is the AF of a 1.4 or 1.8 prime faster than AF-S?

Discussion in 'Lens Lust' started by twig, Aug 19, 2005.

  1. twig

    twig

    745
    May 23, 2005
    Just wondering, I am thinking more and more from my experience shooting basketball under the hoop that my 50/1.8 may be faster focusing than my 17-55AF-S and definitely faster than the 70-200

    This is on a D2H
    Anybody care to comment on this?

    I am thinking the brighter viewfinder, the larger glass, perhaps this allows faster focusing? (at least when coupled with the powerful CAM 2000 of the D body)?

    This is not a scientific opinion, just one that is slowly forming as I shoot more events, anybody else have an opinion on this?

    Anyway I ponder this out loud as I think about "upgrading" the 70-200 with an 85/1.4

    Incidentally I use a 50/1.8 and I find it very quick and VERY accurate to focus (I was shooting at f/2.2 which can be brutal on DOF and it was really onthe money with focusing), is the 1.4 version faster?
     
  2. JeffKohn

    JeffKohn

    Apr 21, 2005
    Houston, TX
    My 50 1.8 definitely wasn't as fast at focusing as any of the AF-S lenses I've used, but that was on the D70. I had already sold the "nifty fifty" by the time I got my D2x.
     
  3. twig

    twig

    745
    May 23, 2005
    yes, this is certainly not a question for D70 or D100 users,
    The D series is no joke though and I think in a simple lens liek the 50/1.8 it may turn that screw faster and have a shorter distance and therefore may out perform AF-S

    I am just wondering, I hope someone can confirm or deny my thoughts definitively.
     
  4. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    On my D100, the 35mm f/2 focuses as faster from being set to infinity to a 5 foot focus than does the 24-120vr (which has AF-S.) From closest focus to5 feet, they are about the same. Of course the 35mm makes more noise.

    The 35mm is a very small lens, while the 85mm f/1.4 you are pondering twig, is large and heavy. I suspect that, given the CAM900 (is that right?) mechanism on the D100, the mass of the glass makes a big difference. Your D2h should be able to sling around considerably more glass.
     
  5. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  6. twig

    twig

    745
    May 23, 2005
    Paul. thanks for your comments.

    Screw drive, yes this is what I meant. On a small simple prime (like the 35/2 I bet, or the 50's) a half or 3/4 turn of that screw is all it needs to go from infinity to quite close, couple that with less heavy elements that move around long distances like in a zoom, and I am thinking on a D body it might be faster than AF-S...

    Anyway. I have almost hte sdame lenses as you, I use the 70-200 and 17-55 while sitting under the hoop. Ishoot womens pro ball (NY Liberty) amd top level streetball which has pro participants, os the action is pretty quick, certainly faster than most high school.

    Sitting right under the basket (well the corner of the paint on the baseline, when people are driving right at me that is the hardest matter for a good focus lock. They are usually airborne, driving to the hoop, and I am shooting at f/2.8 or worse so DOF is tight.

    Perhaps this is part of my problem with the 70-200, even when I limit the focus it seems to slow dow na bit towards the nearest end of hte range. PErhaps if the focus is limited to 2.5m - inf. it doesn;t love doing a lot of focus acquisition in the 2.5-4m range?

    Anyway, tests. I am wondering how good the focus tracking/acquisition and lock is with the 85/1.4 on a subject between 10 and 8 meters running full speed towards you to a distance of aboutt 3-4meters, with you trying to focus at a shallow app on their face.

    I wonder how the keeper rate would compare to the 70-200 in the same situation.

    Second test would be similar but wit hthe 17-55 and the 50/1.8 right under the basket, same idea, but more elevated (dunking, layups blocks, rebounds happening righti n your face).


    Third test would be to compare the 85 and anything on shooting someone about 15-30 feet away in motion (like taking a jump shot), the speed of the focus acquisition. Soi from grabbing the camera on the floor (who knows the focus distance) and just pointing real fast at the shooter and jamming on your shutter, is the first frame in focus? does it take until the third, or is the entire burst OOF because the lens is still getting there.

    This is a lot of testing, I don;t expect you to do it on my account, but thanks for the offer. I have been experimenting a bit on my own, but it is hard to test empirically when shooting an event. I try afterwards to review my shots to see keeper %'s, etc. but every game/lighting situation is so different.

    The more I shoot particular sports and find my positioning and angles, etc. the less I need the flexibility of a zoom. In such situation the ability to shoot at f/2.5 is a plus, also the idea that when I shoot at f/2.8 I am stopped down (more sharpenss) makes me happy the brighter viewfinder is nice too/
     
  7. cwilt

    cwilt

    Apr 24, 2005
    Denver, CO
    twig,

    I can not comment on the focusing speed but I can say that the 50/1.4 is sharper than the 50/1.8 from f4 and wider. From 5.6 on the 1.8 wins for sharpness.
     
  8. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  9. twig

    twig

    745
    May 23, 2005
    ok, quick test, use the lens and have your wife throw a basketball at your head as hard as she can from 20 feet away, goal is one or two sharp frames with the ball at 5-10 feet

    (please don;t actaully try this, but this is the best simulation of what I want to know)

    FYI I rented both 1.4 lenses this afternoon and shot with them, I can say the 50 is lovely, all my 1.8 was and a bit more sharpness.

    The 85 was disappointing in how slow the AF is, too much big glass to move around I suppose, but I would have to wait for an AF-S model for sports IMO.
     
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