Dana C Loc: Buhl, Idaho

I shoot with a D7000 currently and recently bought, (used) a Sigma 17-70 f2.8 w/ OS. My problem is that I just don't seem to be able to get a sharp picture. If I shoot high school basket ball from under the basket sharpness isn't really critical but for other things like the occasional candid portrait it is very important.
I have had many of you use the term calibrate and fine tune a lens and focusing but for the life of me, I can't seem to find anything relating to it in the camera manual. The lens, which is highly thought of by many has a limited aperature range of f2.8-f4, if I remember correctly if that makes a difference. I should also mention that I have been shooting with a single center point focus.
Any thoughts you may have would be greatly appreciated.
Thanks,
Dana

dirtpusher Loc: tulsa oklahoma

big-guy Loc: Peterborough Ontario Canada

OK, center point focus but do you utilize back button focus or some other focus locking mechanism?

If you use manual focus, is your eyepiece diopter set to your shooting eye?

Dana C Loc: Buhl, Idaho

No I don't use the back button no do I lock focus. I almost never use manual focus and when I do, I have set the diopter for my right eye.
Should I use multiple focus points with that lens?

SonyA580 Loc: FL in the winter & MN in the summer

First, check out the focus by eliminating any possible causes of vibration. Use a tripod and remote release, or self timer, and mirror lock-up if possible. Manually focus on a number near the middle of a "yardstick" with either the camera or the yardstick at a 45 degree angle, the lens aperture wide open, plenty of light and use any focus aids your camera has. Look at the results on your computer. Is the number in focus, or, are the 1/16" marks in front or in back of the number more in focus. This should tell you if your lens is OK, front focusing or rear focusing. You may want to check at several different focal lengths. If it's not OK, send it back.

CHG_CANON Loc: the Windy City

I'd suggest posting to this thread an example of a problem photo with 'store original' and the image (JPEG) straight from the camera. There's probably an issue that is best diagnosed from an example image than your memory of your shooting parameters. Calibration may be needed, but only after technique and configuration have been confirmed.

SharpShooter Loc: NorCal

Dana, it's hard to say but even wide open a wide lens gets to infinity in a real hurry. So unles you are doing super close-ups, you should quickly negate any focus issues.
Check a dof table for your usual distance and f-stop with that particular lens. Chances are, it's huge and forgiving.
I know nothing of calibrating Sigma lenses. Maybe it's the same as a corporate lens but don't know.
I can't imagine having problems with a wide-angle and calibration.
Funny, that before calibration it was never a problem. Now everything needs to be calibrated to tenths if a mm!! Just saying. Good luck. ;-)
SS

CO

I have a D7000. AF fine tuning is on page 246 of the manual. I use the DataColor SpyderLensCal to check the autofocus.

The f/2.8-4 range are the maximum apertures that the lens can achieve. The maximum aperture at 17mm is f/2.8 gradually changing to f/4 at 70mm. The lens can be stopped down to a minimum aperture of f/22.

Lenses are usually their sharpest stopped down some from the maximum apertures. Try some shots in the f/5.6 to f/8 range.

dkguill Loc: Elkhart, IN

Can someone answer his question? No one has told us, in detail, how one goes about calibrating a lens. I, for one, would like to know how to do it and, further, if it has to be done for each camera body on which you use the lens. Is the adjustment (calibration) done to the camera body or to the lens? When done for a particular lens, does the change screw up focus for other lenses that are currently working fine? He said he couldn't find calibration mentioned in his manual. Neither can I.

Bud S Loc: Logan Ohio

Bud S Loc: Logan Ohio

I spoke with Sigma yesterday, I have the same lens, never knew how sharp my portraits would be on the D7000. I fine tuned and it helped a bunch, my 7000 front focuses. My D 7100 is much better. That said, Sigma said if my lens is still in warranty to send lens and body to them and they will calibrate the lens to the body no charge, not the same as fine tuning. I use mostly single point AF and back button focus

jerryc41 Loc: Catskill Mts of NY

As you've discovered, focusing is a big topic. Here are too many links about focus-checking and adjusting.

Focusing Charts
http://mansurovs.com/wp-content/uploads/2012/07/Siemens-Star-Focus-Chart.pdf
http://mansurovs.com/wp-content/uploads/2012/07/Focus-Test-Chart.pdf
http://regex.info/blog/photo-tech/focus-chart

How to Check Focus
http://photographylife.com/how-to-quickly-test-your-dslr-for-autofocus-issues
http://www.nphotomag.com/2013/03/05/how-to-recalibrate-your-nikon-dslrs-af-autofocus/
http://www.luminous-landscape.com/essays/are_your_pictures_out_of_focus.shtml
http://regex.info/blog/photo-tech/focus-chart#features
https://photographylife.com/how-to-quickly-test-your-dslr-for-autofocus-issues
http://photographylife.com/how-to-calibrate-lenses
http://www.canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths/
http://cameralightlens.com/newsblog/?p=264

big-guy Loc: Peterborough Ontario Canada

I'm thinking that calibrating the lens is not the issue. If your subject is dead center for every photo and you still have issues then maybe calibration is in order. However, I think you might be just looking and firing whether the subject is dead center or not. With the camera set to central focus then the focus could easily be misread. I would suggest using multiple focus points in the hopes of getting it right. Sometimes it will do good and other times it won't.

A more advanced and precise way is to use back button focus with the central focus point. What this does, is allow you to focus on a single point and then move the camera to re-frame the shot without changing the focal distance. The auto focus is removed from the shutter button and moved to a button on the back of the camera so you would focus with your thumb and the exposure and shutter release is handled by the shutter button. The shutter button will not focus or refocus.

Imagine taking a scenic portrait of your better half at say the Grand Canyon. You want them placed off to the right side of the frame with the canyon taking over the central area. Using BBF you simply put your BH dead center, press the BBF, recompose and take the photo. Using BBF locks the focus distance so they remain in sharp focus regardless of what is set at the dead center of the frame. So if they are only 7' away from you then 7' is locked and the camera will not refocus on the GC which would be at ∞. (infinity)

This method takes very little getting used to and once mastered you will probably never look back. I hope this helps in the quest.

Bud S Loc: Logan Ohio

I recently started using this method, and to use continuous focus
( subject moving to or away from you,) simply keep thumb on back focus button. Works great, all my cameras are set like that.

Bultaco Loc: Aiken, SC

I use a D7100, calibrated a zoom lens at 300mm which turned out very sharp but the short end was worse. I think the in camera tuning would be fine for a fixed lens but would not recommend it for a zoom. I like single point focus for everything except BIF then switch to 9 pt.