Focus Calibration

niemeyjt

Whilst looking for information on the Nikon D7200 SDK I came across a Focus Calibration tool.

One of their FAQ comments is When a camera or lens leaves the factory, it has been set up to work as accurately as possible, but there is always some variation in the calibration. Modern DSLRs have a feature which allows adjustment of the autofocus to compensate for these variations, but it can be difficult to get right.

So what do others think?

Do you calibrate every new lens? Just when there may be a problem? Never?

J

Pistnbroke

Yes always check the focus adjust particularly with long lenses but my experience is that until its done about 2-300 focus in outs the settting may vary ...so if its new go close focus /distant focus about 200 times before you set it and check after you used it for a month or so and then at 6 and 12 months ,,,had lenses new go from +15to -5 over 12 months

spraynpray

I always do a focus check and micro adjust. Haven't ever had one on zero yet.

haroldp

Ultrawides have so much DOF that it is hard to tell, but I fine tine all other lenses to each body including TC combo's.

HipShot

Newbie question: What about zoom lenses? Do you pick a point in the middle of the zoom range, and calibrate?

heartyfisher

Pick the most used focal length AND distance

Pistnbroke

the focus is most critical at the max focal length so I do it there...the simplest way is an extending rule just laid out on the floor with a pencil across it at 16 inches to focus on and just shoot it from eye level from about 20 ft. View on your monitor and zoom in. If its not a VR lens use flash.

haroldp

Use single servo auto focus, and use a tripod.

You can easily move back or forth more than an adjustment increment (about 1/2 inch at 20 ft) between focus and shot if handheld,.

... H

Pistnbroke

http://e-group.uk.net/gallery/data/500/HIL_0037.JPG

spraynpray

http://e-group.uk.net/gallery/data/500/HIL_0037.JPG

Care to tell us a little about the shot Pistnbroke?

BabaGanoush

"Just when there may be a problem?"

It depends on the lens. I never had a problem fine tuning my 70-200mm f2.8 VR on my D7000 or my D800; it gave sharp images over a wide range of micro adjustment values across its entire zoom range, so I Ieft the tuning value at zero. On the other hand, the 16-85mm G lens I once owned front-focused at one end of its zoom range and back-focused at the opposite end of the zoom range. Taking the average adjustment value or fine tuning the lens at some focal length in the middle meant that the optical performance was quite subpar at both ends of the zoom range. I kept a two-dimensional table of micro adjustment corrections in my head which I relied on whenever I used this lens; the corrections, after all, depend on both the focal length and the aperture. They also likely depend on the internal temperature of the camera body, which can be a problem if you shoot in extremely hot or cold environments, but at some point even if you are very, very picky you have to say enough is enough.

spraynpray

I would have sent it off to the repair centre as not fit for purpose Baba.

haroldp

Canon lets you AF tune a zoom lens with different settings at the wide and long end.

Nikon service centers can do this, so it would only need a firmware change to let customers do it.

.. H