PDA

View Full Version : Canon 50mm L F1.2 anyone?



sharath
02-01-2011, 6:31pm
I gifted myself a 50mm f/1.2L after using a 50mm f/1.4.

I'm experiencing focusing problems at f/1.2. I've read the lens has some backfocus issues and elsewhere that these has been corrected. Wanted to get an opinion of users who've used this lens.

thanks!

jjphoto
02-01-2011, 7:44pm
...I've read the lens has some backfocus issues and elsewhere that these has been corrected. ..

Do you mean focus shift? I believe this lens has a bit of a reputatioin for focus shift which is not the same as front/back focusing although it may have both. If you are having focusing problems then you need to carefully test how/when they occur. You can also calibrate your cameras AF for this specific lens so you should probably do that if you haven't already (this will compensate for any fron/back focus but not focus shift). The depth of field at f1.2 is so shallow that if you sway forward or backwards, even slightly, the focus will possibly be out so you need to test on a tripod. You really need to get used to the lens, test as much as you can. I also suggest you find out exactly how much focus shift there is with your lens so that you can work around it. There's lots of info about focus shift on the net so just google it.

http://seriouscompacts.blogspot.com/2008/01/focus-shift-spherical-aberration-and.html

http://diglloyd.com/articles/Focus/FocusShift.html

http://toothwalker.org/optics/spherical.html

Focus shift is not the end of the world but you can make it much worse for yourself by not understanding it and how to work around it if required. Focus shift is not uncommon in lenses, but people knowing about it and understanding it is!

JJ

Brian500au
02-01-2011, 8:01pm
During the Christmas break this was the main lens on my 1DMKIII. I used it for 3 days in a row at all the family Christmas get togethers. I must say I was very critical with this lens - I used it mostly opened up anything from 1.2 up to 5.6 and overall I was very pleased with the results. The conditions of shooting were difficult - night shots with flash (these were the least successful but this was user error), shots in bright sunlight with fill flash, group shots, candid shots, general family portraits. My keeper rate (in focus) was more than 90% and those that I did discard I was not convinced was the lens (more shutter speed and user error).

As i said these are family photos but if you PM me I am willing to share the link with you for comparison and your own information.

Overall I do find the more i practice with this lens the higher the keeper rate. I also have the 85 1.2 and I do have the same OOF problems - once again I am not convinced either lens is at fault - I put it down to user error and experience on my behalf.

sharath
02-01-2011, 8:17pm
thanks JJ.. I did mean focus shift... from the link, its exactly what the lens is doing..

will read on to tame this beast...

sharath
02-01-2011, 8:22pm
Thanks Brian, I think I haven't yet mastered this tricky lens.. I'll practice more..

I was thinking it could be the lens.. but seeing a few sample shots.. I'd now think its me :)

Time to spend more time with this baby.

dulvariprestige
03-01-2011, 10:01pm
I hired this lens for a couple of days and found if I focused and recomposed, and depending how close I was to my subject, I might miss the shot, so I tried moving my focus point around to suit and started to get better results.

sharath
04-01-2011, 9:11am
....so I tried moving my focus point around to suit and started to get better results.

will try it out.. but its a bit annoying that you do not get the images as you see in the viewfinder..