Canon EOS 4000D and EF 50mm 1.8STM

Hello,

I have Canon EOS 4000D and EF 50mm 1.8STM.
I noticed that pictures taken with f/1.8 to f/2.8 are out of focus when I'm focusing on focus dots with auto focus.
When I'm focusing with live preview focus is OK at whole range of f.
I found that my camera have 9 AF points (f/5.6 cross type at centre).
Does it means when I'm using f less than f/5.6 I will have issue with auto focus?

DarkoR wrote:

Hello,

I have Canon EOS 4000D and EF 50mm 1.8STM.
I noticed that pictures taken with f/1.8 to f/2.8 are out of focus when I'm focusing on focus dots with auto focus.
When I'm focusing with live preview focus is OK at whole range of f.
I found that my camera have 9 AF points (f/5.6 cross type at centre).
Does it means when I'm using f less than f/5.6 I will have issue with auto focus?

DarkoR,

I have read that those wide aperture lenses are not at their best when wide open at 1.8 or 2.8, but I saw a picture the other day that was taken at 1.2 that was pretty good.

The thing is that at those wide open apertures, your depth of field is going to be pretty small. The specific thing you are focusing on will probably be in focus, but everything else will look blurry. The depth of field can be so small that one eye in a person's face will be focus, and the other eye won't be.

Steve Thomas

Aoi Usagi wrote:

DarkoR wrote:

Hello,

I have Canon EOS 4000D and EF 50mm 1.8STM.
I noticed that pictures taken with f/1.8 to f/2.8 are out of focus when I'm focusing on focus dots with auto focus.
When I'm focusing with live preview focus is OK at whole range of f.
I found that my camera have 9 AF points (f/5.6 cross type at centre).
Does it means when I'm using f less than f/5.6 I will have issue with auto focus?

If your camera and lens are having trouble achieving precise focus through the viewfinder, but not when in liveview, it could be the camera/lens combo will need some type of micro focus adjustment. This is actually quite common among fast lenses (F1.8, etc). Unfortunately, the 4000D does not have such an adjustment as Canon deemed it as a budget camera. More expensive cameras have this adjustment in the Menu. One option is to call Canon support and tell them. They may ask you to send both the lens and camera to them so they can adjust them accordingly. Of course, you will need to pay a fee.

What you say is correct.

But, it might be just as well to buy a new camera. Something like an EOS 30d or 40d would cost probably about the same as a repair/fix from canon, if such a thing is even possible (the 400d may not be supported by canon any more). A 40d (for example) would have similar specs to the 400d, but it would have AF microadjustment. The only downside (IMO) would be added weight.

There are a lot of folks on the other canon forum who love the 40d.

Try to use just the central AF point.

Post a sample including EXIF

Mind, that depth of field = things in focus, could be around 10cm deep space.
Among others, it depends on the distance; which you didn ‘t mention.

https://www.cambridgeincolour.com/tutorials/dof-calculator.html

http://www.dofmaster.com/dofjs.html

AF point f/5.6 means, if you have less light, for example f/16, it could have focusing problems. 2.8 , even better than 5.6

Btw, not sure what you mean by “less than f/5.6”

Aoi Usagi wrote:

Dunlin wrote:

What you say is correct.

But, it might be just as well to buy a new camera. Something like an EOS 30d or 40d would cost probably about the same as a repair/fix from canon, if such a thing is even possible (the 400d may not be supported by canon any more). A 40d (for example) would have similar specs to the 400d, but it would have AF microadjustment. The only downside (IMO) would be added weight.

There are a lot of folks on the other canon forum who love the 40d.

I don't think the 40D, or any Canon xxD DSLR before that had AFMA. It started with the 50D. It was removed in the 60D and came back with the 70D.

Sorry, my mistake.

Still, a 50d is only about £15 more.

The 4000D also has a higher megapixel count than the 30D, 40D, or 50D.

Megapixels aren't everything.

-

I'm starting to feel like the bad guy who only suggests buying new gear. I'll shut up now.

DarkoR wrote:

In description of camera's specifications, I've found that more expensive cameras like EOS 850D has:
"Via optical viewfinder:
45 cross-type AF points
(45 f/5.6 cross-type AF points, 27 f/8 points (9 cross-type), centre point is f/2.8 and f/5.6 dual cross-type)"

and for EOS 4000D:
"Via optical viewfinder:
9 AF points (f/5.6 cross type at centre)"

As we can see 850D has f/2.8 centre point, and 4000D has only f/5.6.
My question is what is difference between f/2.8 and f/5.6 points?

If an AF point is f/5.6, then it won't work with lenses slower than that aperture, eg. f/8.

On my 7D, the AF centre point is dual-cross type at f/2.8. I think that's what the part about the 850d means.

The 850D uses Dual Pixel AF (in liveview), which allows the camera to focus at f/8 in live view.