1D X AF in Low Light action

[Shawn L]

To the OP, do you happen to know how charged the 1DX's battery was?

I ask because of something I'm seeing. I bought a 24-70 II and have had somewhat mixed results with it. I've taken some really sharp photos and some (with the similar settings in similar conditions) where the focus point (as determined by DPP) simply isn't sharp.

Thinking back on it, the really sharp ones were all taken in low light at a Christmas party. The others were taken outdoors, but in the shade, so somewhat similar overall illumination. The difference is that Christmas party ones were taken with the battery fully charged. The others were taken a week or so later with the battery at 30% or so.

Not saying there's causation, but I'm looking to explain a few things myself

Cheers.

Shawn L.

 

[Shawn L]

Though, examining the photos in question again, I see that many of the really sharp ones were also taken in landscape orientation using focus points in the center three "tall" columns. Many of the soft ones were taken with points outside this region.

One of the really soft ones shot in landscape orientation at 1/500 of a sec uses points just to the right of the three tall columns.

Maybe it's time for me to read up on what's expected from the various focus points. I thought the difference was about ability to focus, not quality of it. But I could have that wrong.

Shawn L.

 

[paolotaverna]

just discouraging!!!

what is cold outside? temperature can also influence the focusing system...I will sure test this over the week end as it's fairly cold here

 

[Shawn L]

I'd say low 60s (F)

Here's the photo in question for those interested. Note that the focus is supposed to be on the chin, according to DPP.

http://home.comcast.net/~sal6/BY5R7623.CR2

(Hoping that upload worked, Comcast has been having FTP issues as of late.)

Shawn L.

 

[Drizzt321]

@Shawn L

Yes, if I remember correctly, the center column (in landscape orientation) is double cross type, with extra sensitive points if used with a compatible lens (I'd be 24-70 v2 and 135L are). Do you have FoCal software? I'm pretty sure you can do a test on all of the AF points to determine which one(s) are reading with high accuracy, and which ones aren't giving as great of accuracy. Something I've been meaning to do, but I'd be it takes quite a while so I haven't taken the time.

 

[Studio1930]

The problem is the lens, not the camera. I have found that my 135 f/2 will not focus well in low light no matter what 1 series camera I use it with. My 70-200 f/2.8 IS II is way better than my 135. I shoot dog sports in very low light and the 1Dx works perfectly at 12 fps in light so low you cant read the buttons but it only works this well with one lens - the Canon 200 f/2. Yes, I understand the price tag, but if you want f/2 and fast accurate focusing then this is the lens to use. It is twice as accurate as my 70-200 so you can imagine how much better it is than the 135 f/2.

Here is a shot in very, very low light (we refuse to shoot there now) where the 1Dx with a 200 f/2 hits the focus without issue. Sorry this is a processed image but the original looks very good and is sharp. The high ISO softens it a bit, but the auto focus hit perfectly and the numbers on the stickers on the shirt were sharp. I actually added grain to this processed image to match the retro color processing. Note: that dog is super fast and runs 7 yards per second!

1DX, 1/800s @ 200mm f/2, ISO 25600, TV mode, +2/3ev, auto ISO, focus mode 4, single point + 4 expansion, using 2 down from center point (x type), 12 fps.

 

[Shawn L]

Drizzt321:

I do have the software and I will check it out (probably won't find the time until next weekend, though).

To Studio1930's point, I've never had an issue with my 70-200 II in low light -- even inside an ice rink. Kind of sad to see the issue with the 24-70 II. Though, I will say that I have used the 24-70 II at night on a moving train and still gotten fairly good pictures (at 1/200 sec with a more fully charged battery).

Still haven't ruled out user error on my part.

Shawn L.