8 out of 10 points and recommendedSharpness, bokeh, speed, macro, priceerratic AF in low light condition a bit soft in the edge
I don't know if it will really help some other people :o but here is my story. (you can open photos in a new tab to make direct comparison in fullhd, by clicking on them)reviewed April 19th, 2010 (purchased for $400)
I needed a standard walkaround lens for my 50D which can be use indoor and near to macro to take pictures of shops, bags, shoes .I would say to take picture of all luxury accessories for a web site.
It was very difficult to get good information about Sigma 20F1.8, 24F1.8 and 28F1.8 .. canon 28F1.8 seems also just acceptable .. and anyway just too long for an APSC.
I could see some reviews were the sigma 20F1.8 was really really soft .. So I decided to buy on ebay a 24F1.8 for 300€.
I own a 24L1.4II which is probably the best lens that exist for FullFrame sharp from edge to edge and an amazing aperture of F1.4..
So I wanted to compare how far is a sigma from a 5 times more expansive canon.
First I had to make an AF micro adjustment otherwise lens is almost unusable :confused: ..(+15 for sigma and +13 for canon) the only lens I can use without adjustment is 85L1.2II ..+0 :cool: ..
so at minimum focus distance I get
So macro capabilities are really sufficient and good for what we am looking for.
First manuel focus with sigma is very very difficult canon is very smooth and precise..
but sigma AF is working rather good even if sometime you need to put to infinity first and then refocus. Canon has a perfect AF ..
I tried to take "real" pictures in the day time, but in spring wether is changing every 10 seconds, so made all pictures incomparable. So I decided to take night pictures which is also interesting as we want to use this lens indoor, nights and almost of the time wide open with no flash.
So first general test
Focus was made on the church in front, and we can see that canon at f1.8 is much sharper, but sigma results are already quite good ..
If we go in some more detailled pictures
I don't think sigma is a real F1.8 ... if I want to get some background sky I have to adjust luminosity to become equivalent to canon
This time, Sigma softness is to noticable on the edges .. even in the general picture feeling. But still acceptable ;)...
Sigma can't reach canon sharpness .. and some flare appears ??...
Some other comparison with very acceptable sigma results
Some other details with colors
Sigma colors are less shiny than canon, not that bad, but difference is quite significant ..
100% crop .. wich shows a very big difference between two lenses ..
In the center, it's acceptable, but outside center, it makes almost impossible to crop heavily
I never use a zoom because I prefer to take time to move my feet to the right place and angle and then use my PC to correct the frame .. with sigma it will give quite limited possibilities to crop
(already 50D limits a lot comparing to my 5DMKII)
I love my 24L1.4II ..
but in real life this sigma, when AF is correctly adjusted, is really impressive.. with a 50D .. it really makes a very affordable couple
As my own conclusion, I would recommand the sigma 24f1.8 EX DG .. it's five time cheaper than canon 24L1.4II and results are more than acceptable.
On my 5DMKII difference is more significant, but for 50D, I imagine to be possible to get, in the real life, very good results unless you have to crop a lot. I made several pictures stopped down, and sharpness became even better, but not really significant if not cropped, so I think sigma can be used mainly between f1.8 and F2.8 unless you need more DOF ..
We are going use that lens as a walkaround lens attached to the 50D .. not very heavy, quite fast, with a good macro capability ..