Sigma 24-105mm f4 OS A vs Canon 50mm f1.4 on Canon 70D

Started Dec 16, 2013 | Discussions thread
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4thnebula
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Sigma 24-105mm f4 OS A vs Canon 50mm f1.4 on Canon 70D
Dec 16, 2013

I just received my Sigma 24-105mm f4 OS from Amazon. I am in the process of testing it to make sure I received a good copy. I have a rack I use for making copies of my artwork. I put one of my recent drawing sketches (drawing from life) from one of our models on the rack and took some photos with the Sigma 24-105mm and my Canon 50mm f1.4 on my Canon 70D. I set the Canon 70D on a tripod and set  the drive to a 2 sec delay no mirror lock-up rather than use a remote mirror lock-up (easier to do and have found no problems using 2 sec delay for copy work as opposed to a remote with mirror lock-up). Below are crops I took of the JPEGs of both lenses at f4 and f5.6. No other editing was done other than the face crops. I also set the 70D on ISO 100. Everything else was on factory default. I turned the Sigma OS to off. I took each lens photo with LV (labeled as CDAF) and PDAF via the prism.  The PDAF was set on center focus so it focused on the arm of the model while the CDAF focused on the face with 4 squares each time since the camera recognized the face.  I have 3 Canon primes: 1) 50mm f1.4, 35mm f2 IS and 28mm f2.8 IS.  The my Canon 35mm f2 IS is the sharpest of the 3 by a small amount but I am using my 50mm f1.4 as a standard here.

My conclusions are that the sharpness differences with each lens are so close that I consider them insignificant.  I also conclude the  differences between CDAF and PDAF are so close that I consider them insignificant.  Some general conclusions though are: 1) that CDAF in LV is slightly more accurate than PDAF overall but so close I am not concerned; 2) that both lenses are slightly better at f5.6 but so close I won't be making any photo decisions based on on sharpnesses at f4 and f5.6 for anything other than copy work for which I use my Canon 35mm f2 IS most of the time; 3) I am so far very pleased that I got an excellent copy of my Sigma 24-105mm f4 OS based on my Canon 50mm f1.4.

I would sure appreciate comments if anyone has them, in particular, based on my conclusions.

Canon 70D with Canon 50mm f1.4 @ f4 CDAF

Canon 70D with Canon 50mm f1.4 @ f4 PDAF

Canon 70D with Canon 50mm f1.4 @ f5.6 CDAF

Canon 70D with Canon 50mm f1.4 @ f5.6 PDAF

Canon 70D with Sigma 24-105 f4 OS @51mm f5.6 CDAF

Canon 70D with Sigma 24-105 f4 OS @51mm f5.6 PDAF

Canon 70D with Sigma 24-105 f4 OS @51mm f4 CDAF

Canon 70D with Sigma 24-105 f4 OS @51mm f4 PDAF

 4thnebula's gear list:4thnebula's gear list
Canon EOS 70D Sony a6000 Sony E 35mm F1.8 OSS Canon EF 35mm f/2 IS USM Olympus PEN E-PL5 +11 more
Canon EOS 70D
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