Comments on: Notes on Lens and Camera Variation http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation Photo/video thoughts from the largest rental house Fri, 24 May 2013 15:01:05 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Han Masden http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-3887 Han Masden Fri, 16 Mar 2012 23:26:52 +0000 http://www.lensrentals.com/blog/?p=3421#comment-3887 It's actually a great and useful piece of information. I am happy that you just shared this useful information with us. Please stay us informed like this. Thank you for sharing. It’s actually a great and useful piece of information. I am happy that you just shared this useful information with us. Please stay us informed like this. Thank you for sharing.

]]> By: Test123 http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-3758 Test123 Fri, 09 Mar 2012 07:31:19 +0000 http://www.lensrentals.com/blog/?p=3421#comment-3758 I'd just like to let u know how much I learnt from your blog Dugg you.Hope 2 be back fast for some more good stuff I’d just like to let u know how much I learnt from your blog Dugg you.Hope 2 be back fast for some more good stuff

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2810 Roger Cicala Wed, 28 Dec 2011 15:42:32 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2810 David, It depends what the finished photo is (difference is readily apparent in a large print, hardly apparent on a web jpg.). But it's about the stop of light and the ability to blur the out of focus areas mostly. Increasing vision is increasingly expensive - an f/1.2 lens is a very special, and expensive thing. But most photographers don't need it. David,

It depends what the finished photo is (difference is readily apparent in a large print, hardly apparent on a web jpg.). But it’s about the stop of light and the ability to blur the out of focus areas mostly. Increasing vision is increasingly expensive – an f/1.2 lens is a very special, and expensive thing. But most photographers don’t need it.

]]> By: David Tombs http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2807 David Tombs Wed, 28 Dec 2011 12:37:47 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2807 Great article, I am sure you can answer my question on lenses. I am looking for a prime lenese for my Canon - about 85mm. I note from the regular data that the same FL lenes range from £650 to over £1200, the latter being the L series. Q. Why the difference in price and does it really make a difference that can be seen in the finished photo or is iot just about a stop of speed? Thanks Great article, I am sure you can answer my question on lenses.
I am looking for a prime lenese for my Canon – about 85mm.
I note from the regular data that the same FL lenes range from £650 to over £1200, the latter being the L series.

Q. Why the difference in price and does it really make a difference that can be seen in the finished photo or is iot just about a stop of speed?

Thanks

]]> By: Scott http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2617 Scott Tue, 06 Dec 2011 17:48:45 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2617 Great article, Roger. Trying to get a sense of how much variability is represented by the cloud in your first graph, I have a question: Suppose I'm walking around my city in daylight, taking actual pictures. I mostly have the lens stopped down a bit, and I pay attention to using appropriate shutter speeds. Is there enough difference between the best and worst results in the cloud (not including the failed lens) to be consistently visible in (say) an 11 x 14 print? Great article, Roger.

Trying to get a sense of how much variability is represented by the cloud in your first graph, I have a question:
Suppose I’m walking around my city in daylight, taking actual pictures. I mostly have the lens stopped down a bit, and I pay attention to using appropriate shutter speeds. Is there enough difference between the best and worst results in the cloud (not including the failed lens) to be consistently visible in (say) an 11 x 14 print?

]]> By: Hendrik http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2559 Hendrik Thu, 01 Dec 2011 10:50:31 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2559 I second Jack C on "interested to see a similarly in-depth analysis of how Contrast Detect AF compares with Phase Detect AF in terms of accuracy and consistency of results". Please. I second Jack C on
“interested to see a similarly in-depth analysis of how Contrast Detect AF compares with Phase Detect AF in terms of accuracy and consistency of results”.
Please.

]]> By: Frans van den Bergh http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2558 Frans van den Bergh Thu, 01 Dec 2011 10:43:12 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2558 If you want to evaluate the sharpness of your own lenses, or you wish to calibrate the AF fine tuning of your DSLR body, you should try MTF Mapper http://sourceforge.net/projects/mtfmapper/ This utility is totally free, and source code is provided. Or you could buy Imatest for $300-$5000 :) Please read the user documentation thoroughly, though. I would appreciate any feedback, and welcome all discussion! If you want to evaluate the sharpness of your own lenses, or you wish to calibrate the AF fine tuning of your DSLR body, you should try MTF Mapper

http://sourceforge.net/projects/mtfmapper/

This utility is totally free, and source code is provided. Or you could buy Imatest for $300-$5000 :)

Please read the user documentation thoroughly, though.

I would appreciate any feedback, and welcome all discussion!

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2375 Roger Cicala Mon, 14 Nov 2011 22:27:03 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2375 Hi John, The weighted average uses Center point x 1, 6 mid points (which include the top and bottom center edges) x 0.75, and corners and lateral edges x 0.5. On bad corner does drag the weighted average down significantly, but more importantly we hardly ever see one bad corner: usually it's a bad side (or top/bottom) and occasionally it's contralateral corners both bad (certain kinds of tilt can cause it) and in such cases the weighted average is awful. But as far as our testing we flunk far more on the weighted average than on center sharpness. Not surprising, really, when you think about how much more a tilt or decentering will affect the outer area of the lens. Roger Hi John,

The weighted average uses Center point x 1, 6 mid points (which include the top and bottom center edges) x 0.75, and corners and lateral edges x 0.5. On bad corner does drag the weighted average down significantly, but more importantly we hardly ever see one bad corner: usually it’s a bad side (or top/bottom) and occasionally it’s contralateral corners both bad (certain kinds of tilt can cause it) and in such cases the weighted average is awful. But as far as our testing we flunk far more on the weighted average than on center sharpness. Not surprising, really, when you think about how much more a tilt or decentering will affect the outer area of the lens.

Roger

]]> By: John Angulo http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2372 John Angulo Mon, 14 Nov 2011 21:08:41 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2372 For these plots, how do you compute the average resolution of the entire lens? You call it a "weighted average" - how is it weighted? In a simple unweighted average of multiple measurements across the image, a fuzzy corner due to decentering might not have much influence on the result, even if some of the measurements capture it. But a fuzzy corner or side is just what makes the difference between good and bad copies for critical purposes. Would it be possible to plot the lowest measured resolution on the vertical axis, whevever on the image that occurred? It might be interesting to see the scatter among different copies in this case. For these plots, how do you compute the average resolution of the entire lens? You call it a “weighted average” – how is it weighted? In a simple unweighted average of multiple measurements across the image, a fuzzy corner due to decentering might not have much influence on the result, even if some of the measurements capture it. But a fuzzy corner or side is just what makes the difference between good and bad copies for critical purposes. Would it be possible to plot the lowest measured resolution on the vertical axis, whevever on the image that occurred? It might be interesting to see the scatter among different copies in this case.

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation/comment-page-2#comment-2326 Roger Cicala Tue, 08 Nov 2011 12:29:00 +0000 http://www.lensrentals.com/blog/?p=3421#comment-2326 Thomas, we do check that and all of the zooms (and a few primes) vary a bit in the actual, versus stated, focal length. For example the Canon 24-70 zoom is actually 25mm to 67mm, the 70-200 is 74mm to 195mm, and the Sigma 50-500 actually is a 55mm to 470mm. I think the rule of thumb is they should be within plus or minus 5% but I'm not certain that's always true. Thomas, we do check that and all of the zooms (and a few primes) vary a bit in the actual, versus stated, focal length. For example the Canon 24-70 zoom is actually 25mm to 67mm, the 70-200 is 74mm to 195mm, and the Sigma 50-500 actually is a 55mm to 470mm. I think the rule of thumb is they should be within plus or minus 5% but I’m not certain that’s always true.

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