Depth of Field....2.8 vs 1.4

one of my customers gave me a Korbel bottle the other day. So when I had a few minutes, I did a comparison test between my Sigma 50 1.4, and a borrowed 24-70@54mm(which by the way is really sharp wide open!!). about the same subject distance(framing anyways), ISO 200, portrait orientation with bottom focus point used(AF). 5Dll, with just a touch of sharpening and punch (LR2.4) for both. These were shot in the back of my UPS truck(I'm a driver full time) on the floor. tell me what you think....Gregg[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.22.00/korbel-1.4-_5B00_1600x1200_5D00_.jpg[/img]


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Well it's hard to compare apples to oranges - or f/1.4 to f/2.8, but it's pretty clear that the 24-70 is sharper.

I can always count on you ,Oren to leave comments!!! I know it was kind of a meaningless comparison(except DOF), but thought it was kinda cool anyways. You have to admit, though, at 1.4 the sigma is pretty darn sharp. I was actually surprised at how sharp the 24-70 was at 2.8!! And these taken at outer focus points...

Nice shot(s).... you have a very clean truck :P

I like the first one better it has a more dreamy look to it, thanks to f1.4.[|-)] Anyway, thats why my screen name is Fast Glass, because I love 50mm primes!

I tried 2 different Sig 50's. Sent the first one back because of the front focusing issue , then had to send the 2nd to get calibrated. It came back very very useable at 1.4. I love the look and feel to it now, and it hits focus 95% of the time(probably user error on the other 5%!!). A fantastic lens!! Thanks for the comments.

Interesting greggf.


Your resizing/resampling leaves both of these images rather "edgey" IMHO. What would be better, is to see normal bicubic resamples @ 640-800 long side with 100% crops of some key text. It appears in the first image that the condensation on the bottle dead center is sharpest and due to the field curvature effect of a 50mm on FF you loose the top and bottom to oof blur. I don't know how close you were but it appears that the f1.4 on the 5D MkIIhas about a 1/4" of acceptable sharpness. According to dofmaster that would put you at 18".


Looks like your enjoying that Sigma.........[:D]

thanks Chuck....I've been trying to get good resampling size for this forum??!! While maintaining the same aspect ratio. I came up with 780x520 thats fits both vert and horiz pics on this forum. that seems to be the largest size that will fit without any cutoff. I think you're right on the distance...I was on my side on the floor of the truck. But I used the bottom most AF(portrait) for focusing, somewhere near the bottom of the R in Korbel(I think). And yes, love the 50. Thanx, Gregg