List fastest AF KM mount lenses here

[Caussway]

Guys of late there are many of arguments on AF performance of KM digital bodies. Why not those who've tested or experienced various KM mount lenses share thier view on AF performance both ourdoor and low light situation for the benefit of KM subforum users. The performance can be both speed and accuracy. I categorize lenses to following groups, but open to suggestion from your guys if you have better idea.

1. Standard zooms ( ie 17 or 18 mm to 35 to 100 mm )
2. Fast primes 50mm, 80mm etc
3. Fast tele zooms i.e 80-200mm
4. Telephoto primes , 200mm onwards

 

[captnj]

i have 80-200apo G used for indoor sports in poor lighting without flash at iso 3200 and 1600 and with flash at iso 100-200. AF-C + this lense is fast enuf to track bball players on the 5d and its accurate. i use spot focus and use the central spot to track the sports action. BUT sometimes when i dont track fast action correctly the focus area is wrong i.e the wall behind is super sharp but the player in fron is not... too bad i guess thats a technuqie problem not a AF problem. I dun relly trust the multi segment AF to autodetect what should be in focus, i rather use the center spot focus.

do the more expereicned guys reccomend multi area AF even for sports? or is center focus area the way to go?

 

[AncientMariner]

Fast telephone zoom - whereever lightning hits the phone lines.:bsmilie:

 

[sulhan]

Hiee pals..

Here is something to ponder about AF accuracy in comparing lens to lens that cover same focal length...but different aperture at widest...

Here is an example of three shots of the same scene (illustration) at 300mm.

So as you can see that at 300mm with DOF already shallow to an extent say for example for a soccer match.....pin-pointing specific focal plane would be much easier with faster lens.
Lots of factors need to be considered when we want to really go look at accuracy. So for those non fast lens....depending on the "depth-of-spread" of subject specific selection of focal plane may be tricky when AF is used - using manual Focus if subject moves form left to right is possible .

As for Focus Speed....

Example here is two different 100mm lens. Given that the one on the left have a longer travel
for Infinity to nearest focus distance vs the on on the right. It will be obviuos that its slower.
Hence giving slower focus speed - but it have better focus resolution - less likely to have problems
with great **** in focus plane errors..

Rgds,
Sulhan

 

[Drudkh]

error in your illustration. i believe the 2nd one you meant f/4?

 

[sulhan]

Thankx.......updated..

rgds,
sulhan

 

[Caussway]

sorry typo :embrass: , was in the middle of work :bsmilie:

Fast telephone zoom - whereever lightning hits the phone lines.:bsmilie:

 

[Drudkh]

do the more expereicned guys reccomend multi area AF even for sports? or is center focus area the way to go?

I use multi-AF points when the subject is big enough to fill (say 3/4) up the VF, if subject isn't that big, then I'll use center AF.

 

[captnj]

I use multi-AF points when the subject is big enough to fill (say 3/4) up the VF, if subject isn't that big, then I'll use center AF.

thanks. Mostly i shoot soccer and basketball so i guess Center is the way to go.

 

[Caussway]

I only use center AF point. Not sure how to use / usefull the rest.

 

[AncientMariner]

Thankx.......updated..

rgds,
sulhan

I wd like to add something expanding on what you mentioned about lens travel (or rotation).
Another factor is where you had focused previous to aiming at a new object.
An example is changing from shooting a distant object to an object at your feet.
So if one can anticipate approximately where your subject will be, one can actually prefocus on the spot and focus lock can be acquired instantly, or even not need to re-focus, even with a slow lens.

 

[sulhan]

I wd like to add something expanding on what you mentioned about lens travel (or rotation).
Another factor is where you had focused previous to aiming at a new object.
An example is changing from shooting a distant object to an object at your feet.
So if one can anticipate approximately where your subject will be, one can actually prefocus on the spot and focus lock can be acquired instantly, or even not need to re-focus, even with a slow lens.

:thumbsup:

THats right.

Most of the itme the photographer may not be prepared - waiting focus at infinity when
subject is nearby. Focusing from infinity to a close focus means having toe rack the whole lens from one end to the other...hence the "slow" ness.

rgds,
sulhan

 

[yeocolin]

That's why there's such a big difference in price between the fast and slow lens. Its not just the 'feel good' factor, but all the speed in focusing and of course shuttle speed, shallow DOF available etc.

 

[sulhan]

That's why there's such a big difference in price between the fast and slow lens. Its not just the 'feel good' factor, but all the speed in focusing and of course shuttle speed, shallow DOF available etc.

Shutter speed.....

rgds,
sulhan

 

[Zenten]

Btw, there are lenses on the market whereby you can limit the focal range of the lens for faster AF....to do it .....focus on the furthest point where your subject will not exceed, then set the limit switch. This will the limit the range that your lens has to AF, thus giving faster AF.

 

[Caussway]

Hi guys how's it's been a while since I came here. Too busy nowdays hardly touch my camera .

Need to relive this thread. I need recommendation for fast AFing general purpose zoom
or prime that atleast 35mm wide.

My kiddy is walking around and it's hard to keep track, 17-35mm is just too slow
Don't mind Sigma / Tamron. Is the 28-75mm 2.8D focuses faster than 17-35mm ?