Wilt wrote in post #16027418
We should not forget that the Canon dSLR uses PHASE difference detection AF, not contrast detection AF. That may account for why an f/4 zoom seems to AF better in lower light than the f/1.2 lens.
snake0ape wrote in post #16027582
Ahhh. Its the new 24-70 f4L. You have the best AF lens here. I read that these newer lens has an "open loop" communication with the newer camera bodies like your 6D/5Diii. So with phase detection, camera send instructions to lens, lens don't like it, send camera back with another set of directions....looping back and forth till there is some kind of agreement. With the older lens like the 85L, camera sends instructions to lens and that is it. But newer bodies are better than the old ones, with the phase detection system they take into account CA signatures and light wavelengths, so its better than older bodies since Phase detection gets confused with what is in focus since "purple" is out of sync (oof) with "green" wavelengths.
I will test out my 85L tonight to see if how low "contrast" I can go in dim lights.
Gee...didn't know that kind of technologies behind these new lenses . I got it for my wife because she likes to do close up food shots...maybe I should trade with her
cdang wrote in post #16027586
I wasn't aware the new firmware helped low light focusing. Care to elaborate ? I thought it was just bad while using speedlites. Thanks in advance.
I do notice these older lens performed considerably better in the newer bodies. My 1v die on me recently so I can't remember how they sound on older bodies but after I gotten the 24-70 IS, I do find that the older lenses like the 50L and 85L sound quite differently upon the shutter release.
Stu Scully wrote in post #16027699
The new firmware fixes an issue with the AF assist beams with Canon flashes. Now it is suppose to work much more reliably and provide better low-light focusing. I don't do a ton of low light shooting with flashes but since I have installed the firmware I have had no noticeable issues with not locking focus at night with a 600EX.
Hmm...so still need to on that. Do you guys leave it on? I find it irritating especially with the sound.
snake0ape wrote in post #16029445
...Of the 4 lens I tested, the 35L wins (but not by much)
second was the S35.
Third was the 85L (close to S35)
And not surprisingly, last is the 24-70ii. (still not by much)
I should have also test out my 50s, but its in my other bag.
All of these lens performed very well in low light. I can't say that anyone of these should avoid low light photography.
Sorry you mean your 24-70 II has the best low light focusing or 35L?
Anyway just an update....keeping in mind what you guys had suggested, I tried it again yesterday night...still 2 monochrome light source, take note of the minimal focusing distance of the lenses, focus on the eyes, hold my breath and surprisingly I got it most of them now! Not much haunting and when I review on the LCD with the focusing screen point displayed, I'm pleasantly surprise that they are all in focus on the eyes!
Thanks you guys for the tips and reminders! I shall start shooting more indoor shots than outdoors now!