T7i Focusing Issues?

[rgfoto]

So... I've shot a few images with a T5i, and then with the T7i (both in manual, same settings, and using a 24-105 Canon lens), and I consistently find that the images shot with the T7i are always out of focus. The camera will tell me, when reviewing the images, where the focus point is, but even that spot is out of focus. The T5i seems to be doing a much better job with the same focus point (as close as possible, anyway) selected.

I tested this earlier, and set a manual focus point and shot a few photos of my sun playing on the deck with the camera in AI Servo. It pretty much missed focus every time. Could someone advise, please? I'm going to shoot some more photos with the camera in a day or two with the Tamron 70-200 and see what happens...

[rgfoto]

by the way, I'm willing to share the photos if someone wants to have a look. Somehow.

[Waddizzle]

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@rgfoto wrote:
by the way, I'm willing to share the photos if someone wants to have a look. Somehow.

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Use One Shot mode, and manually select the center AF point for every shot. Use a fast shutter speed, too.

[TCampbell]

It is possible that this is a focus callibration issue (this is done at the factory).  Camera's in Canon's mid-range and above (70D, 80D, 7D, 6D, 5D, & 1D series) allow for "auto-focus micro-adjustment" (AFMA) which lets you tweak the focus system if you find it's fractionally front-focusing or fractionally back-focusing a subject.  Rebel series bodies do not have the feature.  

You should test the camera by switching to live-view mode to focus and take a shot and compare that to what you get when using the viewfinder.  Live-view mode uses a different focusing system and it isn't subject to the same focus calibration that the normal view-finder focus system uses.

[rgfoto]

TCampbell, yea.. I got a 6D Mk2 coming in the mail. I'm gonna give that a shot as well before I call Canon.

Waddizzle, that defeats the purpose of continuous focus.. I need it to capture a moving toddler/race car/bar fight lol.
Plus, focusing and recomposing with the 24-105 continuously leads to out of focus images. Well, I suppose that could be because of the focusing issues I'm experiencing in the first place.

[TCampbell]

I do not recommend “focus and recompose” techniques unless you shoot with a broad enough depth of field that the error create wont matter.  

Use “One Shot” when you know your subject isn’t going to move.  Use “AI Servo” when you know your subject will be moving (focus distance will be changing).  Use “AI Focus” when you aren’t sure (AI Focus behaves as if you are in One Shot mode... but if the subject distance starts to change it will flip to behave as if you are in AI Servo mode).

One Shot mode uses “focus priority” and it wont take the shot until it thinks it has successfully locked focus ... and then stops focusing once that is achieved and it will then take the shot.  If the subject distances changes after focus is achieved it will NOT update the focus to the new focus distance.   You can probably already tell that this isn’t the mode to use when chasing young children.

AI Servo mode focuses continuously... but it wont chirp to tell you when it has focused and it WILL take the shot when you fully press the shutter button even if the subject you wanted to focus was NOT yet focused.  This behavior is called “release priority” (it takes the shot when you hit the shutter release ... aka “shutter button”).

You should NOT use “AI Servo” all the time.  It might sound like a good idea but the camera can be tricked into thinking something moved and begin updating focus when you hit the shutter release ... and you end up with an out of focus shot (that would not have been out of focus had you used “One Shot” mode for a stationary subject.)

In other words... there’s a reason Canon offers you all these modes ... because no mode is best for every situation.

[ebiggs1]

"I do not recommend “focus and recompose” techniques ..."

I totally disagree with this. I use focus and recompose all the time.  Almost every shoot I go on will have a focus and recompose situation. Focus and recompose is not focusing on a distant mountain and then fixing on a close up tree.

It involves the subject, in perfect focus, and then simply moving the frame.  The subject is just in a different place in the frame not further or closer.

One shot and single center focus point is your most accurate AF.  It should be your priority mode.  Employing the others as situations occur.

As for SS, 1/250 should capture any toddlers movements.  Even fast toddlers!

Your T7i has 25% more resolution than the T5i.  That is good but focus errors will be 25% easier to see vs the T3i.

[rgfoto]

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@ebiggs1 wrote:

"I do not recommend “focus and recompose” techniques ..."

I totally disagree with this. I use focus and recompose all the time.  Almost every shoot I go on will have a focus and recompose situation. Focus and recompose is not focusing on a distant mountain and then fixing on a close up tree.

It involves the subject, in perfect focus, and then simply moving the frame.  The subject is just in a different place in the frame not further or closer.

One shot and single center focus point is your most accurate AF.  It should be your priority mode.  Employing the others as situations occur.

As for SS, 1/250 should capture any toddlers movements.  Even fast toddlers!

Your T7i has 25% more resolution than the T5i.  That is good but focus errors will be 25% easier to see vs the T3i.

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With most lenses this seems to work, but with the 24-105 it seems that the image will be soft. I'm not sure why, but seems to have to do with angles and triganometry. I watched some videos on the subject, and its better to use a different focusing point in camera than focus and recompose.

[ebiggs1]

"... but with the 24-105 it seems that the image will be soft."

I used the ef 24-105mm f4L for years and years.  Two of them as a matter of fact.  Neither exhibited that behavior.  I used them both on Rebels and 1 series and 7 & 5Dxxx cameras.  Focus and recompose is a fact of life if you are in business to sell your work.

The ef 24-105mm f4 isn't the sharpest tack in the drawer but it is plenty sharp.

[Waddizzle]

"As for SS, 1/250 should capture any toddlers movements.  Even fast toddlers!"

Eh, I do not know about that claim of "any" movement.

The rule of thumb says use a minimum shutter speed of 1/FL, FL equals focal length.  On a crop body, I like to go with with 1/(2*FL), because the math is easier than using 1.6.  That works out to roughly 1/200 to 1/250 as a minimum speed.  

So, that 1/250 is really near the bottom end of the range of recommened minimum shutter speeds.  And, the OP asked if 160-250 shutter is fast enough.  The 1/160 speed is not fast enough, at all.  The correct answer is no, using a 160-250 SS is not quite fast enough for an APS-C sensor camera body and that lens combination.