Comments on: Fun with Thumbtacks for Advanced Photogeeks http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks Photo/video thoughts from the largest rental house Sun, 19 May 2013 00:40:17 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Adam http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-752 Adam Tue, 21 Jun 2011 19:16:28 +0000 http://www.lensrentals.com/blog/?p=1325#comment-752 Hi Roger, I always love reading your articles. I had to come back to this one because I find the information very interesting. As an owner of Lens B (or at least I think I am...), there is a certain lack of sharpness at or near wide open that I have never quite put my finger on, but believe that you have. Hopefully the make is coming out with a Mark II version soon. That being said, I would love to see some additional comparisons like this of other popular lenses. Especially between the latest versions and older versions to see the improvements made. I think it would be very popular and generate considerable interest. You have a unique position with access to so many different lenses. This would really help to put some myths to bed. Thanks again for your work! Hi Roger,

I always love reading your articles. I had to come back to this one because I find the information very interesting. As an owner of Lens B (or at least I think I am…), there is a certain lack of sharpness at or near wide open that I have never quite put my finger on, but believe that you have. Hopefully the make is coming out with a Mark II version soon.

That being said, I would love to see some additional comparisons like this of other popular lenses. Especially between the latest versions and older versions to see the improvements made. I think it would be very popular and generate considerable interest. You have a unique position with access to so many different lenses. This would really help to put some myths to bed.

Thanks again for your work!

]]> By: Bubba http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-743 Bubba Tue, 21 Jun 2011 03:28:07 +0000 http://www.lensrentals.com/blog/?p=1325#comment-743 Lens C is non retrofocus 35 Cron? Lens C is non retrofocus 35 Cron?

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-524 Roger Cicala Fri, 10 Jun 2011 00:00:54 +0000 http://www.lensrentals.com/blog/?p=1325#comment-524 Pavan, They're none of the above: except for Zeiss and Leica all the other manufacturers use computer generated MTF charts based on the theory of the lens, not actual testing. Roger Pavan,

They’re none of the above: except for Zeiss and Leica all the other manufacturers use computer generated MTF charts based on the theory of the lens, not actual testing.

Roger

]]> By: Pavan http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-469 Pavan Sat, 21 May 2011 20:06:35 +0000 http://www.lensrentals.com/blog/?p=1325#comment-469 Great article! I finally understand MTF charts. Armed with this new knowledge, I have been looking at the MTF charts of various lenses over the past week. An interesting question comes to mind regarding Sigma lenses... Are the published MTF charts made on Foveon sensor cameras or ones with a Bayer sensor? If the charts are made on a Foveon body, how different might they look if they had been generated on a Canon or Nikon body? Also are the MTF charts of Canon lenses made on full frame or crop sensor bodies? Would be interesting to know. Thanks again for your articles. Great article! I finally understand MTF charts. Armed with this new knowledge, I have been looking at the MTF charts of various lenses over the past week. An interesting question comes to mind regarding Sigma lenses… Are the published MTF charts made on Foveon sensor cameras or ones with a Bayer sensor? If the charts are made on a Foveon body, how different might they look if they had been generated on a Canon or Nikon body?
Also are the MTF charts of Canon lenses made on full frame or crop sensor bodies?
Would be interesting to know. Thanks again for your articles.

]]> By: Doug http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-348 Doug Mon, 11 Apr 2011 18:02:06 +0000 http://www.lensrentals.com/blog/?p=1325#comment-348 Roger, Another great article you've written has taught me quite a bit in a relatively short amount of time. Also, in despite of the fact that you didn't include lens names, I figured it out on my own. That being said, I appreciate the fact that you didn't concentrate on that aspect. Each brand and each lens has its own associations, followers and preconceived notions that would get in the way of the lesson here. Although I am often skeptical when I hear people talk abstractly about the "rendering" or "3d properties" etc of certain lenses, the more I use different lenses, the more I realize their is definitely some validity in this. What you have shown is that there may be scientific reasons behind what lenses we prefer, we just don't necessarily know the names behind the affects that contribute to our assessments. Keep them coming... thanks! Doug Roger,
Another great article you’ve written has taught me quite a bit in a relatively short amount of time. Also, in despite of the fact that you didn’t include lens names, I figured it out on my own. That being said, I appreciate the fact that you didn’t concentrate on that aspect. Each brand and each lens has its own associations, followers and preconceived notions that would get in the way of the lesson here. Although I am often skeptical when I hear people talk abstractly about the “rendering” or “3d properties” etc of certain lenses, the more I use different lenses, the more I realize their is definitely some validity in this. What you have shown is that there may be scientific reasons behind what lenses we prefer, we just don’t necessarily know the names behind the affects that contribute to our assessments.
Keep them coming… thanks!
Doug

]]> By: aK http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-346 aK Fri, 08 Apr 2011 23:18:17 +0000 http://www.lensrentals.com/blog/?p=1325#comment-346 A: Canon 35mm f/2 B: Canon 35mm f/1.4L C: Zeiss 35mm f/2 (probably ZE version assuming Roger used the same body, most like a full frame, high res such as 5D2 or 1Ds3) :) A: Canon 35mm f/2
B: Canon 35mm f/1.4L
C: Zeiss 35mm f/2 (probably ZE version assuming Roger used the same body, most like a full frame, high res such as 5D2 or 1Ds3) :)

]]> By: Phyl http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-333 Phyl Sat, 02 Apr 2011 17:03:07 +0000 http://www.lensrentals.com/blog/?p=1325#comment-333 I always read your articles with interest. They are helpful and informative, even if a lot of it goes over my head. But, your PhotoGeek-a-Thizer is just "tacky"! ;) I always read your articles with interest. They are helpful and informative, even if a lot of it goes over my head.

But, your PhotoGeek-a-Thizer is just “tacky”! ;)

]]> By: Marc de Vries http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-332 Marc de Vries Sat, 02 Apr 2011 14:04:14 +0000 http://www.lensrentals.com/blog/?p=1325#comment-332 hmm, to me it seems that one is good at showing nothing, while the other is good at showing both "how much" and "why" at the same time. The problem I have with the resolution chart is not that I cannot tell what type of abberation causes the blurring, but that I cannot tell there is any significant blurring going on at all. It's very difficult to see any difference in B and C. And it's not only horizontal and vertical lines in that resolution chart. There are numbers that have circles in there too. While it is obvious there is a huge difference between B and C when you look at the dots. Could it be something about the color that makes the blurring easier to see? I wonder what would happen if you put a dot on the resolution chart so you could see both in the same shot. As it looks now, I would forget about test with resolution charts and just test with the "photo-geek-a-thizer" :) hmm, to me it seems that one is good at showing nothing, while the other is good at showing both “how much” and “why” at the same time.

The problem I have with the resolution chart is not that I cannot tell what type of abberation causes the blurring, but that I cannot tell there is any significant blurring going on at all. It’s very difficult to see any difference in B and C. And it’s not only horizontal and vertical lines in that resolution chart. There are numbers that have circles in there too.
While it is obvious there is a huge difference between B and C when you look at the dots.

Could it be something about the color that makes the blurring easier to see?
I wonder what would happen if you put a dot on the resolution chart so you could see both in the same shot.

As it looks now, I would forget about test with resolution charts and just test with the “photo-geek-a-thizer” :)

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-331 Roger Cicala Sat, 02 Apr 2011 12:10:18 +0000 http://www.lensrentals.com/blog/?p=1325#comment-331 The magnification is similar, and what we see as smearing of the larger circle is part of what causes the "blurring" of the resolution in the corners. With thin lines it's difficult to tell what type of aberration causes the blurring, but it gives you a number that quantitate how much has occurred. The larger circles show the type of distortion involved more clearly, but don't quantitate it as well as the lines. Basically it's two different ways of looking at the same effect. One is good at showing "how much", the other is better at showing "why". Roger The magnification is similar, and what we see as smearing of the larger circle is part of what causes the “blurring” of the resolution in the corners. With thin lines it’s difficult to tell what type of aberration causes the blurring, but it gives you a number that quantitate how much has occurred. The larger circles show the type of distortion involved more clearly, but don’t quantitate it as well as the lines. Basically it’s two different ways of looking at the same effect. One is good at showing “how much”, the other is better at showing “why”.
Roger

]]> By: Marc de Vries http://www.lensrentals.com/blog/2011/03/fun-with-thumbtacks-for-advanced-photogeeks/comment-page-1#comment-330 Marc de Vries Sat, 02 Apr 2011 08:44:24 +0000 http://www.lensrentals.com/blog/?p=1325#comment-330 Interesting article, but there is something that I don't understand. Why is the smearing that is so clearly visible in the "dots-on-a-posterboard" test, not visible in the resolution charts? Are we looking at a higher magnification at the dots? Interesting article, but there is something that I don’t understand.
Why is the smearing that is so clearly visible in the “dots-on-a-posterboard” test, not visible in the resolution charts?

Are we looking at a higher magnification at the dots?

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