f/8. As long as the wall is sunlit you will have more than enough shutter speed to know that your focusing issues are not caused by too-slow shutter speeds.
Now download your images and check them for accurate focus. If all of the images are sharp, then you can be sure that your unsharp images were being caused by operator error.
- Stand well off a somewhat busy road with the sun angled so that the approaching vehicles are coming right down sun angle. Use the wide open aperture and choose an ISO that results in shutter speeds greater than 1/2000 sec. Choose AI Servo (Canon) or Continuous (Nikon) and select the center AF sensor. As the cars approach, place the central sensor on the license plate. Once focus is acquired, hold the shutter button down. and make a series of images. Even this simple task requires some practice so be sure to take lots of images. Download the images and sort them into two groups: sharp on the license plate and unsharp on the license plate. Now using an application that allows you to see the position of the active focusing sensor, in this case the central sensor, note the position of the sensor in the unsharp images. If the sensor is consistently on the license plate and the images are unsharp, then you likely have equipment problems. At this point you will need to send both camera and lens to the manufacturer along with a CD of the images.
You can repeat this test with various camera bodies and various lenses in an effort to determine the cause of your problem. Again, when and if you are pretty sure that you have an equipment problem it is best to send the gear to the manufacturer along with a CD of the test images. In the great majority of cases, folks will learn that their equipment is perfectly fine but that poor sharpness or panning techniques, slow shutter speeds, or incorrect AF settings are the cause of the unsharp images. Do also realize the importance of subject movement. While working at the Cozad Ranch probably well more than half of my images were unsharp. This was due in most cases to subject movement. In other cases, the unsharp images were a result of the AF system being unable to maintain sharp focus on the tiny songbirds as they leaped off of their perches. It is important to understand and to realize the limitations of our equipment.
Hi Arthur,
I like your article on Sharpening test, however, I disagree with your following statement
” So using a 500 lens with say an EOS-50D you are really working at an effective focal length of 800mm, not 500mm.”
I believe that you are actually working with a focal length of 500 mm. The sensor is cropping down your picture where it seems to be 800 mm.
I just want to make sure that people do not misunderstand this important fact.
Thanks,
Martin
Thanks for sharing your thoughts. As far as I am concerned that is a matter of semantics… I do not consider it an important fact 🙂
I don’t understand, “Now using an application that allows you to see the position of the active focusing sensor . . . .” I assume you are refering a program that will use your image’s metadata to overlay the focus point on your image on the computer screen? If so what software does that? (Probably another feature of Photoshop CS that I haven’t discovered in years of use.)
Thanks for all your good tips over the years.
Hi Hunter, You got it right. The software that comes with a Canon camera will show you the focus points as will BreezeBrowser. Not sure with the Nikon bodies. Robert O’Toole states that Nikon Capture NX 2 will do it.
Hi Jon, It is good that you followed through with Nikon. In rare instances such as yours, it is the equipment that is faulty. Detailed instructions on how to calibrate Canon bodies are contained in our Mark III/Mark III 1Ds Users Guide that will eventually be upgraded to include the Mark IV bodies as they are quite similar.
If you would like to write detailed instructions for calibrating the Nikon cameras that offer it, I would be glad to publish it in a Bulletin.
Hi Arthur
Late last year, I bought a Nikon 500mm f/4 VR lens. It front-focused very badly in combination with my Nikon D300 and my Nikon TC-14E teleconverter. It front-focused so badly in fact that I was not able to correct the error using the AF fine tune function in my D300.
To prove to Nikon that my lens was faulty, I sent Nikon a number of photos of a Lens Align Pro AF calibration chart. I made these images with my camera mounted on a tripod. I used a cable release and the mirror up function to release the shutter. I also illuminated my AF target entirely with flash.
Eventually Nikon agreed to replace my faulty lens with a new copy. As I was replacing my lens, I decided to get a Nikon 600mm f/4 VR instead of a 500. I am happy to report that the front-focus on my new lens falls well within the bounds of my D300 AF fine tune function.
In the process of proving to Nikon that my first lens was faulty, I tested two D300 bodies, two 500mm lenses, five teleconverters and one 600mm lens. AF calibration was necessary with each and every combination of the above-mentioned equipment.
My experience suggests that it might be worth your while to write a follow-up article describing how to calibrate AF systems. Such an article might be of use to photographers who already practice good long lens technique, but are still experiencing AF issues.
Regards
Jon Thornton
An interesting discussion on sharpness. I’ve used a Canon 500 f4 for a few years and get, to my eyes, impressively sharp images. For reasons of portability, I’ve just added a 400 f4 DO but even when using it on a tripod, the images don’t seem as good. They are OK compared with most lenses but not as crisp as the 500.
I guess I just need to persist and get used to this lens but it spends most of its time in the bag now and I still haul the 500 around!
Best to run the tests. I love my 400 DO and to my eyes it is just as sharp as the 500. I rate the 800 a tad sharper than the other two….
Hi Artie,
As for your quote “most lenses are better than most photographers”, the author is Michael Reichmann over at Luminous Landscape. That’s one of my favorite quotes, especially when I hear folks getting into a (usually bogus) good copy – bad copy lens debate.
Best regards,
Tim
Thanks Tim, I thought that it was Michael but did not want to spell his last name incorrectly. What I have been saying lately is that I am doing pretty good considering that fact that according to the internet experts none of my lenses are sharp and none of my cameras can focus. You gotta love it!
Hi Elliotte,
I do disagree with your comments about relative size. An image needs to be sharp whatever the size. And images should only be sharpened once they are sized for final usage….
Anytime that you crop and enlarge too much, image quality will be poor.
My comments were in reference to quality lenses, not to junk.
Arthur, I’ve been experimenting with sharpness lately and I’m definitely learning a few things. I suspect there are still quite a few ways I can push the sharpness of my images with existing equipment.
However, that said, there are real sharpness differences between lenses that are clearly and easily visible in studio photographs on a tripod. Maybe not at the high end, but in the $1200 and under range I can really see the difference.
I find that how much attention one pays to sharpness has a lot to do with the relative size of the image. If you’re shooting storks that easily fill the frame, then reducing the picture down to a 300 pixel by 450 pixel JPEG, sharpness really isn’t a problem with any remotely plausible lens. Where sharpness becomes an issue is when you’re photographing a warbler 5 or 6 meters away, and then blowing it up to twice life size. Any lack of sharpness in the lens becomes really apparent, really quickly.
Camera shake, subject movement, poor focus and the like will kill a lot of photos no matter what lens you use; but some lenses produce astonishingly sharp photos up to half the time, while other lenses almost never do. Same camera. Same photographer. Just a different lens.
I’m not sure what lenses people are writing you about, but there is a big difference between a kit lens and a 300mm Canon L series. A bad photographer can take poor pictures with any equipment, but a bad lens can take poor pictures with a good photographer too.
Glad to be of help. If you really want to speed up the learning curve, get yourself copies of ABP and ABP II here:
https://store.birdsasart.com/shop/category.aspx?catid=32
Where are you from? What’s the “q” for?
I am just learnin about photography (at 44 yrs old) lol, so this article helped me alot. Bless you 🙂