Fine Tune a Lens??? I have seen in the advertising and several topics discussion about "ability to fine tune a lens." What's the story, if the lens is properly constructed and elements...

rwww80a Loc: Hampton, NH

I have seen in the advertising and several topics discussion about "ability to fine tune a lens." What's the story, if the lens is properly constructed and elements are aligned, what is there to "fine tune." Is there really that much slop in the camera mounts. I have seen that in the one lens does all compacts. If a lens really needs adjustment send it back to the manufacturer. If the "fine tune" is to compensate for poor workmanship, don't buy it in the first place.

MT Shooter Loc: Montana

rwww80a wrote:

I have seen in the advertising and several topics ... (show quote)

The "fine tuning" refers to tuning the AUTOFOCUS accuracy. Cameras and lenses are both built to a tolerance spec, if those tolerances fall at opposite ends of the scale the autofocus can be off. Semi pro and pro cameras all allow you to tune the lens in-camera, entry level models do not. You never know if the lens needs tuning unless you check the accuracy of its focus on your body.
New lenses from Sigma and Tamron allow you to tune the lenses focus OFF the camera via a USB interface device. This allows for more choices in tuning these lenses.

ballsafire Loc: Lafayette, Louisiana

rwww80a wrote:

I have seen in the advertising and several topics ... (show quote)

CO

Phase detection autofocus is error prone. Because of manufacturing tolerances, you will often get camera and lens combinations that will front focus or back focus. The phase detect sensors in the camera are another factor. They must be very precisely aligned.

I can give you an example. I rented the Tamron 45mm f/1.8 lens. It required approximately -12 AF fine tuning. I took a chance and purchased a new one after that. That new lens required only about -3 AF fine tuning on the same camera body. That's due to manufacturing tolerances.

There are no focusing errors when using live view mode. The camera is using its contrast detection autofocus. The camera adjusts the focus until it achieves the highest contrast at the sensor

ballsafire Loc: Lafayette, Louisiana

CO wrote:

Phase detection autofocus is error prone. Because ... (show quote)

As I indicated for my view of fine tuning of lenses -- the OP is correct in every instance - I am paying already for a fine tuned lens-- period. So any other comment?

mwsilvers Loc: Central New Jersey

ballsafire wrote:

As I indicated for my view of fine tuning of lenses -- the OP is correct in every instance - I am paying already for a fine tuned lens-- period. So any other comment?

Clearly you do not understand about manufacturing tolerances. The matchup between a lens and camera has to be extraordinarily precise. All manufacturing of everything is manufactured to a certain tolerance. That degree of tolerance is always plus or minus from the absolute standard. If you get a lens on one end of the tolerance range, and a camera on the other end of the range normal you will have an ever so slight mismatch which is enough, especially with wide aperture lenses, to cause a small amount of back or front focusing.

The fact is that most people are not critical enough about the results and, as a result, never notice that their lenses are a little bit off. At least 50% of the lenses I have ever owned needed some minor amount of adjustments to be dead accurate. To suggest, as some have, that it is a poor quality control issue, is ridiculous

CO

Here's a good diagram of what is happening. Light is being directed to the phase detection sensors in the bottom of the camera.

1) Ray of light
2) Main/Reflex Mirror
3) Secondary Mirror, also known as âSub-Mirrorâ
4) Camera Shutter and Image Sensor
5) Eccentric pin (1.5mm hex) for adjusting the Main Mirror
6) Eccentric pin (1.5mm hex) for adjusting the Secondary Mirror
7) Phase Detect Sensor (AF Sensor)
8) Pentaprism
9) Viewfinder

(Download)

dkguill Loc: Elkhart, IN

MT Shooter wrote:

The "fine tuning" refers to tuning the A... (show quote)

OK...I'll ask a question that has bugged me since I first heard about tuning a lens. I have 3 cameras, a 5D IV, a 5Ds, and 7DII. I have 5 different lenses I use on these 3 bodies. If I'm unhappy with sharpness on one lens and I tune that lens to the 5D IV, would that screw up focus on the other two bodies using that lens, or is the change made in the body and it would mess with focus using other lenses on that body? I'm obviously confused about what gets changed where.

CO

dkguill wrote:

OK...I'll ask a question that has bugged me since I first heard about tuning a lens. I have 3 cameras, a 5D IV, a 5Ds, and 7DII. I have 5 different lenses I use on these 3 bodies. If I'm unhappy with sharpness on one lens and I tune that lens to the 5D IV, would that screw up focus on the other two bodies using that lens, or is the change made in the body and it would mess with focus using other lenses on that body? I'm obviously confused about what gets changed where.

The change is made in the camera body. I'm not sure how many lenses Canon cameras can store. I think it's 20. You should be able to go to that menu and see it. I'm not if Canon has global AF fine tuning that will affect all lenses.

With my Nikons there's global AF fine tuning that will affect all lenses attached or you can AF fine tune individual lenses. It can store AF fine tuning for up to 12 lenses.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

rwww80a wrote:

I have seen in the advertising and several topics ... (show quote)

I have owned probably close to 90 lenses in my life time including close to 30 current auto focus lenses on my Nikon and Sony camera's including a stable of older Minolta auto focus lenses. I have NEVER had any of these or prior lenses FINE TUNED. I have shows that feature 16X24 and 20X30 prints, NO PROBLEMS. Bottom line, some folks are just not happy, even if they could walk on water they would not be happy. Same with camera's, they order one on line, decide they don't like that COPY of the body, they return it and get another, now they are happy with the new body, actually both bodies were exactly the same, but like I said, some folks are not happy, they are not happy with a new lens cause it back or front focuses, so they play and play and fine tune the living daylights out of it. Again, there are photographers, and there are good photographers who take great images with more than 90 lenses with NO PROBLEMS. Good luck and keep on shooting until the end.

nikonkelly Loc: SE Michigan

No, Any adjustment that you make to lens camera combination is only recorded in that camera... the lens retains nothing so you are free to fine tune it another body at any time and never mess things up.

mwsilvers Loc: Central New Jersey

billnikon wrote:

I have owned probably close to 90 lenses in my lif... (show quote)

Your experiences are different than those of many people including legions of professional photographers and talented advanced amateurs and myself. So unless you are suggesting they are all primadonnas and are just being difficult, you might want to be more accepting of what they are seeing. I have had lenses that work better on one body then another, which is VERY noticeable with fast primes when shooting wide open and cropping. I've also experienced that with multiple copies of the same lens on a single body. Practically every pro I know, and I know a bunch, micro adjusts at least some of their lenses on some of their bodies to optimize them.

CanonTom Loc: Birmingham

MT Shooter wrote:

The "fine tuning" refers to tuning the A... (show quote)

MT, thanks for a great detailed, but short enough explanation to fully digest this. I have read various posts regarding this in the past several months I have been here, but now I actually understand the need for the process.

The Villages Loc: The Villages, Florida

mwsilvers wrote:

Clearly you do not understand about manufacturing ... (show quote)

Would the focus issue be of a lesser degree with a higher aperture setting....f8-f11 vs. f3.5? Would need to be more precise with less depth of field?

imagemeister Loc: mid east Florida

ballsafire wrote:

As I indicated for my view of fine tuning of lenses -- the OP is correct in every instance - I am paying already for a fine tuned lens-- period. So any other comment?

Yes, - GOOD LUCK