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09-23-2014, 04:25 AM   #46
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QuoteOriginally posted by D1N0 Quote
This is a well known fact.
This is not corroborating evidence.

It may be a "well-known" myth, but what makes it a "fact" in your eyes?

Can you please point to a source?

09-23-2014, 04:31 AM   #47
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QuoteOriginally posted by Class A Quote
This is not corroborating evidence.

It may be a "well-known" myth, but what makes it a "fact" in your eyes?

Can you please point to a source?
Sigma issues advisory on lens compatibility with Nikon Df: Digital Photography Review

Why do you think Tamron did not put out an advisory and Nikon Lenses have no problem with the Df or D5300. It is not a Myth it is a fact.
09-23-2014, 05:15 AM   #48
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QuoteOriginally posted by D1N0 Quote
Why do you think Tamron did not put out an advisory and Nikon Lenses have no problem with the Df or D5300.
Maybe Tamron lenses have similar issues (with that one particular Nikon model) but Tamron just did not put out an advisory?

The fact that Sigma offers free lens updates to anyone having issues with the Nikon Df does not imply that AF performance was compromised with any earlier camera. It is not proof of the fact that their AF implementation was not up to scratch before.

QuoteOriginally posted by D1N0 Quote
It is not a Myth it is a fact.
I'm sorry, but the fact that a new model breaks compatibility with a third-party product is not proof of sub-standard (and unauthorised) reverse engineering.

Some Metz flash models needed firmware updates to work with new Pentax cameras. Are you saying Metz has sub-standard "retro engineering" as well?

BTW, from a recent interview with Sigma's CEO Kazuto Yamaki:
"To make a lens for Canon and Nikon, we have to use their bayonet mount and have to use some of their patents. We pay for it."
So if Sigma ever has used protocols without paying license fees that is no longer the case at least for Canon and Nikon.
09-23-2014, 05:37 AM   #49
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QuoteOriginally posted by Class A Quote
Maybe Tamron lenses have similar issues (with that one particular Nikon model) but Tamron just did not put out an advisory?

The fact that Sigma offers free lens updates to anyone having issues with the Nikon Df does not imply that AF performance was compromised with any earlier camera. It is not proof of the fact that their AF implementation was not up to scratch before.


I'm sorry, but the fact that a new model breaks compatibility with a third-party product is not proof of sub-standard (and unauthorised) reverse engineering.

Some Metz flash models needed firmware updates to work with new Pentax cameras. Are you saying Metz has sub-standard "retro engineering" as well?

BTW, from a recent interview with Sigma's CEO Kazuto Yamaki:
"To make a lens for Canon and Nikon, we have to use their bayonet mount and have to use some of their patents. We pay for it."
So if Sigma ever has used protocols without paying license fees that is no longer the case at least for Canon and Nikon.
You fail to quote the rest of the sentence: "But we are continuously reverse engineering". Thank you for providing my source. Sigma. They cannot avoid to pay to use the mount, but they do avoid paying for the electronics behind it.

09-23-2014, 05:55 AM   #50
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QuoteOriginally posted by D1N0 Quote
They cannot avoid to pay to use the mount, but they do avoid paying for the electronics behind it.
Pure conjecture on your behalf.

I read Sigma's statement to mean that they find value in additionally reverse-engineering despite having the official documentation of the protocols. That actually makes sense, because you want your product to work in reality, not just adhere to some printed specification.

I'm out now. I hope the OP has success in getting their lens work to their satisfaction. It is a very capable lens model that made many people very happy. There is nothing wrong with its technology per se. Stating otherwise requires evidence (over and above to pointing to an advisory that may just demonstrate a higher degree of diligence).
09-23-2014, 06:02 AM   #51
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QuoteOriginally posted by Class A Quote
Pure conjecture on your behalf.
I don't think so. This is a case of eyes wide shut on your behalf. That is why you make up stuff to defend your stance.
09-23-2014, 06:26 AM   #52
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I think this argument might not be to the benefit of the OP - whose lens is either backfocusing or is maybe decentered? Or the camera is not choosing the intended focus point. Whether Sigma has reverse engineered the lens mount is tangential to the core issue.

BTW, I have a Sigma 28mm and it's dead-on accurate.
09-24-2014, 04:52 PM   #53
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Not so sure this is a back focusing issue. Since the K-5 favors the highest contrast area that would be the rear of the dog. If the AUTO focusing mode is selected the camera will focus on the rear of the animal. If the SEL focusing mode is selected than the photographer must decide which focus point to use. If you are not paying attention it will again select the rear of the dog. Both of those features have always seemed to be a waste to me. This issue can be minimized by switching to CENTER focusing. Focus on the eyes then reframe while holding the shutter button. A very simple technique that has been used since the first Pentax Auto focus system. Personally I NEVER use anything other than CENTER/spot focusing. I find the other methods way to unreliable. Since when do we allow a camera to decide who or what should be in focus?

I also agree, having several Sigma lenses their wide open apertures are soft. I never shoot below 4.0 when using those lenses unless I am doing head shots at which point the extra bit of softness enhances the portrait.

09-24-2014, 04:59 PM   #54
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QuoteOriginally posted by CWRailman Quote
Not so sure this is a back focusing issue. Since the K-5 favors the highest contrast area that would be the rear of the dog. If the AUTO focusing mode is selected the camera will focus on the rear of the animal. If the SEL focusing mode is selected than the photographer must decide which focus point to use. If you are not paying attention it will again select the rear of the dog. Both of those features have always seemed to be a waste to me. This issue can be minimized by switching to CENTER focusing. Focus on the eyes then reframe while holding the shutter button. A very simple technique that has been used since the first Pentax Auto focus system. Personally I NEVER use anything other than CENTER/spot focusing. I find the other methods way to unreliable. Since when do we allow a camera to decide who or what should be in focus?

I also agree, having several Sigma lenses their wide open apertures are soft. I never shoot below 4.0 when using those lenses unless I am doing head shots at which point the extra bit of softness enhances the portrait.
I have to agree, only use a nine point array when you want the camera to track a subject. Any other time, a single focus point in selective focus saves a lot of grief.
09-24-2014, 05:11 PM   #55
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QuoteOriginally posted by normhead Quote
I have to agree, only use a nine point array when you want the camera to track a subject. Any other time, a single focus point in selective focus saves a lot of grief.
That was my question from the original post. The current obsession on this site seems to be with AF fine adjustment, so the obvious questions tend to not get asked. Simply, "What was the indicated focus point". The raw exif will contain this information, but the supplied example had those entries scrubbed.

It seems that the OP has left the thread, so we may never know the cause or the outcome.


Steve
09-24-2014, 05:27 PM   #56
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My first thought was the lens was front focusing due to that patch of sharp grass in front of the dog, then I saw his butt was also in focus but his eyes were not.

The lens is either mounted off kilter or the lens itself is decentered. Since the problem carries across various lenses, barring user error, my first thought would be to see if the mount on the camera is physically damaged or out of whack. It could be something as dumb as the screws having worked loose on the mount and being in need of a bit of tightening.
09-24-2014, 05:29 PM   #57
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QuoteOriginally posted by Rupert Quote
Relax! Just a little time in a cool comfortable spot to adjust the back focus and you will be all set to shoot animals to your hearts content! Animals love a Pentax camera, take it from Otis, and we all know Otis is never wrong!
Hopefully you will make it your life's ambition to shoot handsome squirrels?


Regards!
Rupert that's not your actual hat that you wear all the time is it? You do know that both trees and squirrels carry mites and ticks? Mites and ticks that are quite happy to migrate into anything placed on them and bite you too? Seriously I would not do that unless you like itching. Placing your hat on a tree or near a wild animal is a bit risky. You might get lucky and not get any but I would not risk it. The ticks you could probably see but the mites birds and squirrels carry are pretty tiny. Friend of mine got bird mites once. He was out messing in the yard, just looking at a nest in a tree. They crawled onto his clothing so fast he didn't even see them. What followed was six months of hell. It took the doctors forever to figure it out, and they ended up infesting his whole house before it was through....
09-24-2014, 05:32 PM   #58
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QuoteOriginally posted by stevebrot Quote
That was my question from the original post. The current obsession on this site seems to be with AF fine adjustment, so the obvious questions tend to not get asked. Simply, "What was the indicated focus point". The raw exif will contain this information, but the supplied example had those entries scrubbed.

It seems that the OP has left the thread, so we may never know the cause or the outcome.


Steve
I think he gave Pentax Forums the flick as well as Pentax...
09-24-2014, 05:32 PM   #59
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Did OP ever report back?
09-24-2014, 05:38 PM   #60
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QuoteOriginally posted by Sagitta Quote
My first thought was the lens was front focusing due to that patch of sharp grass in front of the dog, then I saw his butt was also in focus but his eyes were not.
Actually if you look, those two points, the grass and his ass, are in the same plane so both would be in focus.
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