Re: [ap-ug] "Trying to make a silk purse out of a sows ear"


Oct 1, 2013

 


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#66279 Oct 1, 2013

m.dpreview.com/news/2013/09/30/can-computer-corrections-make-simple-lenses-look-good



Always much easier to start with a quality optic and a decent detector.



;D



Pete



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#66280 Oct 1, 2013

If you look at the first lens, there are 13 elements. Theoretically that should give a designer enough variables to produce a perfect image across the entire film plane. In real life this is not the case. Each surface adds a little defect to the image and because of the number of surfaces, it is nearly impossible to produce a diffraction limited image, even on-axis.  In order to make the lens affordable, each element's production process must be minimized as much as possible (i.e. time spent on the polisher held to an absolute minimum). The result is that none of the elements will have optimum or near perfect surfaces, and will contribute substantial defects to the final image. I have a Sony lens on my NEX7 which reveals just how bad these defects are. Although the defects are barely visible on terrestial subjects, when the lens is aimed at star fields, WOAH!!, you get anything but pinpoints. The stars in the corners are flying seagulls some 20 times the diffraction limit. In the center they show all the aberrations in the book, along with lots of chromatic defects. And this is stopped down to a reasonable F5 focal ratio. Wide open is not recommended if you want to resolve anything.  What 13 elements gets you is a short physical length for a given focal length. Also a zoom function. Both of which translates to convenience. Rolando

-----Original Message-----

From: Pete Lardizabal p14@...>

To: ap-ug ap-ug@yahoogroups.com>

Sent: Tue, Oct 1, 2013 11:37 am

Subject: [ap-ug] "Trying to make a silk purse out of a sows ear"

m.dpreview.com/news/2013/09/30/can-computer-corrections-make-simple-lenses-look-good

Always much easier to start with a quality optic and a decent detector.

;D

Pete



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#66281 Oct 1, 2013

Pete, I appreciate the sentiment, but don't think it's always true.  I have often lamented the fact that modern technology sometimes goes to ridiculous lengths to provide a software "fix" to what is really a problem in the manufacturing quality of a device.  But the truth is that this sometimes really is the best solution.

I didn't read the article you referenced - this is just a general comment.

Greg



From: Pete Lardizabal p14@...> To: ap-ug@yahoogroups.com Sent: Tuesday, October 1, 2013 9:37 AM Subject: [ap-ug] "Trying to make a silk purse out of a sows ear"

 m.dpreview.com/news/2013/09/30/can-computer-corrections-make-simple-lenses-look-good



Always much easier to start with a quality optic and a decent detector.



;D



Pete



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#66284 Oct 1, 2013

Here is a good site for understanding camera lenses and their variations: www.lensrentals.com/blog/2013/09/there-is-no-perfect-lens

-----Original Message-----

From: Pete Lardizabal p14@...>

To: ap-ug ap-ug@yahoogroups.com>

Sent: Tue, Oct 1, 2013 11:37 am

Subject: [ap-ug] "Trying to make a silk purse out of a sows ear"

m.dpreview.com/news/2013/09/30/can-computer-corrections-make-simple-lenses-look-good

Always much easier to start with a quality optic and a decent detector.

;D

Pete



---------------

To UNSUBSCRIBE, or for general information on the ap-ug listsee groups.yahoo.com/group/ap-ugYahoo! Groups Links

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#66285 Oct 1, 2013

Hi Greg,

I'm in agreement with you that some of these software capabilities are the way to go. Look what all the software tools have done for all digital imaging! My reference to the old adage was a bit of a tongue-n-cheek reference to software amendments to images collected with non-AP optics... :)

Thanks for the article link Roland!

The potential for "error" propagation is of course present in any multi-component system (mechanical, electrical, analytical, etc...) I continue to be impressed with my everyday run-around camera lens performance in daytime imaging given these challenges. My AP130EDFGT is of nothing but impressive. 

So Roland... when do you think your first "cinema series" lens will be ready for sale?  

XD

Pete

On Oct 1, 2013, at 5:49 PM, chris1011@... wrote:



 

Here is a good site for understanding camera lenses and their variations: www.lensrentals.com/blog/2013/09/there-is-no-perfect-lens

-----Original Message-----

From: Pete Lardizabal p14@...>

To: ap-ug ap-ug@yahoogroups.com>

Sent: Tue, Oct 1, 2013 11:37 am

Subject: [ap-ug] "Trying to make a silk purse out of a sows ear"

m.dpreview.com/news/2013/09/30/can-computer-corrections-make-simple-lenses-look-good

Always much easier to start with a quality optic and a decent detector.

;D

Pete



---------------

To UNSUBSCRIBE, or for general information on the ap-ug listsee groups.yahoo.com/group/ap-ugYahoo! Groups Links

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