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AF Calibration on just the camera?

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Ringwraith69

Ringwraith69

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Hi all,

For some time now I've had some doubts about my SD14's AF. In most shots there is some amount of backfocussing, and this occurs not just with one or two particular lenses, but with, well, really all my lenses. These same lenses work just fine on my SD10, no focussing problems there.

Now I have read about getting the AF calibrated by Sigma, but it usually involves calibrating a camera / lens combination. Now if I was to do that, won't that influence the focussing accuracy of other (non-calibrated) combinations of camera and lenses?

thanks for your input,
Peter

--
'We are only immortal for a limited time'
 
Yes.

Which is why it's usually a good thing to get a big box, and send all the stuff into Sigma if you're doing a lens/camera calibration. I did that and they didn't need to touch my 50 Macro and 70-200 EX, but did work on the 30f1.4 and 10-20.

Jim

--
Jim
 
Jim,

I have noticed a front focusing issue with my 50mm Macro lens and SD14. I have been thinking about sending my lenses and the body to Sigma. I am still waiting to get a 30mm f1.4 lens though :-) Do you mind telling us how much it costs to get the calibration done? Also, were you satisfied with the results? Thanks in advance!
 
Hallo Peter,

email me and i can help what shall you do.

groetjes,
--
Frank
 
Just replied, Frank. Thank you!

groeten uit Harderwijk!

--
'We are only immortal for a limited time'
 
Lenses and bodies are not typically calibrated to each other but to an independent standard. That is a common misperception. By calibrating to a standard, calibration should not affect the performance of other lenses or bodies assuming they were, themselves, calibrated properly.

When folks recommend sending both a body and lens in for calibration, that is because a focus problem could be due to a problem with either the lens or body or both.
--
Leon
http://web.me.com/leonwittwer/landscapes.htm
 
That kind of widespread flaw is something that in unacceptable in most camera companies, but people let Sigma slide on it. That was one of the problems (among others like freezes/lockups, wild color fluctuations, etc.) I had with my SD14. Why do people give Sigma a pass on this? We should all demand better quality from Sigma. I don’t know if that would be trying to squeeze blood from a stone. But it is shoddy workmanship and a lack of quality control that is not the hallmark of a professional company. Over the years I’ve worked with Hasselblads, Nikons, Pentaxes, Canons, Contaxes and Leicas, both manual and AF, and never experienced a common occurrence (from all the comments in different forums) of mis-focusing lenses and the other problems that plague it. It’s just a shame that the Foveon technology has to be in the hands of such a company as Sigma.
Rich
http://www.pbase.com/rich_rivera/sigma_dp1__dp2_photos
 
imagesmatter said:
That kind of widespread flaw is something that in unacceptable in most camera companies, but people let Sigma slide on it. That was one of the problems (among others like freezes/lockups, wild color fluctuations, etc.) I had with my SD14. Why do people give Sigma a pass on this?
Click to expand...
Some people give Sigma a pass because they don't know any better and have "NO" experience with other camera makes to judge Sigma by. Some people give Sigma a pass because they have to defend their own purchase. Some people give Sigma a pass because they have a tenancy to cheer for the under-dog. But the truth is that many of us on this forum "DO NOT" give Sigma a pass on QC and make no excuses for the lack of it. My experience with both Sigma cameras and lenses leads me to believe that they are made as well as any third party manufactures products, but lack that so called "final inspection" that would weed out lenses with soft sides or cameras with missing AF and send both back for calibration. My complaint is that Sigma can easily do this and just plain doesn't and I don't like any company that operates that way. Be it a car company, major appliance company or a camera company. Of course maybe Sigma's tolerance's are just set way to low and some of the lenses and bodies we are getting are well within tolerance according to them. Yes, right, that's it! The only way we can stop Sigma from sweeping these problems under the rug is to openly complain about these very easy to overcome shortcomings. Either complain privately to Sigma or openly in these forums. There should be "NO" free pass!

We should all demand better quality control from Sigma and all it would cost them is a little time. I wish the "big shots " on this forum would do the right thing and speak out with all the rest of us on matters like AF calibration or one sided lenses instead of playing the Three Monkeys. You know, the one with his eyes covered, one with his ears covered and one with his mouth covered. In the end it would only benefit Sigma and make many more new and happy customers. Me, I don't give them a free pass, but I'm still cheering for the under-dog. JohnW
 
Ringwraith69 said:
Rodrigo Cunha said:
Before sending your camera in check this...

http://www.flickr.com/photos/rnbc/2786765620/in/set-72157603099756613/
Click to expand...
I've been looking at this scheme for at least a dozen times now, but: how does it work. Can you adjust focussing without calibarting equipment, is there some 'trick' to it or is it an interesting scheme to look at but something best left alone by non-engineers...?
Click to expand...
There are some threads on dpreview, describing focus adjustments (using that scheme) in more detail.

I've adjusted AF using this scheme; probably needs to adjust one more time (slight backfocus with two lenses; one of these even won't focus on infinity). You need some patience (taking alot of test images), 1.5mm hex wrench and hope to not break IR filter.

It is not preferred way to deal with focus issues; sending your equipment to Sigma would be better choice.

Often it is not easy to tell, is focus problem caused by lens or camera; of course if you have many lens and all these behave well with one body and have same problem with another, then most probably second body is miscalibrated.

--
Arvo
Sigma/Foveon information collection and little gallery:
http://www.stv.ee/~donq/sigma.htm
http://www.stv.ee/~donq/images.htm
 
I always figured that by the time I figured out the schematics and worked up enough nerve to actually try using them I could have sent all my lenses and camera to Sigma and had it done without any problems of damage.

Just my thought on this issue. :)
--
http://www.yukonphotographers.com
Norm Hamilton
'Yukon. A special place in Northern Canada'
Ya gotta come and see!
 
Ringwraith69 said:
Now I have read about getting the AF calibrated by Sigma, but it usually involves calibrating a camera / lens combination.
Click to expand...
Think long and hard before going down that path into the woods. I did that with a camera and a lens and if I ever have it to do over again I will replace rather than repair. Caution, the reality of this may not be as straightforward as it might seem. In addition to the hoped for outcome there are many other possible outcomes which may occur instead and consume time.
--
JohnK
Take a picture, it'll last longer.
 
I had to go through two body's. Actually the second body had some fault which wasn't AF related. How ever I can no longer manual Focus the camera with some lenses. When AF the picture in the viewfinder looks out of focus but in focus when looking at the photo on the camera lcd screen. but when I Manual focus the picture look in focus in the viewfinder but out of Focus when viewed on the lcd. Has anybody else had that problem?
--
http://www.birgir.org
 
Birgir said:
I had to go through two body's. Actually the second body had some fault which wasn't AF related. How ever I can no longer manual Focus the camera with some lenses. When AF the picture in the viewfinder looks out of focus but in focus when looking at the photo on the camera lcd screen. but when I Manual focus the picture look in focus in the viewfinder but out of Focus when viewed on the lcd. Has anybody else had that problem?
Click to expand...
Yes. I've had to adjust the primary mirrors on both of my SD14s to correct for inaccurate manual focusing.
 
I'm confused by the response I'm getting from Sigma about a manual focus problem, and I'd appreciate it if anyone could clarify the situation for me.

I've been using an SD14 body with 50mm and 24mm prime lenses for a little over two years. Over time I grew frustrated with the number of shots I missed because they were back focused, using both manual and auto focus. I finally printed a focus chart and documented that on manual focus I am consistently getting back-focused shots with both the 24mm and 50mm lenses. I don't wear glasses and the diopter slider was set in the middle. Because the issue is occurring with manual focus and both lenses, I was guessing that Sigma would need to move the position of something inside the camera (e.g. sensor or viewfinder distance) because if the image is sharp in the viewfinder but not on the final image, it would seem to me that these two distances aren't equal inside the camera.

I shipped the SD14 body and both lenses to Sigma on Long Island for them to calibrate the focus. I was surprised when the quote that came back and said they won't do anything to the camera, but for the 24mm lens they "NEED TO ADJUST AF DATA" and that they are talking to Sigma Japan about what they can do about the 50mm lens. Confused, I called up and talked to a technician there who said that they can't adjust the sensor position in the camera and that calibrating the AF data in the lens will change the manual focus too. I pressed him on how this would help with the problem I was having, but I didn't get any clarification.

Does this sound right to you guys? First, how can changing the AF calibration data in the lens affect the manual focus? Second, even if they change the manual focus of the lens, how will this help when there seems to be a difference between focusing in the viewfinder vs. on the sensor? Should I push back on them about the focus adjustment image linked to above in this thread? Could it be my technique/ eye and not the fault of the camera?

Thanks in advance for your help.

--Jeremy

P.S. I've kind of given up on AF with this camera. Even with the focus chart, I was getting a mix of front-focus, correct-focus, and back-focus. But that's ok- I'd be happy if I could count on manual focus.
 
snarton said:
Confused, I called up and talked to a technician there who said that they can't adjust the sensor position in the camera and that calibrating the AF data in the lens will change the manual focus too. I pressed him on how this would help with the problem I was having, but I didn't get any clarification.

Does this sound right to you guys? First, how can changing the AF calibration data in the lens affect the manual focus? Second, even if they change the manual focus of the lens, how will this help when there seems to be a difference between focusing in the viewfinder vs. on the sensor? Should I push back on them about the focus adjustment image linked to above in this thread? Could it be my technique/ eye and not the fault of the camera?
Click to expand...
BS. AF tables calibration can in no way affect MF accuracy (imagine using old M42 lens without any AF tables). All that MF needs is precise location of mirror and matte viewfinder screen; like it is seen on one linked image, it can be (at least partially - for center area) corrected using excentric nuts inside mirror box. Sure there must be other adjustment options too (you can put/remove shims behind focus screen for example) - you need to ensure that optical distances are equal both in upper and lower part of image (mirror must be exactly at 45 degrees). For everyday work with MF it would IMHO be enough that center area is in focus.

AF is more complex. In theory adjuster in mirror box is meant for adjusting mirror angle (to ensure that all focus points are treated equaly) and AF sensor locations need to be adjusted either mechanically or algorithmically (or both). Once AF sensors (and mirror) are set up correctly, only then lens AF tables should be corrected.

I don't know about Sigma service centers - do/can they adjust camera AF system or not. Here in Estonia Sigma shop can alter lens AF tables, but not camera side of things - but of course they need both camera and lenses to make them match.

--
Arvo
Sigma/Foveon information collection and little gallery:
http://www.stv.ee/~donq/sigma.htm
http://www.stv.ee/~donq/images.htm
 
There's another very good reason for in body fine tuning of the AF. If you're using your lenses on more than one body, it would be virtually impossible to keep on finetuning. Setting up a lens for one body might make it useless on another, and vice versa. That doesn't make sense.

That's why I find the idea of sending in your camera and all lenses to solve a focussing problem a no go option. If I send in my SD14 and all my lenses (wow, I don't even want to think about shipping costs) to have them tuned to each other, I'll probably end up with a focussing issue on my SD10. Which can only be solved by sending in the SD10 with all my lenses to have them tuned to each other, which will leave me with a focussing issue on my SD14... :x
--
'We are only immortal for a limited time'
 
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