Auto Focus Issues

Viewing 6 reply threads
  • Author
    Posts
    • #53900
      AvatarCartouche
      Participant

      I just bought myself a Canon Rebel T4i.  One of its appeal for me was its autofocus function.  The problem is that the camera is constantly evaluating and re-evaluating its focus;  the images go in and out of focus continuously.  Now if I want to go manual, I have a hard time focusing on the tiny monitor. I'm often guessing if I'm in focus or not.  So would a bigger external monitor be the solution for me?  As of now, I'm disapointed by the AF functtion.  It's  not usable in a continuous way during a shot.  I use it only when my object of focus is not moving during the shot.  I then AF before calling action.

    • #205931
      Avatarbrunerww
      Member

      Cartouch – I feel your pain. I traded my T2i in for a Panasonic GH2, partly because the the T2i couldn't autofocus in video mode. When the T4i came out, I wanted to give Canon another chance, so I rented a T4i to see if they had addressed their autofocus challenges. Here is what I found:

       

      Canon T4i touchscreen autofocus test with autofocus "hunting", STM autofocus motor noise and moire (on green screen):

       

       

      Panasonic GH2 touchscreen autofocus test with rock solid autofocus, silent autofocus motor and no moire on green screen:

       

       

      Canon's autofocus implementation is not very good. The solution is probably not a bigger monitor, it is shooting with a camera whose autofocus actually works.

       

      If video autofocus is important to you, I suggest you trade the T4i in for a GH2 or a GH3.

       

      Best,

       

      Bill

      Hybrid Camera Revolution

    • #205935
      AvatarWoody
      Participant

      I use a 

      Sony CLM-V55 5-Inch Portable LCD Monitor for DSLR cameras

      http://www.amazon.com/gp/product/B004LQ1QDE

       

      quite a bit.

       

      It has "Peaking" but you need to practice with it on different cameras as your actual focus could come up a tad early or late to the peaking you see on the monitor. I like it, its rugged and has served me well. I've used it on a bunch of different cameras.

    • #205940
      AvatarCartouche
      Participant

      Thank you for that Woody.  Definitely on my wishlist now.   Do you ever use AF to "rack focus" during a shot or do you do it manually?  Anyone?  I think that I won't use AF to track a moving subject, it bounces back and forth too much during the shot.  I'll find a specific spot to focus on , make my focus there, lock it and let the object enter out of focus, and get in focus.  It seems that I never had to do that with camcorders.  I don't regret getting my T4i however, the image quality is well worth the price I paid for the camera.

    • #205942
      AvatarWoody
      Participant

      I've used the "Auto/Manual" switch button many times to focus in a shot but its mostly while shooting wildlife or a sign or something. I'll start out of focus in manual and then just hit the button and then hit it again after it comes in focus. It depends on the frame of the shot and how much is in it as it doesn't always work out. I also use the "Peaking" function to creep in a focus at what ever speed I want.

       

      I don't shoot much Inde type work. Mostly commercial stuff and wildlife so I don't use a follow focus wheel type system much for pulling focus. Most of the distances I work with arn't known or pre-set up. I do have a rig for it if I needed it and if I was ever to be shooting for "Film" I would certainly use it but with some practice you can get by on most things with the more expedient methods.  

    • #205964
      AvatarCartouche
      Participant

      Here's a Amazon review that offers some hope on the AF issue on the T4i.    

       
      5.0 out of 5 stars This is THE video lens for the Canon Rebel T4i/650D. August 31, 2012
      Amazon Verified Purchase
      The short version: If you plan on shooting any video with the Rebel T4i, this is the lens you want to buy first.

      The long version: While the new video autofocus feature on the Rebel T4i will work with any Canon autofocus lens, the 18-135mm STM focuses quickly and silently, unlike the 18-55mm lens in the other kit. The 18-55 has a noisy, slow focus motor that constantly 'hunts' for focus while taking video, and the whirring of the non-STM motor is easily picked up by the built-in microphones. It doesn't sound so bad in the field, but once you playback your video clips, it's magnified a great deal, making the audio nearly useless for any serious work. But even with recording Audio separately, the constant focus blur makes the video completely useless anyway, so you may ask yourself why the T4i has any video capability at all.

      Enter the 18-135mm STM. Not only is the STM motor virtually silent, it's fast enough to keep focus while you shoot (well, depending on the speed of the target, of course. No lens can work miracles.) This is the lens all those gorgeous sample videos on the Canon website were taken with, and with good reason.

      Now, there are certainly better Canon lenses for still photography–this isn't even an "L" series lens–but for video work on the T4i, it's hard to beat. It is also both quicker to focus and quieter than the other STM lens currently on the market, the 40mm STM pancake. (I can barely hear the 40mm focus, but the 18-135mm really is next to silent.)

      My recommendation for anyone looking to purchase the Rebel T4i/650D is to insist on the 18-135mm kit and forget the 18-55mm kit. I wish I had. Not that the 18-55 is a horrible lens–it's a decent starter kit lens for still shots. But at the time of this writing, the 18-135mm STM lens is nearly impossible to find by itself–and it lists on the Canon site for $549 when they do have it in stock. So you can either pay the $250 premium for the 18-135 kit over the 18-55 kit, or pay $550 later when you realize the 18-55 won't "do for now" until you can afford the 18-135 STM lens, if you want to take advantage of the video autofocus of the T4i. I suggest the 18-135 kit, plus another $199 for the 40mm STM pancake. That will give you a good solid pair of lenses to get started with, while you save up for an L-series telephoto.''

    • #205977
      AvatarCartouche
      Participant

      I found this video showing AF tests using 18-135mm stm lens and I must say it shows that AF is usable during shots in certain conditions.  http://vimeo.com/48403341Lens is on my wishlist now.

    • #207188
      AvatarTunguy
      Participant

      Bill,

      how is the AF during video with the Nikon D5200?

    • #207192
      Avatarbrunerww
      Member

      [quote=tunguy]

      Bill,

      how is the AF during video with the Nikon D5200?

      [/quote]

       

      Sadly, the D5200's video AF "hunts" and Nikon lenses have noisy AF motors:

       

       

      Contrast that with this Panasonic GH3 AF test.  No hunting and no AF motor noise (just like my GH2 test).

       

       

      If you want AF that works — and whisper quiet lenses — I still recommend the GH2 or GH3.

       

      Best,

       

      Bill

      Hybrid Camera Revolution

Viewing 6 reply threads
  • You must be logged in to reply to this topic.

Best Products

Best camera stabilizers for video — 2021

A camera stabilizer lets you capture smooth shots without sacrificing freedom of movement. Here’s a look at the best handheld stabilizers available today.
homicide-bootstrap