Looking for information on the relation of the aperture and focus distance

[dearlybeloved]

I understand on how its used but say f2.8 will only have so much in focus but how much in meter/feet is that? how about at f11? f22? I'm not totally sure if your focal length also plays a part in the focal distance and and aperture as well so if someone can either help me understand this or direct me to a source of information that would be great.

It would be nice to find a chart where it went down the apertures and listed the estimated focus distance.


thanks for any information!

 

[Big Mike]

You can get all that information with a DOF calculator.
Online Depth of Field Calculator

 

[KmH]

The relationship of lens aperture to point of focus distance varies by focal length and image sensor size.

The shorter the focal length - the deeper the DoF gets. It is virtually impossible to blur the background with an ultra wide angle lens, regardless the point of focus distance or lens aperture used.

The closer the point of focus - the shallower the DoF gets. Point of focus distance also affects the DoF distribution in front of and behind the point of focus.

The smaller the size of the lens aperture - the deeper the DoF. (f/8 is a smaller lens aperture than f/2 is. Being a fraction, f/8 is also a smaller number than f/2 is.)

The smaller the image sensor is - the deeper the DoF

Understanding Depth of Field in Photography

Another online DoF calculator - Online Depth of Field Calculator

And another - http://www.tawbaware.com/maxlyons/calc.htm

 

[AaronLLockhart]

The smaller the image sensor is - the deeper the DoF

You know, I've learned that to be the case, and have alway heard it; as well as seen it in different dSLR models. How ever, if that is the case, how is the iPhone camera capable of producing such a large amount of bokeh?

Given its tiny sensor size, shouldn't it have a constant deep DoF?

 

[Big Mike]

How ever, if that is the case, how is the iPhone camera capable of producing such a large amount of bokeh?

Even with a tiny sensor, if your focus distance is very short, your DOF will be relatively thin.

 

[2WheelPhoto]

There are some sweet phone apps that address this too

 

[KmH]

The smaller the image sensor is - the deeper the DoF

You know, I've learned that to be the case, and have alway heard it; as well as seen it in different dSLR models. How ever, if that is the case, how is the iPhone camera capable of producing such a large amount of bokeh?

Given its tiny sensor size, shouldn't it have a constant deep DoF?

Bokeh is not adjustable. Bokeh and DoF are not the same thing.

Note that DoF calculators have to told what size image sensor, often by asking what camera is being used, before they can do a DoF calculation.

 

[KmH]

Try and wrap your head around this - if subject scale in the image frame is kept constant by changing the point of focus distance - the total DoF changes little, if any with changes in focal length. The following all use f/4.

25 mm, f/4, 2.5 foot point of focus distance:

50 mm, f/4, 5 foot point of focus distance (double the focal length - double the focus distance to keep subject scale constant in the image frame):

100 mm, f/4, 10 feet:

200 mm, f/4, 20 feet

 

[dearlybeloved]

Thanks a lot, all of this information help! I was wondering because I was using a nikon d800e with a tamron 28-75 2.8 with it at 28mm and at f8 with iso 2000. Im wondering how I ended up with it out of focus at the top. I figured f8 would be have kept everything in focus but im thinking now i should have went down to f11. Would that even be enough or should tighten it up even more?

View attachment 40124

 

[Big Mike]

I figured f8 would be have kept everything in focus but im thinking now i should have went down to f11. Would that even be enough or should tighten it up even more?

Depends how close you were (focus distance).

Do you have a smart phone? You can get a DOF calculator app.

Also, look into Hyperfocal Distance

 

[ph0enix]

how is the iPhone camera capable of producing such a large amount of bokeh?

It's really not. Have you tried blurring the background with an iPhone? It won't happen unless you keep the phone/lens a couple of inches (at most) away from the subject.

 

[Patrice]

Thanks a lot, all of this information help! I was wondering because I was using a nikon d800e with a tamron 28-75 2.8 with it at 28mm and at f8 with iso 2000. Im wondering how I ended up with it out of focus at the top. I figured f8 would be have kept everything in focus but im thinking now i should have went down to f11. Would that even be enough or should tighten it up even more?

I'm pretty sure the D800 has a screen on the back that can be used to review the image you've just taken and a button to zoom into various parts of that image. Could check for sharpness before moving on to the next subject.

Just saying.

 

[dearlybeloved]

Thanks a lot, all of this information help! I was wondering because I was using a nikon d800e with a tamron 28-75 2.8 with it at 28mm and at f8 with iso 2000. Im wondering how I ended up with it out of focus at the top. I figured f8 would be have kept everything in focus but im thinking now i should have went down to f11. Would that even be enough or should tighten it up even more?

I'm pretty sure the D800 has a screen on the back that can be used to review the image you've just taken and a button to zoom into various parts of that image. Could check for sharpness before moving on to the next subject.

Just saying.

I'm well aware of said screen as I was zooming in to focus on the water bed. it's just that human flaw of forgetfulness kicked in and i skipped the check.

 

[dearlybeloved]

I figured f8 would be have kept everything in focus but im thinking now i should have went down to f11. Would that even be enough or should tighten it up even more?

Depends how close you were (focus distance).

Do you have a smart phone? You can get a DOF calculator app.

Also, look into Hyperfocal Distance

Thanks for the information! I just downloaded a DOF calculator and now will be using it from now on. I also dig your signature and the perspective of it.

 

[acjones]

This is a really helpful resource for me:
Cambridge in Colour - Photography Tutorials & Learning Community