topic Re: T7i Focusing Issues? in EOS DSLR & Mirrorless Cameras

T7i Focusing Issues?

rgfoto — Thu, 18 Jan 2018 22:06:48 GMT

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...

Re: T7i Focusing Issues?

rgfoto — Thu, 18 Jan 2018 22:25:23 GMT

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

Re: T7i Focusing Issues?

TCampbell — Fri, 19 Jan 2018 00:06:15 GMT

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.

Re: T7i Focusing Issues?

Waddizzle — Fri, 19 Jan 2018 01:04:56 GMT

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

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

Re: T7i Focusing Issues?

rgfoto — Fri, 19 Jan 2018 02:52:08 GMT

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.

Re: T7i Focusing Issues?

TCampbell — Fri, 19 Jan 2018 02:32:11 GMT

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.

Re: T7i Focusing Issues?

Waddizzle — Fri, 19 Jan 2018 11:28:35 GMT

@rgfoto wrote:
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.

A fast shutter speed is what you need fo capture moving toddlers. Are you shooting indoors or outdoors? If you are outdoors, then you should have sufficient light for 1/1000, or faster. If you are indoors, then you may not get the shutter speed you need. You would need a faster lens, like the EF 50mm f/1.8 STM, of the EF 35mm f/2 IS USM.

Re: T7i Focusing Issues?

rgfoto — Sat, 20 Jan 2018 02:09:05 GMT

@Waddizzle wrote:
@rgfoto wrote:
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.
A fast shutter speed is what you need fo capture moving toddlers. Are you shooting indoors or outdoors? If you are outdoors, then you should have sufficient light for 1/1000, or faster. If you are indoors, then you may not get the shutter speed you need. You would need a faster lens, like the EF 50mm f/1.8 STM, of the EF 35mm f/2 IS USM.

You dont think that a 160 - 250 shutter speed is enough? I'll try a higher speed I guess.

That said, at times, my son was sitting quite still... so I donno. I'll continue testing.

Re: T7i Focusing Issues?

Waddizzle — Sat, 20 Jan 2018 02:16:19 GMT

@rgfoto wrote:
@Waddizzle wrote:
@rgfoto wrote:
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.
A fast shutter speed is what you need fo capture moving toddlers. Are you shooting indoors or outdoors? If you are outdoors, then you should have sufficient light for 1/1000, or faster. If you are indoors, then you may not get the shutter speed you need. You would need a faster lens, like the EF 50mm f/1.8 STM, of the EF 35mm f/2 IS USM.
You dont think that a 160 - 250 shutter speed is enough? I'll try a higher speed I guess.
That said, at times, my son was sitting quite still... so I donno. I'll continue testing.

No, not for moving subjects. I use a wide aperture lens, which helps a little to keep high ISO under control. Learn to use the Creative shooting modes: Av, Tv, and M. The P mode is good for learning about the camera. I mostly use M with ISO Auto, and set an upper limit to ISO in the menus.

[EDIT]. Be aware that if your toddler is less than ten feet from the camera, the DOF [depth of field] can make your photos seem to be out of focus, OOF.

Re: T7i Focusing Issues?

rgfoto — Sat, 20 Jan 2018 02:15:01 GMT

I shoot manual.

Re: T7i Focusing Issues?

ebiggs1 — Sun, 21 Jan 2018 15:50:26 GMT

"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.

Re: T7i Focusing Issues?

ebiggs1 — Sun, 21 Jan 2018 16:00:43 GMT

Since you have two cameras using the same lens, one works and one doesn't, you may have a defective camera.

Call Canon support 1 (800) 652-2666

Re: T7i Focusing Issues?

rgfoto — Sun, 21 Jan 2018 18:31:46 GMT

@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.

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.

Re: T7i Focusing Issues?

ebiggs1 — Sun, 21 Jan 2018 19:02:16 GMT

"... 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.

Re: T7i Focusing Issues?

Waddizzle — Sun, 21 Jan 2018 20:53:59 GMT

"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.

Re: T7i Focusing Issues?

TCampbell — Sun, 21 Jan 2018 21:00:29 GMT

@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.

Ernie, it depends on the depth of field (which is why I said I wouldn't do this unless I had a broad depth of field). But this is a well-understood issue. Focus & recompose with a shallow depth of field is a good way to get a lot of out-of-focus shots.

Here's a diagram that will hopefully clear things up.

This is a perfect circle with a camera located at the center. The camer is focused to the radius of the circle such that everything on the blue circle would be in perfect focus.

I've drawn a subject on the circle toward the right and indicated the position of the subject's eyes. I've also drawn a depth of field box ... green is in focus, red is out of focus. There are two of these boxes. The one over the subject is used to establish "focus". The one in the top center of the circle is used for "composition" (e.g. rule of thirds).

Notice when you look at this, that the subject's eyes are no longer on the focus plane.

This is why you really need to be careful when doing focus & recompose if using a shallow depth of field (which often is used for portraiture.)

Do not just rely on the center AF point for everything. There's a good reason the camera has more than one AF point.

Re: T7i Focusing Issues?

ebiggs1 — Sun, 21 Jan 2018 21:30:14 GMT

Tim that might work in the lab or on a pretty graph but it doesn't hold true in the real world shooting. I use it constantly. I used it last week on yearbook photos. No one said darn you recomposed didn't you?

You of all of us should know graphs and charts don't tell the whole tail.

Re: T7i Focusing Issues?

ebiggs1 — Sun, 21 Jan 2018 21:38:46 GMT

"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."

One big problem is, "the rule of thumb" is a suggestion. It is not a law. Not only do you need to know what camera, you need to know what lens and most importantly what subject you are shooting. Even the individual photographer will effect "the rule of thumb".

That is one fast toddler if he can move quicker than 1/250th of a second. I typically avoid shooting babies and toddlers, I leave that to my niece, but when I do, super fast SS is not needed. But you do as you see fit.

Re: T7i Focusing Issues?

TCampbell — Sun, 21 Jan 2018 22:44:07 GMT

Physics is physics. The laws of physics are true everywhere, for everyone, and for everywhen. There are no exceptions.

True, charts & graphs don't tell us everything about a lens. They don't tell us how well image stabilization works or how fast the auto-focus motors can achieve focus. They don't tell us what sort of character we can expect in the out-of-focus background blur. BUT... when we care about in-focus areas... charts and graphs DO tell us that.

BTW, I did qualify that whether or not you can trust "focus & recompose" depends on depth of field. Don't use it when using shallow DoF. If using a broad DoF ... use it all you want.

This news shouldn't be a surprise to anyone. Most experienced photographers know this. I didn't invent the idea.

Re: T7i Focusing Issues?

Waddizzle — Sun, 21 Jan 2018 23:32:12 GMT

"That is one fast toddler if he can move quicker than 1/250th of a second. I typically avoid shooting babies and toddlers, I leave that to my niece, but when I do, super fast SS is not needed. But you do as you see fit."

I see. Once again, you have totally missed the point. It is not about how fast the toddler can move. The point is having a fast enough shutter speed for the focal length that you are using, which in this case means using a 24-105mm lens, or 105mm.

BTW, a 1/400 shutter speed is not super fast, but it is the minimum that I would use with that lens photographing toddlers. With a T7i, you might want to drop that to 1/320, to keep ISO as low as possible.