Is Depth of Field (DOF) and Auto Focus (AF) points sort of the same thing? I think I’m relying too much on DOF for focus. Was only using center AF point and DOF for focus.
Short answer is no they are not. Your focus points just find the point the camera focuses on. Center point will look in the center and try to focus on what is there. That may not be what you want to focus on, your subject can be located in various spots of the image. Center focus is leaned to because it is the most accurate, but using other points may be better depending on the composition, you can also half press and hold the center point then adjust the composition slightly and complete the press to capture the image. It is not perfect because the subjects new location after completing the press of the shutter is not centered and may have shifted angle / distance just a hair. DOF - now depth of field is a math equation for the amount of the captured image that CAN be in focus. This depends on subject distance to the camera, the fstop used and the focal length of the lens. For example you will find at f16 on a 24mm lens almost every thing appears in focus while a 200mm pointed at a subject like a bird at a distance at f4 is soft by the time it gets to the birds tail. So ... Getting a really good focus is very important to making sure DOF is not an issue for shorts like the bird i mentioned above. I would say can with moving subjects trust focus tracking options and use all the focus points available. When center point can be used it is great as it is a bit more accurate than than others. Dial in a specific point manually if you are shooting a stationary object so you can lock in the part of the image you want most in focus. DOF calculation in short - Wide open is in in inches, Stopped down will give you feet or yards in focus. DOF is 1/3 in front of the focus point and 2/3 behind the plane of focus. So lets say you focus on an eye ball and the DOF math works out to 12 inches of DOF. 4 inches in front of eye and 8 inches behind the eye. That's plenty to not see any obvious softness if its a human, but not if its an elephant.
@johnsey Thanks for the explanation on AF and DOF. Seems my technique puts limits on focus; I will expand to the use of all AF points.
All, vs selecting specific points, vs center point .... each situation has a time and place where it makes sense to use. Examples in my post kinda illustrate when it makes sense to venture outside the center point.
Ohm what type of subject/s are you going to be shooting? if you have a subject in the foreground you are intending to shoot and a busy background you may find the AF full point focus wants to jump onto the background because it is the bigger object, i use single box AF for single subjects unless they are on a plain background ie a bid in the sky then the zone or full point focus is good
CR2 converted to JPG. File Info on the bottom. I just wasn't pleased with this focus, hence the question.
actually here i think focus is less the issue, you have f18 which would have plenty of DOF here. Generally the focus looks pretty accurate on the leaves and flower in center and DOF handles much of the bush pretty well. What concerns me is the f18 may be adding in a softness called diffraction which can be more noticeable on certain lenses over others. Generally the shortcomings of a lens show up as you go to the extreme ends of the aperture. F1.8 vs f22 or whatever your lens does, wide end may have some edge softness and chromatic aberrations, as i mention stopped all the way down you can see some general softening because of diffraction. The sharpest point of a lens is usually around f8 or so somewhere in the middle of the aperture range, this number shifts on different lenses and camera formats which is why i say in the middle. Should you overly worry about this, no, just understand that it can happen and why. Every lens performs a little different and that why some cost 2k for a 1.2 L lens which is pretty darn sharp wide open all around. vs a $500 lens that does perform really well 90% of the situations you use it. Now you did mention cr2 to jpg, and I am noticing for one the lighting is bluish and your underexposed a bit unless you were going for that blue look/ you don't have a lot of contrast range here.... its all middle grey. I also assumed you did not apply any unsharp mask? When you shoot raw the camera does nothing to the image, but with JPG canon will process a bit and add color and sharpen to it in camera. An unsharp mask applied to edges of a raw file image will do wonders for what are in focus edges that don't have the pop they should, be careful to not over do it. I think the issue with this image is lack of post process, i could be wrong. I also would be curious what lens that is at f18 and if it is known to be a hair soft all the way stopped down there. Here is a simple page about the unsharp mask, the numbers vary from my normal preferences, but it gives you an idea what to look at dialing in as well as before and after example. https://lenscraft.co.uk/photo-editing-tutorials/tutorial-photoshop-unsharp-mask/
Just for fun i tossed this file you shared in photos app on windows and gave it some slight pop on the sliders and added a dash of sharpening, it really helped. I never edit in photos /windows but my old mac with lightroom is packed away in the office.
