Lens Calibration (Page 2): So easy to do if you read the camera manual or go on youtube... A target is the only thing needed and an understanding of the camera menu to navigate to the...

catchlight.. Loc: Wisconsin USA- Halden Norway

So easy to do if you read the camera manual or go on youtube... A target is the only thing needed and an understanding of the camera menu to navigate to the range adjustments.

I think it would be a waste for anyone to send out a lens to have someone calibrate it for them. Calibration would be a normal expected adjustment as you add lenses to your inventory.

Dngallagher Loc: Wilmington De.

billnikon wrote:

Domino's work better and you can group them tighter and use more of them. But again you can only calibrate for that distance, if you change distance points, you have to do it again, and again, and again. Remember, lens re calibration is only good for the distance you calibrate it for.

Dominos would indeed be a fine target - good idea!

catchlight.. Loc: Wisconsin USA- Halden Norway

billnikon wrote:

Domino's work better and you can group them tighter and use more of them. But again you can only calibrate for that distance, if you change distance points, you have to do it again, and again, and again. Remember, lens re calibration is only good for the distance you calibrate it for.

Yes and no... but bad advise to discount the benefits.

Most lenses do not change with distance enough to tell but rarely that can happen with miss aligned sensors.

Calibration is very beneficial and works fine.

amfoto1 Loc: San Jose, Calif. USA

mborn wrote:

Focus sharpness

Technically, the calibration is done for focus accuracy.

It's more important with large aperture lenses, especially telephotos and if you use them wide open or nearly so a lot, where depth of field is shallow and even slightly missed focus can cause some loss of IQ.

Smaller aperture lenses, wide angle lenses, and any lenses that you tend to use stopped down a bit are all more forgiving of minor focus error.

Reikan FoCal is a software that can be used to automate the calibration process.

Target distances I've seen a number of places are "50X the focal length"... Based on that, a 50mm lens calibration target should be about 8 feet from the film/sensor plane of the camera. With really long focal lengths, there 50X might be impractical, you can probably use 25X (400mm lens example... distance to target: 64 feet).

Ratta Loc: California

billnikon wrote:

Domino's work better and you can group them tighter and use more of them. But again you can only calibrate for that distance, if you change distance points, you have to do it again, and again, and again. Remember, lens re calibration is only good for the distance you calibrate it for.

Why use batteries, dominos or aunt Ethel's calico tablecloth?? There are many fine printable targets, with instructions, available online. Most are free: http://regex.info/blog/photo-tech/focus-chart
This one has a nice tutorial and explanation of back/front focus and the principles involved and a printable target that I have found to work well with reproducible results. There are many others out there.

burkphoto Loc: High Point, NC

Ratta wrote:

Why use batteries, dominos or aunt Ethel's calico tablecloth?? There are many fine printable targets, with instructions, available online. Most are free: http://regex.info/blog/photo-tech/focus-chart
This one has a nice tutorial and explanation of back/front focus and the principles involved and a printable target that I have found to work well with reproducible results. There are many others out there.

The point of batteries and dominoes is to line them up diagonally, at half inch or one inch intervals, establish focus on the middle one, expose at maximum aperture, and see which one is sharpest. If the middle one is sharp, your lens and body mate well. If another one is sharp, you see the error.

I had a brand new Canon 40D that, right out of the box, front-focused 5.5 inches at a distance of six feet. Canon "tried" to adjust it twice, but really didn't do a thing to it. I measured the same exact error each time it came back. They finally agreed to replace it. The replacement was dead-on.

gessman Loc: Colorado

billnikon wrote:

Domino's work better and you can group them tighter and use more of them. But again you can only calibrate for that distance, if you change distance points, you have to do it again, and again, and again. Remember, lens re calibration is only good for the distance you calibrate it for.

Which may be the most compelling reason to shoot prime lens, once calibrated. It is zoom lens that frequently need calibrating more so than primes. With zoom lens, it is suggested that you calibrate at the distance you tend to use most often and let the rest fall where they may, or at the extreme, recalibrate "on the fly" for each shot, pretty impractical. I've also seen it said that you want to calibrate a zoom on both ends and let everything in between fall where it may - not sure how that would work. As amfoto1 said, there is a program that lets your computer do it for you - FoCal by Reiken, downloadable at https://www.reikanfocal.com/, a British company. It does a very good job, plus it has side benefits like to point out where a lens' sweet spot is. Several "hoggers" use FoCal.

Dngallagher Loc: Wilmington De.

Ratta wrote:

Why use batteries, dominos or aunt Ethel's calico tablecloth?? There are many fine printable targets, with instructions, available online. Most are free: http://regex.info/blog/photo-tech/focus-chart
This one has a nice tutorial and explanation of back/front focus and the principles involved and a printable target that I have found to work well with reproducible results. There are many others out there.

With trying several methods to detect & correct front & back focus - I have found it much easier & quicker to set up 5 AA batteries (actually, any 5 targets can be used, as long as they have finely detailed information that would show a tack sharp focus easily) in a diagonal row, an inch or so apart and then to focus on the middle battery - if only the middle battery is sharp and the front and farther back batteries are OOF, bingo.

Of course it is lens/distance dependent and you make adjustments accordingly.

http://cameralightlens.com/newsblog/?p=264

Ratta Loc: California

burkphoto wrote:

The point of batteries and dominoes is to line the... (show quote)

Good to know. I'll give it a try. I still like the chart as I can get dead on focus to the millimeter.

catchlight.. Loc: Wisconsin USA- Halden Norway

gessman wrote:

Which may be the most compelling reason to shoot p... (show quote)

The lens that was my most out of focus for me was the Canon 50mm f/1.2L prime. I was never able to adjust it in range my the MKiii. Disappointing and soft...

After getting the Mk4, all is good and near perfect tack sharp.

Sensor alignment in some cases is the evil factor for soft focus and not the lens... you may never know that unless the lens is tested on two camera bodies.

gessman Loc: Colorado

catchlight.. wrote:

The lens that was my most out of focus for me was the Canon 50mm f/1.2L prime. I was never able to adjust it in range my the MKiii. Disappointing and soft...

After getting the Mk4, all is good and near perfect tack sharp.

Sensor alignment in some cases is the evil factor for soft focus and not the lens... you may never know that unless the lens is tested on two camera bodies.

I suspect any lens is capable of being a rogue lens although that might not be the number one suspect among lens. I have seen several references stating that it nor the f/1.4 are generally as sharp as the f/1.8. Still, from what I have read, zooms are far more likely to have a calibration issue.

wsa111 Loc: Goose Creek, South Carolina

The D7000 is notorious for back focus. I had to do a focus change on every lens. Some took -18 to get the focus tack sharp.
My D7100, D750 & D800 are within +or- 4-5 on every lens.
The D7000 once fine tuned is great. Takes time, but its worth it.

CO

wsa111 wrote:

The D7000 is notorious for back focus. I had to do a focus change on every lens. Some took -18 to get the focus tack sharp.
My D7100, D750 & D800 are within +or- 4-5 on every lens.
The D7000 once fine tuned is great. Takes time, but its worth it.

I had read that a small number of D7000's had a severe back focusing issue. I had one of them. I adjusted AF fine tuning to the extreme and it still wasn't enough to correct the back focusing. The same lenses required only very small AF fine tuning adjustments of about -3 or so on all of my other Nikon DSLR bodies. I ended up returning that D7000 and ordering one from another company. That one is much better. The AF sensors must be calibrated more accurately.

pmackd Loc: Alameda CA

When a camera/lens combination front focuses or back focuses the problem can be in either the lens, the camera(as we see from the previous post), or both. Thus the use of the language "calibrate the lens" is confusing. Nikon uses the term, "Auto Focus Fine Tuning," which implicitly recognizes that the problem can be in either the lens or the camera.

gessman Loc: Colorado

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