New Canon 100D not focusing correctly

Gnocchi wrote:

em28 wrote:

R2D2 wrote:

em28 wrote:

Yes, AI servo, no filters and no hoods. Stock kit 18-55 IS STM.

it simply fails at focus a lot of times, cannot match basic point and shoot compact camera. AF performance is bad on my camera... Maybe others don't have such bad experience, could be it's only my camera, but initial focus is not so good, but as soon as object starts moving, it cannot track it, takes few seconds to get focus back on object, even when object stops. During live view, it's ok, tracks object.

This definitely sounds like a problem. The 100D normally focuses much better than that.

Try another lens first, then if no joy, you might need to send it in (or exchange if that's still an option).

Best of luck!

R2

Actually, my camera did suffer a serious fall (and got back case broken - a small hole which i taped) but from my point of view all looked ok, photos are ok, IS is working, nothing wrong on pictures that i would see... Now i think maybe there is something wrong with my camera - but as i said, on live view performs well.

Hmmm

Now you scared me, is there a way i could check AF? Some test application, some software from canon that does some internal test?

Could it be that over viewfinder AF uses some other parts that live view does not?

Now i spammed this guys topic, sorry about that. Doing half press shutter instead waiting for AI Servo yields better results - so if i don't rely on AI Servo, instead i redo half press, then it does focus properly, but on AI it takes ages to refocus.

the first one is nice with sigma 18-200 which considered not sharp and fast like the telephoto lenses

just have a little question for the others

I know the 100d and 6D have almost the same auto-focus points

but why i see here many photographers use the 100d for sports and action but with the 6D they never do this ? is the 100d better in autofocus system than 6d ?

your are right because i see the users in canon FF forum  are strict in choosing the right body because most of them are professionals  

Simon57 wrote:

The blue Rover SD1 was taken with the 100D with a Canon 70-300 IS USM lens, RAW 1/400 F7.1 ISO 100.If you zoom to 100% you can see detail on the red cobra but blurred on the blue Rover.

This has NOTHING to do with focus.  Have a careful look at the picture.  Can you see anything in focus?

Now look at the fence.  Do you see that the image is doubled in one direction but relatively clear in the other?  Now look at the little white objects in the grass in the foreground.  Notice how they are all streaked in the same direction?

You have camera motion.  Pure and simple.  This picture tells you NOTHING about focus accuracy.

em28 wrote:

Now you scared me, is there a way i could check AF? Some test application, some software from canon that does some internal test?

There are zillions of ways to test AF for accuracy and front focus/back focus.  Do a search and pick your favorite.  I like to use an upright (non-tilted) cereal box (with a ruler set next to it).  Use a single AF point.  After testing, go out and shoot a bunch and evaluate.

Could it be that over viewfinder AF uses some other parts that live view does not?

You're exactly right.  Viewfinder AF uses a separate dedicated AF sensor in the bottom of the mirror box.  This can get jarred (or the mirror can be off), or there may be some junk built up down there which will throw AF off.

Live View tests for contrast peaks in the image file itself.

Doing half press shutter instead waiting for AI Servo yields better results - so if i don't rely on AI Servo, instead i redo half press, then it does focus properly, but on AI it takes ages to refocus.

Still sounds like something is wrong.  I use AI Servo (with Back Button AF) for absolutely everything.  It is very fast and accurate.

Good luck,

R2

Hello Simon57,

In my opinion the first photo with the red car is perfectly in focus. Look at the text on the passenger door. The focus is there. There is some ghosting and flare. The Sigma 18-200mm is not the sharpest lens and while it was OK on your previous camera, the increased resolution of the 100D shows its weaknesses. Also, look at all the chromatic aberation - it subjectively decreases sharpness but can be corrected in post. You can also try to turn on the chromatic aberration correction in the 100D, but I'm not sure if it works with third-party lens. 200mm at 6.3 is the extreme end of this lens and it is where it performs the worst. Your best bet would be to close the aperture down to f/8 on the sigma, if shooting at 200mm.

In the second photo things are a bit trickier. There is evidence of back focus and there is also motion blur. Your equivalent focal length is 480mm. If you want pixel sharp image at that range with a high resolution sensor, you need to double the shutter speed to at least 1/800 in my opinion. Also, keep in mind that when the car is moving towards you, if the camera acquires and locks focus slightly before the shutter is pressed, the car would be out of the focused area. After all the 100D is not a performance sports camera and there is a reason higher end models exist.

I also own 100D and my telephoto lens is the first generation Canon 55-250 IS. I've had some great shots and some disappointing ones, as this lens is also famous for its softness. That is why I am looking forward to upgrading to the STM edition.

To me it seems that your camera is working fine, so your best bet would be to know your gear, its strong and weak points and work around them