"This Lens Is Soft" and Other Myths?

jsherman999 · 02-21-2009, 08:15 PM

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Interesting read: --> This Lens Is Soft and Other Myths

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a a i b · 02-21-2009, 08:27 PM

he neglects to mention the K20D also has the lens calibration feature

jsherman999 · 02-21-2009, 08:37 PM

Originally posted by a a i b

he neglects to mention the K20D also has the lens calibration feature

Yup!

I think he just mentioned off the top of his head what he remembered.

There are some folks in the dpreview Nikon D40-60-80-90 forum forum who think that feature is useless.

JHfwp · 02-21-2009, 08:40 PM

They must get a lot of complaints. And they don't rent Pentax.

Damn Brit · 02-21-2009, 08:43 PM

Originally posted by jsherman999

There are some folks in the dpreview Nikon D40-60-80-90 forum forum who think that feature is useless.

It would be on a Nikon wouldn't it?

photogerald · 01-18-2010, 10:23 PM

Sorry, I'm digging up an old thread again... but I thought this deserved comment.

What the author states rings true with something I've been investigating the past 1/2 year. AF systems are just not that accurate, and this inaccuracy gets exposed by the faster lenses. What was adequate in the film days, is now beginning to show its limitations with higher-res sensors and instant review. Not sure how easy this is to solve, but it may involve a total redesign of the entire AF loop, from body to lens, and back.

asdf · 01-18-2010, 10:34 PM

Originally posted by photogerald

Sorry, I'm digging up an old thread again... but I thought this deserved comment.

What the author states rings true with something I've been investigating the past 1/2 year. AF systems are just not that accurate, and this inaccuracy gets exposed by the faster lenses. What was adequate in the film days, is now beginning to show its limitations with higher-res sensors and instant review. Not sure how easy this is to solve, but it may involve a total redesign of the entire AF loop, from body to lens, and back.

Definitely, a lens does not "front-focus" or "back-focus". The combination of the camera phase detection AF system, lens and subject/light causes this. Lenses have a tint as well as chromatic and spherical aberration that affect focusing, but in the end it's the AF system that decides when to stop hunting and adjusting.

Jewelltrail · 01-18-2010, 10:51 PM

Yes, this article was posted here 6 or 8 months back by another forum member. It is good to see it posted again, because we all need to absorb its message. I think it makes sense, explaining the soft-lens issues of which we hear so much. This is just another example of how makers of things have virtually eliminated their Quality Control department, thereby putting the burden of QC on the consumer. Thanks Jay!

02-21-2009, 08:15 PM	#1
jsherman999 Veteran Member Join Date: Dec 2007 Photos: Gallery Posts: 8,237	"This Lens Is Soft" and Other Myths? . Interesting read: --> This Lens Is Soft and Other Myths .

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02-21-2009, 08:27 PM	#2
a a i b Veteran Member Join Date: Jan 2008 Location: Brooklyn Photos: Gallery Posts: 315	he neglects to mention the K20D also has the lens calibration feature

02-21-2009, 08:37 PM	#3
jsherman999 Veteran Member Join Date: Dec 2007 Photos: Gallery Posts: 8,237 Original Poster	Originally posted by a a i b he neglects to mention the K20D also has the lens calibration feature Yup! I think he just mentioned off the top of his head what he remembered. There are some folks in the dpreview Nikon D40-60-80-90 forum forum who think that feature is useless.

02-21-2009, 08:40 PM	#4
JHfwp Veteran Member Join Date: Feb 2009 Posts: 879	They must get a lot of complaints. And they don't rent Pentax.

02-21-2009, 08:43 PM	#5
Damn Brit Guest	Originally posted by jsherman999 There are some folks in the dpreview Nikon D40-60-80-90 forum forum who think that feature is useless. It would be on a Nikon wouldn't it?

01-18-2010, 10:23 PM	#6
photogerald Senior Member Join Date: Sep 2009 Posts: 253	Sorry, I'm digging up an old thread again... but I thought this deserved comment. What the author states rings true with something I've been investigating the past 1/2 year. AF systems are just not that accurate, and this inaccuracy gets exposed by the faster lenses. What was adequate in the film days, is now beginning to show its limitations with higher-res sensors and instant review. Not sure how easy this is to solve, but it may involve a total redesign of the entire AF loop, from body to lens, and back.

01-18-2010, 10:34 PM	#7
asdf Veteran Member Join Date: Jan 2009 Location: Canada Posts: 1,252	Originally posted by photogerald Sorry, I'm digging up an old thread again... but I thought this deserved comment. What the author states rings true with something I've been investigating the past 1/2 year. AF systems are just not that accurate, and this inaccuracy gets exposed by the faster lenses. What was adequate in the film days, is now beginning to show its limitations with higher-res sensors and instant review. Not sure how easy this is to solve, but it may involve a total redesign of the entire AF loop, from body to lens, and back. Definitely, a lens does not "front-focus" or "back-focus". The combination of the camera phase detection AF system, lens and subject/light causes this. Lenses have a tint as well as chromatic and spherical aberration that affect focusing, but in the end it's the AF system that decides when to stop hunting and adjusting.

01-18-2010, 10:51 PM	#8
Jewelltrail Veteran Member Join Date: May 2008 Location: Rhode Island Photos: Albums Posts: 4,180	Yes, this article was posted here 6 or 8 months back by another forum member. It is good to see it posted again, because we all need to absorb its message. I think it makes sense, explaining the soft-lens issues of which we hear so much. This is just another example of how makers of things have virtually eliminated their Quality Control department, thereby putting the burden of QC on the consumer. Thanks Jay!

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