AF speed comparison through viewfinder Sigma Vs. Canon (video inside)

So this is the best way to explain the differences in AF speed of the two lenses I have. Now I've always said the 85mm is the fastest focusing lens I've used to date and that the Sigma 70-200 2.8 OS AF speed was quite good just not the same speed as my old Canon F4 IS version. Well now having a tamron lens and the canon and the sigma I'm very spoiled every time I use the Canon 85 and how fast and snappy it's AF speed really is.

Test setup: S100 camera held up to the viewfinder of my 7D and taking video of what you actually see.

Conditions: Focused on wall about 7 feet away and in the room on the other end of the house about 35 feet away. Yes, it's low light but the AF speed is seriously the same even if I'm in bright light... also S100 VIDEO THROUGH VIEWFINDER MAKES IT DARK. The actual conditions are much brighter than the video depicts. Also, OS is turned off on the Sigma lens just to keep things equal and less distracting.

This is a LIVE demonstration of the AF speed of two totally different lenses. The Canon 85mm is a very fast focusing lens. The Sigma has more glass to move and is obviously not a match against the 85 but that wasn't the point. This is more of a comparison to give people an understanding of the actual speed compared to a common canon lens.

The verdict:

Sigma. I feel this lens is quieter than the Canon but mainly because it's smoother and less snappy. It flows into where it locks in. The lens is snappy when the difference of focus points is under 15 feet, similar to the canon but beyond that it does take some time. The sigma is slower and I feel that I must "wait" for the focus to come in where the Canon is instant.

Canon. Fast, just as silent except for you can literally hear the lens snap into position. I want all my lenses like this.

Videos:


Youtube -> 85mm 1.8
Direct link -> Canon 85mm 1.8

Youtube -> Sigma 70-200 2.8 OS
Direct link -> Sigma 70-200 2.8 OS

(you might have to "right click save as" for this... clicking on it did nothing for me)

Also if anyone knows a better way to post the videos please let me know thanks.

Youtube?

Maverique wrote in post #14912367
Youtube?

Doh! Good point. I don't however have an account. I'll use my wifes.

who uses all the AF points?

I noticed not a bunch of difference in the AF speed. Either would be fine with me. What I did notice was the you are shooting two targets, 7 and 35 feet away. First shot with both lenses, all AF points light up. Move to second shot and all AF points light up again, even though some are on the 7 foot target, and some are on the 35 foot target. That does not seem right to me. I use a 60D and a 500D and don't have much experience with using multiple AF points. When I do, it seems to me that only the ones obtaining focus light up. How is it possible that all of you AF points light up when some are on a 7 foot target and some are on a 35 foot target? Perhaps I am just not familiar with the 7D. Please explain.

DreDaze wrote in post #14913341
who uses all the AF points?

TSchrief wrote in post #14913416
I noticed not a bunch of difference in the AF speed. Either would be fine with me. What I did notice was the you are shooting two targets, 7 and 35 feet away. First shot with both lenses, all AF points light up. Move to second shot and all AF points light up again, even though some are on the 7 foot target, and some are on the 35 foot target. That does not seem right to me. I use a 60D and a 500D and don't have much experience with using multiple AF points. When I do, it seems to me that only the ones obtaining focus light up. How is it possible that all of you AF points light up when some are on a 7 foot target and some are on a 35 foot target? Perhaps I am just not familiar with the 7D. Please explain.

With the 7D you can have all the AF points visible or only the selected point visable because the points are actually on an LCD overlay in the viewfinder. The center black square is the selected AF point. I'm only using the center point in these videos. In one shot mode when you lock focus the entire lcd that displays these AF points will blink red indicating focus lock which means if you have all points "visible" then they will all blink red... very helpful in seeing this during daytime shooting.

So to answer your questions. I am only using the center AF point in Single point AF mode.

...maybe I should video the viewfinder and go through all the AF modes it has for people to better understand it.

Talley wrote in post #14913699
With the 7D you can have all the AF points visible or only the selected point visable because the points are actually on an LCD overlay in the viewfinder. The center black square is the selected AF point. I'm only using the center point in these videos. In one shot mode when you lock focus the entire lcd that displays these AF points will blink red indicating focus lock which means if you have all points "visible" then they will all blink red... very helpful in seeing this during daytime shooting.

So to answer your questions. I am only using the center AF point in Single point AF mode.

...maybe I should video the viewfinder and go through all the AF modes it has for people to better understand it.

I see. It is user selectable function for it to behave that way. I do understand that could be a useful feature. I knew it had to be my lack of knowledge about the 7D, since nobody else raised the question. Thanks for the explanation.

Now I wish my 60D had that feature. Sometimes I miss when the single AF point I am using lights up. I would not miss 9 of them flashing. Thanks again.